JP2008082307A - Exhaust gas recirculating device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas recirculating device for an engine capable of efficiently cooling recirculated exhaust gas (EGR gas) and simplifying piping structure. <P>SOLUTION: The exhaust gas recirculating device for an engine of the invention comprises exhaust gas recirculation passages 40, 42 for taking out a part of the exhaust gas from an exhaust system of the engine 1 with a plurality of cylinders 6 arranged in a row, cooling and recirculating it to the intake system, wherein main part of the exhaust gas recirculation passages 40, 42 are positioned close to a water jacket 8 formed within a cylinder block 2 of the engine 1 and are constituted of inner passages 32, 44 formed within the cylinder block 2 along the cylinder row of the engine 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exhaust gas recirculation device for an engine, and in particular, an exhaust gas of an engine provided with a recirculation path for extracting and cooling a part of the exhaust gas from an exhaust system of the engine in which a plurality of cylinders are arranged in a row and returning to the intake system. It relates to a reflux apparatus.

  Conventionally, an engine exhaust gas recirculation device (EGR system) that slows combustion by recirculating (recirculating) a part of exhaust gas to the intake system in order to suppress the generation and emission of nitrogen oxides in the engine has been provided. It has been. Further, it is also known that recirculated exhaust gas (recirculation exhaust, EGR gas) is cooled by a cooling device (EGR cooler) provided in the middle of the exhaust recirculation path in order not to reduce the intake efficiency.

  As a conventional example of such an exhaust gas recirculation device for an engine, for example, one described in Patent Document 1 is known. The device described in Patent Document 1 is an EGR cooler that cools EGR gas and is attached to a cylinder block so as to form a water jacket side wall, thereby exchanging heat with engine cooling water flowing through the water jacket. Since the EGR gas can be cooled, the cooling effect is increased, and the EGR cooler serves as a reinforcing member for the cylinder block, which reduces the vibration of the cylinder block side wall and reduces the vibration input to the engine mount attached to the cylinder block. Engine noise is reduced.

Japanese Patent Laid-Open No. 7-42628

However, in the above-described apparatus, although the cooling effect of the EGR gas is increased, the EGR cooler is attached to the cylinder block so as to form the water jacket side wall, so that the attachment structure and the piping structure become complicated, which is not preferable.
Therefore, there is a demand for an exhaust gas recirculation device for an engine that increases the cooling effect of EGR gas and has a simple mounting structure and piping structure.

  Therefore, the present invention has been made in order to satisfy conventional demands, and provides an exhaust gas recirculation device for an engine capable of efficiently cooling recirculated exhaust gas (EGR gas) and simplifying a piping structure. The purpose is that.

In order to achieve the above object, the present invention provides an engine exhaust system having an exhaust gas recirculation path that takes out a portion of exhaust gas from an engine exhaust system in which a plurality of cylinders are arranged in a row and cools it to return it to the intake system. In the recirculation device, a main part of the exhaust recirculation path is configured by an internal passage formed in the cylinder block along the cylinder row of the engine, close to a water jacket formed in the cylinder block of the engine. It is characterized by having.
In the present invention configured as above, the main part of the exhaust gas recirculation path is formed in the cylinder block close to the water jacket formed in the cylinder block of the engine and along the cylinder row of the engine. Since it is constituted by the internal passage, the recirculated exhaust gas from the exhaust system is effectively cooled by the engine coolant in the water jacket, so that the cooling efficiency of the recirculated exhaust gas is increased. Next, since the main part of the exhaust gas recirculation path is formed in the cylinder block as an internal path, the piping system can be simplified correspondingly.

In the present invention, the internal passage is preferably formed in the vicinity of the bottom surface of the water jacket.
In the present invention configured as described above, since the internal passage is formed in the vicinity of the bottom surface of the water jacket, it is not necessary to increase the width of the cylinder block to secure the space for disposing the internal passage. The recirculated exhaust is effectively cooled by the engine coolant in the water jacket, and the cooling efficiency of the recirculated exhaust is increased.

In the present invention, preferably, a part of the internal passage is formed along the cylinder row between the oil gallery formed along the cylinder row direction and the water jacket.
In the present invention configured as above, the oil in the oil character can be used for cooling the recirculated exhaust in addition to the engine cooling water in the water jacket, so that the recirculated exhaust can be effectively and efficiently cooled. Can do.

In the present invention, the internal passage preferably includes an exhaust introduction hole that opens to an exhaust side surface of the cylinder block and an exhaust lead-out hole that opens to an intake side surface of the cylinder block, and the exhaust recirculation path includes an exhaust system and an exhaust introduction hole. And an intake pipe for connecting the intake system and the exhaust outlet hole.
According to the present invention configured as described above, the piping structure for configuring the exhaust gas recirculation path can be simplified.

In the present invention, the internal passage is preferably formed in an annular shape so as to surround the cylinder row, and an exhaust introduction hole and an exhaust lead-out hole are formed on a side surface of the cylinder block.
Here, conventionally, since the upper part of the cylinder block (near the combustion chamber) is relatively hot and the lower part of the cylinder block (below the water jacket) is relatively cold, there is a temperature difference in the vertical direction of the cylinder part of the cylinder block. The cylinder (cylinder bore) may be thermally deformed due to this temperature difference. However, in the present invention configured as described above, since the lower part of the cylinder block is formed in an annular shape so as to surround the cylinder row by the internal passage, the engine cooling water in the water jacket is recirculated and exhausted from the internal passage. As a result, the temperature becomes higher than in the prior art, and the temperature difference in the vertical direction is reduced correspondingly, whereby thermal deformation of the cylinder (cylinder bore) can be reduced.

  According to the exhaust gas recirculation device for an engine of the present invention, the recirculated exhaust gas (EGR gas) can be efficiently cooled and the piping structure can be simplified.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings. First, a first embodiment of an exhaust gas recirculation device for an engine according to the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a sectional view showing an exhaust gas recirculation apparatus for an engine according to a first embodiment of the present invention, and FIG. 2 is a plan sectional view taken along the line II-II in FIG.

  As shown in FIG. 1, reference numeral 1 denotes an automobile engine. The engine 1 includes a cylinder block 2 and a cylinder head 4. A plurality of cylinders (cylinder bores) 6 are formed in the cylinder block 2 in a line. In the present embodiment, the engine 1 has four cylinders. In the cylinder block 2, a water jacket 8 through which engine coolant for cooling the cylinder block 2 itself flows is formed along the cylinder row. Below the water jacket 8 in the cylinder block 2, an oil gallery 10 through which oil flows to cool the bearings and the like is formed along the cylinder rows.

The cylinder head 4 is formed with an intake port 12 and an exhaust port 14, and these are provided with an intake valve 16 and an exhaust valve 18, respectively. A combustion chamber 19 is formed on the bottom surface of the cylinder head 4. Further, an intake manifold 20 and an exhaust manifold 22 are connected to the intake port 12 and the exhaust port 14, respectively.
Next, a catalyst device 24 is provided integrally with the exhaust manifold in a part of the exhaust manifold 22. An exhaust pipe 26 is connected to the downstream end of the exhaust manifold 22, and an extraction pipe 28 that branches from a part of the exhaust pipe 26 and takes out recirculated exhaust gas (EGR gas) is attached to the exhaust pipe 26.

  As shown in FIG. 2, the downstream end of the extraction pipe 28 is connected to an exhaust introduction hole 30 formed on the side surface on the exhaust side of the cylinder block 2.

Here, an internal passage (EGR passage) 32 is formed in the cylinder block 2. As shown in FIG. 1, the internal passage 32 is formed in the vicinity of the water jacket 8, specifically, in the vicinity of the bottom surface 8 a of the water jacket 8 along the cylinder row. More specifically, the internal passage 32 is formed along the cylinder row between the water jacket 8 and the oil gallery 10.
Further, as shown in FIG. 2, the internal passage 32 branches into two internal passages 32a and 32b in the cylinder block 2, and one internal passage 32a is formed on the exhaust side of the silidan block 2, The other internal passage 32 b is formed on the intake side of the cylinder block 2, and is formed so as to surround the columnar cylinders 6.

An exhaust outlet hole 34 is formed on the side surface of the cylinder block 2 on the intake side, and an EGR valve 36 is attached to the exhaust outlet hole 34. An introduction pipe 38 is connected to the EGR valve 36, and the intake manifold 20 described above is connected to the introduction pipe 38.
In this manner, the exhaust pipe 28, the exhaust introduction hole 30, the internal passage 32, the exhaust lead-out hole 34, the EGR valve 36, and the introduction pipe 38 form the exhaust recirculation passage 40, and the main part thereof is the internal passage 32. Is formed inside the cylinder block 2.

  Next, operations and effects in the above-described first embodiment of the present invention will be described. First, the recirculated exhaust gas that has flowed from the exhaust manifold 22 to the exhaust pipe 26 passes through the extraction pipe 28, the exhaust introduction hole 30, the internal passage 32, the exhaust outlet hole 34, the EGR valve 36, and the introduction pipe 38 to the intake manifold 20. Reflux. At this time, when the recirculated exhaust gas passes through the internal passage 32, it is effectively cooled by the engine cooling water in the water jacket 8 in the vicinity of the internal passage 32, so that the cooling efficiency of the recirculated exhaust gas increases.

  Next, in this embodiment, since the main part of the exhaust gas recirculation path 40 is formed in the cylinder block as the internal path 32, it is not necessary to provide an independent cooling device, and the piping system is simplified accordingly. can do.

  Next, since the internal passage 32 is formed in the vicinity of the bottom surface of the water jacket 8, there is no need to increase the width of the cylinder block 2 to secure the space for disposing the internal passage, and the recirculated exhaust from the exhaust system can be recirculated. It is cooled effectively by the engine cooling water in the jacket, and the cooling efficiency of the recirculation waste increases.

  Further, in the present embodiment, a part of the internal passage 32 is formed along the cylinder row between the oil gallery 10 and the water jacket 8 formed along the cylinder row direction. In addition to the engine cooling water in the engine, the oil in the oil gallery 10 can also be used for cooling the recirculated exhaust gas, so that the recirculated exhaust gas can be effectively and efficiently cooled.

  Further, in the present embodiment, the internal passage 32 includes an exhaust introduction hole 30 that opens to the exhaust side surface of the cylinder block 2 and an exhaust lead-out hole 34 that opens to the intake side surface of the cylinder block 2. Since the exhaust pipe 26 and the exhaust introduction hole 30 are connected to each other, and the exhaust pipe 26 is connected to the intake manifold 20 via the EGR valve 36, the exhaust recirculation path 40 is configured. It is possible to simplify the piping structure for doing so.

  Here, conventionally, since the upper part of the cylinder block (near the combustion chamber) is relatively hot and the lower part of the cylinder block (below the water jacket) is relatively cold, there is a temperature difference in the vertical direction of the cylinder part of the cylinder block. The cylinder (cylinder bore) may be thermally deformed due to this temperature difference. However, in the present embodiment, since the lower part of the cylinder block 2 is formed in an annular shape so as to surround the cylinder row by the internal passage 32, the engine coolant in the water jacket 8 is recirculated with the recirculated exhaust gas in the internal passage 32. The heat is exchanged, and the temperature becomes higher than that of the conventional one, and accordingly, the temperature difference in the vertical direction is reduced, thereby reducing the thermal deformation of the cylinder 6 (cylinder bore).

  Next, an exhaust gas recirculation device for an engine according to a second embodiment of the present invention will be described with reference to FIGS. 3 is a plan view showing a cylinder block of an exhaust gas recirculation apparatus for an engine according to a second embodiment of the present invention, and FIG. 4 is a cross-sectional view of the cylinder block shown in FIG. In this 2nd Embodiment, the same code | symbol is attached | subjected to the same part as 1st Embodiment, and those description is abbreviate | omitted.

Also in the second embodiment of the present invention, the exhaust gas recirculation path 42 is constituted by the extraction pipe 28, the exhaust introduction hole 30, the internal passage 44, the exhaust outlet hole 34, the EGR valve 36, and the introduction pipe 38. The internal passage 44 is formed only on the intake side of the cylinder row of the cylinder block 2.
According to the second embodiment, since the internal passage 44 is formed only on the intake side of the cylinder row of the cylinder block 2, the shape of the internal passage 44 is simplified, and the machining process is simplified correspondingly.

1 is a cross-sectional view showing an exhaust gas recirculation device for an engine according to a first embodiment of the present invention. It is the plane sectional view seen along the II-II line of FIG. It is a top view which shows the cylinder block of the exhaust gas recirculation apparatus of the engine by 2nd Embodiment of this invention. It is sectional drawing of the cylinder block shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder block 4 Cylinder head 6 Cylinder 8 Water jacket 10 Oil gallery 20 Intake manifold 22 Exhaust manifold 26 Exhaust pipe 28 Extraction pipe 30 Exhaust inlet hole 32, 44 Internal passage 34 Exhaust outlet hole 36 EGR valve 38 Outlet hole 40, 42 Exhaust gas recirculation path

Claims (5)

An exhaust gas recirculation device for an engine having an exhaust gas recirculation path that takes out a part of the exhaust gas from an exhaust system of the engine in which a plurality of cylinders are arranged in a row and cools it back to the intake system,
The main part of the exhaust gas recirculation path is constituted by an internal passage formed in the cylinder block along the cylinder row of the engine, close to a water jacket formed in the cylinder block of the engine. The engine exhaust gas recirculation system.   2. The exhaust gas recirculation device for an engine according to claim 1, wherein the internal passage is formed in the vicinity of the bottom surface of the water jacket.   3. The exhaust gas recirculation device for an engine according to claim 1, wherein a part of the internal passage is formed along the cylinder row between an oil gallery formed along the cylinder row direction and the water jacket. .   The internal passage includes an exhaust introduction hole that opens to an exhaust side surface of the cylinder block and an exhaust lead-out hole that opens to an intake side surface of the cylinder block, and the exhaust recirculation path is an extraction pipe that connects the exhaust system and the exhaust introduction hole The exhaust gas recirculation device for an engine according to any one of claims 1 to 3, further comprising an introduction pipe connecting the intake system and the exhaust outlet hole.   5. The exhaust gas recirculation device for an engine according to claim 4, wherein the internal passage is formed in an annular shape so as to surround the cylinder row, and the exhaust introduction hole and the exhaust discharge hole are formed on a side surface of the cylinder block.

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