JP2020045871A - Internal combustion engine egr device - Google Patents

Abstract

To provide an EGR device capable of accurately cooling EGR gas without requiring a custom-built EGR cooler.SOLUTION: In an EGR device, an in-head main EGR passage 11 is formed inside a cylinder head 2. The in-head main EGR passage 11 is provided with a heat radiation acceleration member 15 having many fins 15a as a cooling section. Also, the in-head main EGR passage 11 is externally surrounded by cooling water jackets 16 and 17. Thus, the EGR device works as if the same has a built-in EGR cooler, thereby enabling EGR gas to be accurately cooled.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an EGR device for recirculating a part of exhaust gas to an intake system in an internal combustion engine.

  2. Description of the Related Art In an internal combustion engine for an automobile or the like, a part of exhaust gas (EGR gas) is recirculated to an intake system in order to improve fuel efficiency and exhaust gas purification performance. In this case, since the EGR gas has a high temperature, a water-cooled type EGR cooler for cooling the EGR gas is provided to improve the filling efficiency (for example, Patent Document 1).

JP 2009-52868 A

  Now, the EGR gas is taken out of the exhaust system and recirculated to the intake system through the EGR passage. As the aspect of the EGR passage, a) when the entirety is constituted by an EGR pipe, b) a part of the EGR pipe It is roughly classified into three modes, that is, a case where the pipe is formed and the other part is formed in the cylinder head, and c) a case where the whole is formed in the cylinder head.

  When part or all of the EGR passage is formed in the cylinder head as in b) and c), the internal combustion engine can be made compact as a whole, and the EGR pipe becomes unnecessary or the amount used can be reduced, so that the cost is reduced. Can be suppressed.

  On the other hand, conventional EGR coolers such as the one disclosed in Patent Document 1 are arranged outside the cylinder head and inserted into the EGR passage regardless of the mode of the EGR passage, and the cooling water pipe is also connected. As a result, the cost of the main body and the cost of the piping are required, which not only increases the cost, but also requires a certain amount of space for arrangement, which has been an obstacle to downsizing the internal combustion engine.

  The present invention has been made to improve such a situation.

The EGR device according to the present invention has the following features.
"A cooler portion having an increased heat dissipation area is formed in at least a part of the EGR passage formed in the cylinder head in order to enhance heat dissipation from the EGR gas to the cylinder head."
It is a configuration.

  In this case, a specific structure of the cooler portion includes a method of incorporating a heat radiation promoting member provided with a surface area increasing means such as a fin in a passage hole provided in the cylinder head, and a method of casting the EGR passage itself by casting or post-processing. There is a method of integrally forming a surface area increasing portion such as the above. Of course, both can be used in combination.

  Further, the cylinder head is provided with a cooling water jacket through which cooling water flows. In the present invention, it is preferable to effectively use this cooling water. That is, it is preferable to promote heat exchange between the cooling water and the EGR gas by bringing a part of the cooling water jacket close to at least a part of the outer periphery of the EGR passage. It is particularly preferred that the EGR passage is surrounded by a cooling water jacket.

  According to the invention of the present application, the cooler portion formed in the cylinder head can improve the heat dissipation of the EGR gas to the cylinder head, so that the conventional independent EGR cooler can be eliminated or the size can be reduced. Becomes possible. This can contribute to cost reduction and downsizing of the internal combustion engine.

  In particular, if a cooling water jacket formed in the cylinder head is used to adopt a structure for cooling the cooler with cooling water flowing through the cooling water jacket, it is ensured that the cooling water can be replaced with a conventional EGR cooler. Cost reduction and compactness can be ensured.

  In addition, when the EGR passage is surrounded by a cooling water jacket, heat can be directly exchanged from the EGR gas to the cooling water in the cooling water jacket. Can contribute. In the case of an internal combustion engine for an automobile, the heat of the cooling water is used for heating the interior of the vehicle. However, it is possible to raise the temperature of the cooling water early to improve the rise of the heating.

It is the side view which looked at the embodiment from the direction orthogonal to a crankshaft. It is the rear view which looked at the embodiment from the crank axis direction. (A) is a sectional view taken along the line IIIA-IIIA of FIG. 2, and (B) and (C) are other examples. It is sectional drawing of other embodiment.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following, front and rear and left and right words are used to specify the direction, but this direction is similar to the usage commonly used for internal combustion engines, and the crank axis direction is the front and rear direction, the crank axis and the cylinder axis. The direction perpendicular to the direction is defined as the left-right direction.

  Further, in the front-back direction, the side on which the timing chain is arranged is the front, and the side on which the mission is arranged is the back. The direction viewed from behind is the rear view direction, and the left-right direction is the side view direction.

(1) First Embodiment First, a first embodiment shown in FIGS. 1 to 3A will be described. As shown in FIG. 1, the internal combustion engine includes a cylinder block 1 and a cylinder head 2 fixed to an upper surface of the cylinder block 1. An exhaust manifold 3 is fixed to an exhaust side surface 2 a of the cylinder head 2. The catalyst case 4 is connected to the collecting part.

  In the present embodiment, a plurality of exhaust outlets corresponding to each cylinder are opened on the exhaust side surface 2a of the cylinder head 2. Therefore, the exhaust manifold 3 also has a plurality of branch pipes 5. It is also possible to incorporate an exhaust gas collecting portion in the head 2 and form a single exhaust outlet on the exhaust side surface 2 a of the cylinder head 2.

  The lower part of the catalyst case 4 is a lower cone portion 4a that is narrowed down, and a straight exhaust port 7 to which an exhaust pipe 6 is connected is provided at the lower end of the lower cone portion 4a. The exhaust port 7 is provided with a bracket 8 for fixing to the cylinder block 1.

  The starting end (lower end) of an EGR pipe 9 that forms a part of the EGR passage is connected to the lower cone portion 4a of the catalyst case 4. The EGR pipe 9 extends laterally from the lower cone portion 4a of the catalyst case 4 and then bends upward. The upper end portion 9a is bent into an L shape, and the upper end portion 9a of the exhaust side surface 2a of the cylinder head 2 is It is fixed to the rear end.

  As shown in FIG. 2, a main in-head EGR passage 11 communicating with the upper end 9 a of the EGR pipe 9 is formed at the rear end of the cylinder head 2 in a posture that is long in the left-right direction. In the present embodiment, the main EGR passage 11 in the head does not penetrate through the intake side surface 2b of the cylinder head 2 and is formed at a depth of about 2/3 or more of the lateral width of the cylinder head 2.

  A head sub main EGR passage 12 opened on the upper surface of the cylinder head 2 communicates with a rear end of the in-head main EGR passage 11, and an EGR valve 13 is connected to the head sub EGR passage 12. The EGR valve 13 can be partially or entirely incorporated in the cylinder head 2 without being exposed above the cylinder head 2.

  Further, as shown by a dashed line in FIG. 2, the head sub EGR passage 12 is opened on the rear surface of the cylinder head 2, and the EGR valve 13 is disposed on the rear surface of the cylinder head 2. As shown, the main EGR passage 11 in the head may be opened to the intake side surface 2b of the cylinder head 2, and the EGR valve 13 may be disposed on the intake side surface 2b of the cylinder head 2. Further, the EGR valve 13 may be provided in a portion (for example, a surge tank) downstream of the cylinder head 2 in the EGR passage.

  As shown in FIG. 3A, substantially the entire length of the main EGR passage 11 in the head has a structure in which the heat radiation promoting member 15 is fitted into the round hole 14 exactly. The heat dissipation promoting member 15 includes a tube fitted into the round hole 14 and a number of fins 15a projecting inward from the inner surface of the tube. The fins 15a extend parallel to the axis of the tube, but may be twisted at a moderate lead angle.

  The main EGR passage 11 in the head is surrounded (sandwiched) from both upper and lower sides by a first water jacket 16 and a second water jacket 17 provided in the cylinder head 2. The first water jacket 16 is formed as a part of a water jacket formed for cooling the cylinder head 2.

  On the other hand, the second water jacket 17 is newly provided to cool the main EGR passage 11 in the head, and the cooling water is taken in from the water jacket 18 of the cylinder block 1. The second water jacket 17 may also be formed as a part of a water jacket formed for cooling the cylinder head 2.

  Although not shown, both the first water jacket 16 and the second water jacket 17 communicate with a cooling water distribution unit provided at the rear end of the cylinder head 2, and the cooling water distribution unit has a radiator feeder. The port, the radiator return port, and the feed port to the water pump are connected. Therefore, the cooling water comes into contact with the main EGR passage 11 in the head while flowing toward the cooling water distribution unit, and heat is exchanged from the EGR gas to the cooling water.

  In the present embodiment, a cooler portion having an increased heat dissipation area is formed in the main EGR passage 11 in the head by the heat dissipation promoting member 15 having a group of fins 15a. It is surrounded by water jackets 16 and 17 from both upper and lower sides. For this reason, heat exchange from the EGR gas to the cooling water is promoted, and a high cooling effect similar to the case where the conventional EGR cooler is incorporated can be obtained.

  Therefore, it is possible to replace the conventional EGR cooler. As a result, the cost of the members can be greatly reduced, the cost required for the piping can be eliminated, and the cost can be significantly reduced, and the internal combustion engine can be downsized. it can. It is preferable that the heat radiation promoting member 15 is made of a material having as high a thermal conductivity as possible while ensuring corrosion resistance.

(2) Other Embodiment In the second embodiment shown in FIG. 3B, an inward fin (rib) 20 is integrally formed in the main EGR passage 11 in the head as an example of the cooler portion. Although only four inward fins 20 are shown, the number, thickness, inward projection size, and the like can be arbitrarily set. The inward fins 20 are preferably formed by casting when casting the cylinder head 2 from the viewpoint of cost, but may be post-processed by broaching or the like.

  In the third embodiment shown in FIG. 3C, an inward thread 21 is formed as an example of the cooler portion. In the figure, the thread 21 is a single thread. However, if the thread 21 is formed as a multiple thread such as a double thread or a triple thread, the lead angle becomes large while the pitch is made as small as possible. There is an advantage that the heat conductivity can be improved while suppressing the heat transfer.

  The thread 21 may also be formed by casting, or may be formed by post-processing (tapping). Further, the shape of the thread 21 is shown as a square, but other shapes such as a triangle and a trapezoid can be adopted.

  In the fourth embodiment shown in FIG. 4, when the in-head main EGR passage 11 is formed in a cylindrical shape by being surrounded by the first and second water jackets 16 and 17, an example of a cooler portion is provided on the outer peripheral surface. , A large number of fins 22 exposed on the water jackets 16 and 17 are formed. This embodiment is also included in the category of the present invention. It is also possible to combine the embodiment of FIG. 4 and each embodiment of FIG. 3, and in this case, the cooling performance of the EGR gas is further improved.

  The embodiments of the present invention have been described above, but the present invention can be variously embodied. For example, when using a heat dissipation promoting member separate from the cylinder head as the cooler portion, as a form of the heat dissipation promoting member, a form in which a number of fins are provided on the outer surface of the central cylinder, or between the inner cylinder and the outer cylinder Various forms such as a form provided with a large number of fins can be adopted.

  The present invention can be actually embodied in an EGR device. Therefore, it can be used industrially.

Reference Signs List 2 Cylinder head 4 Catalyst case 9 EGR pipe 11 Main EGR passage inside head forming cooler section 12 Sub EGR passage inside head 13 EGR valve 14 Round hole forming main EGR passage inside head 15 Heat dissipation promotion forming cooler section Member 15a Fin 16 and 17 Water jacket 20 Inward fin forming cooler 21 Screw thread forming cooler 22 Outward fin forming cooler

Claims (1)

At least a portion of an EGR passage formed in the cylinder head is provided with a cooler portion having an increased heat radiation area to enhance heat radiation from the EGR gas to the cylinder head.
An EGR device for an internal combustion engine.

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