JP6503274B2 - Exhaust gas recirculation system for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust gas recirculation system for an internal combustion engine.

  As a conventional exhaust gas recirculation system for an internal combustion engine, for example, a system described in Patent Document 1 is known. The exhaust gas recirculation device described in Patent Document 1 includes two EGR passages respectively connected to two exhaust manifolds connected to left and right banks, two EGR valves respectively provided to each EGR passage, and each EGR A junction EGR passage for connecting the passage and the intake pipe, and an EGR cooler provided in the junction EGR passage for cooling the gas flowing through the junction EGR passage are provided.

Unexamined-Japanese-Patent No. 2006-57593

  However, the following problems exist in the above-mentioned prior art. That is, when fuel is added from the injector in a state where the EGR valve is open, the fuel flows into the EGR passage. At this time, unburned gas (for example, HC) in the fuel may flow into the EGR cooler, and the unburned gas may be deposited on the EGR cooler as a deposit. In addition, when the angle formed by the two EGR passages at the connection portion (junction portion) of the two EGR passages is large, the pressure loss at the junction portion becomes large, and the flow rate of the EGR gas supplied to the intake pipe becomes insufficient. .

  An object of the present invention is to provide an exhaust gas recirculation system for an internal combustion engine that can reduce unburned gas flowing into a cooler and reduce pressure loss at a junction of an exhaust gas recirculation passage.

  One aspect of the present invention includes a first cylinder group and a second cylinder group, an intake manifold connected to the first cylinder group and the second cylinder group, a first exhaust manifold connected to the first cylinder group, An exhaust gas recirculation apparatus for an internal combustion engine, comprising: a second exhaust manifold connected to a two-cylinder group; and a fuel addition valve for adding fuel to exhaust gas in the second exhaust manifold, the first exhaust manifold and the second exhaust An exhaust gas recirculation passage which connects the manifold and the intake manifold and guides exhaust gas in the first exhaust manifold and the second exhaust manifold to the intake manifold as exhaust gas recirculation gas; and an exhaust gas recirculation passage. A cooler for cooling the exhaust gas recirculation flowing through the exhaust gas recirculation passage, the exhaust gas recirculation passage comprising a first individual passage connected to the first exhaust manifold, and a second exhaust manifold And a junction passage connecting the connection portion between the first individual passage and the second individual passage and the cooler, wherein the second individual passage includes a main passage portion and a main passage portion. And a throttle passage portion having a diameter smaller than that of the portion, and an angle formed by the first individual passage and the second individual passage at the connection portion between the first individual passage and the second individual passage is 90 degrees or less. I assume.

  In such an exhaust gas recirculation device, the second individual passage has a throttle passage portion smaller in diameter than the main passage portion, so that even if the fuel added from the fuel addition valve gets around in the second individual passage, the fuel It becomes difficult for the unburned gas inside to flow into the merging passage by the throttle passage portion. Thereby, the unburned gas flowing into the cooler is reduced. Further, by setting the angle between the first individual passage and the second individual passage to be 90 degrees or less at the connection portion between the first individual passage and the second individual passage, the exhaust gas recirculation gas flowing through the first individual passage and the second The collision with the exhaust gas recirculation gas flowing through the individual passages is alleviated. This reduces the pressure loss at the junction of the exhaust gas recirculation passage.

  The first individual passage and the merging passage may be constituted by a first pipe, and the second individual passage may be constituted by a second pipe welded to the first pipe. In this case, the connection portion between the first individual passage and the second individual passage can be easily configured.

  The throttle passage portion may be provided at an end of the second pipe on the side of connection with the first pipe. In this case, since the throttle passage portion having a diameter smaller than that of the main passage portion is welded to the first pipe, welding of the first pipe and the second pipe can be easily performed.

  According to the present invention, an exhaust gas recirculation apparatus for an internal combustion engine is provided which can reduce unburned gas flowing into a cooler and reduce pressure loss at the junction of the exhaust gas recirculation passage.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows a diesel engine as an internal combustion engine provided with the exhaust gas recirculation apparatus which concerns on one Embodiment of this invention. It is an enlarged view which shows the part containing the confluence | merging part of the EGR passage in the EGR apparatus shown by FIG. As a comparative example, it is an enlarged view which shows the part containing the confluence | merging part of the EGR passage in the conventional EGR apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements will be denoted by the same reference symbols, without redundant description.

  FIG. 1 is a schematic configuration view showing a diesel engine as an internal combustion engine provided with an exhaust gas recirculation device according to an embodiment of the present invention. In the figure, a diesel engine (hereinafter simply referred to as an engine) 1 according to the present embodiment is a V-type 8-cylinder diesel engine.

  The engine 1 is arranged in one direction with a right bank 3A (first cylinder group) consisting of four cylinders 2A (in order # 1, # 3, # 5 and # 7 cylinders) arranged in one direction. The left bank 3B (second cylinder group) including four cylinders 2B (in order # 2, # 4, # 6 and # 8 cylinders) is provided. Although not shown, injectors for injecting fuel into the combustion chamber are respectively disposed in the cylinders 2A and 2B.

  The explosion order of each cylinder 2A is # 1 cylinder → # 7 cylinder → # 3 cylinder → # 5 cylinder. The order of explosion of each cylinder 2B is # 2 cylinder → # 4 cylinder → # 6 cylinder → # 8 cylinder. The order of explosion for each of the cylinders 2A and 2B is # 1 → # 2 → # 7 → # 3 → # 4 → # 5 → # 6 → # 8.

  The engine 1 also includes an intake manifold 4 connected to one side (a side opposite to each other) of the right bank 3A and the left bank 3B. The intake manifold 4 is connected to an intake passage (not shown) for drawing air into the combustion chamber of each of the cylinders 2A and 2B.

  The engine 1 also includes an exhaust manifold 5A (first exhaust manifold) connected to the other side of the right bank 3A, an exhaust manifold 5B (second exhaust manifold) connected to the other side of the left bank 3B, and an exhaust manifold 5A connected to the exhaust passage 6 for exhausting the exhaust gas generated in the combustion chamber of each cylinder 2A and the exhaust manifold 5B, the exhaust gas generated in the combustion chamber of each cylinder 2B is burned in each cylinder 2A And an exhaust passage 7 for exhausting together with the exhaust gas generated indoors.

  One end of the exhaust passage 6 is connected to the end of the # 7 cylinder located at one end of the cylinders 2A in the exhaust manifold 5A, and the other end of the exhaust passage 6 is connected to each cylinder 2B in the exhaust manifold 5B. It is connected to the end of the # 8 cylinder located at one end of the above. One end of the exhaust passage 7 is connected to an end of the exhaust manifold 5B on the side of the # 8 cylinder so as to be in communication with the exhaust passage 6.

  The exhaust passage 7 is provided with a turbine of a turbocharger 8. The compressor of the turbocharger 8 is disposed in an intake passage (not described) (not shown).

  The engine 1 also includes a fuel addition valve 9 for adding fuel to the exhaust gas in the exhaust manifold 5B. The fuel addition valve 9 is disposed at a portion corresponding to # 8 cylinder among the cylinders 2B. That is, the fuel addition valve 9 is disposed at a portion of the exhaust manifold 5B connected to the exhaust passages 6 and 7. The fuel addition valve 9 is controlled to add fuel when the # 8 cylinder is exhausted after the # 8 cylinder has exploded.

  Furthermore, the engine 1 is provided with an EGR device 10 which is an exhaust gas recirculation device of the present embodiment. The EGR device 10 connects the exhaust manifolds 5A and 5B and the intake manifold 4, and guides the exhaust gas in the exhaust manifolds 5A and 5B to the intake manifold 4 as EGR gas (exhaust gas recirculation gas) A recirculation passage) and an EGR cooler 12 (cooler) disposed in the EGR passage 11 for cooling the EGR gas flowing through the EGR passage 11 are provided.

  The EGR passage 11 includes an individual passage 13A (first individual passage) connected to the exhaust manifold 5A, an individual passage 13B (second individual passage) connected to the exhaust manifold 5B, and an individual passage 13A and an individual passage 13B. A junction passage 14 connecting the connection portion M and the EGR cooler 12 is provided. A connection portion M between the individual passage 13A and the individual passage 13B is a junction portion in the EGR passage 11 where the EGR gas flowing through the individual passage 13A and the EGR gas flowing through the individual passage 13B merge. Although not shown, EGR valves are respectively disposed in the individual passages 13A and 13B.

  The individual passage 13A is connected to a connection portion between the exhaust manifold 5A and the exhaust passage 6. That is, the individual passage 13A is connected in the vicinity of a portion corresponding to the # 7 cylinder among the cylinders 2A in the exhaust manifold 5A. The individual passage 13B is connected to a portion corresponding to the # 4 cylinder among the cylinders 2B in the exhaust manifold 5B. That is, the individual passage 13B is connected to a portion apart from the connection portion with the exhaust passage 7 in the exhaust manifold 5B.

  FIG. 2 is an enlarged view showing a portion including the junction portion of the EGR passage 11 in the EGR device 10. In FIG. 2, the individual passages 13 </ b> A and the merging passage 14 are configured in common by a cylindrical pipe 15 (first pipe). The individual passage 13 </ b> B is configured by a cylindrical pipe 16 (second pipe) welded to the pipe 15. The material of the pipes 15 and 16 is, for example, stainless steel or the like.

  The individual passage 13B has a main passage portion 17 and a throttle passage portion 18 whose diameter is smaller than that of the main passage portion 17. The throttle passage portion 18 is provided at the end of the individual passage 13B on the side of connection with the individual passage 13A. That is, the throttle passage 18 is provided at the end of the pipe 16 on the side connected to the pipe 15. The diameter of the throttle passage 18 is set to be small so as not to impede the flow of the EGR gas. The diameter of the throttle passage 18 is, for example, 1/2 or more of the diameter of the main passage 17 and 2/3 or less of the diameter of the main passage 17. The diameter of the main passage portion 17 is equal to the diameter of the individual passage 13A. The diameter of the main passage portion 17 is smaller than the diameter of the merging passage 14.

  The pipe 15 constituting the individual passage 13A and the merging passage 14 has a curved portion 15a. The pipe 16 constituting the individual passage 13 B having the main passage portion 17 and the throttle passage portion 18 is welded to the curved outer portion of the curved portion 15 a of the pipe 15. For example, after the pipes 15 and 16 are formed by molding, a hole is opened in the curved outer portion of the curved portion 15a of the pipe 15, and the end of the pipe 16 on the side of the throttle passage 18 is formed at the edge of the hole of the pipe 15. Weld.

  As a result, a connection portion M between the individual passage 13A and the individual passage 13B (a merging portion of the EGR passage 11) is formed. At this time, an angle formed by the individual passage 13A and the individual passage 13B (merging angle of the individual passages 13A and 13B) α at the connection portion M between the individual passage 13A and the individual passage 13B is 90 degrees or less.

  FIG. 3 is an enlarged view showing a portion including a junction of an EGR passage in a conventional EGR device as a comparative example. In FIG. 3, the EGR passage 50 has individual passages 51A, 51B and a joining passage 52 in place of the individual passages 13A, 13B and the joining passage 14 described above.

  Unlike the individual passage 13B described above, the individual passage 51B does not have a throttle passage portion. Further, at a connection portion M between the individual passage 51A and the individual passage 51B, an angle (merging angle of the individual passages 51A and 51B) α between the individual passage 51A and the individual passage 51B is 120 degrees.

  By the way, as described above, fuel is added from the fuel addition valve 9 when the # 8 cylinder is exhausted after the # 8 cylinder has exploded. Then, after the # 8 cylinder explodes, the # 2 cylinder explodes. The individual passage 51B is connected to a portion of each of the cylinders 2B in the exhaust manifold 5B that corresponds to the # 4 cylinder. For this reason, the fuel added from the fuel addition valve 9 flows into the individual passage 51B before being pushed back to the exhaust passage 7 side by the exhaust gas discharged from the # 2 cylinder. In this case, as shown in FIG. 3, unburned gas (for example, HC) in the fuel flows into the EGR cooler 12 through the individual passage 51B and the merging passage 52, and the unburned gas is used as a deposit for the EGR cooler 12 May deposit on

  Further, since the merging angle α of the individual passages 51A and 51B is wide by 120 degrees, the EGR gas flowing through the individual passage 51A and the EGR gas flowing through the individual passage 51B easily collide with each other. Loss increases. As a result, it becomes difficult for the EGR gas to flow through the merging passage 52, so the flow rate of the EGR gas supplied to the intake manifold 4 decreases.

  On the other hand, in the present embodiment, since the individual passage 13B has the throttle passage portion 18 having a diameter smaller than that of the main passage portion 17, even if the fuel added from the fuel addition valve 9 gets around in the individual passage 13B, Unburned gas in the fuel is less likely to flow to the merging passage 14 by the throttle passage portion 18. Thereby, the unburned gas flowing into the EGR cooler 12 is reduced. As a result, it is possible to prevent unburned gas from being deposited on the EGR cooler 12 as a deposit.

  Further, since the merging angle α of the individual passages 13A and 13B is 90 degrees or less, the collision between the EGR gas flowing in the individual passage 13A and the EGR gas flowing in the individual passage 13B is alleviated. Thus, the pressure loss at the junction of the EGR passage 11 is reduced. As a result, the EGR gas easily flows through the merging passage 14, so the flow rate of the EGR gas supplied to the intake manifold 4 increases.

  Further, the individual passage 13A and the merging passage 14 are constituted by the pipe 15, and the individual passage 13B is constituted by the pipe 16 welded to the pipe 15. Thereby, the connection part M of 13 A of individual passages and the individual passage 13B can be comprised easily.

  Further, the throttle passage portion 18 is provided at the end of the pipe 16 on the side connected to the pipe 15. As a result, since the throttle passage portion 18 having a diameter smaller than that of the main passage portion 17 is welded to the pipe 15, welding between the pipe 15 and the pipe 16 can be easily performed.

  Furthermore, even if an expensive device such as a flow control valve is not added, the unburned gas flowing into the EGR cooler 12 is reduced only by changing the shape of the individual passage 13B so as to provide the throttle passage 18 in the individual passage 13B. can do.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the throttle passage portion 18 is provided at the end of the individual passage 13B on the connection side with the individual passage 13A, but the invention is not particularly limited thereto. The throttle passage portion 18 may be located between the two main passage portions 17 by providing the throttle passage portion 18.

  Further, in the above embodiment, the individual passage 13A and the merging passage 14 are constituted by the pipe 15, and the individual passage 13B is constituted by the pipe 16. However, the invention is not particularly limited thereto. For example, the individual passages 13A and 13B and the merging The passages 14 may be configured by different pipes.

  In addition, although the EGR device 10 of the above embodiment is provided in a V-type 8-cylinder diesel engine, the present invention is not particularly limited thereto, and is also applicable to, for example, a V-type 6-cylinder diesel engine. The present invention is also applicable to an internal combustion engine such as a gasoline engine.

  Reference Signs List 1 diesel engine (internal combustion engine) 3A right bank (first cylinder group) 3B left bank (second cylinder group) 4 intake manifold 5A exhaust manifold (first exhaust manifold) 5B exhaust Manifold (second exhaust manifold), 9: fuel addition valve, 10: EGR device (exhaust gas recirculation device), 11: EGR passage (exhaust gas recirculation passage), 12: EGR cooler (cooler), 13A: individual passage (No. 1 individual passage), 13B individual passage (second individual passage) 14 joint passage 15 piping (first piping) 16 piping (second piping) 17 main passage portion 18 throttle passage portion , M ... connection part.

Claims (3)

A first cylinder group and a second cylinder group, an intake manifold connected to the first cylinder group and the second cylinder group, a first exhaust manifold connected to the first cylinder group, and a second cylinder group An exhaust gas recirculation apparatus for an internal combustion engine, comprising: a second exhaust manifold connected to the first exhaust manifold; and a fuel addition valve for adding fuel to exhaust gas in the second exhaust manifold,
An exhaust for connecting the first exhaust manifold, the second exhaust manifold, and the intake manifold, and guiding the exhaust gas in the first exhaust manifold and the second exhaust manifold as the exhaust gas recirculation gas to the intake manifold Recirculation passage,
A cooler disposed in the exhaust gas recirculation passage for cooling the exhaust gas recirculation gas flowing through the exhaust gas recirculation passage;
The exhaust gas recirculation passage includes a first individual passage connected to the first exhaust manifold, a second individual passage connected to the second exhaust manifold, and the first individual passage and the second individual passage. And a junction passage connecting the connection portion and the cooler,
The second individual passage has a main passage portion and a throttle passage portion smaller in diameter than the main passage portion,
An exhaust gas recirculation system for an internal combustion engine, wherein an angle between the first individual passage and the second individual passage is 90 degrees or less at a connection portion between the first individual passage and the second individual passage. The first individual passage and the merging passage are constituted by a first pipe,
The exhaust gas recirculation system for an internal combustion engine according to claim 1, wherein the second individual passage is constituted by a second pipe welded to the first pipe.   The exhaust gas recirculation device for an internal combustion engine according to claim 2, wherein the throttle passage portion is provided at an end of the second pipe on a side connected to the first pipe.

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