JP2017066888A - Exhaust gas recirculation device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation device for an internal combustion engine that can reduce unburned gas flowing into a cooler and pressure loss at a merging portion of an exhaust gas recirculation passage.SOLUTION: An EGR device 10 includes: an EGR passage 11 for connecting two exhaust manifolds with an intake manifold: and an EGR cooler 12 disposed in the EGR passage 11 to cool EGR gas flowing in the EGR passage 11. The EGR passage 11 includes: an individual passage 13A connected to one exhaust manifold; an individual passage 13B connected to the other exhaust manifold; and a merging passage 14 for connecting a connection portion M between the individual passage 13A and the individual passage 13B with the EGR cooler 12. The individual passage 13B includes: a main passage section 17; and a narrowed passage section 18 having a diameter smaller than that of the main passage section 17. At the connection portion M between the individual passage 13A and the individual passage 13B, an angle α between the individual passage 13A and the individual passage 13B is 90 degrees or less.SELECTED DRAWING: Figure 2

Description

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

  As a conventional exhaust gas recirculation device for an internal combustion engine, for example, a device 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 provided in each EGR passage, and each EGR passage. A merging EGR passage that connects the passage and the intake pipe, and an EGR cooler that is provided in the merging EGR passage and cools the gas flowing through the merging EGR passage.

JP 2006-57593 A

  However, the following problems exist in the prior art. That is, if fuel is added from the injector while the EGR valve is open, the fuel goes around 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. Further, if the angle formed by the two EGR passages is large at the connection portion (junction portion) between the two EGR passages, the pressure loss of the confluence portion increases, 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 device for an internal combustion engine that can reduce the unburned gas flowing into the cooler and reduce the pressure loss at the junction of the 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, In an exhaust gas recirculation device for an internal combustion engine, comprising a second exhaust manifold connected to a group of two cylinders 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 for connecting the manifold and the intake manifold to guide 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 gas flowing through the exhaust gas recirculation passage, the exhaust gas recirculation passage being connected to the first exhaust manifold, and the second exhaust manifold. A second individual passage connected to the relay, a junction between the first individual passage and the second individual passage and a cooler, and the second individual passage includes a main passage portion, a main passage, And a throttle passage portion having a smaller diameter than the portion, and an angle formed by 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. And

  In such an exhaust gas recirculation device, the second individual passage has a throttle passage portion whose diameter is smaller than that of the main passage portion, so that even if the fuel added from the fuel addition valve goes around the second individual passage, the fuel The unburned gas inside is less likely to flow into the merging passage by the throttle passage portion. Thereby, the unburned gas which flows into a cooler is reduced. Further, the angle formed by the first individual passage and the second individual passage at the connecting portion between the first individual passage and the second individual passage is 90 degrees or less, so that the exhaust gas recirculation gas flowing through the first individual passage and the second Collisions with the exhaust gas recirculation flowing through the individual passages are alleviated. Thereby, the pressure loss of the confluence | merging part of an exhaust gas recirculation passage is reduced.

  The first individual passage and the merging passage may be configured by a first pipe, and the second individual path may be configured 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 connection side with the first pipe. In this case, since the throttle passage portion having a smaller diameter than the main passage portion is welded to the first pipe, the first pipe and the second pipe can be easily welded.

  According to the present invention, there is provided an exhaust gas recirculation device 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.

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 channel | path 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 channel | path 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 are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic configuration diagram showing a diesel engine as an internal combustion engine including 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 this 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) composed of four cylinders 2A arranged in one direction (in order, # 1, cylinder # 3, # 5 and # 7). And a left bank 3B (second cylinder group) comprising four cylinders 2B (# 2 cylinder, # 4 cylinder, # 6 cylinder and # 8 cylinder in order). Although not shown, each cylinder 2A, 2B is provided with an injector for injecting fuel into the combustion chamber.

  The explosion order of each cylinder 2A is # 1 cylinder → # 7 cylinder → # 3 cylinder → # 5 cylinder. The explosion order of each cylinder 2B is # 2 cylinder → # 4 cylinder → # 6 cylinder → # 8 cylinder. The explosion order of each cylinder 2A, 2B as a whole is # 1 cylinder → # 2 cylinder → # 7 cylinder → # 3 cylinder → # 4 cylinder → # 5 cylinder → # 6 cylinder → # 8 cylinder.

  Further, the engine 1 includes an intake manifold 4 connected to one side (side facing each other) of the right bank 3A and the left bank 3B. An intake passage (not shown) for sucking air into the combustion chambers of the cylinders 2A and 2B is connected to the intake manifold 4.

  The engine 1 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. Connected to 5A, exhaust passage 6 for discharging exhaust gas generated in the combustion chamber of each cylinder 2A, and exhaust manifold 5B connected to exhaust manifold 5B, exhaust gas generated in the combustion chamber of each cylinder 2B is combusted in each cylinder 2A. And an exhaust passage 7 for exhausting together with the exhaust gas generated in the room.

  One end of the exhaust passage 6 is connected to the end of the # 7 cylinder located at one end of each cylinder 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. Are connected to the end of the # 8 cylinder located at one end. One end of the exhaust passage 7 is connected to the end of the exhaust manifold 5B on the side of the # 8 cylinder so as to communicate with the exhaust passage 6.

  A turbine of a turbocharger 8 is disposed in the exhaust passage 7. Note that a compressor of the turbocharger 8 is disposed in an intake passage (not shown) (not shown).

  The engine 1 also includes a fuel addition valve 9 that adds fuel to the exhaust gas in the exhaust manifold 5B. The fuel addition valve 9 is disposed at a portion corresponding to the # 8 cylinder in each cylinder 2B. That is, the fuel addition valve 9 is disposed at a site on the connection portion side with the exhaust passages 6 and 7 in the exhaust manifold 5B. The fuel addition valve 9 is controlled to add fuel when the # 8 cylinder exhausts after the # 8 cylinder explodes.

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

  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, an individual passage 13A, and an individual passage 13B. A junction passage 14 that connects the connecting portion M and the EGR cooler 12 is provided. The connection portion M between the individual passage 13A and the individual passage 13B is a joining 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 provided in the individual passages 13A and 13B, respectively.

  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 away 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 merging portion of the EGR passage 11 in the EGR device 10. In FIG. 2, the individual passage 13 </ b> A and the merging passage 14 are configured to be shared 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.

  The individual passage 13 </ b> B includes a main passage portion 17 and a throttle passage portion 18 having a diameter smaller than that of the main passage portion 17. The throttle passage 18 is provided at the end of the individual passage 13B on the connection side with the individual passage 13A. That is, the throttle passage 18 is provided at the end of the pipe 16 on the connection side with the pipe 15. The diameter of the throttle passage 18 is set so small that it does not hinder the flow of EGR gas. The diameter of the throttle passage portion 18 is, for example, not less than ½ of the diameter of the main passage portion 17 and not more than 2/3 of the diameter of the main passage portion 17. Note that 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 merge 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> 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 made of a mold, a hole is formed in the curved outer portion of the curved portion 15a of the pipe 15, and the end of the pipe 16 on the narrowing passage portion 18 side is provided at the edge of the hole of the pipe 15. Weld.

  Thereby, the connection part M (merging part of the EGR passage 11) between the individual passage 13A and the individual passage 13B is formed. At this time, the angle (the merging angle between the individual passages 13A and 13B) α formed by the individual passage 13A and the individual passage 13B in the connecting 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 confluence portion of an EGR passage in a conventional EGR device as a comparative example. In FIG. 3, the EGR passage 50 includes individual passages 51 </ b> A and 51 </ b> B and a joining passage 52 instead of the individual passages 13 </ b> A and 13 </ b> B and the joining passage 14.

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

  Incidentally, 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 exploded, the # 2 cylinder exploded. The individual passage 51B is connected to a portion corresponding to the # 4 cylinder among the cylinders 2B in the exhaust manifold 5B. Therefore, the fuel added from the fuel addition valve 9 wraps around 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 merge passage 52, and the unburned gas is deposited as the EGR cooler 12. May be deposited on.

  In addition, since the merging angle α of the individual passages 51A and 51B is as wide as 120 degrees, the EGR gas flowing through the individual passage 51A and the EGR gas flowing through the individual passage 51B are likely to collide, and the pressure at the merging portion of the EGR passage 50 Loss increases. As a result, the EGR gas is less likely to flow through the merge passage 52, and the flow rate of the EGR gas supplied to the intake manifold 4 is reduced.

  On the other hand, in the present embodiment, the individual passage 13B has a throttle passage portion 18 having a diameter smaller than that of the main passage portion 17, so even if the fuel added from the fuel addition valve 9 wraps around the individual passage 13B, The unburned gas in the fuel becomes difficult to flow into the merging passage 14 by the throttle passage portion 18. Thereby, the unburned gas which flows into the EGR cooler 12 is reduced. As a result, unburned gas can be prevented from depositing 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 through the individual passage 13A and the EGR gas flowing through the individual passage 13B is alleviated. Thereby, the pressure loss of the confluence | merging part of the EGR channel | path 11 is reduced. As a result, the EGR gas easily flows through the merging passage 14, and the flow rate of the EGR gas supplied to the intake manifold 4 increases.

  Further, the individual passage 13 </ b> A and the merging passage 14 are constituted by a pipe 15, and the individual passage 13 </ b> B is constituted by a pipe 16 welded to the pipe 15. Thereby, the connection part M of the individual passage 13A and the individual passage 13B can be configured easily.

  Further, the throttle passage 18 is provided at the end of the pipe 16 on the connection side with the pipe 15. As a result, the throttle passage 18 having a diameter smaller than that of the main passage 17 is welded to the pipe 15, so that the pipe 15 and the pipe 16 can be easily welded.

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

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

  Moreover, in the said embodiment, although the separate channel | path 13A and the confluence | merging channel | path 14 are comprised by the piping 15, and the separate channel | path 13B is comprised by the piping 16, it is not restricted to the form in particular, For example, individual channel | path 13A, 13B and merging The passage 14 may be composed of different pipes.

  Moreover, although the EGR apparatus 10 of the said embodiment is provided in the V type 8 cylinder diesel engine, this invention is not limited to it in particular, For example, it can apply also to a V type 6 cylinder diesel engine etc. The present invention can also be applied to an internal combustion engine such as a gasoline engine.

  DESCRIPTION OF SYMBOLS 1 ... Diesel engine (internal combustion engine), 3A ... Right bank (1st cylinder group), 3B ... Left bank (2nd cylinder group), 4 ... Intake manifold, 5A ... Exhaust manifold (1st exhaust manifold), 5B ... Exhaust Manifold (second exhaust manifold), 9 ... fuel addition valve, 10 ... EGR device (exhaust recirculation device), 11 ... EGR passage (exhaust recirculation passage), 12 ... EGR cooler (cooler), 13A ... individual passage (first) 1 individual passage), 13B ... individual passage (second individual passage), 14 ... confluence 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 the second cylinder group. An exhaust gas recirculation apparatus for an internal combustion engine comprising: a second exhaust manifold connected to the exhaust gas; and a fuel addition valve for adding fuel to the exhaust gas in the second exhaust manifold.
Exhaust gas for connecting the first exhaust manifold, the second exhaust manifold, and the intake manifold, and leading exhaust gas in the first exhaust manifold and the second exhaust manifold as exhaust gas recirculation gas to the intake manifold. A recirculation passage,
A cooler that is disposed in the exhaust gas recirculation passage and cools 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, the first individual passage, and the second individual passage. A confluence passage connecting the connecting portion and the cooler;
The second individual passage has a main passage portion and a throttle passage portion having a diameter smaller than that of the main passage portion,
An exhaust gas recirculation device for an internal combustion engine, wherein an angle formed by 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 configured by a first pipe,
2. The exhaust gas recirculation device 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.   3. The exhaust gas recirculation device for an internal combustion engine according to claim 2, wherein the throttle passage is provided at an end of the second pipe on the connection side with the first pipe.

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