JP2019065808A - Intake system structure for internal combustion engine - Google Patents

Abstract

To effectively promote mixing of fresh air and EGR gas.SOLUTION: An intake system structure for an internal combustion engine includes: a recirculation exhaust gas recirculation section 22 for introducing recirculation exhaust gas recirculated from an exhaust system of the internal combustion engine E; an intake air mixing section 23 extended from a downstream end of the recirculation exhaust gas recirculation section 22 and mixing fresh air and the recirculation exhaust gas; an intake air distribution section 25 for distributing the intake air mixed by the intake air mixing section 23 to intake ports 12A, B; and a partition wall section 28 extended at an adjacent portion between the intake air mixing section 23 and the intake air distribution section 25 for partitioning of the intake air mixing section 23 and the intake air distribution section 25.SELECTED DRAWING: Figure 2

Description

  The technology of the present disclosure relates to an intake system structure of an internal combustion engine, and more particularly to an intake channel structure of an intake manifold.

  BACKGROUND Conventionally, in an internal combustion engine, an exhaust gas recirculation system (hereinafter referred to as an EGR system) for recirculating at least a part of exhaust gas to an intake system has been widely put to practical use. An EGR device of this type is disclosed, for example, in Patent Document 1 and the like. The EGR device disclosed in the document is a so-called high pressure EGR device in which an EGR pipe is joined to an intake system (for example, an intake manifold) on the downstream side of a compressor of a turbocharger.

JP 2017-125447 A

  In the high pressure EGR device, when the EGR pipe is joined to the intake manifold, the distance between the EGR recirculation unit for introducing the EGR gas into the intake manifold and the intake distribution unit for distributing the intake to each intake port becomes short. When the distance between the EGR recirculation unit and the intake air distribution unit becomes short, the EGR gas may flow into the intake air distribution unit without being sufficiently mixed with the fresh air.

  If intake air with insufficient mixing of EGR gas and fresh air is supplied to each cylinder, a misfire occurs in a cylinder where the EGR gas concentration is excessively high, or the combustion temperature rises in a cylinder where the oxygen concentration is excessively high. There is a problem that knocking occurs due to Such a phenomenon tends to occur particularly in an engine fueled with natural gas.

  The technique of the present disclosure aims to effectively promote mixing of fresh air and EGR gas in an intake system structure of an internal combustion engine.

  The technology of the present disclosure extends from a downstream end of the recirculated exhaust gas recirculation unit to a recirculated exhaust gas recirculation unit that introduces recirculated exhaust gas that is recirculated from the exhaust system of the internal combustion engine, and extends fresh air and the recirculated exhaust gas. An intake air mixing portion to be mixed, and an intake air distribution portion for making at least a part thereof adjacent to the intake air mixing portion and distributing the intake air mixed in the intake air mixing portion to an intake port formed in a cylinder head of the internal combustion engine And a partition wall portion extended in an adjacent part of the intake air mixing portion and the intake air distribution portion to separate the intake air mixing portion and the intake air distribution portion.

  Further, it is preferable to further include an intake turn-around portion that connects the downstream end of the intake mixing portion and the upstream end of the intake distribution portion and turns back the intake air flowing from the intake mixing portion toward the intake distribution portion.

  The air intake manifold may be one in which the recirculation exhaust gas recirculation unit, the intake air mixing unit, the intake air distribution unit, the partition wall, and the intake air return unit are integrally formed.

  Further, a curved portion may be provided on the downstream end side of the intake air return portion so as to be convex in a circular arc shape closer to the cylinder head than the intake distribution portion.

  Further, a linear portion may be provided on the downstream side of the curved portion of the intake air-folded portion to secure a predetermined distance between the curved portion and the upstream end of the intake air distribution portion.

  According to the technology of the present disclosure, mixing of fresh air and EGR gas can be effectively promoted.

BRIEF DESCRIPTION OF THE DRAWINGS It is a typical whole block diagram which shows the intake and exhaust system of the internal combustion engine which concerns on this embodiment. It is a schematic diagram which shows the principal part of the intake system structure which concerns on this embodiment.

  Hereinafter, an intake system structure of an internal combustion engine according to the present embodiment will be described based on the attached drawings. The same parts are given the same reference numerals, and their names and functions are also the same. Therefore, detailed description about them will not be repeated.

  FIG. 1 is a schematic overall configuration diagram showing an intake and exhaust system of an internal combustion engine according to the present embodiment. An engine E as an internal combustion engine mainly includes an engine main body 10 including a cylinder head, a cylinder block, and the like. The cylinder block of the engine body 10 is provided with a plurality of cylinders (hereinafter referred to as cylinders) # 1 to # 4 each accommodating a piston (not shown) so as to be capable of reciprocating. Further, intake ports 12A, B and exhaust ports 13A, B are formed in the cylinder head of the engine main body portion 10.

  Although the engine E is illustrated as a four-cylinder in-line engine in the illustrated example, the present invention is not limited thereto, and may be a single cylinder or a multi-cylinder engine other than four cylinders. Further, although the engine E is shown as a four-valve engine provided with two intake ports 12A, B and two exhaust ports 13A, B for each of the cylinders # 1 to # 4, it is a two-valve engine. May be

  On the intake side of the cylinder head of the engine body 10, an intake manifold 20 for distributing intake air (fresh air and a mixture of fresh air and EGR gas) to the intake ports 12A and B is attached. An intake pipe 50 is connected to the intake manifold 20. In the intake pipe 50, an air cleaner 51, a compressor 81 of a supercharger 80, an intercooler 52, an intake throttle valve 53, and the like are provided in this order from the upstream side.

  On the exhaust side of the cylinder head of the engine body 10, an exhaust manifold 60 for collecting exhaust from the exhaust ports 13A and 13B is attached. An exhaust pipe 61 is connected to the exhaust manifold 60. The exhaust pipe 61 is provided with a turbine 82 of the turbocharger 80, an exhaust gas purification device 83, and the like in order from the upstream side.

  The EGR device 70 is a so-called high pressure EGR device, and is provided to an EGR pipe 71 and an EGR pipe 71 which are branched from the exhaust pipe 61 (or the exhaust manifold 60) upstream of the turbine 82 and merge into the intake manifold 20. The EGR cooler 72, the EGR valve 73 provided on the downstream side of the EGR cooler 72 of the EGR pipe 71, and the reed valve 74 functioning as a check valve are provided. In the EGR device 70, the degree of opening and closing of the EGR valve 73 is controlled by a control unit (not shown) according to the operating state of the engine E, whereby the amount of EGR gas (EGR rate) is appropriately adjusted. There is.

  Next, details of the intake manifold, which is a main part of the intake system structure according to the present embodiment, will be described based on FIG.

  As shown in FIG. 2, in the intake manifold 20, in order from the upstream side, a fresh air inlet 21 to which the outlet of the intake pipe 50 (or an intake throttle valve unit not shown) is connected, and an outlet of the EGR pipe 71 The intake air return portion 24 which folds back the intake air (the mixture of fresh air and EGR gas) which has passed through the intake air mixing portion 23 and the intake air mixing portion 23 which mixes fresh air and EGR gas. And the intake distribution unit 25 that distributes the intake air folded back at the intake return unit 24 to the cylinders # 1 to # 4, and the intake air distributed by the intake distribution unit 25 to the intake ports 16A and B. The first to fourth supply pipes 30, 35, 40, 45 are integrally provided.

  The first to fourth intake pipe sections 30, 35, 40, 45 are sequentially opened from the upstream side into first to fourth intake air introduction sections 31, 36, 41, 46 facing the inside of the intake distribution section 25, and The first to fourth intake air introducing portions 31, 36, 41, 46 are bifurcated and provided with connecting pipe portions 32, 37, 42, 47 respectively connected to the respective intake ports 16A, B. First to fourth injectors 38, 39, 48, which inject fuel (in the present embodiment, for example, natural gas, for example) into the first to fourth intake air introduction portions 31, 36, 41, 46 and premix them with intake air. 49 are provided respectively.

  The fresh air inlet portion 21 has a predetermined amount from the outer wall of a portion corresponding to a substantially intermediate position between the first intake air introduction portion 31 and the second intake air introduction portion 36 of the intake air distribution portion 25 in the top view. It is disposed at a spaced position. The upstream end of the EGR recirculation unit 22 is integrally coupled to the downstream end of the fresh air inlet unit 21.

  The EGR recirculation portion 22 is provided on the outer wall of a portion corresponding to a substantially intermediate position between the second intake air introduction portion 36 and the third intake air introduction portion 41 of the intake distribution portion 25 from the downstream end of the fresh air inlet 21 in top view. It is extended diagonally. The upstream end of the intake air mixing unit 23 is integrally coupled to the downstream end of the EGR recirculation unit 22. That is, the EGR gas flowing into the EGR recirculation unit 22 is introduced into the intake air mixing unit 23 together with the fresh air flowing from the fresh air inlet 21. In addition, the shape of the EGR recirculation | reflux part 22 is not limited to the shape of the example of illustration, According to arrangement | positioning or the shape of the fresh air inlet part 21 or the EGR piping 71, etc., it can deform | transform suitably.

  The intake mixing portion 23 extends substantially in parallel with the cylinder arrangement direction in top view, and is provided adjacent to the intake distribution portion 25. At the downstream end of the intake air mixing portion 23, the upstream end of the intake air folded portion 24 is integrally coupled. In the present embodiment, at the boundary between the intake mixing unit 23 and the intake distribution unit 25, a partition wall 28 for dividing these spaces is provided over the entire length from the upstream end to the downstream end of the intake mixing unit 23. . Preferably, the downstream end 29 of the intake mixer 23 and the partition wall 28 in the cylinder arrangement direction (longitudinal direction) of the cylinder arrangement direction (longitudinal direction) is the intake distributor 25 with respect to the intake flow direction X in the intake mixer 23. It is set to have a length located downstream of the opening 46A of the fourth intake air inlet 46 facing the inside.

  Thus, by providing the partition wall 28, fresh air flowing from the fresh air inlet 21 into the intake mixing unit 23 through the EGR recirculation unit 22 and EGR gas flowing from the EGR recirculation unit 22 into the intake mixing unit 23 are While being flowed along the partition wall 28 in the intake air mixing portion 23, the mixing is effectively performed. Further, by positioning the downstream end 29 of the partition wall 28 downstream of the opening 46A of the fourth intake air introduction portion 46 in the intake flow direction X, the intake does not pass through the intake air return portion 24 and the fourth intake air introduction Direct and concentrated flow into the portion 46 can be effectively prevented.

  The intake air-folded portion 24 includes a first curved portion 24A, a second curved portion 24B, and a linear portion 24C in this order from the upstream side.

  The first curved portion 24A is formed in a curved shape whose outer wall extends from the downstream end outer wall of the intake air mixing portion 23 toward the cylinder head CH in a semicircular arc shape in top view. That is, the intake air flowing from the intake mixing section 23 into the intake turn back section 24 flows along the inner wall surface of the first curved section 24A, thereby reliably directing the flow of intake air toward the cylinder head CH side. The mixing of air and EGR gas is further promoted.

  The second curved portion 24B has an outer wall extending from the downstream end outer wall of the first curved portion 24A toward the cylinder head CH and is convex in a circular arc shape toward the cylinder head CH side from the intake distribution portion 25 in top view It is curved and formed. That is, at least a portion of the intake air flowing along the inner wall surface of the second curved portion 24B is directed in an oblique direction in which the inside of the intake distribution portion 25 gradually separates from the cylinder head CH side as shown by arrow Y in the drawing. It is supposed to be. As a result, the intake air folded back at the intake air return portion 24 is distributed to the cylinders # 1 to # 4 while effectively suppressing the concentrated distribution to the fourth intake air introduction portion 46 on the most upstream side. Uniform flow rate of the intake air.

  The straight portion 24C extends in the cylinder arrangement direction from the downstream end of the second curved portion 24B toward the upstream end of the intake distribution portion 25 in a predetermined length in a top view. Thus, between the downstream end of the second curved portion 24B and the upstream end of the intake air distribution unit 25 adjacent to the opening 46A of the fourth intake air introduction unit 46, the linear portion 24C securing these distances is By providing, the intake (refer to arrow Z in the figure) flowing along the linear portion 24C without being directed in the arrow Y direction in the figure at the second curved portion 24B flows into the fourth intake inlet portion 46 in a concentrated manner. Can be effectively prevented.

  The intake air distribution unit 25 is formed to extend substantially in parallel with the cylinder arrangement direction in a top view and to narrow the flow passage width from the upstream side toward the downstream side. As described above, by gradually narrowing the flow passage width of the intake distribution unit 25, the decrease in the flow velocity of intake air in the downstream region in the intake distribution unit 25 is effectively suppressed.

  According to this embodiment described in detail above, the intake mixing unit 23 is connected to the downstream end of the EGR recirculation unit 22, and a partition that divides these spaces into adjacent parts of the intake mixing unit 23 and the intake distribution unit 25. A wall 28 is provided. That is, the fresh air flowing from the fresh air inlet 21 and the EGR gas flowing into the EGR recirculation unit 22 are reliably circulated in the intake mixing unit 23 without directly flowing into the intake distribution unit 25. ing. As a result, fresh air and EGR gas are caused to flow along the partition wall 28 in the intake air mixing unit 23, and it becomes possible to effectively promote mixing of these fresh air and EGR gas.

  Further, by providing the first curved portion 24A on the upstream side of the intake air return portion 24, providing the second curved portion 24B on the downstream side of the intake air return portion 24 while further promoting the mixing of the fresh air and the EGR gas. As a result, at least a portion of the intake air is directed obliquely in the intake distribution portion 25 gradually away from the cylinder head CH side, and by providing the linear portion 24C at the downstream end of the intake return portion 24, the fourth A distance between the intake air introduction portion 46 and the opening 46A is secured. As a result, it becomes possible to effectively prevent the intake air folded back at the intake air folding portion 24 from being concentrated to the fourth intake air introducing portion 46 most upstream, and each cylinder # 1 to # 4. It is possible to achieve uniform flow of intake air distributed to the

  The present invention is not limited to the embodiments described above, and can be appropriately modified and implemented without departing from the spirit of the present invention.

  For example, the intake system structure of the present embodiment includes the fresh air inlet 21, the EGR recirculation unit 22, the intake mixing unit 23, the intake folding unit 24, the intake distribution unit 25, and the first to fourth supply pipes 30, 35, Although the intake manifold 20 has been described as integrally formed 40 and 45, a part of these may be formed separately from the intake manifold 20.

  Further, although the engine E has been described as using natural gas as the fuel, the invention is not limited thereto, and can be widely applied to other internal combustion engines such as a gasoline engine and a diesel engine.

E Engine CH Cylinder Head 10 Engine Body 20 Engine Intake Manifold 21 Fresh Air Inlet 22 EGR Reflow Unit 23 Intake Mixing Unit 24 Intake Inverted Portion 24A First Curved Section 24B Second Curved Section 24C Straight Section 25 Intake Distribution Section 28 Partition Wall 50 intake pipe 71 EGR piping

Claims (5)

A recirculated exhaust gas recirculation unit for introducing a recirculated exhaust gas recirculated from the exhaust system of the internal combustion engine;
An intake mixing unit extending from the downstream end of the recirculation exhaust gas recirculation unit and mixing fresh air with the recirculation exhaust gas;
An intake distribution unit for making at least a part thereof adjacent to the intake mixing unit and distributing the intake air mixed in the intake mixing unit to an intake port formed in a cylinder head of the internal combustion engine;
An intake system structure of an internal combustion engine, comprising: a partition wall portion extended to an adjacent portion between the intake air mixing portion and the intake air distribution portion to separate the intake air mixing portion and the intake air distribution portion. The internal combustion engine according to claim 1, further comprising an intake air return portion connecting the downstream end of the intake air mixing portion and the upstream end of the intake air distribution portion and turning back the intake air flowing from the intake air mixing portion toward the intake air distribution portion. Intake system structure. The intake system structure of an internal combustion engine according to claim 2, wherein the recirculation exhaust gas recirculation unit, the intake mixing unit, the intake distribution unit, the partition wall portion, and the intake return portion are integrally formed. The intake system of an internal combustion engine according to claim 2 or 3, wherein on the downstream end side of the intake air return portion, a curved portion which is curved so as to be arcuately convex closer to the cylinder head than the intake distribution portion. Construction. The internal combustion engine according to claim 4, wherein a linear portion for securing a predetermined distance between the curved portion and the upstream end of the intake distribution portion is provided on the downstream side of the curved portion of the intake turnaround portion. Intake system structure.

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