JP2013130111A - Egr gas cooling system in internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling system which prevents gas flow from being interrupted in an intake system and cools an EGR gas in an internal combustion engine.SOLUTION: The cooling system of the EGR gas in the internal combustion engine 10 includes: an exhaust recirculation device 50 configured to make exhaust enter an intake path 36 by opening an intake valve between an expansion cycle and an exhaust cycle and the exhaust enter a combustion chamber 42; a fin 64 as a cooling member which is provided in the intake path 36 for cooling the exhaust entered into the combustion chamber 42 by the exhaust recirculation device 50; and a spacer part 66 located between the fine an intake port 22 of a cylinder head 18 and configured to make an installed part of the cooling member and the intake port 22 in a fluid-communicated state.

Description

  The present invention relates to a cooling system for EGR gas in an internal combustion engine having an exhaust gas recirculation device.

  Conventionally, in an internal combustion engine, an exhaust gas recirculation device (EGR device) for causing exhaust gas to flow into a cylinder during an intake stroke is known. By this inflow of exhaust gas, the combustion temperature can be reduced and NOx generation can be suppressed. The EGR device includes a so-called external EGR device that recirculates exhaust gas to the intake system via an EGR passage that connects the exhaust passage and the intake air passage, and a so-called internal EGR device that recirculates exhaust gas to the intake system by opening the intake valve. Is known.

  Patent Document 1 discloses an example of an internal combustion engine provided with an internal EGR device. This internal combustion engine is provided with a heat exchanger for cooling exhaust gas (EGR gas) recirculated from the cylinder directly to the intake port at the intake port.

JP 2007-32402 A

  By the way, what is equipped with a cooling fin is often used as a heat exchanger for cooling, ie, a cooling device. Such a cooling device with cooling fins can be provided such that the cooling fins are located in the intake port of the internal combustion engine, referring to the description in Patent Document 1. However, in this case, the opening cross-sectional area of the intake port is reduced by the cooling fin as compared with the opening cross-sectional area of the intake port without the cooling fin, and thereby, when the exhaust air is blown back to the intake system in the internal EGR device. There is a risk that pressure loss in the intake system becomes high, and generation and supply of internal EGR gas becomes difficult.

  Accordingly, the present invention has been made in view of such a point, and an object thereof is to provide a system that makes it possible to cool EGR gas without hindering the flow of gas in the intake system. .

  One aspect of the present invention is an exhaust gas recirculation device configured to cause exhaust gas to flow into an intake passage by opening an intake valve between an expansion stroke and an exhaust stroke, and to flow the exhaust gas into a combustion chamber during the intake stroke. The cooling member is positioned between the cooling member provided in the intake passage and the cooling member and the intake port of the cylinder head so as to cool the exhaust gas flowing into the combustion chamber by the exhaust gas recirculation device. A cooling system for EGR gas in an internal combustion engine is provided, which includes a spacer portion configured to bring a fluid communication state between the installation location of the intake port and the intake port.

  Preferably, the cooling member includes a plurality of fins.

  Preferably, with respect to one cylinder, the effective passage cross-sectional area at the installation location of the cooling member is larger than the effective passage cross-sectional area at the intake port, and the spacer portion allows fluid flow through the installation location of the cooling member and the intake port. It may be formed so as not to inhibit.

  Preferably, with respect to one cylinder, the spacer section defines a passage having an effective passage cross-sectional area larger than an effective passage cross-sectional area at the installation location of the cooling member in the entire region in the fluid flow direction.

  Preferably, with respect to one cylinder, the spacer section defines a passage that changes so that the effective passage sectional area increases from the intake port side to the cooling member side.

  Preferably, the internal combustion engine has a plurality of cylinders, and the spacer portion has a plurality of passages each corresponding to any one of the plurality of cylinders, and the plurality of passages are independent of each other. .

1 is a conceptual diagram of an internal combustion engine according to a first embodiment of the present invention. FIG. 3 is another conceptual diagram of the internal combustion engine of FIG. 1. It is a figure showing an example of the change of the valve lift of the intake / exhaust valve in the internal combustion engine of FIG. FIG. 6 is a diagram illustrating another example of a change in valve lift of the intake and exhaust valves in the internal combustion engine of FIG. 1. FIG. 2 is a schematic diagram of a part of an intake system in the internal combustion engine of FIG. 1. FIG. 2 is a schematic diagram showing a change in an effective passage sectional area of a part of an intake passage of the internal combustion engine of FIG. 1. It is the schematic diagram showing the change of the effective passage sectional area of a part of intake passage of the internal combustion engine as a comparative example. It is a schematic diagram of a part of an intake system in an internal combustion engine according to a second embodiment of the present invention. It is a schematic diagram of a part of an intake system in an internal combustion engine according to a third embodiment of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  1 and 2 conceptually show an internal combustion engine (hereinafter referred to as an engine) 10 according to a first embodiment of the present invention. The engine 10 can be mounted on a vehicle, and here is configured as a compression ignition type internal combustion engine.

  The engine 10 includes an engine main body 12, and an intake manifold 14 and an exhaust manifold 16 are connected to the engine main body 12. The engine main body 12 includes a cylinder head 18, a cylinder block 20, and a crankcase (not shown).

  An intake port 22 and an exhaust port 24 are formed in the cylinder head 18. The cylinder head 18 is provided with a fuel injection valve 26, an intake valve 28 that opens and closes the intake port 22, and an exhaust valve 30 that opens and closes the exhaust port 24. The intake valve 28 is driven by a valve operating device 32, and the exhaust valve 30 is driven by a valve operating device 34.

  Each of the valve gears 32 and 34 is a variable motion that can change the valve opening / closing timing and the valve lift amount by changing the circumferential width of the valve cam or moving the valve cam in the axial direction. It can have a valve mechanism. Or each of the valve operating apparatuses 32 and 34 can have a structure which can change them using an electric actuator. The valve gears 32 and 34 can each have a conventionally known configuration.

  Air introduced into the intake passage 36 via an air cleaner (not shown) reaches the intake manifold 14 via the compressor 40 of the turbocharger 38, passes through each intake port 22, and opens each combustion chamber 42 when the intake valve 28 is opened. To be supplied. The combustion chamber 42 is defined by the cylinder head 18, the cylinder 44 of the cylinder block 20, and the piston 46.

  The fuel injected from the fuel injection valve 26 into the combustion chamber 42 is combusted in the combustion chamber 42. The gas, that is, the exhaust gas generated by the combustion of the air-fuel mixture, that is, the fuel, is discharged from the combustion chamber 42 to the exhaust passage 48 via the exhaust valve 30. Exhaust gas reaches the exhaust manifold 16 from each combustion chamber 42 via each exhaust port 24, and is discharged to the outside via a turbine 49 of a turbocharger 38 provided in the exhaust passage 48 and an exhaust purification device (not shown).

  The engine 10 includes an exhaust gas recirculation device (EGR device) 50. The EGR device 50 is a device for causing exhaust to flow into the combustion chamber in the intake stroke. The EGR device 50 is a so-called internal EGR device, in which exhaust gas flows into (or flows out or recirculates) the intake passage 36 during the expansion stroke to the exhaust stroke, and the exhaust gas is combined with air (fresh air) in the subsequent intake stroke. 44 is configured to flow into the combustion chamber 42 or into the combustion chamber 42. The EGR device 50 includes an intake valve 28, a valve operating device 32, and a control unit for the valve operating device 32.

  The engine 10 has an electronic control unit (ECU) 52 that functions as a control device or control means. The ECU 52 includes a calculation device and a storage device, and is configured as a so-called computer. The control unit of the EGR device 50 corresponds to a part of the ECU 52. Various sensors are connected to the ECU 52, for example, an engine rotation speed sensor 54 and an engine load sensor 56 are connected. The engine rotation speed sensor 54 may be a crank angle sensor for detecting a rotation angle (crank angle) of a crankshaft connected to the piston 46 via a connecting rod 58. The engine load sensor 56 may be an air flow meter or intake pressure sensor provided in the intake passage 36, or an accelerator opening sensor for detecting the amount of depression of the accelerator pedal. The ECU 52 outputs an operation signal to the fuel injection valve 26, the valve gears 32, 34, and the like based on the outputs from these sensors. Thus, the amount of fuel injected from the fuel injection valve 26 and the fuel injection timing are controlled, and the opening / closing timings of the intake and exhaust valves 28 and 30 are controlled. Note that the ECU 52 stores data for increasing the EGR rate during low load operation and decreasing the EGR rate during high load operation. However, the ECU 52 can also have data or a map for EGR rate control different from this.

  FIG. 3 is a diagram illustrating an example of changes in the valve lifts of the intake valve 28 and the exhaust valve 30 with respect to changes in the crank angle when exhaust gas, that is, EGR gas is introduced into the combustion chamber 42 by the operation of the EGR device 50. The exhaust valve 30 is driven by the valve gear 34 so as to be lifted along a locus indicated by Ex in FIG. 3 mainly during the exhaust stroke. On the other hand, the intake valve 28 is driven by the valve operating device 32 so as to open in the middle of the exhaust stroke and to lift mainly along the locus indicated by In in FIG. 3 during the intake stroke. Thus, the EGR device 50 can introduce the internal EGR gas into the combustion chamber 42 by overlapping the valve opening periods of the intake valve 28 and the exhaust valve 30. In short, by opening the intake valve 28 in the exhaust stroke, the exhaust gas once flows into the intake passage, and by flowing this exhaust gas into the combustion chamber 42 in the intake stroke, the EGR device 50 causes so-called internal EGR gas to flow into the combustion chamber. 42. In addition to opening the intake valve 28 in the exhaust stroke as described above, the EGR device 50 controls the valve operating device 34 so that the intake valve 28 is lifted in the locus indicated by In2 in FIG. 4 from the expansion stroke to the exhaust stroke. Thus, the internal EGR gas may be configured to be introduced into the combustion chamber 42. The adjustment of the internal EGR gas amount can be realized by controlling at least one of the opening / closing timings of both or either of the intake / exhaust valves 28 and 30.

  Further, the engine 10 includes a cooling device 60. The cooling device 60 is provided so as to cool the exhaust gas that is caused to flow into the combustion chamber by the EGR device 50. In the present embodiment, the cooling device 60 is provided integrally with the intake manifold 14. The cooling device 60 includes a cooler core 60a including a refrigerant passage pipe 62 and a plurality of fins 64, a refrigerant tank (not shown), and a refrigerant supply pump. As the cooling device 60 is provided, the spacer portion 66 is positioned between the intake port 22 of the cylinder head 18 and the plurality of fins 64 as cooling members of the cooling device 60. Therefore, the spacer part 66 keeps the cooler core 60a, that is, the place where the cooling fins 64 as cooling members are installed and the intake port 22 in a separated state. However, in the present embodiment, the spacer portion 66 is provided integrally with the cylinder head 18. The cooling device 60 is a liquid cooling type cooling device, and water is used as the refrigerant here, but other refrigerants may be used. However, the present invention does not exclude that the cooling device is configured as an air-cooled device.

  FIG. 5 is an enlarged schematic view of a part of the intake system of the engine 10. 5B is a schematic cross-sectional view taken along the line AA in FIG. 5A, and FIG. 5C is a schematic side view of the intake manifold 14 in FIG. 5A.

  As shown in FIG. 5, the intake manifold 14 has an intake air collecting portion 14a, and includes a cooler core 60a of the cooling device 60 on the downstream side of the intake air collecting portion 14a. The cooler core 60a includes a refrigerant passage pipe 62 disposed outside the intake passage portion, and a plurality of cooling fins 64 formed so as to extend from the pipe 62 in a direction substantially perpendicular to the pipe axial direction. Here, since the pipe axial direction of the pipe 62 is substantially parallel to the cylinder arrangement direction D of the engine body 12, the plurality of cooling fins 62 as cooling members extend substantially at right angles to the cylinder arrangement direction D, and substantially extend to the cylinder head 18. It extends at a right angle.

  The spacer portion 66 is configured to appropriately bring the cooler core 60a, that is, the installation location of the cooling fins 64 as cooling members, and the intake port 22 into fluid communication. The cooling fin 64 is installed in the intake manifold 14, that is, in the intake passage, on the downstream side of the intake manifold portion 14a. The spacer portion 66 is provided so as not to obstruct or smooth the flow of gas (fluid) through the installation location of the cooling fin 64 and the intake port 22. The spacer portion 66 defines four passages 66 a that are independent from each other, and each of the four passages 66 a communicates with the intake port 22 of a separate cylinder 44.

  Here, FIG. 6 schematically shows a change in the effective passage cross-sectional area of the intake passage from the cooler core 60 a to the intake port 22 of the intake manifold 14. Here, the effective passage cross-sectional area is an area of a cross section in a direction perpendicular to the fluid flow direction of a passage (space) portion through which a fluid, that is, a gas can flow. For example, at the location where the cooler core 60a, that is, the plurality of cooling fins 64 is installed, the effective passage sectional area is the sum of the gaps between the fins or the sectional area of the passages excluding those fins.

  As shown in FIG. 6, with respect to one cylinder 44, the effective passage sectional area at the installation location S of the plurality of fins 64 is larger than the effective passage sectional area at the intake port 22 (here, the two intake ports 22). With respect to one cylinder 44, the spacer portion 66 defines a passage 66a having an effective passage cross-sectional area larger than the effective passage cross-sectional area at the installation location S of the plurality of fins 64 in the entire region in the fluid flow direction. Further, with respect to one cylinder 44, the passage 66a of the spacer portion 66 changes so that the effective passage cross-sectional area increases from the intake port 22 side to the cooling member 64 side. And the cooler core 60a and the spacer part 66 are designed so that these relationships may be established for any cylinder 44. Note that the installation location S of the plurality of fins 64 for one cylinder 44 can also be referred to as an intake branch passage.

  Therefore, according to the cooling system or the cooling structure of the present embodiment including the cooling device 60 and the spacer portion 66, the flow of exhaust gas, that is, EGR gas into the intake passage 36 by the EGR device 50 is not hindered. That is, the exhaust is appropriately introduced into the intake passage 36 by the pumping action by the piston 46 when the intake valve 28 is opened between the expansion stroke and the exhaust stroke as shown in FIG. 3 or FIG. It can be sent to not only 22 but also the cooler core 60a. Therefore, the internal EGR gas can be appropriately generated, and the EGR gas can be suitably cooled, and NOx generation can be suppressed more effectively.

  Here, changes in the effective passage cross-sectional area of the intake passage from the cooler core 160a of the intake manifold 114 to the intake port 122 in the engine 110 as a comparative example are schematically shown in FIG. Unlike the engine 10, the engine 110 does not have the spacer portion 66. In the engine 110, a cooling device 160 with a plurality of cooling fins 164 is applied to an intake manifold 114 directly connected to an intake port 122 of a cylinder head 118, and a cooler core 160a is adjacent to the upstream side of the intake port 122. Yes. As is apparent from FIG. 6, in this case, the effective passage cross-sectional area immediately upstream of the intake port 122 is considerably smaller than the effective passage cross-sectional area at the intake port 122, and the exhaust passage to the intake passage by the internal EGR device is obtained. Inflow can be inhibited.

  Next, a second embodiment according to the present invention will be described with reference to FIG. The engine 210 of the second embodiment is different from the engine 10 of the first embodiment in the arrangement of the pipes of the cooler core 260a of the cooling device 260.

  FIG. 8 is an enlarged schematic diagram of the intake system of the engine 210 of the second embodiment. FIG. 8B is a schematic cross-sectional view taken along line BB in FIG. 8A, and FIG. 8C is a schematic side view of the intake manifold 214 in FIG.

  As shown in FIG. 8, the cooler core 260a of the cooling device 260 is provided between the cylinder head 218 and the intake air collecting portion 214a. The refrigerant passage pipe 262 of the cooler core 260a is positioned in the intake passage 236. A plurality of cooling fins 264 are arranged so as to extend from the refrigerant passage pipe 262 in a direction substantially perpendicular to the axis thereof.

  Thus, in this embodiment, since the refrigerant passage pipe 262 and the cooling fins 264 as cooling members are directly provided in the intake passage, the cooling effect of the exhaust by the cooling device 260 is extremely excellent. Although not described further, in the second embodiment, the cooling device 260 and the spacer portion 266 are configured so that the effective passage sectional area of the intake passage changes as described with reference to FIG. 6 in the first embodiment. Has been.

  Next, a third embodiment according to the present invention will be described with reference to FIG. The engine 310 of the third embodiment is different from the engine 10 of the first embodiment in the configuration of the cooler core 360a of the cooling device 360.

  The cooler core 360 a is positioned between the intake manifold portion 314 a of the intake manifold 314 and the spacer portion 366. The spacer portion 366 defines four passages 366 a each corresponding to each cylinder 344. The cooler core 360 a has a wall portion 360 b that partitions the intake branch passage to each cylinder 344.

  As described above, in the first to third embodiments, the spacer portion is provided integrally with the cylinder head. However, the spacer portion, that is, the spacer member and the cylinder head can be separated and connected. . However, although the spacer portion can be made of various materials, the spacer portion is preferably made of the same material as the cylinder head from the viewpoint of reliability and strength, particularly thermal stress. Further, the spacer portion may be configured integrally with the cooler core or the intake manifold. Furthermore, in the first to third embodiments, the cooling device is integrally provided in the intake manifold. However, the intake manifold, particularly the intake manifold portion, and the cooling device may be separate elements and connected. . For example, the cooling device may be configured integrally with the cylinder head.

  Further, in the above embodiment, the cooling device is provided to cool the internal EGR gas. However, the cooling device as described above may be used to cool the external EGR gas. The external EGR gas is exhaust introduced into the intake system via the EGR passage that connects the exhaust passage and the intake passage. A so-called external EGR device including the EGR passage can include an EGR valve.

  Although the engine in the above embodiment is configured as a compression ignition type internal combustion engine, the present invention can be similarly applied to an internal combustion engine having another configuration such as a spark ignition type internal combustion engine. Further, the engine to which the present invention is applied does not matter about the cylinder arrangement, the number of cylinders, and the number of intake ports per cylinder.

  As described above, the present invention has been described based on the above embodiment and its modifications. However, the present invention is not limited to these embodiments and the like, and other embodiments are allowed. The present invention includes all modifications, applications, and equivalents included in the spirit of the present invention defined by the claims.

10, 210, 310 Engine 14, 214, 314 Intake manifold 50 EGR device 60, 260, 360 Cooling device 64, 264, 364 Fin 66, 266, 366 Spacer section

Claims (6)

An exhaust gas recirculation device configured to cause the exhaust gas to flow into the intake passage by opening the intake valve between the expansion stroke and the exhaust stroke, and to flow the exhaust gas into the combustion chamber in the intake stroke;
A cooling member provided in the intake passage so as to cool the exhaust gas flowing into the combustion chamber by the exhaust gas recirculation device;
EGR gas in an internal combustion engine comprising: a spacer portion positioned between the cooling member and an intake port of the cylinder head and configured to place the cooling member in fluid communication with the intake port. Cooling system.   The cooling system for an EGR gas in an internal combustion engine according to claim 1, wherein the cooling member includes a plurality of fins.   With respect to one cylinder, the effective passage cross-sectional area at the installation location of the cooling member is larger than the effective passage cross-sectional area at the intake port, and the spacer portion allows fluid flow through the installation location of the cooling member and the intake port. The cooling system for EGR gas in an internal combustion engine according to claim 1 or 2, wherein the cooling system is configured not to inhibit.   The said spacer part defines the channel | path which has an effective channel | path cross-sectional area larger than the effective channel | path cross-sectional area in the installation location of the said cooling member in the whole area | region of a fluid flow direction regarding one cylinder. A cooling system for EGR gas in an internal combustion engine.   The said spacer part divides and forms the channel | path which changes so that an effective channel | path cross-sectional area may become large as it goes to the said cooling member side from the said intake port side regarding one cylinder. EGR gas cooling system for internal combustion engines.   The internal combustion engine has a plurality of cylinders, and the spacer portion has a plurality of passages each corresponding to any one of the plurality of cylinders, and the plurality of passages are independent from each other. The cooling system of EGR gas in the internal combustion engine according to any one of claims 1 to 5.

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