JP2022006563A - Internal combustion engine - Google Patents

Abstract

To actively produce condensed water in an EGR distribution passage and discharge the condensed water from the EGR distribution passage, and furthermore to enable suppression of flowing in of the condensed water into a specified cylinder biasedly, in an internal combustion engine comprising the EGR distribution passage for distributing EGR gas into a plurality of intake branch passages which are each arranged at a plurality of cylinders.SOLUTION: An internal combustion engine comprises: a plurality of cylinders; an intake passage having a plurality of intake branch passages which are connected to the plurality of cylinders; and an EGR distribution passage for distributing an EGR gas to the plurality of intake passages. The EGR distribution passage includes per-cylinder EGR flow passages which are connected to the plurality of intake branch passages. The per-cylinder EGR flow passages are formed in a vertically extending manner, and introduce the EGR gas to the corresponding intake branch passages from above in the vertical direction. Fresh air introduction pipes which are formed in a vertically extending manner, and in which fresh air flows are arranged in the per-cylinder EGR flow passages.SELECTED DRAWING: Figure 1

Description

The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine including an EGR distribution passage for distributing EGR gas to each cylinder.

Patent Document 1 discloses an intake device for an internal combustion engine. This intake device is provided with an EGR gas distribution pipe that distributes EGR gas to each cylinder. This EGR gas distribution pipe has a structure that suppresses the condensate water generated inside the EGR gas distribution pipe from flowing into a specific cylinder in a biased manner. Specifically, the structure provided in the EGR gas distribution pipe regulates the flow of condensed water from the EGR gas distribution pipe to the specific cylinder.

Japanese Unexamined Patent Publication No. 2012-06794

In a structure that regulates the flow of condensed water as in the measures described in Patent Document 1 described above, it is difficult to sufficiently suppress the bias of the condensed water when the amount of condensed water generated increases. Is a concern.

The present invention has been made in view of the above-mentioned problems, and in an internal combustion engine provided with an EGR distribution passage for distributing EGR gas to a plurality of intake branch passages provided in a plurality of cylinders, the inside of the EGR distribution passage is provided. It is an object of the present invention to be able to suppress the uneven inflow of condensed water to a specific cylinder while actively generating the condensed water in the EGR distribution passage and discharging the condensed water from the EGR distribution passage.

The internal combustion engine according to the present invention includes a plurality of cylinders, an intake passage, and an EGR distribution passage. The intake passage has a plurality of intake branch passages connected to each of the plurality of cylinders. The EGR distribution passage distributes the EGR gas to a plurality of intake branch passages.
The EGR distribution passage includes a cylinder-specific EGR passage connected to each of the plurality of intake branch passages.
The cylinder-specific EGR flow path is formed so as to extend along the vertical direction, and EGR gas is introduced from above in the vertical direction with respect to the corresponding intake branch passage.
Inside the EGR flow path for each cylinder, a fresh air introduction pipe that is formed so as to extend along the vertical direction and through which fresh air flows is arranged.

According to the present invention, the moisture contained in the EGR gas is positively condensed in the EGR flow path for each cylinder by using the wall surface of the fresh air introduction pipe through which the fresh air having a temperature lower than that of the EGR gas flows. be able to. Then, the generated condensed water can be positively discharged to each intake branch passage by utilizing the flow of EGR gas and the action of gravity. Therefore, it is possible to prevent the condensed water from flowing into a specific cylinder in a biased manner.

It is a schematic diagram for demonstrating the structure of the main part of the internal combustion engine which concerns on this embodiment. FIG. 3 is a cross-sectional view taken along the line AA in FIG. 1 regarding an EGR flow path for each cylinder and a fresh air introduction pipe. It is a perspective view of the EGR flow path and the fresh air introduction pipe for each cylinder cut by the line BB in FIG. It is a schematic diagram for demonstrating the structure of the main part of the internal combustion engine which concerns on the reference example of this invention. It is a figure which looked at the EGR flow path for each cylinder of two adjacent cylinders from the direction of the arrow C in FIG. It is sectional drawing which shows the structure around the partition wall cut along the DD line in FIG.

Hereinafter, embodiments and reference examples of the present invention will be described with reference to the accompanying drawings. However, the elements common to each figure are designated by the same reference numerals, and duplicate explanations will be omitted or simplified. In addition, when the number, quantity, quantity, range, etc. of each element is mentioned in the embodiments and reference examples shown below, except when explicitly stated or when the number is clearly specified in principle. , The invention is not limited to the numbers mentioned. In addition, the structures and the like described in the embodiments and reference examples shown below are not necessarily essential to the present invention, except when explicitly stated or clearly specified in principle.

1. 1. Internal combustion engine according to the embodiment 1-1. Configuration FIG. 1 is a schematic diagram for explaining the configuration of a main part of the internal combustion engine 10 according to the present embodiment. The internal combustion engine 10 is mounted on a vehicle such as an automobile. The internal combustion engine 10 includes a plurality of (for example, four) cylinders 12 and an intake passage 14 connected to each cylinder 12. FIG. 1 shows two cylinders 12 # 1 and 12 # 2 out of the four cylinders 12 and a portion of an intake passage 14 connected to these cylinders 12 # 1 and 12 # 2.

Specifically, an air cleaner 16 is arranged at the entrance of the intake passage 14. A throttle 18 for controlling the intake air flow rate is arranged on the downstream side of the air cleaner 16 in the intake passage 14. The intake passage 14 on the downstream side of the throttle 18 includes an intake manifold 20. The intake manifold 20 includes a collecting portion 22 and a plurality of (for example, four) intake branch passages 24 connected to each cylinder 12 via the intake port 26. In FIG. 1, only the two intake branch passages 24 # 1 and 24 # 2 corresponding to the two cylinders 12 # 1 and 12 # 2 shown are shown. A piston 28 that reciprocates inside the cylinder 12 is arranged in each cylinder 12.

The internal combustion engine 10 further includes an EGR distribution passage 30. The EGR distribution passage 30 is used to recirculate the exhaust gas flowing through the exhaust passage (not shown) of the internal combustion engine 10 to the intake passage 14 as EGR gas. Specifically, the EGR distribution passage 30 includes a cylinder-specific EGR passage 32 connected to each of the four intake branch passages 24 in order to distribute the EGR gas to each cylinder 12. More specifically, the cylinder-specific EGR flow path 32 is an EGR flow path after the EGR gas is branched toward the individual cylinders 12 in the EGR distribution passage 30. In FIG. 1, only the cylinder-specific EGR flow paths 32 # 1 and 32 # 2 corresponding to the intake branch passages 24 # 1 and 24 # 2 are shown.

Like the cylinder-specific EGR flow paths 32 # 1 and 32 # 2 exemplified in FIG. 1, the cylinder-specific EGR flow paths 32 of each cylinder 12 are formed so as to extend in the vertical direction, and the corresponding intake air is taken. The EGR gas is configured to be introduced from above in the vertical direction with respect to the branch passage 24. Inside each cylinder-specific EGR flow path 32, a fresh air introduction pipe (hollow pipe) is formed so as to extend in the vertical direction like the cylinder-specific EGR flow path 32, and fresh air flows. 34 are arranged. In FIG. 1, only two of the fresh air introduction pipes 34 # 1 and 34 # 2 are shown.

More specifically, one end (upstream end) of the fresh air introduction pipe 34 of each cylinder 12 is one end (downstream) of the fresh air bypass flow path 36 as in the fresh air introduction pipe 34 # 1 exemplified in FIG. It is connected to the end). In the example shown in FIG. 1, the other end (upstream end) of the fresh air bypass flow path 36 is a portion on the downstream side of the throttle 18 and on the upstream side of the connection port 38 of the cylinder-specific EGR flow path 32 with respect to the intake branch passage 24. (That is, it is connected to the intake passage 14 at the gathering portion 22 of the intake manifold 20). The other end (downstream end) of the fresh air introduction pipe 34 extends to the vicinity of the connection port 38 as an example. In addition, when the fresh air introduction pipe 34 and the fresh air bypass flow path 36 are viewed as one fresh air flow path, the fresh air introduction pipe 34 constituting a part of the fresh air flow path is the EGR flow path 32 for each cylinder. It is inserted through the wall of the wall and extends vertically along the EGR flow path 32 for each cylinder.

Next, a specific structural example of the fresh air introduction pipe 34 will be described with reference to FIGS. 2 and 3. FIG. 2 is a sectional view (cross-sectional view) taken along the line AA in FIG. 1 regarding the EGR flow path 32 # 1 for each cylinder and the fresh air introduction pipe 34 # 1. FIG. 3 is a perspective view of the EGR flow path 32 # 2 and the fresh air introduction pipe 34 # 2 for each cylinder cut along the line BB in FIG. 1 (direction orthogonal to the flow of fresh air and EGR gas). .. Although the illustrations of the fresh air introduction pipes 34 # 1 and 34 # 2 are referred to here, the shapes of the fresh air introduction pipes 34 of each cylinder 12 are the same.

The temperature of the fresh air flowing inside the fresh air introduction pipe 34 is lower than the temperature of the EGR gas flowing outside the fresh air introduction pipe 34. Specifically, the temperature of the fresh air (outside air) is, for example, −60 ° C. to + 40 ° C. in consideration of cold regions and hot regions. On the other hand, the temperature of the EGR gas changes depending on the EGR gas flow rate, and is, for example, in the range of 40 ° C. for a very small amount to 100 ° C. for a large amount. When the EGR gas touches the outer wall of the fresh air introduction pipe 34 through which fresh air at a lower temperature flows, active and intensive production of condensed water is promoted.

The fresh air introduction pipe 34 of the present embodiment is provided with cooling fins 40 in order to further promote the generation of condensed water. In the example shown in FIGS. 2 and 3, a plurality of cooling fins 40 are formed so as to extend radially in the radial direction of the fresh air introduction pipe 34. Further, as shown in FIG. 3, each cooling fin 40 is formed so as to extend along the vertical direction. By having the cooling fins 40 thus formed, the fresh air introduction pipe 34 can increase the contact area with the EGR gas for the positive generation of condensed water, and the generated water droplets of the condensed water can be increased. Can be led to the intake port 26.

The fresh air introduction pipe 34 is formed by using a material having high thermal conductivity (for example, a metal such as aluminum) in order to promote the generation of condensed water. Similarly, the cooling fins 40 are also formed by using a material having a high thermal conductivity (for example, a metal such as aluminum). As the material of the wall constituting the EGR distribution passage 30, a material having a low thermal conductivity (for example, resin) is used in order to suppress heat transfer from the outside air around the EGR distribution passage 30. Further, a heat insulating material may be attached to the outer surface of the wall constituting the EGR distribution passage 30. As a result, the EGR distribution passage 30 can be more reliably insulated from the outside air, so that the generation of condensed water on the inner wall surface of the EGR distribution passage 30 can be suppressed as much as possible.

1-2. Operation As the piston 28 descends in the intake stroke of each cylinder 12, an intake negative pressure is generated in the intake passage 14. As a result, a flow of fresh air toward each cylinder 12 is formed inside the intake passage 14 via each intake branch passage 24. Further, when the EGR operation is performed, the EGR gas is sucked into each cylinder 12 through the EGR distribution passage 30 by the action of the above-mentioned intake negative pressure. Therefore, during EGR operation, a mixed gas of fresh air and EGR gas is sucked into each cylinder 12.

In the internal combustion engine 10 of the present embodiment, the flow of fresh air occurs not only inside the intake manifold 20 but also inside the fresh air bypass flow path 36 and the fresh air introduction pipe 34. More specifically, the fresh air is squeezed as it flows into each intake branch passage 24, and its flow velocity increases. Due to the ejector effect obtained as a result, the fresh air in the fresh air introduction pipe 34 is sucked into the intake branch passage 24. That is, a flow of fresh air toward the intake branch passage 24 via the fresh air bypass flow path 36 and the fresh air introduction pipe 34 is also formed.

As described above, using the fresh air introduction pipe 34 through which fresh air flows, condensed water is positively and intensively generated in the cylinder-specific EGR flow path 32 as described above. More specifically, as shown in FIG. 3, the water content in the EGR gas condenses between the outer surface of the fresh air introduction pipe 34, which is a hollow pipe, and the cooling fins 40. Then, the generated water droplets flow downward in the vertical direction by being pushed by the flow of EGR gas through the cooling fins 40 and by being pulled by gravity, and are discharged into the intake branch passage 24. .. The EGR distribution passage 30 is formed so as to evenly distribute the EGR gas to each cylinder 12. Therefore, the condensed water generated in the EGR flow path 32 for each cylinder is evenly discharged to the intake port 26 of each cylinder 12 via the intake branch passage 24. That is, according to the EGR distribution passage 30 having the EGR flow path 32 for each cylinder into which the fresh air introduction pipe 34 is inserted, the condensed water generated inside the EGR distribution passage 30 is suppressed from flowing into the specific cylinder in a biased manner. To.

1-3. Effect As described above, the internal combustion engine 10 of the present embodiment includes an EGR distribution passage 30 having a cylinder-specific EGR flow path 32 into which a fresh air introduction pipe 34 is inserted. As a result, even when the vehicle is turning, accelerating or decelerating, or when the vehicle is tilted, condensed water is actively generated in the EGR distribution passage 30 and condensed water is discharged from the EGR distribution passage 30 while condensing. It becomes possible to suppress the uneven inflow of water to a specific cylinder. As a result, misfire caused by the inflow of a large amount of condensed water can be suppressed. In addition, the measures for suppressing the bias of the condensed water in the present embodiment do not utilize the structure that regulates the flow of the condensed water, but positively use the condensed water at the intended site (fresh air introduction pipe 34) (the fresh air introduction pipe 34). And intensively), and the generated condensed water is evenly discharged to each cylinder 12.

1-4. Supplementary Explanation In the example shown in FIG. 1 described above, the upstream end of the fresh air bypass flow path 36 connected to the fresh air introduction pipe 34 is connected to the intake passage 14 on the downstream side of the throttle 18. However, the upstream end of the fresh air bypass flow path 36 may be connected to the intake passage 14 at a portion (downstream side of the air cleaner 16 and upstream side of the throttle 18) instead of such an example. According to the example in which the fresh air bypass flow path 36 is connected to the upstream side of the throttle 18 in this way, the upstream end of the fresh air bypass flow path 36 and the downstream end of the fresh air introduction pipe 34 are compared with the example shown in FIG. A large differential pressure between the intake and the intake can be secured. Therefore, it is possible to secure a large flow rate of fresh air flowing through the fresh air introduction pipe 34. This leads to the promotion of heat exchange between the low-temperature fresh air flowing through the fresh air introduction pipe 34 and the EGR gas.

Further, in the example shown in FIG. 1, it was explained that the EGR flow path 32 for each cylinder and the fresh air introduction pipe 34 were formed so as to extend in the vertical direction. In this regard, "along the vertical direction" here does not necessarily require that the EGR flow path 32 for each cylinder and the fresh air introduction pipe 34 extend exactly parallel to the vertical direction, but for each cylinder. The EGR flow path 32 and the fresh air introduction pipe 34 may be configured to extend substantially parallel to the vertical direction.

2. 2. Reference example "We made it possible to suppress the uneven inflow of condensed water to a specific cylinder while actively generating condensed water in the EGR distribution passage and discharging the condensed water from the EGR distribution passage." It can also be realized by the internal combustion engine 50 according to the reference example described below with reference to FIGS. 4 to 6.

FIG. 4 is a schematic diagram for explaining the configuration of a main part of the internal combustion engine 50 according to the reference example of the present invention. The internal combustion engine 50 according to this reference example is different from the internal combustion engine 10 according to the above-described embodiment in the configuration of the intake branch passage and the EGR distribution passage.

Specifically, the internal combustion engine 50 includes an intake passage 52 including an intake manifold 54. The intake manifold 54 includes a gathering portion 22 and an intake branch passage 56 (only 56 # 1 and 56 # 2 are shown) for each cylinder 12. Further, the internal combustion engine 50 includes an EGR distribution passage 58 having an EGR flow path 60 for each cylinder (only 60 # 1 and 60 # 2 are shown). As shown in FIG. 4, each cylinder-specific EGR flow path 60 is formed so as to extend along the intake branch passage 56.

The internal combustion engine 50 according to this reference example is characterized by the configuration of a partition wall 62 (only 62 # 1 and 62 # 2 are shown) that separates the intake branch passage 56 and the cylinder-specific EGR flow path 60. The partition wall 62 is formed so as to extend in a direction along the flow of fresh air in the intake branch passage 56 and the flow of EGR gas in the EGR flow path 60 for each cylinder. Further, as shown in FIG. 4, the partition wall 62 is formed so as to go down in the vertical direction toward the downstream side in the flow direction of the EGR gas.

FIG. 5 shows each of these cylinders from the direction of arrow C in FIG. 4 (from the upstream side of the branch point 64 branching toward the EGR flow path 60 # 1 for each cylinder and the EGR flow path 60 # 2 for each cylinder). It is a figure which looked at the EGR flow path 60 # 1 and 60 # 2. FIG. 6 is a cross-sectional view showing the configuration around the partition wall 62 # 1 cut along the DD line (direction orthogonal to the flow of fresh air and EGR gas) in FIG.

The partition wall 62 is formed by using a material having high thermal conductivity (for example, a metal such as aluminum). As shown in FIG. 6, cooling fins 66 are formed on the wall surface of the partition wall 62 (62 # 1) on the cylinder-specific EGR flow path 60 (60 # 1) side. As an example, a plurality of cooling fins 66 are formed so as to extend in a direction along the flow direction of the EGR gas.

According to the internal combustion engine 50 provided with the EGR distribution passage 58 described above, the EGR gas flowing into the cylinder-specific EGR flow path 60 may be a part of the wall of the intake branch passage 56 through which fresh air having a temperature lower than that of the EGR gas flows. By touching a certain partition wall 62, active and intensive generation of condensed water in the cylinder-specific EGR flow path 60 is promoted. Also, the formation of condensed water is further promoted by the presence of the cooling fins 66. Further, the condensed water generated in this way has the action of the flow of EGR gas in the EGR flow path 60 for each cylinder and the action of the inclination of the partition wall 62 formed so as to decrease toward the downstream side of the EGR gas flow (gravity). (Action)), the gas is evenly discharged from the cylinder-specific EGR flow path 60 to the intake branch passage 56.

As described above, the internal combustion engine 50 according to this reference example also suppresses the uneven inflow of condensed water generated inside the EGR distribution passage 58 into the specific cylinder.

10, 50 Internal combustion engine 12 Cylinder 14, 52 Intake passage 18 Throttle 20, 54 Intake manifold 22 Intake manifold assembly 24, 56 Intake manifold intake branch passage 26 Intake port 30, 58 EGR distribution passage 32, 60 EGR flow by cylinder Road 34 Fresh air introduction pipe 36 Fresh air bypass flow path 38 Connection port of EGR flow path for each cylinder to intake branch passage 40, 66 Cooling fin 62 Partition

Claims (1)

With multiple cylinders,
An intake passage having a plurality of intake branch passages connected to the plurality of cylinders, respectively.
An EGR distribution passage that distributes EGR gas to the plurality of intake branch passages,
It is an internal combustion engine equipped with
The EGR distribution passage includes a cylinder-specific EGR passage connected to each of the plurality of intake branch passages.
The cylinder-specific EGR flow path is formed so as to extend along the vertical direction, and EGR gas is introduced from above the vertical direction into the corresponding intake branch passage.
An internal combustion engine characterized in that a fresh air introduction pipe, which is formed so as to extend along the vertical direction and allows fresh air to flow, is arranged inside the cylinder-specific EGR flow path.

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