JP2018141412A - Exhaust device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To early increase a temperature of a catalyst to an activation temperature or more while suppressing degradation of fuel consumption.SOLUTION: A first catalyst 71 and a second catalyst 72 are disposed between banks 18. As heat from a left bank 21 and a right bank 31 easily accumulate between the banks 18, temperatures of the first catalyst 71 and the second catalyst 72 hardly lower due to heat accumulating between the banks 18, and heat retention performance is improved. As it becomes unnecessary to increase a temperature of an exhaust gas by increasing a fuel injection amount to increase the temperatures of the first catalyst 71 and the second catalyst 72 to the activation temperature or more, the temperatures of the first catalyst 71 and the second catalyst 72 can be easily increased to the activation temperature or more without degrading the fuel consumption.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an exhaust device for a V-type internal combustion engine having a first bank and a second bank.

  For example, a V-type internal combustion engine as disclosed in Patent Document 1 has a first bank and a second bank arranged on the left and right, respectively. A first bank exhaust pipe is connected to the first bank, and a second bank exhaust pipe is connected to the second bank. The first bank exhaust pipe and the second bank exhaust pipe join together on the downstream side in the exhaust gas flow direction. A single merged exhaust pipe is connected to the merged portion of the first bank exhaust pipe and the second bank exhaust pipe. A catalyst is provided in the merged exhaust pipe. The exhaust gas flowing in the merged exhaust pipe is purified by the catalyst.

JP 2010-275999 A

  By the way, since the catalyst exhibits the exhaust gas purification ability when the temperature rises above the activation temperature, for example, when the temperature of the exhaust gas is low, the temperature of the catalyst does not rise above the activation temperature. In some cases, the exhaust gas may not be sufficiently purified by the catalyst. In order to increase the temperature of the exhaust gas, it is necessary to increase the fuel injection amount, so that the fuel consumption deteriorates.

  Further, the catalyst may be disposed under the floor of the vehicle, which is a place where it is easy to secure an arrangement space. When the catalyst is arranged under the floor of the vehicle, the catalyst is arranged in a state of being separated from the internal combustion engine, so that the heat of the exhaust gas is taken away from the internal combustion engine through the exhaust system, and the temperature of the exhaust gas is reduced. Tends to decrease, and the time until the temperature of the catalyst rises above the activation temperature becomes longer.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to exhaust an internal combustion engine that can raise the temperature of the catalyst earlier than the activation temperature while suppressing deterioration of fuel consumption. To provide an apparatus.

  An exhaust system for an internal combustion engine that solves the above problems is connected to the first bank exhaust pipe connected to the first bank of the first bank and the second bank arranged in a V shape, and to the second bank. The second bank exhaust pipe, the first bank exhaust pipe and the second bank exhaust pipe on the downstream side in the flow direction of the exhaust gas flowing through the first bank exhaust pipe and the second bank exhaust pipe, respectively. An exhaust system for an internal combustion engine, comprising: one merged exhaust pipe connected to a merge portion where the pipe merges; and a catalyst provided in the merged exhaust pipe, wherein the catalyst includes the first bank It is arranged between banks that are between the second bank.

  According to this, since heat from the first bank and the second bank tends to be trapped between the banks, the temperature of the catalyst disposed between the banks is less likely to decrease due to the heat trapped between the banks, and the heat retention is improved. To do. Accordingly, it is not necessary to increase the temperature of the exhaust gas by increasing the fuel injection amount in order to raise the temperature of the catalyst above the activation temperature. Can be raised above the activation temperature.

  In the exhaust system for an internal combustion engine, the first bank and the second bank have a plurality of cylinders, and the arrangement directions of the plurality of cylinders in each of the first bank and the second bank coincide with each other. A plurality of the catalysts are provided in the merging exhaust pipe, each of the plurality of catalyst cases is cylindrical, and a longitudinal direction of the case is an axial direction of the case; Are preferably arranged side by side in the direction in which the axial direction of each case coincides with the arrangement direction and is orthogonal to the arrangement direction.

  According to this, since the outer surfaces extending in the longitudinal direction of the plurality of catalyst cases are adjacent in the direction in which the plurality of catalysts are arranged side by side, for example, the outer surfaces extending in the short direction of the plurality of catalyst cases are Compared to the case where the catalysts are arranged side by side in the juxtaposed direction, it becomes easier to ensure the heat transfer area between the cases of the adjacent catalysts. Therefore, the temperature of the plurality of catalysts is not easily lowered, and the heat retention is improved.

In the exhaust system for an internal combustion engine, the merged exhaust pipe may be provided with two of the catalysts, and a connection exhaust pipe for connecting the two catalysts may be disposed between the banks.
According to this, since the temperature of the exhaust gas flowing in the connection exhaust pipe is less likely to decrease due to the heat trapped between the banks and the heat retention is improved, of the two catalysts, the downstream of the connection exhaust pipe. It is possible to easily raise the temperature of the arranged catalyst to be higher than the activation temperature.

  According to this invention, the temperature of the catalyst can be quickly raised to the activation temperature or higher while suppressing deterioration of fuel consumption.

1 is a schematic view of an exhaust device for an internal combustion engine in an embodiment. The front view of an internal combustion engine.

Hereinafter, an embodiment embodying an exhaust device for an internal combustion engine will be described with reference to FIGS. 1 and 2. The internal combustion engine of this embodiment is mounted on a vehicle.
As shown in FIGS. 1 and 2, the internal combustion engine 10 includes a cylinder block 11. As shown in FIG. 2, the cylinder block 11 includes a main body 20, a left bank 21 as a first bank, and a right bank 31 as a second bank. The left bank 21 includes a left cylinder head 22 for the left bank 21, and the right bank 31 includes a right cylinder head 32 for the right bank 31. The left bank 21 and the right bank 31 extend in a branched manner with respect to the main body 20 and are arranged in a V shape. A crankshaft 12 is accommodated in the main body 20.

  As shown in FIG. 1, the left bank 21 has four cylinders 23. The right bank 31 has four cylinders 33. Therefore, the left bank 21 and the right bank 31 have a plurality of cylinders. The internal combustion engine 10 of this embodiment is a V-type 8-cylinder diesel engine. The arrangement directions X1 of the four cylinders 23 and 33 of the left bank 21 and the right bank 31 are the same.

  As shown in FIG. 2, pistons 24 that can reciprocate in the cylinders 23 are accommodated in the cylinders 23 of the left bank 21. Each piston 24 is connected to the crankshaft 12 via a connecting rod 25. The reciprocating motion of each piston 24 is converted into the rotational motion of the crankshaft 12 by the connecting rod 25.

  In addition, in each cylinder 33 of the right bank 31, pistons 34 that can reciprocate in the respective cylinders 33 are housed. Each piston 34 is connected to the crankshaft 12 via a connecting rod 35. The reciprocating motion of each piston 34 is converted into the rotational motion of the crankshaft 12 by the connecting rod 35.

  An oil pan 15 is attached to the main body portion 20 of the cylinder block 11. The oil pan 15 is attached to an end surface (lower surface) opposite to the left bank 21 and the right bank 31 with respect to the main body 20. Engine oil is stored in the oil pan 15.

  The left bank 21 has a left bank inclined surface 21 a extending from the main body 20 and positioned on the right bank 31 side. The left bank inclined surface 21 a includes an inclined surface 211 of a portion of the cylinder block 11 that forms the left bank 21 and a surface 22 a of the left cylinder head 22 that is continuous with the inclined surface 211.

  The right bank 31 has a right bank inclined surface 31a extending from the main body 20 and positioned on the left bank 21 side. The right bank inclined surface 31 a includes an inclined surface 311 of a portion of the cylinder block 11 that forms the right bank 31 and a surface 32 a of the right cylinder head 32 that is continuous with the inclined surface 311.

  The main body 20 has a valley surface 20a that connects the left bank inclined surface 21a and the right bank inclined surface 31a. And the virtual straight line L1, the left bank inclined surface 21a, the right bank connecting the edge of the left bank inclined surface 21a opposite to the valley surface 20a and the edge of the right bank inclined surface 31a opposite to the valley surface 20a. A space surrounded by the inclined surface 31 a and the valley surface 20 a is an interbank space 18 between the left bank 21 and the right bank 31.

  As shown in FIG. 1, the exhaust device 40 includes a left bank exhaust pipe 41 as a first bank exhaust pipe connected to the left bank 21 and a second bank exhaust pipe connected to the right bank 31. And a right bank exhaust pipe 51. The left bank exhaust pipe 41 is an exhaust manifold used to collect exhaust gas from the cylinders 23 of the left bank 21 in one exhaust pipe. The right bank exhaust pipe 51 is an exhaust manifold used to collect exhaust gas from the cylinders 33 of the right bank 31 into one exhaust pipe. Further, the exhaust device 40 joins the left bank exhaust pipe 41 and the right bank exhaust pipe 51 on the downstream side in the flow direction of the exhaust gas flowing through the left bank exhaust pipe 41 and the right bank exhaust pipe 51, respectively. Part 60. The exhaust device 40 includes one merged exhaust pipe 61 connected to the merge unit 60.

  A turbine 62 constituting a turbocharger is installed in the merged exhaust pipe 61. In FIG. 1, the illustration of the compressor constituting the turbocharger provided in the intake passage is omitted. The turbine 62 is rotated by the exhaust pressure of the exhaust gas flowing in the merged exhaust pipe 61, and the compressor is driven as the turbine 62 rotates, so that fresh air flowing in the intake passage is compressed and is supplied to the internal combustion engine 10. Supercharging is performed.

  Further, the exhaust device 40 includes a first catalyst 71 and a second catalyst 72 as catalysts provided in the merged exhaust pipe 61. Therefore, the merging exhaust pipe 61 is provided with a plurality of catalysts. In the present embodiment, the merging exhaust pipe 61 is provided with two catalysts. The first catalyst 71 and the second catalyst 72 are provided on the downstream side of the turbine 62 in the merged exhaust pipe 61. The first catalyst 71 is provided upstream of the second catalyst 72 in the merged exhaust pipe 61. The first catalyst 71 and the second catalyst 72 are installed in series with the merged exhaust pipe 61. The first catalyst 71 is, for example, an oxidation catalyst that oxidizes and purifies unburned fuel components in the exhaust gas. The second catalyst 72 is an SCRF catalyst in which a NOx purification catalyst that purifies nitrogen oxides in exhaust gas and a DPF that collects PM in exhaust gas are integrated.

  The combined exhaust pipe 61 has a first exhaust pipe 61a, a second exhaust pipe 61b, and a third exhaust pipe 61c. The first exhaust pipe 61 a connects the turbine 62 and the first catalyst 71. The second exhaust pipe 61 b is a connection exhaust pipe that connects the first catalyst 71 and the second catalyst 72. The third exhaust pipe 61c is connected to the second catalyst 72 and the exhaust gas that has passed through the second catalyst 72 flows. The second catalyst 72 is arranged on the downstream side of the second exhaust pipe 61b.

  As shown in FIG. 2, the case 71a of the first catalyst 71 has a cylindrical shape. The longitudinal direction of the case 71a is the axial direction of the case 71a. The case 72a of the second catalyst 72 is cylindrical. The longitudinal direction of the case 72a is the axial direction of the case 72a. The first catalyst 71 and the second catalyst 72 are disposed between the banks 18. In the present embodiment, the first catalyst 71 and the second catalyst 72 are arranged with respect to the internal combustion engine 10 so that most of the first catalyst 71 and most of the second catalyst 72 are located between the banks 18. Has been. As for the 1st catalyst 71 and the 2nd catalyst 72, each case 71a, 72a is attached to the cylinder block 11 via the attachment member which is not shown in figure.

  As shown in FIG. 1, the first catalyst 71 and the second catalyst 72 are arranged side by side in a direction in which the axial directions of the cases 71a and 72a coincide with the arrangement direction X1 and are orthogonal to the arrangement direction X1. Has been. An outer surface 71b extending in the longitudinal direction of the case 71a of the first catalyst 71 and an outer surface 72b extending in the longitudinal direction of the case 72a of the second catalyst 72 are adjacent to each other in the juxtaposition direction of the first catalyst 71 and the second catalyst 72. Yes.

  A first exhaust pipe 61a is connected to one end in the longitudinal direction of the case 71a of the first catalyst 71, and a second exhaust pipe 61b is connected to the other end in the longitudinal direction of the case 71a of the first catalyst 71. . A third exhaust pipe 61c is connected to one end in the longitudinal direction of the case 72a of the second catalyst 72, and a second exhaust pipe 61b is connected to the other end in the longitudinal direction of the case 72a of the second catalyst 72. . The second exhaust pipe 61 b is disposed between the banks 18 and is folded back between the banks 18.

Next, the operation of this embodiment will be described.
By the way, the first catalyst 71 and the second catalyst 72 exhibit the exhaust gas purification ability when the temperature rises above the activation temperature. For example, when the temperature of the exhaust gas is low, the first catalyst 71 and the second catalyst 72 The temperature of the second catalyst 72 may not rise above the activation temperature, and the exhaust gas may not be sufficiently purified by the first catalyst 71 and the second catalyst 72.

  Since the heat between the left bank 21 and the right bank 31 tends to be accumulated in the bank 18, the temperature of the first catalyst 71 and the second catalyst 72 arranged in the bank 18 is lowered by the heat accumulated in the bank 18. It becomes difficult and heat retention improves. Thereby, the temperature of the 1st catalyst 71 and the 2nd catalyst 72 rises more than the activation temperature at an early stage.

In the above embodiment, the following effects can be obtained.
(1) The first catalyst 71 and the second catalyst 72 are arranged between the banks 18. According to this, since the heat between the left bank 21 and the right bank 31 tends to be accumulated in the bank 18, the temperature of the first catalyst 71 and the second catalyst 72 is not easily lowered by the heat accumulated in the bank 18. Thermal insulation is improved. Thereby, in order to raise the temperature of the 1st catalyst 71 and the 2nd catalyst 72 more than activation temperature, since it is not necessary to raise the temperature of exhaust gas by increasing fuel injection quantity, it suppresses deterioration of fuel consumption. However, the temperature of the first catalyst 71 and the second catalyst 72 can be raised to the activation temperature or higher at an early stage.

  (2) The first catalyst 71 and the second catalyst 72 are arranged side by side in a direction in which the axial directions of the cases 71a and 72a coincide with the arrangement direction X1 and are orthogonal to the arrangement direction X1. According to this, the outer surfaces 71 b and 72 b of the cases 71 a and 72 a are adjacent to each other in the juxtaposition direction of the first catalyst 71 and the second catalyst 72. Therefore, for example, the first catalyst 71 and the second catalyst 71 that are adjacent to each other in comparison with the case where the outer surfaces extending in the short direction of the cases 71 a and 72 a are adjacent to each other in the juxtaposition direction of the first catalyst 71 and the second catalyst 72. It becomes easy to ensure the heat transfer area between the cases 71a and 72a of the catalyst 72. Therefore, the temperature of the first catalyst 71 and the second catalyst 72 is not easily lowered, and the heat retention is improved.

  (3) The second exhaust pipe 61 b is disposed between the banks 18. According to this, since the temperature of the exhaust gas flowing in the second exhaust pipe 61b is not easily lowered by the heat trapped between the banks 18, and the heat retention is improved, the temperature of the second catalyst 72 is set to the activation temperature. It can make it easy to raise as mentioned above.

  (4) The inter-bank 18 is effectively used as an arrangement space for the first catalyst 71 and the second catalyst 72. For this reason, it is not necessary to prepare the arrangement space for the first catalyst 71 and the second catalyst 72 separately.

  (5) Since the first catalyst 71 and the second catalyst 72 can be arranged at a position close to the internal combustion engine 10, the temperature of the exhaust gas is hardly lowered, and the temperatures of the first catalyst 71 and the second catalyst 72 are activated. The time until the temperature rises above the temperature can be shortened.

  (6) For example, when the first catalyst 71 and the second catalyst 72 are arranged below the floor of the passenger space of the vehicle behind the engine room, the first catalyst 71 and the second catalyst 72 are separated from the internal combustion engine 10. The first catalyst 71 and the second catalyst 72 are easily cooled. However, in the present embodiment, since the first catalyst 71 and the second catalyst 72 can be disposed at positions close to the internal combustion engine 10, the first catalyst 71 and the second catalyst 72 are difficult to cool.

  (7) When a predetermined amount of PM accumulates in the second catalyst 72, so-called PM regeneration is performed in which the exhaust temperature is set high and the filter is regenerated by burning the PM with the exhaust heat. At this time, according to the present embodiment, since the temperature of the second catalyst 72 is not easily lowered by the heat accumulated between the banks 18, heat dissipation during PM regeneration is suppressed, and the time required for PM regeneration can be shortened. .

In addition, you may change the said embodiment as follows.
In the embodiment, the first catalyst 71 and the second catalyst 72 may be arranged such that the axial directions of the cases 71a and 72a coincide with the arrangement direction X1 and are aligned in the arrangement direction X1. In this case, the second exhaust pipe 61b is not folded back between the banks 18 and extends in the arrangement direction X1.

  In the embodiment, the first catalyst 71 and the second catalyst 72 are arranged in such a manner that the axial directions of the cases 71a and 72a coincide with the direction orthogonal to the arrangement direction X1 and are aligned in the arrangement direction X1. Also good.

  In the embodiment, the first catalyst 71 and the second catalyst 72 are arranged in a direction in which the axial directions of the cases 71a and 72a coincide with the direction perpendicular to the arrangement direction X1 and perpendicular to the arrangement direction X1. They may be arranged side by side.

  In the embodiment, there is no second exhaust pipe 61b connecting the first catalyst 71 and the second catalyst 72, and the case 71a of the first catalyst 71 and the case 72a of the second catalyst 72 are in direct communication. It may be a configuration.

  In the embodiment, the first catalyst 71 and the second catalyst 72 are arranged with respect to the internal combustion engine 10 such that the entire first catalyst 71 and the entire second catalyst 72 are located between the banks 18. May be. In short, the first catalyst 71 and the second catalyst 72 are arranged with respect to the internal combustion engine 10 so that at least a part of the first catalyst 71 and at least a part of the second catalyst 72 are located between the banks 18. It only has to be done.

In the embodiment, the number of cylinders 23 in the left bank 21 and the number of cylinders 33 in the right bank 31 are not particularly limited.
In the embodiment, the number of catalysts is not particularly limited.

In the embodiment, the type of catalyst may be changed as appropriate.
In the embodiment, the internal combustion engine 10 may be other than a diesel engine, for example, a gasoline engine.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 18 ... Between banks, 21 ... Left bank as 1st bank, 23, 33 ... Cylinder, 31 ... Right bank as 2nd bank, 40 ... Exhaust device, 41 ... As exhaust pipe for 1st bank Left bank exhaust pipe, 51... Right bank exhaust pipe as a second bank exhaust pipe, 60... Merging section, 61... Merging exhaust pipe, 61 b. First catalyst, 71a, 72a, case, 72, second catalyst as catalyst.

Claims (3)

A first bank exhaust pipe connected to the first bank of the first bank and the second bank arranged in a V shape;
A second bank exhaust pipe connected to the second bank;
Connected to a junction where the first bank exhaust pipe and the second bank exhaust pipe merge on the downstream side in the flow direction of the exhaust gas flowing through the first bank exhaust pipe and the second bank exhaust pipe, respectively. One combined exhaust pipe to be
An exhaust device for an internal combustion engine comprising a catalyst provided in the merged exhaust pipe,
The exhaust system for an internal combustion engine, wherein the catalyst is disposed between banks which are between the first bank and the second bank. The first bank and the second bank have a plurality of cylinders,
The arrangement directions of the plurality of cylinders in each of the first bank and the second bank are the same,
The merged exhaust pipe is provided with a plurality of the catalysts,
Each of the plurality of catalyst cases is cylindrical, and the longitudinal direction of the case is the axial direction of the case.
2. The internal combustion engine according to claim 1, wherein the plurality of catalysts are arranged side by side in a direction in which an axial direction of each case coincides with the arrangement direction and is orthogonal to the arrangement direction. Exhaust system. The merging exhaust pipe is provided with two of the catalysts,
The exhaust system for an internal combustion engine according to claim 2, wherein a connection exhaust pipe for connecting the two catalysts is arranged between the banks.

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