JP2016121651A - Exhaust device of multicylinder internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make uniform the state of exhaust gas introduced to an air-fuel ratio sensor irrespectively of a flow velocity of the exhaust gas.SOLUTION: A columnar member 12 is provided at a position apart from an inner wall surface of each of passages 6a, 6b (an inner wall of an exhaust gas collecting pipe 7), the columnar member 12 separates a flow of exhaust gas to a side in the direction of an air-fuel ratio sensor 11 on a side opposite to the inner wall, and makes uniform a state of the flow of the exhaust gas flowing along the inner wall of the exhaust gas collecting pipe 7 whether a flow velocity of the exhaust gas is low or high.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an exhaust device for a multi-cylinder internal combustion engine having an exhaust gas sensor in an exhaust collecting pipe.

  Exhaust gas from a multi-cylinder internal combustion engine (multi-cylinder engine) is sent from an exhaust gas passage of each cylinder to an exhaust collecting pipe and discharged through an exhaust purification device or the like. The exhaust collecting pipe is provided with an exhaust gas sensor (air-fuel ratio sensor) that detects the oxygen concentration in the exhaust gas and obtains the air-fuel ratio. The exhaust collecting pipe has a shape in which the exhaust gas of a plurality of exhaust gas passages gathers by reducing the pipe diameter. For this reason, in a multi-cylinder engine, the exhaust gas from the cylinder at the end is guided along the curved surface of the inner wall of the exhaust collecting pipe and comes into contact with the air-fuel ratio sensor.

  Since the exhaust gas from the cylinder at the end is guided along the curved surface of the inner wall of the exhaust collecting pipe, the exhaust gas is separated from the inner wall on the upstream side of the curved surface when the flow rate of the exhaust gas is high, and the air-fuel ratio sensor Contact strongly. Conversely, when the exhaust gas flow rate is slow, the exhaust gas is guided downstream along the curved surface and contacts the air-fuel ratio sensor.

  If the exhaust gas flow rates are different, especially when the exhaust gas strikes the air-fuel ratio sensor strongly at the end cylinder, a part of the exhaust gas hits the side of the air-fuel ratio sensor and the remaining exhaust gas is the air-fuel ratio sensor. There will be a case of passing through.

  If the exhaust gas contact status with the air-fuel ratio sensor varies depending on the exhaust gas flow rate, the exhaust gas contact status with the air-fuel ratio sensor becomes non-uniform due to the change in the flow rate, and when the detection result of the air-fuel ratio sensor is fed back Therefore, it is necessary to control the air-fuel ratio by performing correction according to the flow rate of the exhaust gas.

  For this reason, a technique has been proposed in which a protruding member for directing the flow of exhaust gas to the air-fuel ratio sensor is provided on the inner wall of the exhaust collecting pipe (see Patent Document 1). With the technique of Patent Document 1, even when the flow rate of exhaust gas is low, the exhaust gas along the inner wall of the exhaust collecting pipe can be brought into contact with the air-fuel ratio sensor without being guided downstream.

  However, the technique of Patent Document 1 devises the shape of the inner wall of the exhaust collecting pipe so that the exhaust gas of the end cylinder flowing along the inner wall of the exhaust collecting pipe is brought into good contact with the air-fuel ratio sensor, thereby The exhaust gas is uniformly brought into contact with the air-fuel ratio sensor.

  For this reason, if the flow rate of the exhaust gas is different, the direction of the exhaust gas flowing along the inner wall remains the same, and the contact state of the exhaust gas with the air-fuel ratio sensor becomes uneven due to the change in the flow rate. .

  For this reason, the flow to the air-fuel ratio sensor cannot be made uniform regardless of the exhaust gas flow rate, and there is a limit to accurately detecting the air-fuel ratio, and the air-fuel ratio correction according to the exhaust gas flow rate is limited. The fact is that it cannot be simplified.

JP-A-9-25841

  The present invention has been made in view of the above situation, and makes the state of the flow of the exhaust gas flowing along the inner wall of the exhaust collecting pipe uniform regardless of the flow rate of the exhaust gas so that the exhaust gas contacts the exhaust gas sensor. An object of the present invention is to provide an exhaust device for a multi-cylinder internal combustion engine capable of performing

  In order to achieve the above object, an exhaust system for a multi-cylinder internal combustion engine of the present invention according to claim 1 is arranged in communication with an exhaust gas passage of each cylinder of the multi-cylinder internal combustion engine and an exhaust gas passage of each cylinder. The exhaust gas collecting pipe in which the exhaust gas in the exhaust gas passage is gathered with a reduced diameter, the exhaust gas sensor disposed in the exhaust gas collecting pipe, the upstream side of the exhaust gas sensor, and the position away from the inner wall And a columnar member arranged in the exhaust collecting pipe.

  According to the first aspect of the present invention, the exhaust gas flowing along the inner wall of the exhaust collecting pipe is divided into a flow that flows through the inner wall side by the columnar member and a flow that faces the exhaust gas sensor on the opposite side of the inner wall. For this reason, even when the flow rate is fast or slow, it is possible to form a flow that circulates on the inner wall side and a flow toward the exhaust gas sensor.

  Therefore, regardless of the flow rate of the exhaust gas, it becomes possible to make the state of the flow of the exhaust gas flowing along the inner wall of the exhaust collecting pipe uniform and to contact the exhaust gas with the exhaust gas sensor.

  An exhaust system for a multi-cylinder internal combustion engine according to a second aspect of the present invention is the exhaust system for a multi-cylinder internal combustion engine according to the first aspect, wherein the columnar member is disposed on the opposite side of the inner wall of the exhaust collecting pipe. It has a corner portion.

  In the present invention according to claim 2, by forming the corners in the columnar member, the exhaust gas can be reliably separated at the corners, and the flow flowing through the inner wall side and the flow toward the exhaust gas sensor can be reliably performed. Can be formed.

  An exhaust system for a multi-cylinder internal combustion engine according to a third aspect of the present invention is the exhaust system for a multi-cylinder internal combustion engine according to the second aspect, wherein the columnar portion of the corner portion on the rear side in the exhaust gas flow direction is used. The member is formed with an extension extending along the flow of exhaust gas.

  In this invention which concerns on Claim 3, since the extension part was formed in the back side of a corner | angular part, the exhaust gas peeled off by the corner | angular part can be guided along the flow of exhaust gas.

  An exhaust device for a multi-cylinder internal combustion engine according to a fourth aspect of the present invention is the exhaust device for a multi-cylinder internal combustion engine according to any one of the first to third aspects, wherein the exhaust gas sensor is in the longitudinal direction. The length of the columnar member is longer than the length of the exhaust gas sensor.

  In the present invention according to claim 4, since the length of the columnar member is equal to or longer than the length of the exhaust gas sensor, the flow toward the exhaust gas sensor can be accurately guided.

  An exhaust system for a multi-cylinder internal combustion engine according to a fifth aspect of the present invention is the exhaust system for a multi-cylinder internal combustion engine according to any one of the first to fourth aspects, wherein the exhaust gas sensor is the exhaust system. An air-fuel ratio sensor in which a gas contacting element is covered with a cylindrical cover, the exhaust gas inlet is formed on the peripheral surface of the cover, and the columnar member is located upstream of the exhaust gas flow. And at least a part of the inflow port is arranged to face each other.

  In the present invention according to claim 5, as the exhaust gas sensor, an air-fuel ratio sensor in which an element that contacts the exhaust gas is covered with a cylindrical cover is applied, and a flow toward the exhaust gas sensor is formed regardless of the flow rate of the exhaust gas. can do.

  The exhaust system for a multi-cylinder internal combustion engine of the present invention can make the state of the flow of exhaust gas flowing along the inner wall of the exhaust collecting pipe uniform regardless of the flow rate of the exhaust gas, and bring the exhaust gas into contact with the exhaust gas sensor. It becomes possible.

1 is a schematic external view of a multi-cylinder internal combustion engine including an exhaust device according to an embodiment of the present invention. 1 is a schematic plan view of an exhaust device according to an embodiment of the present invention. It is the III-III sectional view taken on the line in FIG. It is a schematic plan view showing the flow of exhaust gas. It is a schematic plan view of the exhaust apparatus which concerns on the other Example of this invention. It is a schematic plan view of the exhaust apparatus which concerns on the other Example of this invention.

An exhaust system according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic external view of a main part of a multi-cylinder internal combustion engine provided with an exhaust device according to an embodiment of the present invention as viewed from the exhaust side, and FIG. 2 is an exhaust device according to an embodiment of the present invention. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2, and shows a side view of the relationship between the air-fuel ratio sensor as the exhaust gas sensor and the columnar member. It is shown.

The entire exhaust system will be described with reference to FIGS.
As shown in FIGS. 1 and 2, three exhaust passages 3 are provided in a cylinder head 2 of a three-cylinder engine 1 that is a multi-cylinder internal combustion engine (multi-cylinder engine), and an end of the exhaust passage 3 serving as an exhaust gas passage is provided. The part opens toward the outside.

  An exhaust manifold 5 is connected to a portion of the exhaust passage 3 of the cylinder head 2 via a gasket 4. The exhaust manifold 5 is formed by a passage 6 as an exhaust gas passage continuing to the exhaust passage 3 and an exhaust collecting pipe 7 in which the diameter of the pipe is reduced and the passage 6 (exhaust gas in the passage 6) is gathered.

  As shown in FIG. 2, the passages 6a, 6b, 6c of the exhaust manifold 5 communicate with the three exhaust passages 3a, 3b, 3c, and the exhaust gas passes through the exhaust passages 3a, 3b, 3c and the passages 6a, 6b, 6c. A passage is constructed. An exhaust collecting pipe 7 is arranged facing the central exhaust passage 3b and passage 6b (exhaust gas passage). An exhaust gas sensor (air-fuel ratio sensor) 11 is provided in the exhaust collecting pipe 7.

  The inner wall (inner wall surface) of the passage 6a that communicates with the exhaust passage 3a at one end, the inner wall (inner wall surface) of the passage 6c that communicates with the exhaust passage 3c at the other end, Each of them has a curved surface.

  When the flow rate of the exhaust gas flowing through the passages 6a and 6c is high, the exhaust gas flows away from the inner wall surface in the middle of the curved surface. When the flow velocity of the exhaust gas flowing through the passages 6a and 6c is slow, it flows along the inner wall surface up to the most downstream side of the curved surface. For this reason, the path (streamline) through which the exhaust gas flows differs according to the flow velocity, and the contact state of the exhaust gas to the air-fuel ratio sensor 11 varies depending on the flow velocity.

  In order to make the contact state of the exhaust gas to the air-fuel ratio sensor 11 uniform regardless of the flow rate of the exhaust gas, a columnar member 12 is provided in the exhaust collecting pipe 7 on the side of the passages 6a, 6c on the upstream side of the air-fuel ratio sensor 11. Each is provided. The columnar member 12 is disposed at a position separated from the inner wall surfaces of the passages 6a and 6c.

  For this reason, the exhaust gas flowing along the inner wall surfaces of the passages 6a and 6c (inner wall of the exhaust collecting pipe 7) is directed to the air-fuel ratio sensor 11 on the opposite side of the inner wall from the flow flowing through the inner wall side by the columnar member 12. Divided by flow.

The columnar member 12 will be specifically described with reference to FIGS.
As shown in FIGS. 2 and 3, the columnar member 12 is formed of a rectangular plate-like long member, and a corner portion 13 is formed on the opposite side of the inner wall surfaces of the passages 6 a and 6 c (inner wall of the exhaust collecting pipe 7). Has been. That is, the columnar member 12 includes an upstream rectangular portion 14 disposed on the upstream side of the passages 6 a and 6 c and a downstream rectangular portion 15 continuously disposed on the downstream side of the upstream rectangular portion 14.

  Then, the downstream rectangular shape with respect to the extension line X of the width of the upstream rectangular portion 14 in the exhaust gas flow direction, that is, the width of the section along the line AA in FIG. The width of the portion 15 in the flow direction of the exhaust gas, that is, the width Y of the cross section along the line AA in FIG. 3 and the width Y of the surface along the paper surface in FIG. 2 is an angle α (for example, 45 degrees). The boundary portion between the upstream rectangular portion 14 and the downstream rectangular portion 15 is a corner portion 13.

  The columnar member 12 is composed of an upstream rectangular portion 14 and a downstream rectangular portion 15, and the corner portion 13 is formed by arranging the upstream rectangular portion 14 and the downstream rectangular portion 15 according to the inclination of the angle α. Separation can be ensured, and a flow flowing through the inner wall surfaces of the passages 6a and 6c (inner wall of the exhaust collecting pipe 7) and a flow toward the air-fuel ratio sensor 11 can be reliably formed.

  Since the columnar member 12 forms the corner portion 13 by arranging the upstream rectangular portion 14 and the downstream rectangular portion 15 with the inclination of the angle α, an extension portion (downstream) extending along the exhaust gas flow behind the corner portion 13. A rectangular portion 15) is formed. For this reason, the exhaust gas peeled off at the corner 13 can be guided along the flow of the exhaust gas to the downstream side of the passages 6a and 6c (the outlet side of the exhaust collecting pipe 7).

A schematic configuration of the air-fuel ratio sensor 11 and an arrangement state of the columnar members 12 will be described based on FIG.
As shown in FIG. 3, the air-fuel ratio sensor 11 is configured by covering an element 21 that contacts exhaust gas with a cylindrical cover 22. An exhaust gas inflow port 23 (inflow portion) is formed in the lower peripheral surface of the cover 22, and an exhaust gas outflow port 24 is formed in the bottom portion of the cover 22.

  An inner cylinder 25 is provided inside the cover 22. Exhaust gas flowing in from the inlet 23 is guided to the outer periphery of the intermediate cylinder 25 and guided to the element 21 from above, and the exhaust gas contacting the element 21 is the middle cylinder. It is guided to the inner periphery of 25 and led to the outlet 24.

  The columnar member 12 is installed in the passages 6 a and 6 c, and the air-fuel ratio sensor 11 is installed in the exhaust collecting pipe 7. The length H of the columnar member 12 with respect to the longitudinal direction (vertical direction in FIG. 3) of the cover 22 of the air-fuel ratio sensor 11 is the same as the length h of the cover 22 (more than the length h of the cover 22). ) It is possible to make the length H of the columnar member 12 longer than the length h of the cover 22.

  Since the length H of the columnar member 12 is equal to or longer than the length h of the cover 22, the flow of exhaust gas toward the air-fuel ratio sensor 11 can be accurately guided.

The flow of the exhaust gas of the exhaust device described above will be described with reference to FIG.
FIG. 4 shows a cross-sectional view of the connection state between the exhaust passage and the exhaust manifold showing the flow state of the exhaust gas, and the left cylinder passage (passage 6a) in the drawing shows the flow state of the exhaust gas having a low flow velocity. In the drawing, the right cylinder passage (passage 6c) is a flow of exhaust gas having a high flow velocity.

  Since the exhaust collecting pipe 7 has a shape in which the exhaust diameters of the three exhaust gas passages are gathered by reducing the pipe diameter, the exhaust gas from the exhaust passages 3a, 3c of the cylinders at the end portions passes through the passages 6a, 6c. It is guided along the curved surface of the inner wall of this and comes into contact with the air-fuel ratio sensor 11.

  Since exhaust gas from the exhaust passages 3a and 3c of the end cylinders is guided along the curved surface of the inner wall of the passages 6a and 6c, when the exhaust gas has a high flow rate, the exhaust gas flows into the inner wall upstream of the curved surface. And comes into strong contact with the air-fuel ratio sensor 11. Conversely, when the exhaust gas flow rate is slow, the exhaust gas is guided downstream along the curved surface, and a part of the exhaust gas comes into contact with the air-fuel ratio sensor 11.

  By providing the columnar member 12, when the exhaust gas flow rate is slow, the exhaust gas flowing downstream along the curved surface is guided to the air-fuel ratio sensor 11, and the inner wall surfaces of the columnar member 12 and the passages 6a and 6c. Guided between.

  That is, as shown by the solid line in FIG. 4, when the exhaust gas flow rate is slow, a part of the exhaust gas flowing downstream along the curved surface is guided to the corner 13 side of the columnar member 12 and peeled off. Guided to the air-fuel ratio sensor 11. The remaining exhaust gas is guided between the columnar member 12 and the inner wall surfaces of the passages 6a and 6c.

  Thereby, even if the flow rate of the exhaust gas is slow, the exhaust gas can be guided and circulated to the air-fuel ratio sensor 11 without increasing the flow resistance.

  Further, when the flow rate of the exhaust gas is high due to the provision of the columnar member 12, a part of the exhaust gas separated from the inner wall surface on the upstream side of the curved surface of the passages 6a and 6c is part of the columnar member 12 and the passages 6a and 6c. And the air-fuel ratio sensor 11.

  That is, as shown by the dotted line in FIG. 4, when the exhaust gas flow rate is high, a part of the exhaust gas that peels from the inner wall surface on the upstream side of the curved surface of the passages 6 a and 6 c is separated from the columnar member 12 and the passage 6 a. It is guided between the inner wall surface of 6c. The remaining exhaust gas passes through the corner 13 and is guided to the air-fuel ratio sensor 11.

  Thereby, even if the flow rate of the exhaust gas is high, a part of the exhaust gas can be circulated to the side of the air-fuel ratio sensor 11 without increasing the flow resistance.

  Therefore, the exhaust gas flowing along the inner wall surfaces of the passages 6a and 6c (inner wall of the exhaust collecting pipe 7) is caused to flow by the columnar member 12 regardless of whether the flow rate of the exhaust gas is slow or fast. The flow of gas flowing through the side and the flow toward the air-fuel ratio sensor 11 on the opposite side of the inner wall are divided, and the state of the exhaust gas guided to the air-fuel ratio sensor 11 can be made uniform.

  As a result, regardless of the flow rate of the exhaust gas, the state of the exhaust gas flowing along the inner wall of the passages 6a and 6c (the inner wall of the exhaust collecting pipe 7) is made uniform, and the exhaust gas is sent to the air-fuel ratio sensor 11. Can be brought into contact with each other, and stable detection performance can be obtained.

  In the above-described embodiments, the three-cylinder engine 1 is described as an example of the multi-cylinder engine. However, the present invention is applicable to a two-cylinder engine, a four-cylinder engine, an in-line six-cylinder engine, or a multi-cylinder engine having more cylinders. It is also possible to do.

Another embodiment of the present invention will be described with reference to FIGS.
5 and 6 show schematic plan views of an exhaust device according to another embodiment of the present invention. The embodiment shown in FIGS. 5 and 6 differs in the shape of the columnar member. For this reason, the same code | symbol is attached | subjected to the member same as the member capital shown in FIG. 2, FIG.

  The embodiment shown in FIG. 5 is an example in which a quadrangular columnar columnar member 31 having a rectangular cross section is provided. The columnar member 31 is disposed at a position spaced from the inner wall surfaces of the passages 6a and 6c, and the corner opposite to the inner wall surfaces of the passages 6a and 6c is a corner portion 32 having an angle of 90 degrees.

  By providing the quadrangular columnar columnar member 31, the exhaust gas flows along the inner wall surfaces of the passages 6a and 6c (inner wall of the exhaust collecting pipe 7) regardless of whether the flow rate of the exhaust gas is slow or fast. The exhaust gas is divided by the columnar member 31 into a flow flowing on the inner wall side and a flow toward the air-fuel ratio sensor 11 on the opposite side of the inner wall, and the state of the exhaust gas guided to the air-fuel ratio sensor 11 is made uniform. Can do.

  The embodiment shown in FIG. 6 is an example in which a triangular columnar columnar member 35 having a right-angled triangular cross section is provided. The columnar member 35 is disposed at a position separated from the inner wall surfaces of the passages 6a and 6c, and a vertex portion is disposed on the opposite side of the inner wall surfaces of the passages 6a and 6c to form a corner portion 36 having an angle of 90 degrees. , 6c is a straight wall with a bottom portion disposed on the side facing the inner wall surface.

  By providing the triangular columnar member 35, the exhaust gas flowing along the inner wall surfaces of the passages 6a and 6c (inner wall of the exhaust collecting pipe 7), regardless of whether the flow rate of the exhaust gas is slow or fast. The gas is divided by the columnar member 35 into a flow that circulates on the inner wall side and a flow that faces the air-fuel ratio sensor 11 on the opposite side of the inner wall, and the situation of the exhaust gas guided to the air-fuel ratio sensor 11 can be made uniform. it can.

  And since the side facing the inner wall surface of the passages 6a and 6c is a flow path along the straight wall, the pressure loss is suppressed to the minimum, the flow through the inner wall side and the opposite side of the inner wall The exhaust gas can be divided by the flow toward the air-fuel ratio sensor 11.

  As the columnar member, a polygonal columnar member such as a pentagonal columnar shape or a hexagonal columnar shape can be applied. Moreover, it is also possible to apply a member having no corner, for example, a columnar or elliptical columnar member.

  The present invention can be used in the industrial field of an exhaust system for a multi-cylinder internal combustion engine having an exhaust gas sensor in an exhaust collecting pipe.

1 3 cylinder engine 2 cylinder head 3 exhaust passage 4 gasket 5 exhaust manifold 6 passage 7 exhaust collecting pipe 11 exhaust gas sensor (air-fuel ratio sensor)
12, 31, 35 Columnar member 13, 32, 36 Corner 21 Element 22 Cover 23 Inlet 24 Outlet 25 Middle cylinder

Claims (5)

An exhaust gas passage of each cylinder of the multi-cylinder internal combustion engine;
An exhaust collecting pipe that is arranged in communication with the exhaust gas passages of the respective cylinders, the pipe diameter of which is reduced, and the exhaust gas of the exhaust gas passages collects;
An exhaust gas sensor disposed in the exhaust collecting pipe;
An exhaust system for a multi-cylinder internal combustion engine, comprising: a columnar member disposed on the exhaust collecting pipe upstream of the exhaust gas sensor and spaced from the inner wall. The exhaust system for a multi-cylinder internal combustion engine according to claim 1,
The columnar member has a corner on the opposite side of the inner wall of the exhaust collecting pipe. An exhaust system for a multi-cylinder internal combustion engine, wherein: The exhaust system for a multi-cylinder internal combustion engine according to claim 2,
An exhaust device for a multi-cylinder internal combustion engine, characterized in that an extension portion extending along the flow of exhaust gas is formed in the columnar member at the rear portion of the corner portion in the flow direction of exhaust gas. The exhaust device for a multi-cylinder internal combustion engine according to any one of claims 1 to 3,
The length of the said columnar member with respect to the longitudinal direction of the said exhaust gas sensor is more than the length of the said exhaust gas sensor. The exhaust apparatus of the multicylinder internal combustion engine characterized by the above-mentioned. The exhaust device for a multi-cylinder internal combustion engine according to any one of claims 1 to 4,
The exhaust gas sensor is an air-fuel ratio sensor in which an element in contact with the exhaust gas is covered with a cylindrical cover,
The exhaust gas inlet is formed on the peripheral surface of the cover,
The exhaust device for a multi-cylinder internal combustion engine, wherein the columnar member is disposed so that at least a part of the inflow port faces the upstream side of the flow of the exhaust gas.

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