JP6418384B2 - Exhaust device for multi-cylinder internal combustion engine - Google Patents

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. In a multi-cylinder engine, the length and path conditions of exhaust gas passages from each cylinder to the exhaust collecting pipe (air-fuel ratio sensor) differ depending on the layout of equipment in the engine room.

  If the length and path conditions of the exhaust gas passage from each cylinder to the exhaust collecting pipe (air-fuel ratio sensor) are different, the exhaust gas passage where the exhaust gas strongly hits the side of the air-fuel ratio sensor, the total amount of exhaust gas is the air-fuel ratio There will be an exhaust gas passage that strikes strongly from the front of the sensor, an exhaust gas passage where a part of the exhaust gas hits the side of the air-fuel ratio sensor and the remaining gas passes by the side of the air-fuel ratio sensor.

  If the contact of the exhaust gas to the air-fuel ratio sensor is different for each exhaust gas passage, the detection performance of the exhaust gas air-fuel ratio sensor for each cylinder becomes non-uniform, and when the detection result of the air-fuel ratio sensor is fed back, Therefore, it was necessary to control the air-fuel ratio by performing correction.

  For this reason, there has conventionally been a technique in which a rod-shaped member is provided on the upstream side of the air-fuel ratio sensor of the exhaust collecting pipe, turbulent flow is generated in the exhaust gas to make the exhaust gas uniform, and the exhaust gas contacts the air-fuel ratio sensor over a wide area. It has been proposed (see Patent Document 1). With the technique of Patent Document 1, the exhaust gas in the exhaust collecting pipe can be made uniform and brought into contact with the air-fuel ratio sensor.

  However, since the technique of Patent Document 1 has a configuration in which a rod-like member is provided in the exhaust collecting pipe, the exhaust gas flow rate cannot be made uniform due to the difference in the state of the exhaust gas passage of each cylinder. Only exhaust gases with different exhaust gas flow rates can be made uniform.

  For this reason, the flow rate of the exhaust gas in each cylinder cannot be made uniform to make the exhaust gas contact state with the air-fuel ratio sensor uniform, and there is a limit to accurately detecting the air-fuel ratio. The actual situation is that correction of the detected air-fuel ratio cannot be simplified.

JP 2012-77615 A

  The present invention has been made in view of the above circumstances, and provides an exhaust device for a multi-cylinder internal combustion engine that can make the exhaust gas flow velocity uniform in each cylinder of the multi-cylinder internal combustion engine and allow the exhaust gas to contact an exhaust gas sensor. The purpose is to do.

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 communicates with an exhaust passage of each cylinder provided in a cylinder head of the multi-cylinder internal combustion engine and an exhaust passage of each of the cylinders. And an exhaust collecting pipe that is connected to the cylinder head and collects exhaust gas in the exhaust passage, and a gasket that is interposed between the cylinder head and the exhaust collecting pipe and that has an opening that opens the exhaust passage. And an exhaust gas sensor provided in the exhaust collecting pipe, wherein the gasket increases the pressure loss of the exhaust passage according to the distance from the opening to the exhaust gas sensor, and the distance from the cylinder to the exhaust gas sensor is increased. The opening portion of the relatively short exhaust passage is narrower than the other opening portions .

  In the present invention according to claim 1, in the exhaust gas passage where the exhaust gas flow velocity is high, the flow area of the opening portion of the gasket is made narrower than other opening portions, the pressure loss of the exhaust gas is increased, and the flow velocity is lowered. The exhaust gas flow rate in each cylinder is made uniform.

  As a result, even in a multi-cylinder internal combustion engine, even if there is an exhaust gas passage having a fast exhaust gas flow rate (a large amount of circulation per unit time), the exhaust gas flow rate in the exhaust gas passage of each cylinder is made uniform. The exhaust gas can be brought into contact with the exhaust gas sensor.

  For example, in a three-cylinder internal combustion engine, an exhaust gas is collected in a central exhaust gas passage among three exhaust gas passages arranged in parallel (an exhaust passage of a cylinder head and an exhaust gas passage connecting the exhaust passage and the exhaust collecting pipe). When the pipes are arranged to face each other and the exhaust gas sensor is arranged at the central portion of the exhaust collecting pipe, the flow of the exhaust gas may be as follows.

  Exhaust gas in the exhaust gas passages on both sides across the center passes through the exhaust gas passage where the exhaust gas is curved and passes through the exhaust gas sensor in contact therewith. The exhaust gas in the central exhaust gas passage passes through the short exhaust gas passage which is linear and short with respect to the exhaust gas sensor at a high flow rate.

  In this state, for example, based on the detection status of the exhaust gas sensor with respect to the exhaust gas in the central exhaust gas passage, the exhaust gas having a relatively slow flow rate with respect to the exhaust gas in the exhaust gas passages on both sides across the center. As a result, the detection performance of the exhaust gas sensor is deteriorated.

  Therefore, when the exhaust gas sensor is used as an air-fuel ratio sensor and the air-fuel ratio is feedback controlled based on the detection status of the exhaust gas in the exhaust gas passages on both sides across the center, the desired air-fuel ratio cannot be controlled. There is a possibility that the gas performance cannot be satisfied.

  In such a case, according to the present invention, the flow area of the opening of the gasket of the central exhaust gas passage (exhaust gas passage having a high flow velocity) is made narrower than other openings, and the pressure loss of the exhaust gas is increased to increase the flow velocity. The exhaust gas is brought into contact with the exhaust gas sensor by making the exhaust gas flow rate uniform in each cylinder and making the flow rate of the exhaust gas uniform.

  As a result, the detection performance of the exhaust gas sensor of each cylinder by the exhaust gas sensor can be made uniform, and the feedback control can be accurately performed to prevent the exhaust gas performance from being deteriorated.

  Incidentally, as a technique for making a gas flow into a desired state using a gasket, for example, Japanese Patent Laid-Open No. 2005-98191 discloses a baffle plate that protrudes upstream from an exhaust gas inlet gasket of an exhaust gas recirculation device. And a technique for satisfactorily introducing exhaust gas into the intake passage without increasing the flow resistance of the intake air is disclosed.

  The technique of Japanese Patent Laid-Open No. 2005-98191 is the same in that the flow of exhaust gas is controlled by the shape of the circulation part of the gasket, but the exhaust gas when introducing the exhaust gas to the intake air in the exhaust gas recirculation device. It is a technology that adjusts the flow of gas. For this reason, this is a technique different from the present invention in which the flow of exhaust gas to the exhaust gas sensor in the exhaust passage is in a desired state.

An exhaust apparatus for a multi-cylinder internal combustion engine according to a second aspect of the present invention is the exhaust apparatus for a multi-cylinder internal combustion engine according to the first aspect, wherein the exhaust passage has the shortest distance from the opening to the exhaust gas sensor. The opening is made narrower than the other openings .

  In the present invention according to claim 2, the exhaust passage facing the opening portion of the gasket whose flow area is narrower than the other opening portions is the exhaust passage having the shortest distance between the exhaust gas sensor and the opening portion, that is, the exhaust passage. Since the exhaust gas flow rate per unit time for the gas sensor includes the largest exhaust passage, the flow rate of the exhaust gas to the exhaust gas sensor is lowered, and the flow rate of the exhaust gas in the exhaust passage of each cylinder is made uniform to accurately distribute the flow rate. It can be made uniform.

  An exhaust device for a multi-cylinder internal combustion engine according to a third aspect of the present invention is the exhaust device for a multi-cylinder internal combustion engine according to the first or second aspect, wherein the diameter of at least one opening of the gasket is used. Is set to be smaller than the diameter of the other opening.

  In the present invention according to claim 3, by setting the diameter of the opening through which the exhaust gas for reducing the flow velocity passes is smaller than that of the other openings, the pressure loss during passage is increased and the flow velocity is lowered. Can do.

  An exhaust system for a multi-cylinder internal combustion engine according to a fourth aspect of the present invention is the exhaust system for a multi-cylinder internal combustion engine according to the first or second aspect, wherein at least one of the openings of the gasket includes: The opening is divided into a plurality of parts.

  In the present invention according to claim 4, the flow rate per unit area of the exhaust gas applied to the exhaust gas sensor is reduced by dividing the opening of the opening through which the exhaust gas for reducing the flow rate passes into a plurality of portions, thereby reducing the flow rate. Can be in a state.

  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. The element that contacts the gas is an air-fuel ratio sensor covered with a cylindrical cover, and the exhaust gas inlet is formed on the peripheral surface of the cover.

  In the present invention according to claim 5, the flow rate of the exhaust gas flowing into the cover can be made uniform with respect to the air-fuel ratio sensor in which the element is covered with the cylindrical cover.

  The exhaust system for a multi-cylinder internal combustion engine according to the present invention makes it possible to make the exhaust gas flow rate uniform in each cylinder of the multi-cylinder internal combustion engine so that the exhaust gas contacts the exhaust gas sensor.

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 explanatory drawing of a gasket. It is explanatory drawing of an air fuel ratio sensor. It is a schematic plan view of the exhaust apparatus explaining the flow of exhaust gas. It is explanatory drawing of the gasket of the exhaust apparatus which concerns on 2nd Example. It is a schematic plan view of the exhaust apparatus which concerns on 3rd Example. It is explanatory drawing of the gasket of the exhaust apparatus which concerns on 3rd Example.

  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 shows a state of the opening of the gasket, and FIG. 4 shows a schematic configuration of the air-fuel ratio sensor. FIG. 5 shows a schematic plane (corresponding to FIG. 2) of the exhaust device for explaining the flow of exhaust gas.

  The entire exhaust system will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, the cylinder head 2 of a three-cylinder engine 1 which is a multi-cylinder internal combustion engine (multi-cylinder engine) is provided with three exhaust passages 3, and the end of the exhaust passage 3 faces outward. Open.

  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 passages 6 are gathered. The gasket 4 is formed with an opening 8 communicating the exhaust passage 3 and the passage 6.

  As shown in FIG. 2, the three exhaust passages 3a, 3b, 3c communicate with the passages 6a, 6b, 6c of the exhaust manifold 5, and the three exhaust passages 3a, 3b, 3c and the passage 6a of the exhaust manifold 5 Gasket 4 is interposed between 6b and 6c. An exhaust collecting pipe 7 is arranged opposite to the central exhaust passage 3b and the passage 6b. An exhaust gas sensor (air-fuel ratio sensor) 11 is provided in the exhaust collecting pipe 7.

  Since the air-fuel ratio sensor 11 is disposed in the exhaust gas collection pipe 7 facing the central exhaust passage 3b and the passage 6b, the exhaust gas in the exhaust passage 3b and the passage 6b is in strong contact with the air-fuel ratio sensor 11 almost entirely. Then pass. That is, the exhaust passage 3b and the passage 6b are exhaust passages having the shortest distance between the air-fuel ratio sensor 11 and an opening of a gasket described later, and the exhaust passage having the maximum amount of exhaust gas per unit time with respect to the air-fuel ratio sensor 11. Thus, the exhaust passage has the fastest exhaust gas flow velocity.

As shown in FIGS. 2 and 3, the diameter r of the opening 8b of the gasket 4 between the exhaust passage 3b and the passage 6b, which is the exhaust passage of the exhaust gas having the fastest flow rate with respect to the air-fuel ratio sensor 11, is
The diameter is set smaller than the diameter R of the openings 8a and 8c of the gasket 4 between the exhaust passages 3a and 3c and the passages 6a and 6c.

  Since the diameter r of the opening 8b of the gasket 4 is set smaller than the diameter R of the openings 8a and 8c of the gasket 4, the pressure loss of the exhaust gas flowing through the exhaust passage 3b increases, and the exhaust flowing through the passage 6b. The gas flow rate can be reduced. Therefore, the flow rate of the exhaust gas sent from the exhaust passages 3a and 3c and the passages 6a and 6c to the air-fuel ratio sensor 11 is suppressed with respect to the flow rate of the exhaust gas sent from the exhaust passage 3b and the passage 6b to the air-fuel ratio sensor 11. .

  Therefore, even if there is an exhaust passage having a high exhaust gas flow rate with respect to the air-fuel ratio sensor 11, the flow rates of the exhaust gas from the three exhaust passages 3a, 3b, 3c can be made uniform and sent to the air-fuel ratio sensor 11. .

  A schematic configuration of the air-fuel ratio sensor 11 will be described with reference to 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.

  Based on FIG. 5, the state of the exhaust gas flow in the exhaust passages 3a, 3b, 3c and the passages 6a, 6b, 6c of each cylinder in the above-described exhaust device will be described.

  The exhaust gas G1 and G3 in the exhaust passages 3a and 3c and the passages 6a and 6c on both sides across the center have a longer flow rate than the center, and the passage is bent. Further, the air-fuel ratio sensor 11 passes through a portion where the flow velocity outside the main flow is low. The exhaust gas G2 in the central exhaust passage 3b and the passage 6b increases in pressure loss at the opening 8b of the gasket 4 to decrease the flow velocity, and passes through the air-fuel ratio sensor 11 at a low flow velocity.

  Therefore, the flow rates of the exhaust gases G1, G2, and G3 in the three exhaust passages 3a, 3b, and 3c and the passages 6a, 6b, and 6c become uniform, and the contact with the air-fuel ratio sensor 11 is made uniform. That is, the flow rate per unit time of the exhaust gases G1, G2, and G3 in the exhaust passages 3a, 3b, and 3c and the passages 6a, 6b, and 6c of each cylinder is made uniform, and the exhaust gases G1, G2, and G3 are air-fuel ratios. It comes in contact with the sensor 11.

  For this reason, the exhaust gas G1, G2, G3 in each cylinder of the three-cylinder internal combustion engine has a uniform flow rate per unit time, that is, the exhaust gas G1, G2, G3 has a uniform flow rate, and the exhaust gas G1, G2 and G3 can be brought into contact with the air-fuel ratio sensor 11.

  As a result, the detection performance of the air-fuel ratio sensor 11 for the exhaust gases G1, G2, and G3 in the three exhaust passages 3a, 3b, and 3c and the passages 6a, 6b, and 6c becomes uniform, and the exhaust passages 3a, 3b, 3c, and the passage 6a , 6b, and 6c do not vary the detection performance of the exhaust gases G1, G2, and G3.

  Therefore, even if the air-fuel ratio is feedback-controlled based on the detection status of the exhaust gas G1, G2, G3 in any of the three exhaust passages 3a, 3b, 3c and the passages 6a, 6b, 6c, the desired air The exhaust gas performance is not deteriorated regardless of the exhaust passages 3a, 3b, 3c and the passages 6a, 6b, 6c through which the detected exhaust gas can be controlled.

  In the above-described embodiment, the three-cylinder engine 1 is described as an example of the multi-cylinder engine. However, the present invention can be applied to a four-cylinder engine, an in-line six-cylinder engine, or a multi-cylinder engine having more cylinders. It is.

  For example, in the case of a 4-cylinder engine, the flow through the opening of the gasket 4 of the exhaust gas passage where the exhaust gas passage has a high flow rate of exhaust gas at or both of the central two-cylinder exhaust gas passages except for both sides. It is possible to reduce the area.

  Further, in the case of an in-line 6-cylinder engine, the exhaust gas passage in the central four cylinders excluding both sides, or any one to three, that is, at least an exhaust gas passage with a high exhaust gas flow rate is used. It is possible to narrow the distribution area of the four openings.

  Another embodiment of the present invention will be described with reference to FIGS.

FIG. 6 shows the state of the opening of the gasket of the exhaust device according to the second embodiment, and FIG. 7 shows a cross-sectional view in a plane state of the connection portion between the exhaust passage and the exhaust manifold which is the exhaust device according to the third embodiment of the present invention . FIG. 8 shows the state of the opening of the gasket of the exhaust device according to the third embodiment.

The second embodiment shown in FIG. 6 includes an exhaust passage 3b (see FIG. 5) and a passage 6b ( see FIG. 5) which are exhaust passages of exhaust gas having the fastest flow velocity with respect to the air-fuel ratio sensor 11 (see FIG. 5). The shape of the opening of the gasket 4 is different from that of the first embodiment.

An opening 9b between the exhaust passage 3b (see FIG. 5) and the passage 6b ( see FIG. 5) of the gasket 4 is composed of two semicircular openings 10, and a partition 16 exists between the openings 10. doing. Openings 9a and 9c between the exhaust passages 3a and 3c (see FIG. 5) and the passages 6a and 6c ( see FIG. 5) of the gasket 4 are formed in a circular shape.

Central exhaust passage 3b, the exhaust gas G2 passage 6b (see FIG. 5) (see FIG. 5), an opening 9a at the partition portion 16, is divided into an exhaust gas passing through the 9c, the air-fuel ratio sensor 11 (see FIG. 5 Pass next to ) .

Therefore, the exhaust gas G2 ( see FIG. 5) in the exhaust passage 3b and the passage 6b (see FIG. 5) is prevented from hitting the air-fuel ratio sensor 11, and the three exhaust passages 3a, 3b, 3c (see FIG. 5) , It is possible to make the contact of the exhaust gases G1, G2, G3 (see FIG. 5) with the air-fuel ratio sensor 11 ( see FIG. 5) in the passages 6a, 6b, 6c (see FIG. 5) uniform (flow velocity). Can be made uniform).

  In the third embodiment shown in FIGS. 7 and 8, the air-fuel ratio sensor 11 is arranged offset from the center of the exhaust collecting pipe 7, and the diameter of the opening of the gasket 4 depends on the distance from the air-fuel ratio sensor 11. The diameter of the opening of the gasket 4 is changed.

  The air-fuel ratio sensor 11 is disposed at a portion of the exhaust collecting pipe 7 that is close to the exhaust passage 3a and the passage 6a.

  The diameter r of the opening 15 of the gasket 4 includes the diameter r1 of the opening 15b between the exhaust passage 3b and the passage 6b, the diameter r2 of the opening 15a between the exhaust passage 3a and the passage 6a, and the exhaust passage 3c and the passage. It is set so as to increase in the order of the diameter r3 of the opening 15c between 6c.

  That is, as the distance to the air-fuel ratio sensor 11 increases, the diameter r of the opening 15 of the gasket 4 increases in order.

  For this reason, the pressure loss of the flow path having a short distance to the air-fuel ratio sensor 11 is increased according to the distance, the flow rate of the exhaust gas is decreased according to the distance, and the three exhaust passages 3a, 3b, 3c, the passages 6a, 6b , 6c can make the flow rates of the exhaust gases G1, G2, and G3 uniform so that the contact with the air-fuel ratio sensor 11 can be made uniform (the flow rate can be made uniform). .

  Then, by setting the diameter r of the opening of the gasket 4 according to the position of the air-fuel ratio sensor 11, that is, by setting the opening area of the opening according to the position of the air-fuel ratio sensor 11, the air-fuel ratio sensor Regardless of the arrangement state of the fuel cell 11, it is possible to improve the contact state of the exhaust gas to the air-fuel ratio sensor 11 and make the detection performance uniform.

  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.

DESCRIPTION OF SYMBOLS 1 3 cylinder engine 2 Cylinder head 3 Exhaust passage 4 Gasket 5 Exhaust manifold 6 Passage 7 Exhaust collecting pipe 8, 9, 15 Opening 10 Opening 11 Exhaust gas sensor (air-fuel ratio sensor)
16 Partition part 21 Element 22 Cover 23 Inlet 24 Outlet 25 Middle cylinder

Claims (5)

An exhaust passage of each cylinder provided in a cylinder head of a multi-cylinder internal combustion engine;
An exhaust collecting pipe connected to the cylinder head in communication with the exhaust passage of each cylinder and collecting exhaust gas in the exhaust passage;
A gasket interposed between the cylinder head and the exhaust collecting pipe and having an opening in which a portion of the exhaust passage opens;
An exhaust gas sensor provided in the exhaust collecting pipe,
The gasket increases the pressure loss of the exhaust passage according to the distance from the opening to the exhaust gas sensor,
An exhaust system for a multi-cylinder internal combustion engine, wherein the opening of the exhaust passage having a relatively short distance from a cylinder to the exhaust gas sensor is narrower than the other openings . The exhaust system for a multi-cylinder internal combustion engine according to claim 1,
An exhaust system for a multi-cylinder internal combustion engine, wherein the opening of the exhaust passage having the shortest distance from the opening to the exhaust gas sensor is narrower than the other openings . The exhaust system for a multi-cylinder internal combustion engine according to claim 1 or 2,
An exhaust device for a multi-cylinder internal combustion engine, wherein a diameter of at least one of the openings of the gasket is set smaller than a diameter of other openings. The exhaust system for a multi-cylinder internal combustion engine according to claim 1 or 2,
An exhaust system for a multi-cylinder internal combustion engine, wherein the opening of at least one portion of the gasket is divided into a plurality of openings. 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,
An exhaust system for a multi-cylinder internal combustion engine, wherein the exhaust gas inlet is formed on a peripheral surface of the cover.

Images