JP2013217288A - Exhaust port structure for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily execute both the high-temperature durability design of a supercharger and the warmup control design of an exhaust purifying catalyst.SOLUTION: A structure contains a first exhaust collection port 10 having a collection part 16 for mutually connecting a first exhaust port 11 and a fourth exhaust port 14 to be collected therein, a second exhaust collection port 20 having a collection part 26 for mutually connecting a second exhaust port 22 and a third exhaust port 23 to be collected therein. Outlets 18, 28 of the respective exhaust ports 10, 20 are situated between a second cylinder #2 and a third cylinder #3 in a cylinder arranging direction and arranged close to each other. A passage cross-sectional area S2 of the outlet in the second exhaust collection port 20 with a shorter port length of the exhaust collection ports 10, 20 is set smaller than a passage cross-sectional areas S1 of the outlet in the first exhaust collection port 10 with a long port length (S2<S1).

Description

  The present invention relates to an exhaust port structure of a multi-cylinder internal combustion engine.

  Conventionally, an exhaust port that is opened and closed by an exhaust valve is connected to each cylinder of a multi-cylinder internal combustion engine, and an exhaust manifold that joins exhaust from these exhaust ports is connected to the downstream side of each exhaust port. .

  An internal combustion engine equipped with an exhaust turbine supercharger (hereinafter referred to as a supercharger) is well known (see, for example, Patent Document 1). The supercharger described in Patent Document 1 is a twin scroll turbocharger in which two scroll passages are formed inside a turbine housing. In this internal combustion engine, a branch pipe connected to the exhaust port of the first cylinder and a branch pipe connected to the exhaust port of the fourth cylinder are connected to each other among the branch pipes of the exhaust manifold. Is introduced into one of the scroll passages. Further, the branch pipe connected to the exhaust port of the second cylinder and the branch pipe connected to the exhaust port of the third cylinder are connected to each other, and the exhaust from these branches is introduced into the other scroll passage. ing. Further, an exhaust purification catalyst for purifying exhaust gas is provided on the downstream side of the turbine housing.

According to the internal combustion engine equipped with such a supercharger, the exhaust from each branch pipe is prevented from interfering with each other.
In addition, instead of connecting the two branch pipes of the exhaust manifold to each other, it is conceivable to connect the two exhaust ports to each other. That is, as shown in FIG. 10, the exhaust port of the first cylinder # 1 (hereinafter referred to as the first exhaust port 511) and the exhaust port of the fourth cylinder # 4 (hereinafter referred to as the fourth exhaust port 514) are connected to each other. It is conceivable to connect the exhaust port of the second cylinder # 2 (hereinafter referred to as the second exhaust port 522) and the exhaust port of the third cylinder # 3 (hereinafter referred to as the third exhaust port 523). Further, a collecting portion 516 where the first exhaust port 511 and the fourth exhaust port 514 gather together and a gathering portion 526 where the second exhaust port 522 and the third exhaust port 523 gather together are arranged in close proximity, and these It is conceivable to connect a turbine housing downstream of the collecting portions 516 and 526.

JP 2009-287434 A

  Incidentally, as shown in FIG. 10, the lengths of the second exhaust port 522 and the third exhaust port 523 are shorter than the lengths of the first exhaust port 511 and the fourth exhaust port 514. Therefore, when the exhaust passes through the second exhaust port 522 and the third exhaust port 523, the cylinder head 501 is not easily deprived of the heat of the exhaust. As a result, the temperature of the exhaust discharged from the second exhaust port 522 and the third exhaust port 523 is higher than the temperature of the exhaust discharged from the first exhaust port 511 and the fourth exhaust port 514.

  Therefore, when designing the high temperature durability of the supercharger, the supercharger can withstand the exhaust discharged from the second exhaust port 522 and the third exhaust port 523, that is, the exhaust at a higher temperature. This causes a problem that the design becomes difficult.

  Further, when designing the warm-up control of the exhaust purification catalyst, even if the exhaust is exhausted from the first exhaust port 511 and the fourth exhaust port 514, that is, the exhaust gas is at a lower temperature, the exhaust purification catalyst is warmed up. As described above, the ignition timing of the first cylinder # 1 and the fourth cylinder # 4 must be retarded, resulting in a problem that the control becomes complicated.

  Such a problem is not limited to the structure including only the above-described exhaust collecting port, and similarly occurs in an exhaust port structure including an exhaust port having no collecting portion.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an exhaust port of an internal combustion engine that can easily perform both high-temperature durability design of a supercharger and warm-up control design of an exhaust purification catalyst. To provide a structure.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
(1) The invention according to claim 1 is an exhaust port structure formed in a cylinder head of a multi-cylinder internal combustion engine, in which exhaust port outlet portions extending from a plurality of cylinders are arranged in close proximity to each other. In the exhaust port structure of an engine, when the length of the passage from the inlet connected to the cylinder to the outlet opening at the end face of the cylinder head in the exhaust port is defined as the port length, the passage of the outlet portion in the exhaust port having a short port length is cut off. The main point is that the area is smaller than the passage cross-sectional area of the outlet portion of the exhaust port having a long port length.

  According to this configuration, the exhaust flow rate is high at the outlet portion of the exhaust port with a short port length, so that the flow of the exhaust gas is easily disturbed, and heat exchange between the exhaust gas and the inner wall of the exhaust port is promoted. become. For this reason, the temperature of the exhaust discharged from the exhaust port tends to decrease.

  On the other hand, according to the above configuration, the exhaust flow rate is low at the outlet portion of the exhaust port having a long port length, so that the flow of exhaust gas is less likely to be disturbed, and heat exchange between the exhaust gas and the inner wall of the exhaust port is suppressed. Become so. For this reason, the temperature of the exhaust discharged from the exhaust port is unlikely to decrease.

From these things, according to the said structure, the temperature difference of the exhaust_gas | exhaustion discharged | emitted through each exhaust port becomes small.
Therefore, according to the present invention, both the high temperature durability design of the supercharger and the warm-up control design of the exhaust purification catalyst can be easily performed.

  (2) The invention according to claim 2 is the exhaust port structure of the internal combustion engine according to claim 1, wherein the outlet portion side of another exhaust port adjacent to the outlet portion on the inner peripheral surface of the outlet portion of the exhaust port is provided. The gist is that the portion located at the end protrudes inward.

  In the cylinder head, the portion between these outlet portions tends to be high in temperature, and the temperature rise of the portion becomes more remarkable as the distance between these outlet portions becomes shorter. Therefore, it becomes difficult to ensure the high temperature durability of the part.

  In this regard, according to the above configuration, the portions located on the outlet portion side of the other exhaust ports adjacent to the outlet portion on the inner peripheral surface of the outlet portion of the exhaust port protrude inward, so that these outlet portions are mutually connected. The distance between each exit part can be ensured without expanding the space for arranging adjacently side by side outside. For this reason, the thickness of the site | part between these exit parts in a cylinder head can be ensured, and the high temperature durability in the said site | part can be ensured suitably.

  (3) The invention according to claim 3 is the exhaust port structure of the internal combustion engine according to claim 1 or claim 2, wherein the cross section of the outlet portion of each exhaust port is perpendicular to the direction in which the outlet portions are arranged. The gist is that the length of each is larger than the length in the same direction.

  According to this configuration, the passage cross section of the outlet portion of the exhaust port has an elongated shape, so that the heat of the exhaust gas passing through the outlet portion is easily taken away by the cylinder head. Thereby, the temperature of the whole exhaust gas discharged through each outlet portion can be lowered. Moreover, according to the said structure, the magnitude | size of the whole exit part in the said arrangement direction can be made small. For this reason, it becomes possible to reduce the size of the cylinder head and the size of the exhaust pipe connected to the downstream side of each exhaust port.

  (4) The invention according to claim 4 is the exhaust port structure of the internal combustion engine according to any one of claims 1 to 3, wherein the exhaust ports extending from a plurality of cylinders are connected to each other and gathered together. An exhaust collecting port having a portion is provided, and the size relationship between the passage sectional area of the outlet portion in the exhaust collecting port and the passage sectional area of the outlet portion in another exhaust port or the exhaust collecting port is the exhaust port constituting the exhaust collecting port Among them, the gist is that the port length of the exhaust port with the shortest port length is set as the port length of the exhaust collecting port.

  For example, the outlet part of the exhaust collecting port and the outlet part of another exhaust port are arranged adjacent to each other, and the port length of the exhaust port having the shortest port length among the exhaust ports constituting the exhaust collecting port. However, when the port length of the other exhaust port is made shorter, the passage sectional area of the outlet portion in the exhaust collecting port is made smaller than the passage sectional area of the outlet portion in the other exhaust port.

  Further, for example, the outlet portion of the exhaust collecting port and the outlet portion of another exhaust collecting port are arranged in close proximity to each other, and the exhaust port having the shortest port length among the exhaust ports constituting the exhaust collecting port is used. When the port length is shorter than the port length of the exhaust port having the shortest port length among the exhaust ports constituting the other exhaust collecting port, the passage cross-sectional area of the outlet portion of the exhaust collecting port is different from that of the other exhaust collecting port. It is made smaller than the passage cross-sectional area of the outlet portion at the exhaust collecting port.

  (5) According to a fourth aspect of the invention, as in the fifth aspect of the invention, the internal combustion engine is an in-line four-cylinder internal combustion engine, and two exhaust ports extending from two outer cylinders are connected to each other. And a second exhaust collection port in which two exhaust ports extending from the two inner cylinders are connected to each other, and an outlet portion of these exhaust collection ports has a cylinder arrangement direction. In the embodiment, the passage sectional area of the outlet portion of the second exhaust collecting port is made smaller than the passage sectional area of the outlet portion of the first exhaust collecting port. Can be

The schematic diagram which shows the structure of each exhaust gas collection port about the exhaust port structure of the internal combustion engine which concerns on 1st Embodiment of this invention. The schematic diagram which shows the cross-section of the 4th exhaust port along the AA line of FIG. The schematic diagram which shows the cross-section of the exit part of each gathering part along the BB line of FIG. The schematic diagram which shows the structure of each exhaust gas collection port about the exhaust port structure of the internal combustion engine which concerns on 2nd Embodiment of this invention. The schematic diagram which shows the cross-sectional shape of the 4th exhaust port along CC line | wire of FIG. The schematic diagram which shows the cross-sectional shape of each gathering part along the DD line | wire of FIG. The schematic diagram which shows the structure of each exhaust gas collection port about the modification of the exhaust port structure of the internal combustion engine which concerns on this invention. The schematic diagram which shows the structure of each exhaust gas collection port about the other modification of the exhaust port structure of the internal combustion engine which concerns on this invention. The schematic diagram which shows the structure of each exhaust gas collection port about the other modification of the exhaust port structure of the internal combustion engine which concerns on this invention. The schematic diagram which shows the structure of each exhaust port about the exhaust port structure of the conventional internal combustion engine.

A first embodiment in which the present invention is embodied as an exhaust port structure of an in-line four-cylinder internal combustion engine will be described below with reference to FIGS.
FIG. 1 schematically shows the structure of each exhaust collecting port in the exhaust port structure of the internal combustion engine according to the present embodiment.

  As shown in FIG. 1, four cylinders # 1 to # 4 are formed in series inside the cylinder head 1. Further, two exhaust collecting ports (first exhaust collecting port 10 and second exhaust collecting port 20) extending from the cylinders # 1 to # 4 toward the outer end face 1a are formed in the cylinder head 1.

Hereinafter, the arrangement direction of the cylinders # 1 to # 4 (the left-right direction in FIG. 1) is simply referred to as a cylinder arrangement direction.
The first exhaust collecting port 10 includes a first exhaust port 11, a fourth exhaust port 14, and a collecting portion 16 in which the exhaust ports 11 and 14 are connected to each other and gather.

  The first exhaust port 11 has two inlets 11a and 11b that open to the first cylinder # 1. Further, the first exhaust port 11 extends from the inlets 11a and 11b toward the outer end face 1a, and extends obliquely between the second cylinder # 2 and the third cylinder # 3. The inlets 11a and 11b are opened and closed by a known exhaust valve.

  The fourth exhaust port 14 has two inlets 14a and 14b that open to the fourth cylinder # 4. The fourth exhaust port 14 extends from the inlets 14a, 14b toward the outer end face 1a, and extends inclined between the third cylinder # 3 and the second cylinder # 2. Each inlet 14a, 14b is opened and closed by a known exhaust valve.

The collecting portion 16 is located between the second cylinder # 2 and the third cylinder # 3 in the cylinder arrangement direction. Further, the outlet 18 of the first exhaust collecting port 10 opens to the outer end face 1a.
The second exhaust collecting port 20 has a second exhaust port 22, a third exhaust port 23, and a collecting portion 26 in which the exhaust ports 22 and 23 are connected to each other.

  The second exhaust port 22 has two inlets 22a and 22b that open to the second cylinder # 2. The second exhaust port 22 extends from the inlets 22a and 22b toward the outer end face 1a, and extends inclined between the second cylinder # 2 and the third cylinder # 3. Each inlet 22a, 22b is opened and closed by a known exhaust valve.

  The third exhaust port 23 has two inlets 23a and 23b that open to the third cylinder # 3. Further, the third exhaust port 23 extends from the inlets 23a and 23b toward the outer end face 1a, and extends inclined between the third cylinder # 3 and the second cylinder # 2. Each inlet 23a, 23b is opened and closed by a known exhaust valve.

The collecting portion 26 is located between the second cylinder # 2 and the third cylinder # 3 in the cylinder arrangement direction. Further, the outlet 28 of the second exhaust collecting port 20 opens to the outer end face 1a.
Here, the collecting portions 16 and 26 including the outlets 18 and 28 of the exhaust collecting ports 10 and 20 are arranged adjacent to each other along a direction orthogonal to the cylinder arrangement direction.

  The port length of the first exhaust port 11 and the port length of the fourth exhaust port 14 are the same, and the port length of the second exhaust port 22 and the port length of the third exhaust port 23 are the same. The port lengths of the first exhaust port 11 and the fourth exhaust port 14 are longer than the port lengths of the second exhaust port 22 and the third exhaust port 23. The port length refers to the inlets 11a, 11b, 14a, 14b, 22a, 22b, 23a, and 23b connected to the cylinders # 1 to # 4 to the outlets 18 and 28 that open to the outer end surface 1a of the cylinder head 1. Means the length of the passageway.

  Further, a turbine housing constituting an exhaust turbine supercharger is connected to the downstream side of the exhaust collecting ports 10 and 20 via an exhaust pipe, and an exhaust purification catalyst is connected to the downstream side of the turbine housing.

  Next, the cross-sectional shape of each exhaust port 11, 14, 22, 23 will be described. Since the sectional shapes of the exhaust ports 11, 14, 22, and 23 are basically the same, the sectional shape of the fourth exhaust port 14 will be described here, and the other exhaust ports 11, 22, 23 are described. A description of the cross-sectional shape is omitted.

FIG. 2 schematically shows a cross-sectional shape of the fourth exhaust port 14 along the line AA of FIG.
As shown in FIG. 2, the passage cross section of the fourth exhaust port 14 has an elliptical shape.
Next, the cross-sectional shape of the exit part of each gathering part 16 and 26 is demonstrated.

FIG. 3 schematically shows the cross-sectional shape of the outlet portion of each of the collecting portions 16 and 26 along the line BB in FIG. In the figure, as a comparative example, two identical ellipses are indicated by broken lines.
As shown in FIG. 3, the passage cross sections of the outlet portions of the collecting portions 16 and 26 are both elliptical, and the length in the cylinder arrangement direction is larger than the length in the arrangement direction of the collecting portions 16 and 26. ing.

  Here, the passage sectional area S2 of the outlet portion in the second exhaust collecting port 20 is made smaller than the passage sectional area S1 of the outlet portion in the first exhaust collecting port 10 (S2 <S1). Specifically, the lengths of the collecting portions 16 and 26 in the cylinder arrangement direction are the same in the passage sections of the collecting portions 16 and 26. On the other hand, the length of the gathering portion 16 in the arrangement direction is larger than the reference ellipse, whereas the length of the gathering portion 26 in the arrangement direction is smaller than the reference ellipse. The sum of the passage cross-sectional areas of these collecting portions 16 and 26 is the same as the sum of the cross-sectional areas of the two ellipses in the comparative example.

Next, the operation of this embodiment will be described.
At the outlet portion of the second exhaust collecting port 20 having a short port length, the flow velocity of the exhaust becomes high, so that the flow of the exhaust is easily disturbed, and heat exchange between the exhaust and the inner wall of the collecting portion 26 is promoted. Become. For this reason, the temperature of the exhaust gas discharged from the collecting portion 26 tends to decrease.

  On the other hand, at the outlet portion of the first exhaust collecting port 10 having a long port length, the flow velocity of the exhaust gas is low, so that the flow of the exhaust gas is not easily disturbed, and heat exchange between the exhaust gas and the inner wall of the collecting portion 16 is suppressed. It becomes like this. For this reason, it becomes difficult for the temperature of the exhaust gas discharged from the collecting portion 16 to decrease.

  For these reasons, according to the present embodiment, the temperature difference between the exhaust gases discharged through the collecting portions 16 and 26 of the exhaust collecting ports 10 and 20 becomes small. As a result, the maximum value of the temperature of the exhaust gas introduced into the supercharger can be made smaller than the configuration of the comparative example shown by the broken line in FIG. 3, and the durable temperature of the turbine can be lowered. Become. Further, the minimum value of the temperature of the exhaust gas flowing into the exhaust purification catalyst can be made larger than that of the configuration of the comparative example shown by the broken line in FIG. 3, and the warm-up control frequency of the exhaust purification catalyst can be reduced. become able to.

According to the exhaust port structure of the internal combustion engine according to the present embodiment described above, the following effects (1) to (3) can be obtained.
(1) The first exhaust port 10 having the collecting portion 16 where the first exhaust port 11 and the fourth exhaust port 14 are connected to each other and the second exhaust port 22 and the third exhaust port 23 are connected to each other. And a second exhaust collecting port 20 having a collecting portion 26 that gathers together. The outlets 18 and 28 of the exhaust collecting ports 10 and 20 are located between the second cylinder # 2 and the third cylinder # 3 in the cylinder arrangement direction, and are arranged adjacent to each other. The passage cross-sectional area S2 of the outlet portion of the second exhaust collecting port 20 having a short port length among the exhaust collecting ports 10 and 20 is larger than the passage cross-sectional area S1 of the outlet portion of the first exhaust collecting port 10 having a long port length. (S2 <S1). According to such a configuration, both the high temperature durability design of the supercharger and the warm-up control design of the exhaust purification catalyst can be easily performed.

  (2) The length in the cylinder arrangement direction in the passage cross section of the outlet portion of each exhaust collecting port 10, 20 is larger than the length in the arrangement direction of each collecting portion 16, 26. According to such a configuration, the passage cross section of each of the collecting portions 16 and 26 is formed in an elongated shape, so that the heat of the exhaust gas passing through these outlet portions is easily taken away by the cylinder head 1. Thereby, the temperature of the whole exhaust gas discharged through each outlet portion can be lowered. Moreover, according to such a structure, the magnitude | size of the gathering parts 16 and 26 whole in the said arrangement direction can be made small. For this reason, it is possible to reduce the size of the cylinder head 1 and the size of the exhaust pipe connected to the downstream side of each of the exhaust collecting ports 10 and 20.

  (3) The lengths in the cylinder arrangement direction are the same in the passage cross sections of the collecting portions 16 and 26. According to such a configuration, since the lengths of the collecting portions 16 and 26 in the cylinder arrangement direction are the same in the passage cross sections of the collecting portions 16 and 26, they are connected to the downstream side of the exhaust collecting ports 10 and 20. This makes it possible to simplify the structure of the exhaust pipe.

Next, a second embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, the cross-sectional shapes of the collecting portion 116 of the first exhaust collecting port 110 and the collecting portion 126 of the second exhaust collecting port 120 are different from those of the first embodiment. In addition, about the structure which is the same as that of 1st Embodiment or corresponding | compatible, the code | symbol which added "100" is attached | subjected and the duplicate description is omitted.

The following description will be focused on the differences from the first embodiment.
As shown in FIG. 4, the first exhaust collecting port 110 is connected to the first exhaust port 111, the fourth exhaust port 114, and the exhaust ports 111, 114 in the same manner as in the first embodiment. It has the gathering part 116 which gathers. Similarly to the first embodiment, the second exhaust collecting port 120 is a second exhaust port 122, a third exhaust port 123, and a collecting portion 126 where these exhaust ports 122, 123 are connected to each other and gather together. have.

FIG. 5 schematically shows a cross-sectional shape of the fourth exhaust port 114 along the line CC in FIG.
As shown in FIG. 5, the passage cross section of the fourth exhaust port 114 has an elliptical shape. The cross-sectional shapes of the other exhaust ports 111, 122, 123 are basically the same as the cross-sectional shape of the fourth exhaust port 114.

Next, the cross-sectional shape of the exit part of each gathering part 116 and 126 is demonstrated.
FIG. 6 schematically shows a cross-sectional shape of the outlet portion of each collecting portion 116, 126 along the line DD in FIG.

  As shown in FIG. 6, the passage cross sections of the outlet portions of the collecting portions 116 and 126 are both substantially elliptical, and the length in the cylinder arrangement direction is larger than the length of the collecting portions 116 and 126 in the arrangement direction. Has been. Further, a protruding portion 116a that is curved and protrudes inward is formed on a portion of the inner peripheral surface of the collecting portion 116 located on the collecting portion 126 side. Further, a protruding portion 126a that is curved and protrudes inward is formed on a portion of the inner peripheral surface of the collecting portion 126 located on the collecting portion 116 side.

Next, the operation of this embodiment will be described.
In general, in a cylinder head, a portion between two collecting portions tends to be high in temperature, and as the distance between these collecting portions becomes shorter, the temperature rise of the portion becomes more remarkable. Therefore, it becomes difficult to ensure the high temperature durability of the part.

  In this regard, according to the present embodiment, the portion located on the other assembly portion 126 (116) side adjacent to the assembly portion 116 (126) on the inner peripheral surface of the assembly portion 116 (126) protrudes inward. Therefore, it is possible to secure a distance between the respective collective portions 116 and 126 without expanding a space for arranging the collective portions 116 and 126 adjacent to each other. For this reason, in the cylinder head 101, the thickness of the site | part between these assembly parts 116 and 126 can be ensured, and the high temperature durability in the said site | part is suitably ensured.

According to the exhaust port structure of the internal combustion engine according to the present embodiment described above, the following effect (4) can be obtained in addition to the effects (1) to (3) of the first embodiment. become.
(4) On the inner peripheral surface of the collecting portion 116 (126) of the exhaust collecting port 110 (120), a portion located on the other collecting portion 126 (116) side adjacent to the collecting portion 116 (126) protrudes inward. Yes. According to such a configuration, the cylinder head 101 suitably ensures high-temperature durability at the portion between the collecting portions 116 and 126 without expanding the space for arranging the collecting portions 116 and 126 adjacent to each other. Will be able to.

  The exhaust port structure of the internal combustion engine according to the present invention is not limited to the configuration exemplified in the above-described embodiment, and can be implemented as, for example, the following forms appropriately modified.

  In each of the above-described embodiments, the example in which the outlet portions of the exhaust collecting ports 10, 20, 110, and 120 are arranged close to each other along a direction orthogonal to the cylinder arrangement direction is illustrated. However, the direction in which the outlet portions of the exhaust collecting ports are arranged is not limited to this. For example, the outlet portions may be arranged close to each other along the cylinder arrangement direction.

  As shown in FIG. 7, if the crotch portion 215 of the first exhaust port 211 and the fourth exhaust port 214 has an acute angle shape, the exhaust from one exhaust port 211 (214) The exhaust port 214 (211) is restrained from entering the exhaust port 214 (211), and the exhaust is suitably discharged to the outlet 218 of the first exhaust collecting port 210. For this reason, it is possible to suitably suppress the temperature drop of the exhaust discharged from the first exhaust collecting port 210, and to further reduce the temperature difference of the exhaust discharged through the collecting portion of each exhaust collecting port. Become.

  -In the said 1st Embodiment, it illustrated about what the channel | path cross section of the exit part of each collection part 16 and 26 makes an elliptical shape. However, the present invention is not limited to this. For example, the passage cross section of the outlet portion of each collecting portion may have a polygonal shape.

  In each of the above-described embodiments and modifications thereof, the present invention is applied to the exhaust port structure of an in-line four-cylinder internal combustion engine. However, the present invention is not limited to this, and for example, in-line three-cylinder The present invention can also be applied to an internal combustion engine, an in-line 5-cylinder internal combustion engine, an in-line 6-cylinder internal combustion engine, and the like.

Here, an example in which the present invention is applied to an in-line three-cylinder internal combustion engine will be described with reference to FIG.
As shown in FIG. 8, the exhaust collecting port 310 includes a collecting portion 316 in which a first exhaust port 311 extending from the first cylinder # 1 and a second exhaust port 312 extending from the second cylinder # 2 are connected to each other and gather. The same collecting portion 316 is formed at the position of the second cylinder # 2 in the cylinder arrangement direction. Further, the outlet portion 336 of the third exhaust port 333 extending from the third cylinder # 3 is formed at the position of the second cylinder # 2 in the cylinder arrangement direction. Here, since the port length of the second exhaust port 312 is shorter than the port length of the first exhaust port 311, the passage cross-sectional area of the collecting portion 316 of the exhaust collecting port 310 and the passage of the outlet portion 336 of the third exhaust port 333. In setting the magnitude relationship with the cross-sectional area, the port length of the second exhaust port 312 is set as the port length of the exhaust collecting port 310. At this time, since the port length of the exhaust collecting port 310 (port length of the second exhaust port 312) is shorter than the port length of the third exhaust port 333, the passage sectional area of the collecting portion 316 is larger than the passage sectional area of the outlet portion 336. It is also small.

  In each of the above embodiments and modifications thereof, the present invention is applied to the exhaust port structure of an internal combustion engine that includes only one cylinder row in which three or more cylinders are provided in series. However, the present invention is applied to an exhaust port structure of an internal combustion engine other than a series internal combustion engine, for example, a V-type internal combustion engine having two cylinder rows, a horizontally opposed internal combustion engine, or a W-type internal combustion engine. You can also.

  As shown in FIG. 9, the present invention can also be applied to the exhaust port structure of an in-line two-cylinder internal combustion engine. In this case, since the second exhaust port 421 extending from the second cylinder # 2 is shorter than the port length of the first exhaust port 411 extending from the first cylinder # 1, the passage sectional area of the outlet portion 426 of the second exhaust port 421 is small. The passage sectional area of the outlet portion 416 of the first exhaust port 411 is made smaller.

  DESCRIPTION OF SYMBOLS 1,101,501 ... Cylinder head, 1a, 101a ... Outer end surface 10, 110, 210 ... First exhaust collecting port, 11, 111, 211, 511 ... First exhaust port, 11a, 11b, 111a, 111b ... Inlet , 14, 114, 214, 514 ... fourth exhaust port, 14a, 14b, 114a, 114b ... inlet, 16, 116, 216, 516 ... collecting part, 18, 118, 218 ... outlet, 20, 120 ... second exhaust Collective port 22, 122, 522 ... second exhaust port, 22a, 22b, 122a, 122b ... inlet, 23, 123, 523 ... third exhaust port, 23a, 23b, 123a, 123b ... inlet, 26, 126, 526 ... collection part, 28, 128 ... outlet, 116a, 126a ... projection, 215 ... crotch part, 310 ... exhaust collection port, 311 ... first Air port 312, second exhaust port, 316 ... collecting portion, 333 ... third exhaust port, 336 ... outlet portion, 411 ... first exhaust port, 416 ... outlet portion, 421 ... second exhaust port, 426 ... outlet portion , # 1- # 4 ... cylinders.

Claims (5)

An exhaust port structure formed in a cylinder head of a multi-cylinder internal combustion engine, wherein an exhaust port outlet portion extending from a plurality of cylinders is arranged in close proximity to each other,
When the length of the passage from the inlet connected to the cylinder at the exhaust port to the outlet opening at the end face of the cylinder head is the port length,
An exhaust port structure for an internal combustion engine, characterized in that a passage sectional area of an outlet portion in an exhaust port having a short port length is smaller than a passage sectional area of an outlet portion in an exhaust port having a long port length. The exhaust port structure of the internal combustion engine according to claim 1,
An exhaust port structure for an internal combustion engine, wherein a portion located on the outlet portion side of another exhaust port adjacent to the outlet portion on the inner peripheral surface of the outlet portion of the exhaust port protrudes inward. In the exhaust port structure of the internal combustion engine according to claim 1 or 2,
An exhaust port structure for an internal combustion engine, characterized in that the length in the direction perpendicular to the direction in which the outlet portions are arranged in the passage cross section of the outlet portion of each exhaust port is larger than the length in the same direction. In the exhaust port structure of the internal combustion engine according to any one of claims 1 to 3,
An exhaust collecting port having a collecting portion in which exhaust ports extending from a plurality of cylinders are connected to each other and provided;
The relationship between the cross-sectional area of the outlet portion of the exhaust collecting port and the cross-sectional area of the outlet portion of another exhaust port or the exhaust collecting port is that of the exhaust port having the shortest port length among the exhaust ports constituting the exhaust collecting port. An exhaust port structure for an internal combustion engine, characterized in that the port length is set to be the port length of the exhaust collecting port. The exhaust port structure of the internal combustion engine according to claim 4,
The internal combustion engine is an in-line 4-cylinder internal combustion engine,
A first exhaust collecting port in which two exhaust ports extending from two outer cylinders are connected to each other and gathered;
A second exhaust collecting port in which two exhaust ports extending from the two inner cylinders are connected to each other and gathered,
The outlet portions of these exhaust collecting ports are provided close to the inner two cylinders in the cylinder arrangement direction,
An exhaust port structure for an internal combustion engine, characterized in that a passage sectional area of an outlet portion in the second exhaust collecting port is smaller than a passage sectional area of an outlet portion in the first exhaust collecting port.