JP2017066884A - Exhaust connection part structure of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust connection part structure of an engine in which a structure of an exhaust system is reviewed so that even when a no-load or light-load operation continues for a long period, leakage of liquid unburned material from a connection part between a cylinder head and an exhaust manifold is avoided or reduced.SOLUTION: An exhaust connection part structure of an engine includes an exhaust passage 9 attached to a cylinder head 2, and an exhaust port 13 provided in the cylinder head 2, and an exhaust route H is formed by the exhaust passage 9 and the exhaust port 13, where an outlet wall 16 of the exhaust port 13 in the cylinder head 2 and an inlet wall 17 of an exhaust manifold 9 are connected so as to hold a gasket 18 arranged between the walls 16, 17, the exhaust port 13 is inclined so that the position of a port outlet 13a opened to the outlet wall 16 becomes the highest position, and the exhaust manifold 9 is inclined so that the position of a passage inlet 9a opened to the inlet wall 17 becomes the highest position.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an engine exhaust joint structure, such as a structure of a connection part between an exhaust side of a cylinder head and an exhaust manifold in a diesel engine.

  Exhaust joint structure of this type of engine, that is, an engine having an exhaust port provided in a cylinder head and an exhaust passage attached to the cylinder head, and an exhaust path is formed by the exhaust passage and the exhaust port As the exhaust joint structure, those disclosed in Patent Document 1 and Patent Document 2 are known. In this case, as described in Patent Document 2 (see FIGS. 1 and 3), a gasket is usually interposed between the cylinder head and the exhaust manifold.

  By the way, in a diesel engine, when a no-load (or light load) operation is performed, (1) the combustion temperature is low, (2) the fuel injection rate is low and the spray becomes rough, (3) the clearance between the piston and the cylinder. Therefore, there is a chronic problem that unburned fuel and engine oil are generated in the cylinder and discharged out of the cylinder together with the exhaust.

  As the engine continues to operate normally, the combustion temperature and fuel injection rate increase, and unburned fuel and engine oil are combusted to become combustion gas. The problem of (3) is eliminated in a general driving | running state.

  However, if no-load (or light-load) operation is performed for a long time, such as when idling continues for a long time or light-load operation continues in the winter, unburned gas will be discharged into the exhaust system such as a muffler or exhaust manifold May stay inside.

  In this case, liquid unburned matter such as unburned fuel or engine oil staying in the exhaust port or exhaust manifold of the cylinder head may leak out from the joint (connecting portion) between the cylinder head and the exhaust manifold. . In many cases, the exhaust joint is provided with a gasket, but in this case, the gasket is eroded over time, and the leakage may occur.

JP, 2015-161225, A JP 2004-156547 A

  It is an object of the present invention to mainly cause liquid unburned matter to leak from the joint between the cylinder head and the exhaust manifold, even if no-load (or light-load) operation is performed for a long time due to a further structural review of the exhaust system. The object is to provide an improved engine exhaust joint structure so that this is avoided or reduced.

The invention according to claim 1 includes an exhaust port 13 provided in the cylinder head 2 and an exhaust passage 9 attached to the cylinder head 2, and the exhaust passage 9 and the exhaust port 13 provide an exhaust path. In the exhaust joint structure of the engine where H is formed,
An outlet wall 16 of the exhaust port 13 in the cylinder head 2 and an inlet wall 17 of the exhaust passage 9 are connected with a gasket 18 disposed between both of them,
The exhaust port 13 is inclined so that the port outlet 13a that opens to the outlet wall 16 has the highest height position, and the exhaust passage 9 is connected to a passage inlet 9a that opens to the inlet wall 17. Is characterized in that it is inclined so that its height position is the highest.

The invention according to claim 2 is the engine exhaust joint structure according to claim 1,
The inclination angle α of the exhaust port 13 and the inclination angle β of the exhaust passage 9 are set to 2 to 7 degrees, respectively.

The invention according to claim 3 is the engine exhaust joint structure according to claim 1 or 2,
The length range L1 of the inclination angle α of 2 to 7 degrees in the exhaust port 13 is 30 to 70 mm from the port outlet 13a, and the length range of the inclination angle β of 2 to 7 degrees in the exhaust passage 9 L2 is set to 30 to 70 mm from the passage entrance 9a, respectively.

The invention according to claim 4 is the engine exhaust joint structure according to any one of claims 1 to 3,
The cylinder head 2 is provided with a step 19 in which a recess or a hole or an outlet wall side is lowered at the bottom of a portion of the exhaust port 13 that is closer to the combustion chamber side by a predetermined length from the port outlet 13a. It is what.

According to the first aspect of the present invention, since the exhaust port and the exhaust passage are inclined such that the joint portion between the cylinder head and the exhaust passage is at the highest position, unburned fuel, engine oil, etc. Even if the liquid unburned material is discharged from the combustion chamber, it moves to the combustion chamber side in the exhaust port and moves to the exhaust outlet side in the exhaust passage due to gravity, so that it does not stay at the joint. Therefore, liquid unburned material does not exist in the joint, or even if it exists, the liquid unburned material may leak from the joint.

It can be reduced or avoided.
As a result, liquid unburned matter leaks from the joint between the exhaust passage and the cylinder head, such as an exhaust manifold, even if no-load (or light-load) operation is performed for a long time, mainly due to a further structural review of the exhaust system. An improved engine exhaust joint structure can be provided so that this is avoided or reduced.

  If the inclination angle of the exhaust port and the inclination angle of the exhaust passage are set to 2 to 7 degrees as in the invention of claim 2, the liquid unburned material can be moved gently away from the joint by gravity. This is advantageous because the exhaust path does not bend at a steep angle at the joint due to the steep inclination angle exceeding 7 degrees.

  As in the invention of claim 3, if the lengths of the inclined portions in the exhaust port and the exhaust passage are set to 30 to 70 mm from the joint, respectively, the exhaust port and the exhaust passage are designed. There is an advantage that the effect of preventing leakage of the liquid unburned product from the joint portion can be exhibited while shortening the restriction condition (restricted portion) as much as possible so as not to impair the design freedom as much as possible.

  According to the fourth aspect of the present invention, a recess or a hole or a step that lowers the outlet wall side is provided at the bottom of a portion of the exhaust port that is close to the combustion chamber side by a predetermined length. The liquid unburned matter that moves to the combustion chamber side is trapped in the depressions, holes, or steps, which can avoid the disadvantage of returning directly to the combustion chamber side, which is advantageous.

Diesel engine right side view Plan view of the diesel engine shown in FIG. Cross section of the main part showing the exhaust system joint structure (A) is a front view (step Z of FIG. 3) which shows the level | step difference of an exhaust port, (b) is sectional drawing of the principal part which shows another structure of an exhaust port.

  Embodiments of an engine exhaust joint structure according to the present invention will be described below with reference to the drawings in the case of a vertical in-line three-cylinder diesel engine.

  As shown in FIGS. 1 and 2, the engine has a cylinder head 2 assembled to the upper part of the cylinder block 1, a head cover 3 assembled to the upper part of the cylinder head 2, and an oil pan 4 attached to the lower part of the cylinder block 1. The gear case 5 is assembled to the front portion of the cylinder block 1. A flywheel housing 6 is assembled to the rear portion of the cylinder block 1, and a flywheel (not shown) assembled to the crankshaft 7 is accommodated in the flywheel housing 6.

  In this engine, as shown in FIG. 2, an intake manifold 8 is assembled on the left side of the cylinder head 2, and an exhaust manifold (an example of an exhaust passage) 9 whose schematic shape is indicated by phantom lines on the right side of the cylinder head 2. Is assembled. Although not shown in the figure, a supercharger may be provided on the upper portion of the exhaust manifold 9, and the supercharger may be supercharged to the intake inlet portion of the intake manifold 8 through a pipe. Next, the structure of the exhaust path (engine exhaust joint structure) will be described.

Embodiment 1
As shown in FIG. 3, a combustion chamber 11 is formed between the piston 10 housed in a cylinder 1 </ b> A that is an upper part of the cylinder block 1 and the cylinder head 2. The combustion chamber 11 faces an intake port (not shown) in which an intake valve (not shown) is arranged and an exhaust port 13 in which an exhaust valve 12 is arranged. An exhaust path H of the engine is constituted by the exhaust port 13 and the internal exhaust path 9A in the exhaust manifold 9 described above.

  The exhaust port 13 of the cylinder head 2 has an exhaust inlet 15 made of a valve seat 14 made of an annular metal material. The exhaust inlet 15 is closed by an exhaust valve body 12A formed at the lower end of the exhaust valve 12 (state shown in FIG. 3) or opened by a downward movement of the exhaust valve 12. In the exhaust process in which the piston 10 moves upward, the exhaust valve body 12A slightly lowers from the closed position shown in FIG. 3, the exhaust inlet 15 opens, and exhaust gas and the like flow to the exhaust port 13.

  As shown in FIG. 3, the outlet wall 16 of the exhaust port 13 in the cylinder head 2 and the inlet wall 17 of the exhaust manifold 9 serving as the starting end of the internal exhaust passage 9 </ b> A are arranged between the two 16 and 17. The gasket 18 is connected with bolts (not shown) or the like with the gasket 18 interposed therebetween. The gasket 18 is a general annular ring having a small thickness. The exhaust port 13 is inclined so that the port outlet 13a that opens to the outlet wall 16 has the highest height position, and the internal outlet 9A also has a passage inlet 9a that opens to the inlet wall 17. The state where the height is the highest is inclined.

  The inclination of the exhaust port 13 is a port inclination angle α that falls to a state where the combustion chamber 11 side becomes low (the outlet wall 16 side becomes high), and the port inclination angle α is set in the range of 2 to 7 degrees. Preferably it is set to 3 degrees. The inclination of the exhaust passage 9 is an exhaust manifold inclination angle β that falls in a state where the inlet wall 17 side becomes higher, and the exhaust manifold inclination angle β is set in a range of 2 to 7 degrees, preferably set to 3 degrees. Yes. In FIG. 3, A is a horizontal line. The internal exhaust passage 9 </ b> A is configured to bend and extend in the lateral direction in the middle of the exhaust manifold 9.

  The length range L1 of the port inclination angle α of 3 degrees (2 to 7 degrees) in the exhaust port 13 is set to 30 to 70 mm, preferably 50 mm, from the port outlet 13a to the combustion chamber 11 side. The length range L2 of the exhaust manifold inclination angle β of 3 degrees (2 to 7 degrees) in the internal exhaust passage 9A is set to 30 to 70 mm, preferably 50 mm, from the passage inlet 9a toward the downstream side of the exhaust flow. . In addition, the cylinder head 2 has a step that becomes lower on the outlet wall 16 side at the bottom portion of the exhaust port 13 that is closer to the combustion chamber 11 side from the port outlet 13a by a predetermined length ("a depression or a hole or the outlet wall side becomes lower An example of “step” is provided.

  For example, as shown in FIG. 4A showing the arrow Z in FIG. 3, the step 19 is changed from a circular portion to a vertically long oval (rounded corner shape) as a cross-sectional shape of the exhaust port 13. It is constituted by. The vertical length d of the step 19 is set to 3 to 7 mm, preferably 5 mm, although it depends on the diameter and cross-sectional area of the exhaust port 13. Note that the cross-sectional shape of the exhaust port 13 may be changed from an oval shape to a circular shape from the position of the step 19 toward the outlet wall 16 side. In the structure shown in FIG. 3, a step 19 is formed at a location in the exhaust port 13 that is 50 mm away from the port outlet 13 a toward the combustion chamber 11.

In a diesel engine having such an exhaust path H, as shown in FIG. 3, unloaded (or lightly loaded) operation is performed over a long period of time. When the liquid unburned matter r is discharged from the combustion chamber 11, the liquid unburned matter r in the exhaust port 13 moves toward the combustion chamber 11 due to gravity due to the port inclination angle α and accumulates at the level difference 19. . Then, the liquid unburned substance r in the internal exhaust passage 9A moves in the direction of the exhaust outlet (opposite side of the passage inlet 9a, not shown) due to gravity due to the exhaust manifold inclination angle β (rightward direction in FIG. 3). go.
Therefore, the liquid unburned material r does not accumulate in the joint portion where the gasket 18 is provided, and thus the possibility that the liquid unburned material r leaks from the joint portion is eliminated or greatly reduced.

  Note that the liquid unburned substance r existing in the exhaust path H becomes combustion gas and goes out of the muffler when the engine is in a normal operation state such as a steady operation. As described above, when the engine is in a normal operation at a high temperature, it is discharged out of the exhaust path H, so that the engine does not stay in the exhaust path H such as the exhaust port 13 or the internal exhaust path 9A.

As described above, in the exhaust joint structure of the engine according to the present invention, the outlet wall 16 of the exhaust port 13 and the inlet wall 17 of the exhaust passage 9 in the cylinder head 2 are disposed between the two. The exhaust port 13 is inclined so that the port outlet 13a that opens to the outlet wall 16 has the highest height position, and the exhaust passage 9 The passage inlet 9a opening in the wall 17 is inclined so that the height position is the highest.
The inclination angle α of the exhaust port 13 and the inclination angle β of the exhaust passage 9 are set to 2 to 7 degrees, preferably 3 degrees, respectively. The length range L1 of the port inclination angle α is 30 to 70 mm, preferably 50 mm from the port outlet 13a, and the length range L2 of the exhaust manifold inclination angle β is 30 to 70 mm, preferably 50 mm, from the passage inlet 9a. Each is set. In addition, a step 19 is provided at the bottom of the exhaust port 13 where the port exit 13a approaches the combustion chamber 11 side for a predetermined length.

With the above configuration, the following effects 1) to 3) are also obtained.
1) The liquid unburned substance r in the cylinder head 2 is easily returned into the cylinder 1A.
2) In the vicinity of the port outlet 13 a of the exhaust port 13, the liquid unburned substance r stays in the step (recess or hole) 19 and does not reach the joint with the exhaust manifold 9. Further, the wall surface of the step (recess or hole) 19 makes it difficult for the liquid unburned matter r to be exposed to the exhaust gas and to be pushed out to the joint.
3) The liquid unburned substance r in the vicinity of the passage inlet 9a of the exhaust manifold 9 is difficult to return to the joint.
Due to the above effects 1) to 3), the liquid unburned substance r does not leak from the joint.

[Another embodiment]
For example, as shown in FIG. 4B, the exhaust port 13 has a curved path whose angle gradually changes, and is 2 to 3 degrees at the port outlet 13 a that is the smallest of the port inclination angles α. It may be a joint structure of an engine having a cylinder head 2 configured as described above.
Further, as shown in FIG. 4B, a hole (an example of “a depression or a hole or a step where the outlet wall is lowered”) 19 that spreads in a belt shape in the circumferential direction is formed at the bottom of the exhaust port 13 in the middle of the path. The structure to provide may be sufficient.

2 Cylinder head 9 Exhaust passage 9a Passage inlet 13 Exhaust port 13a Port outlet 16 Outlet wall 17 Inlet wall 18 Gasket 19 Step (step where depression or hole or outlet wall side is lowered)
H Exhaust path L1 Port tilt angle length range (length range of tilt angle α)
L2 exhaust manifold inclination angle length range (degree inclination angle β length range)
α Port inclination angle (Exhaust port inclination angle)
β exhaust manifold inclination angle (inclination angle of exhaust passage)

Claims (4)

An engine exhaust joint structure comprising an exhaust port provided in a cylinder head and an exhaust passage attached to the cylinder head, wherein an exhaust path is formed by the exhaust passage and the exhaust port. ,
The outlet wall of the exhaust port in the cylinder head and the inlet wall of the exhaust passage are connected with a gasket disposed therebetween,
The exhaust port is inclined so that the port outlet opening to the outlet wall has the highest height position, and the exhaust passage has the passage inlet opening to the inlet wall having the highest position. Exhaust joint structure of the engine with a slope in the rising state.   The engine exhaust joint structure according to claim 1, wherein an inclination angle of the exhaust port and an inclination angle of the exhaust passage are each set to 2 to 7 degrees.   The length range of the inclination angle of 2 to 7 degrees in the exhaust port is 30 to 70 mm from the port outlet, and the length range of the inclination angle of 2 to 7 degrees in the exhaust passage is 30 from the passage entrance. The engine exhaust joint structure according to claim 1 or 2, wherein the engine exhaust joint structure is set to ~ 70 mm.   4. The cylinder head according to claim 1, wherein a depression or a hole or a step that lowers the outlet wall side is provided at a bottom portion of the exhaust port at a position near the combustion chamber side by a predetermined length from the port outlet. The engine exhaust joint structure according to claim 1.

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