JP2017066974A - 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 has a connection part S at which an outlet wall 16 including an outlet 13a of an exhaust port 13 in a cylinder head 2 and an inlet wall 17 including an inlet 9a of an exhaust passage 9A of an exhaust structure 9 are connected in a state where the outlet 13a and the inlet 9a are oppositely disposed, where between the outlet wall 16 and the inlet wall 17, provided is a gasket 18 including an opening 18a configured to communicate between the outlet 13a and the inlet 9a, and the gasket 18 has a pocket part 21 opened to a peripheral surface 20 and comprising a peripheral groove recessed radially outside.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.

  An exhaust joint structure of this type of engine, that is, an outlet wall provided with an outlet of an exhaust port in a cylinder head and an inlet wall provided with an inlet of an exhaust passage in the exhaust structure are connected to each other in an opposed arrangement. As an exhaust joint structure of an engine having a joint portion formed as described above, 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 often 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. . Even in the case where a gasket is provided at the exhaust joint, the leakage of the gasket can occur because the gasket sag with time.

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

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

The invention according to claim 1 includes an exhaust structure 9 having an exhaust passage 9A, a cylinder head 2 having an exhaust port 13, and an outlet wall 16 having an outlet 13a of the exhaust port 13 in the cylinder head 2. An exhaust joint of an engine having a joint S formed by connecting an inlet wall 17 provided with an inlet 9a of the exhaust passage 9A in the exhaust structure 9 in a state where the outlet 13a and the inlet 9a are arranged to face each other. In structure
Provided between the outlet wall 16 and the inlet wall 17 is a gasket 18 having an opening 18a for communicating the outlet 13a and the inlet 9a;
The gasket 18 is characterized in that it has a pocket portion 21 which is open on the inner peripheral surface 20 of the gasket 18 and has a plurality of depressions or holes recessed in the radially outer side or a circumferential groove.

The invention according to claim 2 is the engine exhaust joint structure according to claim 1,
The gasket 18 has the pocket portion 21 configured by stacking a plurality of divided gaskets 18A having a thickness on the inner peripheral side reduced from the outer peripheral side.

The invention according to claim 3 is the engine exhaust joint structure according to claim 2,
The gasket 18 includes two split gaskets 18A having a thickness on the inner circumferential side reduced from the outer circumferential side so that only one of the sealing surfaces 22, 23 is a stepped surface. It has the said pocket part 21 comprised by mutually accumulating and arranging the stepped surfaces 23 and 23, It is characterized by the above-mentioned.

According to a fourth aspect of the present invention, in the exhaust joint structure for an engine according to the third aspect,
One of the two split gaskets 18A, 18A is provided with a protruding large diameter portion 26 having a diameter larger than the diameter of the joint portion S,
The gasket 18 has a reservoir 27 formed by folding the outer peripheral portion of the protruding large diameter portion 26 toward the stepped surface.

The invention according to claim 5 is the engine exhaust joint structure according to claim 4,
A protruding large-diameter portion 28 having a diameter larger than the diameter of the joint portion S is provided on the other 18A of the two split gaskets 18A and 18A.
The gasket 18 has a large-diameter facing portion 29 that is disposed so as to be opposed so that the protruding large-diameter portion 28 of the other divided gasket 18A covers or hides the pool portion 27.

According to the first aspect of the present invention, the gasket 18 that is press-contacted between the cylinder head and the exhaust structure is provided with the pocket portion 21 that opens to the inner peripheral surface 20 thereof.
Therefore, even if the liquid unburned substance r is discharged from the combustion chamber 11 to the exhaust path H and stays in the vicinity of the joint portion S, it enters the pocket portion 21 and is stored, and therefore leaks from the joint portion S to the outside. It is possible to prevent it from coming out or to clearly delay the penetration into the joint S. That is, it is possible to avoid or reduce the leakage of the liquid unburned material r from the joint portion S.
As a result, liquid unburned matter may leak from the joint between the cylinder head and the exhaust structure, even if no load (or light load) operation is performed for a long time, mainly due to further structural review of the exhaust system. An improved engine exhaust joint structure can be provided to be avoided or reduced.

  According to the second aspect of the present invention, the non-penetrating (hole-shaped) pocket portion 21 that is recessed toward the radially outer side is a means that is configured by overlapping a plurality of divided gaskets 18A. Compared with the means for forming the pocket portion in the gasket made of the above member, the manufacturing and processing method is facilitated. Therefore, it is possible to provide an engine exhaust joint structure which has an advantage that a gasket can be easily manufactured at low cost.

  According to the third aspect of the present invention, two split gaskets 18A, in which only one of them becomes the stepped surface 23, are stacked together with the stepped surfaces 23, 23 attached to each other, and the same split gasket is used to save the economy. In addition, an advantage that a gasket having a pocket portion can be constructed is added.

  According to the fourth aspect of the present invention, when liquid unburned matter leaks from the joint, it can be stored in the reservoir 27 formed in the one split gasket 18A. Therefore, even if the liquid unburned material leaks out, there is an added advantage that it is possible to avoid the possibility that the liquid unburned material is dispersed and contaminated.

  According to the invention of claim 5, the presence of the large-diameter facing portion 29 can suppress or regulate the dispersion of the liquid unburned material r from the pool portion 27. Further, the protruding large-diameter portion 28 and the large-diameter opposing portion 29 have an advantage that they can function as a heat shield plate that makes it difficult for radiant heat from the engine, the exhaust structure 9, and the like to reach the reservoir portion 27.

Diesel engine right side view Plan view of the diesel engine shown in FIG. Sectional drawing which shows the engine exhaust joint structure (Embodiment 1) FIG. 3 is an enlarged cross-sectional view showing the main part of the joint of FIG. The gasket of Embodiment 1 is shown, (a) is a partially omitted front view, (b) is a cross-sectional view taken along the line AA in FIG. 5 (a). Sectional drawing of the junction part which shows the gasket of another structure (Embodiment 2)

  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.

  As shown in FIG. 2, this engine has an intake manifold 8 assembled on the left side of the cylinder head 2, and an exhaust manifold (an example of an exhaust structure) whose schematic shape is indicated by an imaginary line on the right side of the cylinder head 2. 9 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.

  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 exhaust passage 9A formed in a pipe shape inside 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.

Embodiment 1
As shown in FIG. 3, the diesel engine includes an outlet wall 16 including a port outlet 13 a of the exhaust port 13 in the cylinder head 2, and an inlet wall 17 including a passage inlet 9 a of the exhaust passage 9 </ b> A in the exhaust manifold 9. A joint S is formed by connecting the port outlet 13a and the passage inlet 9a so as to face each other by bolts (not shown). P is the axis of the exhaust port 13 and Q is the axis of the exhaust passage 9A.

As shown in FIG. 3, the joint portion S is configured by providing a gasket 18 having an opening 18 a that allows the port outlet 13 a and the passage inlet 9 a to communicate with each other between the outlet wall 16 and the inlet wall 17. . The joint portion S is connected in a state where the wall surface 16A of the outlet wall 16 and the wall surface 17A of the inlet wall 17 are in close contact (or pressure contact) via the gasket 18.
A tapered peripheral surface 9b is provided at the start end of the exhaust passage 9A so that the upstream side in the exhaust flow direction (arrow X) has a large diameter so that the diameter (size) of the passage inlet 9a is larger than the port outlet 13a. It is convenient if provided.

As shown in FIGS. 3 and 4, the gasket 18 has a pocket portion 21 which is opened on the inner peripheral surface 20 of the gasket 18 and has a plurality of depressions or holes recessed in the radially outer side or a circumferential groove. doing. The gasket 18 has a pocket portion 21 configured by stacking a plurality of divided gaskets 18A having a thickness on the inner peripheral side reduced from the outer peripheral side.
The gasket 18 includes two split gaskets 18A each having a thickness on the inner peripheral side reduced from the outer peripheral side so that only one of the seal surfaces 22 and 23 becomes a stepped surface. The stepped surfaces 23 and 23 are attached to each other and overlapped with each other to have a pocket portion 21 formed of a circumferential groove.

The gasket 18 will be described in detail. As shown in FIGS. 3 and 4, the divided gasket 18 </ b> A includes a seal surface 22 that is a smooth annular surface, and an outer periphery having a thickness D between the seal surface 22 and the seal surface 22. A stepped surface 23 formed by an inner peripheral surface 23B having a thickness d smaller than the thickness D between the surface 23A and the seal surface 22 and a tapered surface 23C connecting the outer peripheral surface 23A and the inner peripheral surface 23B. And have.
Therefore, the pocket portion 21 is configured as a circumferential groove that opens to the inner peripheral surface 20 by the outer peripheral surface 23A and the tapered surface 23C of one divided gasket 18A and the outer peripheral surface 23A and the tapered surface 23C of the other divided gasket 18A. Has been.

As shown in FIGS. 3 and 4, the gasket 18 in the assembled state as the joint portion S has a total thickness of 2D, and is located on each of the upstream side and the downstream side in the exhaust flow direction (arrow X). It has inner circumferential surfaces 20 and 20 each having a width (thickness) d, and has a pocket portion 21 formed of a circumferential groove having a width (thickness) of 2D-2d. Each inner peripheral surface 20, 20 forms an opening 18 a having the same diameter as that of the exhaust port 13.
Seal of the wall surface 16A of the outlet wall 16, the seal surface 22 of one split gasket 18A, the outer peripheral surface 23A of one split gasket 18A, the outer peripheral surface 23A of the other split gasket 18A, and the seal of the other split gasket 18A The surface 22 and the wall surface 17A of the inlet wall 17 are in pressure contact with each other.

  As shown in FIG. 5, in the free state, the gasket 18 is formed by connecting and integrating portions corresponding to the joint portions S at three locations by the belt-like portions 19 (see FIG. 5A). The portions of the tapered surface 23C and the inner peripheral surface 23B of the divided gasket 18A are bent so as to be bent toward the seal surface 22 side.

  As shown in FIG. 5 (b), the outer peripheral surface 23A of the divided gasket 18A has a convex curved portion protruding on the circumference so as to protrude toward the seal surface 22 side in the one divided gasket 18A. 24 and the other divided gasket 18A are each formed with a concave bent portion 25 protruding on the circumference so as to be convex toward the stepped surface 23 side.

  Accordingly, the pair of split gaskets 18A and 18A are identical in shape and shape to each other in a state where they are assembled and compressed in the joint portion S, but in a free state, the pair of divided gaskets 18A and 18A have a concave curvature. They are classified into those having a part 25.

According to the exhaust joint structure of the diesel engine having the above-described configuration, the following operational effects can be achieved. When the engine is continuously operated at a relatively low temperature, such as no load or light load, in the state where the temperature of the joint S reaches a predetermined engine operating temperature, as shown in FIG. A liquid unburned substance r such as combustion fuel or engine oil is discharged to the exhaust port 13.
Even if the liquid unburned matter r stays in the vicinity of the joint S, the liquid unburned matter r enters the pocket portion 21 and is stored, and leaks from between the wall surfaces 16A, 17A and the gasket 18 to the outside. It comes to be prevented from taking out.

  The liquid unburned matter r present in the exhaust path H including the joint S becomes a combustion gas and is discharged out of the muffler when the engine is in a normal operation state such as a steady operation. . In this way, when the engine is in a normal operation at a high temperature, the liquid unburned substance r is discharged outside the exhaust path H, so that it stays in the exhaust path H such as the exhaust port 13 and the exhaust passage 9A, There is no inconvenience of leaking from S.

[Embodiment 2]
The engine exhaust connection structure according to the second embodiment is different from that according to the first embodiment only in the gasket 18. Specifically, other functions are added to the gasket 18 according to the first embodiment, and all the configurations according to the first embodiment are provided. Therefore, basically, only the added part of the new configuration will be described.

As shown in FIG. 6, the gasket 18 is provided with a reservoir 27 capable of temporarily storing the liquid unburned substance r, a large-diameter opposing portion 29 that is disposed opposite to the reservoir 27, and the like. .
That is, one of the two divided gaskets 18A, 18A on the outlet wall 16 side is provided with a protruding large diameter portion 26 having a diameter larger than the diameter of the joint portion S. The outer peripheral portion of the protruding large-diameter portion 26, specifically, the reservoir portion 27 is configured by folding the lower outer peripheral portion toward the stepped surface 23.

Then, as shown in FIG. 6, the protruding large-diameter portion having a larger diameter than the diameter of the joint portion S is also formed on the other divided gasket 18 </ b> A on the inlet wall 17 side of the two divided gaskets 18 </ b> A and 18 </ b> A. 28 is provided, and the protruding large-diameter portion 28 is bent in the direction away from the one divided gasket 18A in the vicinity of the outer peripheral portion of the inlet wall 17.
The bent large-diameter portion 28 is a large-diameter opposed portion 29 that is disposed so as to cover or hide the reservoir 27 when viewed from the downstream side in the exhaust flow direction (arrow X). have.

  In the exhaust connection structure of the engine according to the second embodiment, if the liquid unburnt substance r leaks from the joint S due to some cause, as shown in FIG. 6, the split gasket 18A on the outlet wall 16 side It descends along the stepped surface 23 and is stored in the reservoir 27 at the lower end. Therefore, it is possible to avoid the possibility that the liquid unburned substance r leaked from the joint portion S is dispersed around and contaminated.

  Further, since the large-diameter opposed portion 29 of the protruding large-diameter portion 28 is arranged slightly apart in the direction in which the liquid unburned material r exits from the reservoir 27, the liquid unburned material r is dispersed from the reservoir 27. This can be suppressed or regulated. Further, the protruding large-diameter portion 28 and the large-diameter facing portion 29 have an advantage that they can function as a heat shield plate that makes it difficult for radiant heat due to overheating of the engine and the exhaust manifold 9 to reach the reservoir portion 27.

[Another embodiment]
A single gasket 18 having a pocket portion 21 as shown in FIGS. A gasket 18 having a three-layer structure in which an intermediate gasket (not shown) having an inner diameter larger than that of the split gasket 18A is sandwiched between the pair of split gaskets 18A and 18A shown in FIGS.
The shape and number of gaskets 18 can be variously changed and set.

2 Cylinder head 9 Exhaust structure 9A Exhaust passage 9a Inlet (passage entrance)
13 Exhaust port 13a Exit (port exit)
16 outlet wall 17 inlet wall 18 gasket 18A split gasket 18a opening 20 inner peripheral surface 21 pocket portion 22 seal surface 23 seal surface (stepped surface)
26 Protruding large diameter portion 27 Reservoir portion 28 Protruding large diameter portion 29 Large diameter facing portion S Joint portion

Claims (5)

An exhaust structure having an exhaust passage, a cylinder head having an exhaust port, an outlet wall having an outlet of the exhaust port in the cylinder head, and an inlet wall having an inlet of the exhaust passage in the exhaust structure. The engine exhaust joint structure having a joint formed by connecting the outlet and the inlet in a state of being opposed to each other,
Between the outlet wall and the inlet wall, a gasket having an opening for communicating the outlet and the inlet is provided,
The exhaust joint structure of an engine, wherein the gasket has a pocket portion that is open on the inner peripheral surface of the gasket and has a plurality of depressions or holes recessed in the radially outer side or a circumferential groove.   2. The engine exhaust joint structure according to claim 1, wherein the gasket has the pocket portion configured by stacking a plurality of divided gaskets each having a thickness on the inner peripheral side reduced from the outer peripheral side.   The gasket includes two split gaskets having a thickness on the inner peripheral side reduced from the outer peripheral side so that only one of the two seal surfaces becomes a stepped surface. The engine exhaust joint structure according to claim 2, wherein the engine has the pocket portion configured to be overlapped with each other. One of the two split gaskets is provided with a protruding large diameter portion that is larger than the diameter of the joint portion,
The engine exhaust joint structure according to claim 3, wherein the gasket has a reservoir portion formed by folding an outer peripheral portion of the protruding large diameter portion toward the stepped surface. Providing the other of the two split gaskets has a protruding large diameter portion that is larger than the diameter of the joint portion,
5. The engine exhaust joint according to claim 4, wherein the gasket has a large-diameter facing portion formed so as to face the concealed portion so that the protruding large-diameter portion of the other split gasket covers or hides the pool portion. Construction.

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