JP2017066973A - 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 mainly 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 structure is avoided or reduced.SOLUTION: An exhaust connection part structure of an engine includes an exhaust port 13 of a cylinder head 2 and an exhaust manifold 9, and has a connection part S at which an outlet wall 16 including an outlet 13a of the exhaust port 13 and an inlet wall 17 including an inlet 9a of an exhaust passage 9A of the exhaust manifold 9 are connected, where in a peripheral groove 19 formed on the outlet wall 16, a seal ring 18 made of thermally expandable material is stored in a state of being compressed in a depth direction of the peripheral groove 19.SELECTED DRAWING: Figure 4

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.

  This type of engine has an exhaust joint structure, that is, an exhaust port provided in the cylinder head and an exhaust passage of an exhaust structure attached to the cylinder head, and an exhaust path is formed by the exhaust passage and the exhaust port. As an exhaust joint structure of an engine that is used, 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 a cylinder head 22 having an exhaust port 13 and an exhaust structure 9 having an exhaust passage 9A, and an outlet wall 16 having an outlet 13a of the exhaust port 13 in the cylinder head, In an exhaust joint structure of an engine having a joint S formed by connecting an inlet wall 17 having an inlet 9a of an exhaust passage 9A in the exhaust structure 9;
A circumferential groove 19 formed in the outlet wall 16 in a state surrounding the outlet 13a or a circumferential groove 19 formed in the inlet wall 17 in a state surrounding the inlet 9a;
A seal ring 18 made of a thermally expanding material is housed in the circumferential groove 19 in a compressed state in the depth direction of the circumferential groove 19.

The lateral width w of the seal ring 18 is equal to or less than the depth dimension d of the circumferential groove 19 (w ≦ d) when the temperature of the joint S is normal temperature, and the temperature of the joint S is a predetermined value. The engine operating temperature is set to a state (w> d) exceeding the depth dimension d of the circumferential groove 19.

The invention according to claim 2 is the engine exhaust joint structure according to claim 1,
The circumferential groove 19 is formed in the inlet wall 17.

The invention according to claim 3 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, In an exhaust joint structure of an engine having a joint S formed by connecting an inlet wall 17 having an inlet 9a of an exhaust passage 9A in the exhaust structure 9;
A circumferential groove 19 formed on one of the outlet wall 16 and the inlet wall 17 and an annular protrusion 20 formed on either one of the inner circumferential surface 19A of the circumferential groove 19 and the The outer peripheral surface 20B of the ring projection 20 is fitted in a state of being an interference fit at room temperature,
Between the outer peripheral surface 19B of the circumferential groove 19 and the inner peripheral surface 20A of the ring projection 20, a seal made of a material having a thermal expansion coefficient higher than that of the material constituting the ring projection 20 The ring 18 is accommodated in a state of being fitted to the inner peripheral surface 20A of the ring protrusion 20 at room temperature.

According to a fourth aspect of the present invention, in the exhaust joint structure for an engine according to the third aspect,
The circumferential groove 19 is formed in the outlet wall 16, and the ring protrusion 20 is formed in the inlet wall 17.

The invention according to claim 5 is the engine exhaust joint structure according to any one of claims 1 to 4,
The seal ring 18 is characterized in that a cross section cut in the radial direction is set to have a bow shape.

According to the invention of claim 1, since the thermally expanding seal ring 18 is accommodated in the circumferential groove 19 in a compressed state in the depth direction, if the joint S is configured by being assembled, The joint S is in a good sealed state by the seal ring 18.
When the temperature of the joint portion S reaches a predetermined engine operating temperature, the seal ring 18 accommodated in the circumferential groove 19 is thermally expanded, so that the outlet wall 16 of the cylinder head 2 and the inlet wall of the exhaust structure 9 are expanded. 17 is pushed more strongly in the directions of the axial centers P and Q, and the outlet wall 16 and the inlet wall 17 can be firmly sealed.
Therefore, even if the liquid unburned matter r stays in the exhaust port 13 or the exhaust passage 9A, the joint S is formed by the seal ring 18 that exhibits excellent sealing performance by thermally expanding mainly in the directions of the shaft centers P and Q. It is possible to greatly reduce or avoid the leakage of the liquid unburned material r from the liquid.

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.
In addition, if it is set as the structure by which the circumferential groove 19 is formed in the entrance wall 17 like invention of Claim 2, the process of the circumferential groove 19 is easy and it is convenient.

According to the invention of claim 3, in a state where the temperature of the joint portion S reaches a predetermined engine operating temperature, the seal ring 18 accommodated in the circumferential groove 19 is thermally expanded, and the ring protrusion 20 is moved outwardly from the diameter. The ring protrusion 20 that is already tightly pressed and the outlet wall 16 (or the inlet wall 17) of the circumferential groove 19 is pressed further in the radial direction to be in pressure contact.
Therefore, even if the liquid unburned matter r stays in the exhaust port 13 or the exhaust passage 9A, the liquid unburned from the joint S by the seal ring 18 that exhibits excellent sealing performance mainly by thermal expansion in the radial direction. It is possible to greatly reduce or avoid the leakage of the object r.

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.
As in the invention of claim 4, if the circumferential groove 19 is formed on the outlet wall 16 and the annular protrusion 20 is formed on the inlet wall 17, it is easy to process and is convenient.

  According to the invention of claim 5, since the cross-sectional shape cut in the radial direction of the seal ring 18 is set to an arcuate shape, the deformation when thermally expanded can be performed in a preset direction. There is an advantage that the effect can be obtained as designed.

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 dimensional relationship between the seal ring and the circumferential groove is shown, (a) is the state when assembled at room temperature, (b) is the state when the engine is operating Sectional drawing which shows the exhaust joint structure 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 is slightly lowered from the closed position closed in FIG. 3, the exhaust inlet 15 is opened, and exhaust gas and the like flow into 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 seal ring 18 is provided, and a joint S is formed by connecting with a bolt (not shown) or the like.

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).
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.

  3, the exhaust manifold 9 is provided with a circumferential groove 19 formed in the inlet wall 17 so as to surround the inlet 9a. The circumferential groove 19 includes an inner circumferential surface 19A, an outer circumferential surface 19B having a smaller diameter than the inner circumferential surface 19A, and a side circumferential surface 19C that connects the inner circumferential surface 19A and the outer circumferential surface 19B, and is open toward the outlet wall 16. It is formed in the annular groove. The circumferential groove 19 is a rectangular groove having a rectangular cross-sectional shape in the radial direction.

  A seal ring 18 made of a thermally expanding material is accommodated in the circumferential groove 19, and the lateral width w of the seal ring 18 is slightly smaller than the depth dimension d of the circumferential groove 19 when the temperature of the joint portion S is normal temperature. Is set to a large value (w ≧ d). When the temperature of the joint portion S is a predetermined engine operating temperature, the state is set so as to greatly exceed the depth dimension d of the circumferential groove 19 (w> d), and a stronger sealing action is exhibited. The lateral width w (w1, w2) is the length of the exhaust port 13 in the axial center P direction or the exhaust passage 9A in the axial center Q direction.

  As shown in FIG. 5A, the seal ring 18 accommodated in the circumferential groove 19 has a curved shape in which the central portion in the width direction has a slightly smaller diameter than the diameter k1 at both ends in the width direction, as shown in FIG. If it is made to have a cross section, it is convenient because it can be easily inserted into the circumferential groove 19. As an example, the seal ring 18 is set to have a bow-shaped cross section cut in the radial direction, and has a higher coefficient of thermal expansion than cast iron, which is a material of the cylinder head 2 and the exhaust manifold 9, such as stainless steel. It is made of the material it has.

  The outer peripheral surface 19B of the circumferential groove 19 is set to have a diameter equal to or larger than the minimum diameter of the seal ring 18 at room temperature, and the depth d of the circumferential groove 19 is slightly smaller than the lateral width w1 (w) of the seal ring 18. Each is set to a long value. Therefore, as shown in FIG. 5A, at the time of assembly, the seal ring 18 can be inserted and accommodated in the circumferential groove 19, and the seal ring 18 is compressed as it is bolted. ing.

When the engine is operated without load and the temperature rises and the temperature of the joint S reaches a predetermined engine operating temperature, as shown in FIGS. 3, 4, and 5 (b), the thermally expanded seal The ring 18 is greatly curved, and the ring 18 is accommodated in the circumferential groove 19 in a state where it is more strongly compressed between the side circumferential surface 19C of the circumferential groove 19 and the wall surface 16A of the outlet wall 16.
Accordingly, at the joint S at a predetermined engine operating temperature, the outlet wall 16 and the inlet wall 17 are more strongly outside the diameter of the port outlet 13a (outside the diameter of the passage inlet 9a) due to the thermal expansion of the seal ring 18. It is in a sealed state and is regulated so that the liquid unburned substance r does not leak from the joint S.

  As shown in FIG. 5 (b), when the seal ring 18 alone reaches a predetermined engine operating temperature, a value that is clearly larger than the depth of the circumferential groove 19 from w 1 whose lateral width is slightly slightly larger than the depth of the circumferential groove 19. And the diameter expands from k1 to k2. However, in a state where the exhaust manifold 9 is housed in the circumferential groove 19 and the exhaust manifold 9 is assembled to the cylinder head 2, the lateral width is restricted to d and the seal ring 18 cannot freely expand, and there is a sufficient diameter in the circumferential groove 19. It can be transformed only in the direction.

As a result, the curved shape is greatly deformed in the circumferential groove 19 as compared with the normal temperature shown in FIG. 5A, and the side circumferential surface 19C and the wall surface 16A are more strongly pressed and pressed. By this stronger pressure contact, the outlet wall 16 and the inlet wall 17 can be sealed more firmly than before.
Since the seal ring 18 expands more when the engine is normally operated and the joint portion S reaches a higher temperature than during no-load operation, the sealing performance is further enhanced. Therefore, the “predetermined engine operating temperature” can be said to be a relatively low temperature at which the liquid unburned product r is generated, such as during no-load operation.

  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 unburnt substance r is discharged out of the exhaust path H, so that it does not stay in the exhaust path H such as the exhaust port 13 and the exhaust passage 9A. become.

  If the cross section of the seal ring 18 is arcuate, the direction of bending deformation during compression can be set to a predetermined direction, which is convenient. In the joint portion S, the seal ring 18 has already been compressed and sufficient sealing performance has been generated. However, due to thermal expansion, the seal ring 18 having an arcuate cross section is further curved and deformed, and the wall surface 16A of the outlet wall 16 is The wall surface 17A of the entrance wall 17 can be more firmly attached.

[Embodiment 2]
The engine exhaust joint structure shown in FIG. 6 may be used. That is, the peripheral groove 19 formed in the outlet wall (an example of “one of the outlet wall and the inlet wall”) 16 and the inlet wall (an example of “the other of the outlet wall and the inlet wall”) 17 The annular projection 20 formed on the inner circumferential surface 19A of the circumferential groove 19 and the outer circumferential surface 20B of the annular projection 20 are fitted in an interference fit at room temperature.

  And between the outer peripheral surface 19B of the circumferential groove 19 and the inner peripheral surface 20A of the ring protrusion 20, a seal ring made of a material having a higher thermal expansion coefficient than that of the material constituting the ring protrusion 20 is provided. 18 is accommodated in a state of being closely fitted to the inner peripheral surface 20A of the ring protrusion 20 at room temperature (an example of fitting). The depth of the circumferential groove 19 (the length in the axial center P, Q direction) is set to a value larger than the length L of the ring protrusion 20.

That is, with the exhaust manifold 9 attached to the cylinder head 2, the inner peripheral surface 20A of the circumferential groove 19 and the ring projection 20 are already in pressure contact, and the liquid unburned material r and other things are joined. A seal portion that prevents leakage from the portion S is formed.
Then, when the engine is operated without load and the temperature rises and the temperature of the joint portion S reaches a predetermined engine operating temperature, the thermally expanded seal ring 18 causes the inner peripheral surface 20A of the ring projection 20 to be radially outward. The diameter-expanding action of the ring-shaped projection 20 is generated by pushing strongly.

As a result, the outer peripheral surface 20B of the ring projection 20 and the inner peripheral surface 19A of the circumferential groove 19 are more strongly pressed against each other, and an effect that a strong sealing performance can be exhibited is obtained.
In order to obtain this excellent sealing property, it is desirable to take a sufficient length L of the ring protrusion 20, and the thickness (radial width) of the ring protrusion 20 is more effective if there is no problem in strength. It is.
Further, a grinding relief R portion that slightly narrows the root of the ring protrusion 20 may be provided so that the aforementioned diameter expansion deformation of the ring protrusion 20 is likely to occur.
The cross-sectional shape of the seal ring 18 may be a shape other than an arc shape (see FIG. 6) such as a rectangle.

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 seal ring 19 circumferential groove 19A inner circumferential surface 19B outer circumferential surface 20 ring projection 20A inner circumferential surface 20B outer circumferential surface S joint

Claims (5)

An exhaust structure having an exhaust passage and a cylinder head having an exhaust port, and connecting 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. An engine exhaust joint structure having a joint formed by
A circumferential groove formed in the outlet wall in a state surrounding the outlet or a circumferential groove formed in the inlet wall in a state surrounding the inlet;
An engine exhaust joint structure in which a seal ring made of a thermally expanding material is accommodated in the circumferential groove in a compressed state in the depth direction of the circumferential groove.

Is contained in the circumferential groove,
The width of the seal ring is equal to or less than the depth dimension of the circumferential groove when the temperature of the joint is normal, and when the temperature of the joint is a predetermined engine operating temperature, The engine exhaust joint structure is set to exceed the depth dimension.   The engine exhaust joint structure according to claim 1, wherein the circumferential groove is formed in the inlet wall. An exhaust structure having an exhaust passage and a cylinder head having an exhaust port, and connecting 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. An engine exhaust joint structure having a joint formed by
A circumferential groove formed on one of the outlet wall and the inlet wall, and a ring protrusion formed on the other are an inner circumferential surface of the circumferential groove and an outer circumferential surface of the ring protrusion. Are fitted in an interference fit at room temperature,
Between the outer circumferential surface of the circumferential groove and the inner circumferential surface of the ring projection, a seal ring made of a material having a thermal expansion coefficient higher than that of the material constituting the ring projection is the ring. The engine exhaust joint structure is housed in a state of being fitted to the inner peripheral surface of the strip protrusion at room temperature.   The engine exhaust joint structure according to claim 3, wherein the circumferential groove is formed in the outlet wall, and the ring protrusion is formed in the inlet wall.   The engine exhaust joint structure according to any one of claims 1 to 4, wherein the seal ring is set to have a bow-shaped cross section cut in a radial direction.

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