The present invention relates to an exhaust system for an engine.
In a conventional exhaust system for an engine, the generation of red rust due to exhaust heat in the exhaust passage component can be prevented by a rustproof resin film. However, in a case where the exhaust passage component is fastened to other parts, when the pressure receiving surface that receives the fastening force of the fastener is covered with the rustproof resin film, the plastic deformation of the rustproof resin film may greatly reduce the fastening force of the fastener.
An object of the present invention is to provide an exhaust system for an engine in which a fastening force of a fastener hardly decreases.
In the present invention, an oxide film of triiron tetraoxide is formed on a pressure receiving surface of an exhaust passage component.
According to the present invention, a fastening force of a fastener (2) is less likely to decrease. Further, the generation of red rust due to exhaust heat on a pressure receiving surface (1a) of an exhaust passage component (1) is prevented.
In this embodiment, a vertical water-cooled in-line multi-cylinder diesel engine will be described.
As illustrated in
The crankshaft (9) is cranked by a starter motor (22). The engine cooling fan (11) is driven from the crankshaft (9) via a belt transmission (19). An oil filter (21) is attached to the front cover (10) via an oil cooler (20).
This engine includes an intake system, a fuel supply device, and an exhaust system.
As illustrated in
As illustrated in
As illustrated in
An exhaust muffler or an exhaust duct is connected to the exhaust downstream side of the exhaust relay pipe (5) illustrated in
As illustrated in
A specific example of the exhaust passage component (1) will be described later.
As illustrated in
Hence, the exhaust system has the following effects.
That is, as compared to the rustproof resin film, the oxide film (1b) of triiron tetraoxide is less likely to be plastically deformed, and the fastening force of the fastener (2) is less likely to decrease.
Further, the rustproof action of the oxide film (1b) of triiron tetraoxide prevents the generation of red rust due to exhaust heat on the pressure receiving surface (1a) of the exhaust passage component (1).
As illustrated in
Hence, the exhaust system has the following effects.
That is, as compared to the rustproof resin film, the oxide film (1b) of triiron tetraoxide has excellent heat resistance, and hardly causes cracking or discoloration on the outer surface (1c) of the exhaust passage component (1).
Further, the oxide film (1b) of triiron tetraoxide prevents the generation of red rust due to exhaust heat on the outer surface (1c) of the exhaust passage component (1) excluding the pressure receiving surface (1a).
As illustrated in
Hence, the exhaust system has the following effects.
That is, the oxide film (1b) of triiron tetraoxide also prevents the generation of red rust due to exhaust heat on the inner surface (1d) of the exhaust passage component (1).
In this embodiment, as illustrated in
Hence, the exhaust system has the following effects.
That is, since the fastening force of the fastener (2) received on the pressure receiving surface (1a) of the exhaust manifold (3) illustrated in
As illustrated in
This fastener (2) is a headed bolt (2a) and includes a bolt head (2b) and a male screw (2c). The male screw (2c) passes through a bolt insertion hole (3b) of the exhaust inlet flange (3a) and is screw-fitted into a female screw hole (6b) of the side wall (6a) of the cylinder head (6). The exhaust inlet flange (3a) is sandwiched between the bolt head (2b) and the cylinder head (6) together with a washer (2d) and a first gasket (3c), and a fastening force of the headed bolt (2a) is applied to the pressure receiving surface (1a) formed on each of the front and back surfaces of the exhaust inlet flange (3a).
The oxide film (1b) of triiron tetraoxide is formed on the pressure receiving surface (1a).
As illustrated in
The fastener (2) is a stud bolt and nut (2e) and includes a stud bolt (20 and a nut (2g). The stud bolt (20 is screw-fitted into a female hole (3e) of the exhaust outlet flange (3d) of the exhaust manifold (3). The stud bolt (20 penetrates a bolt insertion hole (4c) of the exhaust inlet flange (4b) of the exhaust turbine housing (4a) in the supercharger (4), and the nut (2g) is screw-fitted to this stud bolt (20. The exhaust inlet flange (4b) of the exhaust turbine housing (4a) is sandwiched between the exhaust outlet flange (3d) of the exhaust manifold (3) and the nut (2g) together with the washer (2d) and a second gasket (4d). A fastening force of the stud bolt and nut (2e) is applied to the pressure receiving surface (1a) formed on the upper surface of the exhaust outlet flange (3d) of the exhaust manifold (3).
The oxide film (1b) of triiron tetraoxide is also formed on the pressure receiving surface (1a).
In this embodiment, as illustrated in
Hence, the exhaust system has the following effects.
That is, the fastening force of the fastener (2) received on the pressure receiving surface (1a) of the exhaust turbine housing (4a) illustrated in
As illustrated in
Therefore, the fastening force of the stud bolt and nut (2e) is applied to the pressure receiving surface (1a) formed on each of the upper and lower surfaces and the vertical front and back surfaces of the exhaust inlet flange (4b) of the exhaust turbine housing (4a).
The oxide film (1b) of triiron tetraoxide is formed on the pressure receiving surface (1a).
As illustrated in
This fastener (2) is a headed bolt (2a) and includes the bolt head (2b) and the male screw (2c). The male screw (2c) passes through the bolt insertion hole (5b) of the exhaust inlet flange (5a) of the exhaust relay pipe (5) and is screw-fitted into a female screw hole (40 of the exhaust outlet (4e) of the exhaust turbine housing (4a). The exhaust inlet flange (5a) of the exhaust relay pipe (5) is sandwiched between the bolt head (2b) and the exhaust outlet (4e) of the exhaust turbine housing (4a) together with the washer (2d) and a third gasket (4g). The fastening force of the headed bolt (2a) is applied to the pressure receiving surface (1a) formed on the rear surface of the exhaust outlet (4e) of the exhaust turbine housing (4a).
The oxide film (1b) of triiron tetraoxide is also formed on the pressure receiving surface (1a).
In this embodiment, as illustrated in
Hence, the exhaust system has the following effects.
That is, the fastening force of the fastener (2) received on the pressure receiving surface (1a) of the exhaust relay pipe (5) illustrated in
As illustrated in
Therefore, the fastening force of the headed bolt (2a) is applied to the pressure receiving surface (1a) formed on each of the front and back surfaces in the front-rear direction of the exhaust inlet flange (5a) of the exhaust relay pipe (5).
The oxide film (1b) of triiron tetraoxide is also formed on the pressure receiving surface (1a).
As illustrated in
The mounting flange (5c) of the exhaust relay pipe (5) is fastened to the upper surface of the mounting seat (30 disposed on the upper side of the exhaust manifold (3) with the fastener (2).
This fastener (2) is a headed bolt (2a) and includes the bolt head (2b) and the male screw (2c). The male screw (2c) passes through a bolt insertion hole (5d) of the mounting flange (5c) of the exhaust relay pipe (5) and is screw-fitted into a female screw hole (3g) of a mounting seat (30 of the exhaust manifold (3). The mounting flange (5c) of the exhaust relay pipe (5) is sandwiched between the bolt head (2b) and the mounting seat (30 of the exhaust manifold (3) together with the washer (2d). The fastening force of the headed bolt (2a) is applied to the pressure receiving surface (1a) formed on the upper surface of the mounting seat (30 of the exhaust manifold (3).
The oxide film (1b) of triiron tetraoxide is also formed on the pressure receiving surface (1a).
As illustrated in
Thus, the fastening force of the fastener is applied to the pressure receiving surface (1a) formed on each of the front and back surfaces in the front-rear direction of the exhaust outlet flange (5e) of the exhaust relay pipe (5).
The oxide film (1b) of triiron tetraoxide is also formed on the pressure receiving surface (1a).
As illustrated in
The oxide film (1b) of triiron tetraoxide is also formed on each of the inner surfaces (1d) of the exhaust passage inside the collector (3h), the bolt insertion hole (3b) of the exhaust inlet flange (3a) illustrated in
As illustrated in
The oxide film (1b) of triiron tetraoxide is also formed on each of the inner surfaces (1d) of the exhaust passage of the housing body (4h), an exhaust inlet (not illustrated) of the exhaust inlet flange (4b), and the exhaust outlet (not illustrated) of the exhaust outlet (4e).
As illustrated in
The oxide film (1b) of triiron tetraoxide is also formed on each of the inner surfaces (1d) of the exhaust passage inside the pipe (5g), the bolt insertion hole (5d) of the mounting flange (5c) illustrated in
The oxide film (1b) of triiron tetraoxide preferably has a thickness of 5 μm to 11 μm.
In this case, the following effects can be obtained.
When the thickness of the oxide film (1b) is less than 5 μm, the rustproof function of the oxide film (1b) against red rust is insufficient. When the film thickness exceeds 11 μm, the treatment time for forming the oxide film (1b) is long, or the treatment temperature is high, whereas when the film thickness is 5 μm to 11 μm, the rustproof action of the oxide film (1b) against red rust is sufficient, and the treatment time is short, or the treatment temperature is low.
To form the oxide film (1b) of triiron tetraoxide on the surface of the exhaust passage component (1) of ferrous metal, the exhaust passage component (1) of ferrous metal is treated in a steam atmosphere.
The oxide film (1b) of triiron tetraoxide has a thickness of more than 11 μm and not more than 20 μm.
The reason for that is as follows.
Like an industrial engine in which high-load operation continues for a long time, when the use conditions of the engine are severe and the rate of thermal deterioration of the oxide film (1b) due to combustion heat is high or the wear rate of the oxide film (1b) due to vibration is high, the service life of the oxide film (1b) may be insufficient with the film thickness being 11 μm or less. On the other hand, when the film thickness exceeds 20 μm, the processing time of the oxide film (1b) may exceed the allowable range for manufacturing efficiency, or the processing temperature may exceed the allowable range for protection of manufacturing equipment.
In contrast, in a case where the thickness of the oxide film (1b) of triiron tetraoxide is more than 11 μm and not more than 20 μm, even when the use conditions of the engine are severe, a sufficient service life can be obtained, the processing time is easily within the allowable range for manufacturing efficiency, and the processing temperature is also easily within the allowable range for protection of manufacturing equipment.
For the same reason as above, the lower limit of the film thickness may be set to 10 μm, and the range of the film thickness may be set to 10 μm to 20 μm.
In the above embodiment, the oxide film (1b) of triiron tetraoxide is formed on the surface of the exhaust passage component (1) which has not been subjected to the surface treatment, but may be formed on the surface of the exhaust passage component (1) which has been subjected to the surface treatment.
For example, an oxide film (1b) of triiron tetraoxide may be formed on the surface of the nitrogen compound layer of the exhaust passage component (1) obtained by the surface treatment of nitriding.
In this case, the following effects can be obtained.
The nitrogen compound layer can increase the hardness of the pressure receiving surface, and the oxide film (1b) prevents the nitrogen compound layer from softening due to denitrification, so that the fastening force of the fastener (2) does not easily decrease.
In the above embodiment, cast iron has been used as the ferrous metal to be the material of the exhaust passage component (1), but steel may be used.
Steel is used as a material of the fastener (2), the washer (2d), and each of the gaskets (3c), (4d), and (4g).
Number | Date | Country | Kind |
---|---|---|---|
2019-085480 | Apr 2019 | JP | national |
2019-175020 | Sep 2019 | JP | national |