JP3185788B2 - Exhaust passage exit structure for outboard engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exhaust passage outlet structure for an outboard motor engine.

[0002]

2. Description of the Related Art As shown in FIG. 3, an engine 1 of an outboard motor accommodates a piston (not shown) in a cylinder block 2, and a cylinder head gasket 3, a cylinder head 4, a cylinder head cover gasket 5 and Cylinder head cover 6 is superimposed sequentially,
These are fixed using bolts (not shown). Further, the piston is connected to a crankshaft (not shown) via a connecting rod (not shown) or the like, and the crankshaft is housed in the cylinder block 2 and the crankcase 7.

FIG. 4 is a front view of the cylinder block 2 as viewed in IV direction in FIG. 3, and FIG. 5 is a cross-sectional view taken along line VV in FIG.

[0005] As shown in FIG. 5, a cylinder bore 8 is formed in the cylinder block 2, and a cylinder 9 is fitted into the cylinder bore 8. A plurality of scavenging ports 10 are opened in the cylinder bore 8 and the cylinder 9, and an exhaust port 11 is provided.
Is also opened. The scavenging port 10 is communicated with the inside of the crankcase 7 and guides fresh air into the cylinder 9.

On the other hand, a curved exhaust passage 12 communicates with the exhaust port 11. The exhaust passage 12 is surrounded by an exhaust passage element 13 formed in the cylinder block 2 and an exhaust cover 14. The exhaust cover 14 is an exhaust cover mounting surface 1 shown in FIG.
5 is attached using bolts (not shown). Reference numeral 16 denotes a bolt mounting hole of an exhaust cover mounting bolt.

The outlet 17 of the exhaust passage 12 shown in FIG.
An exhaust tube (not shown) is attached via an under oil seal housing (not shown). FIG.
Reference numeral 23 denotes a bolt mounting hole of an exhaust tube mounting bolt. Exhaust gas burned in a combustion chamber (not shown)
From the cylinder 9 through the exhaust port 11, through the exhaust passage 12,
It is discharged outside through an exhaust tube or the like.

[0007] The cylinder block 2 having the above configuration
Is generally manufactured by die casting. In this die casting, the outlet 17 of the exhaust passage 12
In the vicinity, a water jacket 18 and an exhaust bypass passage 19 shown in FIG. 6 are formed using a main core (not shown). This main core, as shown by arrow A in FIG.
Cylinder block 2 in which outlet 17 of exhaust passage 12 is open
Is extracted in the vertical direction with respect to the side surface 20. The core for forming the exhaust passage element 13 of the exhaust passage 12 is pulled out in the direction in which the exhaust cover 14 is removed, as shown by the arrow B in FIG.

The outlet 17 of the exhaust passage 12 needs to be formed obliquely with respect to the side surface 20 of the cylinder block 2. Therefore, a tunnel core (not shown) is provided in the main core. The child is formed by extracting the child in the direction of arrow C in FIG. Since the outlet 17 of the exhaust passage 12 is formed obliquely with respect to the side surface 20, the flow of the exhaust gas in the exhaust passage 12 becomes smooth.

Reference numeral 21 in FIG. 4 indicates a thermostat insertion hole, and reference numeral 22 in FIG. 5 indicates a parting line in casting.

[0010]

However, when the cylinder block 2 is manufactured by die casting, a tunnel core is used to form the outlet 17 of the exhaust passage 12, so that the molding die of the cylinder block 2 is generally used. And the mold cost increases.

As described above, since the tunnel core is used to form the outlet 17 of the exhaust passage 12, the opening at the outlet 17 of the exhaust passage 12 is limited to a rectangular shape as shown in FIG. However, the degree of freedom of the opening shape is limited.

Further, if it is attempted to form the outlet 17 of the exhaust passage 12 with the main core without using the tunnel core, the main core is a core extracted in the direction of arrow A in FIG. The 12 outlets 17 cannot be formed in a shape oblique to the side surface 20 of the cylinder block 2.
Therefore, there is a disadvantage that the flow of the exhaust gas flowing through the exhaust passage 12 is not smooth.

The present invention has been made in consideration of the above facts, and makes the flow of exhaust gas guided through an exhaust passage smooth and smooth. An object of the present invention is to provide an exhaust passage outlet structure of an outboard motor engine in which an outlet and a water jacket can be formed, a mold cost can be reduced, and a degree of freedom of an opening shape of the exhaust passage outlet is large.

[0014]

According to a first aspect of the present invention, an exhaust passage outlet structure for an outboard motor engine according to the present invention is provided. A cylinder bore for fitting a cylinder into the cylinder block is formed, and a downwardly curved exhaust passage is formed in communication with an exhaust port opened in the cylinder bore. A mounting component such as an under oil seal housing is provided at an outlet of the exhaust passage. In the exhaust passage outlet structure of the outboard engine in which a water jacket is formed on the side of the outlet of the exhaust passage, the side of the cylinder block on the exhaust port side is die-cut to the side. By forming an exhaust space, an exhaust cover is attached to the side opening of the exhaust space, and the upper exhaust passage is The lower portion of the cylinder block is formed in the lower portion of the cylinder block by cutting the lower portion of the cylinder block downward, thereby forming an exhaust outlet portion communicating with the upper exhaust passage at the lower portion of the cylinder block. The exhaust guide of the above-mentioned attachment part is provided with a guide surface that is flush with the inner surface of the exhaust passage of the exhaust cover, and the upper end of the guide surface is located at the upper end of the upper exhaust passage. A lower exhaust passage communicating with the upper exhaust passage by a guide surface of the exhaust guide at a lower portion of the cylinder block and extending near a parting line of a die formed at a lower portion of the upper portion of the exhaust outlet portion; At the side of the lower exhaust passage formed in the lower part of the cylinder block, the die is removed in the die-cutting direction at the time of forming the exhaust outlet. Water jacket of the lower open is integrally formed with the lower opening portion of the water jacket is one which is closed by the fitting.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of an exhaust passage outlet structure of an outboard motor engine according to the present invention, in which the present invention is applied to a vertical multi-cylinder engine of an outboard motor. This vertical multi-cylinder engine includes a cylinder block corresponding to FIG. 5, and FIG. 1 is a sectional view of the cylinder block. In this embodiment, the same parts as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted.

This outboard engine is a two-cylinder vertical engine as shown in FIG. 1, in which two cylinder bores 8 are formed in a die-cast cylinder block 2 and these cylinder bores 8 have cylinders 9 respectively. Are fitted respectively. An exhaust port 11 is provided at a lower portion on one side of each cylinder bore 8.
Are opened diagonally downward toward the outside, and these exhaust ports 11 are respectively connected to exhaust passages 12 curved downward.

The exhaust passage 12 includes an upper exhaust passage 12a and a lower exhaust passage 12b. Upper exhaust passage 12a
Is surrounded by an exhaust passage element 13 formed in the cylinder block 2 and an exhaust cover 14. The upper exhaust passage 12 a bypasses the lower cylinder 9 and is curved so as to bulge outward, while extending downward from the exhaust port 11 formed in the upper cylinder 9 and formed at the lower portion of the cylinder block 2. Lower exhaust passage 12
b. The lower exhaust passage 12b communicates with an outlet 25 that opens to the lower surface 20 of the cylinder block 2. The exhaust cover 14 is attached to the exhaust cover mounting surface (FIG. 4).
See)).

More specifically, as shown in FIG. 1, an exhaust space is formed by cutting the side of the cylinder block 2 on the exhaust port 11 side in a direction substantially perpendicular to the cylinder axis. Exhaust cover 1 at the side opening of the space
The upper exhaust passage 12 a is formed between the cylinder block 2 and the exhaust cover 14 by attaching the exhaust passage 4.

The lower exhaust passage 12b is formed between the lower portion of the cylinder block 2 and the exhaust guide 27 by cutting the lower portion of the lower portion in a direction substantially perpendicular to the cylinder axis.
Specifically, the lower portion of the cylinder block 2 is die-cut downward, so that an exhaust outlet portion communicating with the upper exhaust passage 12a is formed at the lower portion of the cylinder block 2. This exhaust outlet portion is specified by the shape of a main core (not shown) that is drawn downward, and has a downward substantially straight pipe-shaped portion along the die-cutting direction.

As shown in FIG. 1, an exhaust guide 27 is formed integrally or integrally with the under oil seal housing 26. The exhaust guide 27 extends along the straight pipe-shaped portion of the exhaust outlet formed in the lower portion of the cylinder block 2 to the parting line 22 of the die, and terminates. The exhaust guide 27 engages (fits) on the back side of the exhaust outlet portion at the lower portion of the cylinder block 2, and
2b. Exhaust guide 27
The guide surface 28 is formed such that the lower exhaust passage 12b formed at the lower exhaust outlet portion of the cylinder block 2 is smoothly connected to the upper exhaust passage 12.

Upper exhaust passage 12a in exhaust passage 12
The lower exhaust passage 12b at the exhaust outlet portion communicates with the lower exhaust passage 12b through a parting line 22 that is cut out from the mold. The lower exhaust passage 12b at the lower end of the parting line communicates with the outlet 25 of the exhaust passage 12. The outlet 25 is a straight tubular outlet formed in the cylinder block 2 so as to have a substantially straight pipe shape downward by a main core (not shown) that is drawn downward in the direction of arrow A in FIG. A water jacket 18 is formed on the side of the lower exhaust passage 12b. As shown in FIG. 1, the water jacket 18 also has a jacket wall 18a formed substantially downward in a straight pipe shape, and a main core (not shown). It is provided on the cylinder block 2. That is, the water jacket 18
Is configured to be the same as the exit direction of the outlet 25 of the exhaust passage 12. The lower opening portion of the water jacket 18 is closed by an under oil seal housing 26 as a mounting part.

On the other hand, an unillustrated exhaust tube mounting bolt is screwed into the bolt mounting hole 23 on the side surface 20 of the cylinder block 2, and an under oil seal housing 26 as a mounting part is mounted.

When the under oil seal housing 26 is mounted on the lower surface 20 of the cylinder block 2, the exhaust guide 27 is substantially straight tubular outlet 25 of the exhaust passage 12.
Is provided so as to be fittable. The guide surface 28 of the exhaust guide 27 is provided in a shape that is continuous with the exhaust passage curved surface 29 of the exhaust cover 14 that forms the upper exhaust passage 12a.

According to the exhaust passage outlet structure of the outboard motor engine, an exhaust port 11 that opens obliquely downward is formed at the lower side of each cylinder bore 8 of the vertical engine.
These exhaust ports 11 are communicated with the upper exhaust passages 12a of the downwardly curved exhaust passages 12, so that the direction of exhaust gas exhausted from each exhaust port 11 can be made to substantially match the direction of the curved upper exhaust passages 12a, The exhaust can be performed smoothly and smoothly. The substantially straight tubular downward outlet 25 of the exhaust passage 12 can be formed by a main core vertically drawn out from the lower surface of the cylinder block 2, so that the opening shape of the exhaust passage outlet 25 has a large degree of freedom. it can.

According to the above-described embodiment, since the substantially straight tubular downward outlet 25 of the exhaust passage 12 is formed by the main core which is drawn vertically to the lower surface 20 of the cylinder block 2, the straight tubular outlet in the exhaust passage 12 is formed. The degree of freedom of the 25 opening shapes is increased. For example, as shown in FIG. 2, the opening shape of the straight tubular outlet 25 is configured to have a semicircular shape at the center of the plurality of bolt mounting holes 23. By doing so, it is not necessary to bend the exhaust tube (not shown) attached to the under oil seal housing 26 into a complicated shape, and it is possible to improve the engine output and achieve a suitable layout of the exhaust tube.

Further, in the die casting, since the main core is used for forming the straight tubular outlet 25 of the exhaust passage 12 without using the tunnel core, the molding die of the cylinder block 2 does not become large, and the die cost can be reduced. In this exhaust passage outlet structure, one exhaust passage 12 can be formed by cutting the mold in one side of the cylinder block 2 and in two downward directions substantially perpendicular to the sides.

Further, the under oil seal housing 2
The exhaust surface of the exhaust passage 12 is formed into a surface shape that is continuous with the curved surface 29 of the exhaust passage 14 by the guide surface 28 of the exhaust guide 27 of FIG. be able to.

According to the above embodiment, the case where the exhaust guide 27 is formed in the under oil seal housing 26 has been described.
When the exhaust tube can be directly attached to the exhaust tube, the exhaust tube 27 of the above embodiment may be provided on the exhaust tube.

[0030]

As described above, according to the exhaust passage outlet structure for an outboard motor engine according to the present invention, exhaust ports that open diagonally downward are formed at the lower side portions of the cylinder bores of the vertical engine, respectively. These exhaust ports are communicated with downwardly curved exhaust passages, and the flow of exhaust gas exhausted from each exhaust port can be made to substantially coincide with the direction of the curved exhaust passages. Is subjected to the action of centrifugal force, and the exhaust port of the lower cylinder bore can be made to face the inside of the curved portion of the exhaust passage where the centrifugal force is unlikely to act, so that the exhaust is performed smoothly and smoothly.

An exhaust outlet portion is formed by cutting a lower portion of the cylinder block downward, and a lower exhaust passage is formed by attaching an exhaust guide mounting component having a guide surface to the exhaust outlet portion. Therefore, there is no need to use a tunnel core during die casting. Furthermore, an exhaust guide having a surface shape continuous with the curved surface of the upper exhaust passage is provided integrally with the mounting component, and the mounting component has a guide surface that is continuous with the inner surface of the upper exhaust passage. With this arrangement, a smooth flow of exhaust gas in the exhaust passage can be ensured, and one exhaust passage can be formed by cutting the cylinder block in two directions substantially perpendicular to each other. The cost of the mold can be reduced, and the degree of freedom of the shape of the opening of the exhaust passage outlet can be increased.

Further, a water jacket is formed on the side of the outlet of the exhaust passage of the cylinder block, and the die removing direction of the water jacket and the die of the exhaust passage outlet are the same. By removing the mold, both the exhaust passage outlet and the water jacket can be molded with a single core (main core), so there is no need to use a tunnel core at the time of die casting, the molding die is small, and the cost of the mold can be reduced. it can.

[Brief description of the drawings]

FIG. 1 is a view of a cylinder block to which an embodiment of an exhaust passage outlet structure of an outboard motor engine according to the present invention is applied;
Sectional drawing corresponding to FIG.

FIG. 2 is a view taken in the direction of the arrow II in FIG.

FIG. 3 is an assembled perspective view showing an engine of the outboard motor.

FIG. 4 is a front view of the cylinder block as viewed in IV direction in FIG. 3;

FIG. 5 is a sectional view taken along the line VV in FIG. 4;

FIG. 6 is a view taken in the direction of arrow VI in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder block 8 Cylinder bore 11 Exhaust hole 12 Exhaust passage 12a Upper exhaust passage 12b Lower exhaust passage 14 Exhaust cover 25 Straight tubular outlet of exhaust passage 26 Under oil seal housing 27 Exhaust guide 28 Guide surface 29 Exhaust passage curved surface

Continuation of the front page (51) Int.Cl. ⁷ identification code FI F02F 1/00 F02F 1/22 A 1/22 B63H 21/26 E (58) Field surveyed (Int.Cl. ⁷ , DB name) F02F 1 / 42 F02F 1/22 F02F 1/00 F02B 67/00 F01P 3/02 B63H 20/24

Claims (1)

(57) [Claims] A cylinder bore for fitting a cylinder into a cylinder block constituting a vertical engine of an outboard motor is formed, and a downwardly curved exhaust passage communicating with an exhaust port opened in the cylinder bore is formed. In an exhaust passage outlet structure for an outboard motor engine, an attachment part such as an under oil seal housing is configured to be attachable to an outlet of the exhaust passage, and a water jacket is formed on a side of the outlet of the exhaust passage. An exhaust space is formed by cutting the side of the exhaust port sideways, and an exhaust cover is attached to the side opening of the exhaust space to form an upper exhaust passage between the cylinder block and the exhaust cover. On the other hand, the lower part of the cylinder block is die-cut downward, and the exhaust outlet communicates with the upper exhaust passage. A mounting part integrally formed with an exhaust guide is detachably attached to the lower end surface of the cylinder block, and the exhaust guide of the mounting part is flush with the inner surface of the exhaust passage of the exhaust cover. With a continuous guide surface
An upper end of the guide surface is extended near a parting line of a die formed at a lower portion of the upper exhaust passage and an upper portion of the exhaust outlet portion, and communicates with the upper exhaust passage by a guide surface of the exhaust guide at a lower portion of the cylinder block. A water jacket having a lower opening is formed integrally with a side of a lower exhaust passage formed in a lower portion of the cylinder block by die-cutting in a die-cutting direction at the time of forming an exhaust outlet. An exhaust passage exit structure for an outboard engine, wherein a lower open portion of the water jacket is closed by a mounting part.