JPH0450097A - Exhausting device for four-cycle outboard motor - Google Patents

Abstract

PURPOSE:To effectively prevent engine cooling wastewater from adhering to the external wall of an oil pan and eroding the external wall of the oil pan by introducing the engine cooling wastewater on the outer periphery of a exhaust gas passage, and islating the engine cooling wastewater from the oil pan. CONSTITUTION:The propellant unit of an outboard motor is mounted to the hull so that it can freely turn up and down, and right and left. An exhaust pipe 36 from an engine 10 extends downward, and theexhaust pipe 36 is connected to an exhaust gas expansion chamber 38. The engine is firmly installed to a supporting plate 42 mounted to the upper end of an upper casing 12, and the above oil pan 34 is hung and fixed in a state that it is held between the supporting plate 42 and the upper casing 12. For the exhaust pipe 36, a water passage is partitioned and formed around the exhaust pipe 36, and ita lower end is connected to a water reservoir 54 formed around the expansion chamber 38, and the inside of the expansion chamber 38. The upper opening parts of the expansion chamber 38 and the water reservoir 54 are closed with a cover body 48 to isolate them from the oil pan 34.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exhaust system for a four-stroke outboard motor, and particularly to a structure around an oil pan housed in a casing.

[Conventional technology]

Generally, a four-stroke engine requires an oil pan to store engine oil. When such a four-stroke engine is used as an outboard motor, the oil pan is housed in the upper part of the amplifier casing of the propulsion unit, as described in, for example, Japanese Utility Model Publication No. 47-27113. The engine is mounted on this casing, and the exhaust gas from the engine is discharged through an exhaust passage that passes near the oil pan, an exhaust expansion chamber that houses the oil pan, and an exhaust outlet that opens into the water at the bottom of the casing. . Conventionally, in order to cool the exhaust gas in the exhaust passage, cooling water after cooling the engine has been passed through the outer wall of the exhaust passage. This engine cooling waste water is introduced between the pan and the exhaust passage and into the exhaust expansion chamber to cool both.

[Problem B to be solved by the invention] As described above, in the structure in which engine cooling water is introduced between the oil pan and the exhaust passage and into the exhaust expansion chamber, the cooling water comes into contact with or adheres to the outer wall of the oil pan. It turns out. This engine cooling water takes in the seawater around the outboard motor, so the seawater that adheres to the oil pan when the engine is stopped is heated by the oil in the oil pan, and its salt crystallizes, making it more It firmly adheres to the outer wall of the oil pan. These crystals grow each time the engine is used. When the outboard motor is not in use, this crystallized salt absorbs moisture from the air due to its deliquescent action, and when it comes into contact with the air, it is supplied with oxygen and corrodes the outer wall of the oil pan. There is.

The present invention has been made in view of the problems of the prior art, and its purpose is to prevent engine cooling water introduced to cool the exhaust passage from adhering to the outer wall of the oil pan. To provide an exhaust system for a four-stroke outboard motor which effectively prevents corrosion of the outer wall of the outboard motor.

(Means for Solving the Problems) In order to achieve such an object, the present invention provides a tffl
The engine is mounted on the unit housing, an oil pan is housed near the top of the casing, an exhaust loca is formed at the bottom of the casing that opens underwater, and the engine and this exhaust outlet are connected to an exhaust passage near the oil pan. In the four-stroke outboard motor, which is connected to the four-cycle outboard motor, engine cooling water is introduced into the outer periphery of the exhaust passage, and the engine cooling water and the oil pan are separated from each other.

In this configuration, the exhaust passage is composed of an exhaust pipe that extends downward from the engine through the vicinity of the oil pan, and an exhaust expansion chamber that communicates with the exhaust pipe formed below the oil pan. The oil passes through a cooling water passage defined around the pipe and isolated from the oil pan, and is introduced into a water reservoir defined at least around the exhaust expansion chamber, and a lid is attached above the water reservoir. It is best to have a configuration where the pan and water reservoir are separated.

[Effect]

By isolating the oil pan from the engine cooling waste water introduced to the outer periphery of the exhaust passage, it is possible to prevent the engine cooling waste water containing salt from adhering to the outer wall of the oil pan, thereby preventing corrosion of the oil pan outer wall.

In particular, when a water reservoir is defined on the outer periphery of the exhaust expansion chamber to cool the exhaust expansion chamber as well, by installing a lid above the water reservoir, the oil pan and the water reservoir are isolated. Therefore, due to exhaust pressure or external forces acting on the outboard motor, engine cooling waste water may be scattered and splashed onto the outer wall of the oil pan, or water in the water reservoir may be blown up by the rotation of the drive shaft, causing this water to spill onto the outer wall of the oil pan. It can reliably prevent scattering.

The oil stored and lubricated in the oil pan has a large heat capacity, so even if the oil continues to heat the outer wall of the oil pan, water containing salt will not come into contact with or adhere to it, so corrosion of the outer wall of the oil pan will not occur. Does not occur.

〔Example〕

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 1 shows the overall structure of an outboard motor for boat fishing. The engine 10 is an upper casing 12 of the propulsion unit.
It is placed on top and covered by the cowling 4. The output of the engine 10 is transmitted to a drive shaft 18 that passes through the upper casing 12 and extends to the lower casing 16, and is transmitted to the lower casing 16 via a shift mechanism 20.
is transmitted to a propeller 22 provided at The upper casing 12 is supported by a swivel bracket 24 and is rotatable left and right around a swivel shaft 25 (FIG. 2). The swivel bracket 24 has a tilt axis 28 relative to a clamp bracket 26 fixed to the stern plate 30 of the hull.
The propulsion unit is connected to be rotatable up and down around the hull, and thereby the propulsion unit is attached to be rotatable up and down and left and right with respect to the hull.

Reference numeral 32 is a steering bracket.

Reference numeral 34 is an oil pan, which will be described later, and is housed in the upper part of the amplifier casing 12.
An exhaust pipe 36 from the engine 10 extends downward in the vicinity,
The exhaust pipe 36 is connected to an exhaust expansion chamber 38. This expansion chamber passes through the lower casing 16 and communicates with an exhaust outlet 40 formed in the boss portion of the propeller 22.

As shown in detail in FIGS. 2 to 4, the engine 10
is firmly attached to the support plate 42 attached to the upper end of the upper casing 12, and
2 is connected to the steering bracket 32 via an upper support mount 43. This support plate 42
The oil pan 34 is suspended and fixed to the support plate 42 while being sandwiched between the upper casing 12 and the upper casing 12 . The oil pan 34 has a substantially box-like shape with a bottom, and its central portion is depressed when viewed from a plane, as shown in FIG. 4, in order to allow the exhaust pipe 36 to pass up and down. Reference numeral 44 denotes a screen facing the bottom of the oil pan 34; 45;
is an oil suction pipe, and 46 is a relief valve for oil flowing through from the engine 10.

The upper end of the exhaust pipe 36 communicates with an exhaust boat (not shown) of the engine 10 via a passage formed in the support plate 42 . The lower end of the exhaust pipe 36 extends further downward than the bottom wall of the oil pan 34, and is supported in a liquid-tight manner by a sealing member 50 between it and a lid 48, which will be described later, in the middle. It extends and ends. Reference numeral 52 designates a water passage that is integrally formed with the exhaust pipe 36 and is divided around the exhaust pipe 36. As shown in FIG. It communicates with the formed water reservoir 54 as well as with the expansion chamber 38 . The upper openings of the expansion chamber 38 and the water reservoir 54 are closed by a lid 48 and isolated from the oil pan 34. A drain hole 55 is formed at the lower end of the water reservoir 54.

A throttle passage 56 for discharging exhaust gas at low speed from the expansion chamber 38 is formed in the upper part of the wall defining the expansion chamber 38, and the throttle passage 56 is connected to the inner wall of the upper casing 12 and the partition wall 57.
It communicates with an exhaust outlet 60 provided at the upper part of the outer wall of the upper casing 12 via a sub-expansion chamber 58 formed between the upper casing 12 and the upper casing 12 . Here, this sub-expansion chamber 58 is also isolated from the outer wall of the oil pan 34.

The cooling water is seawater around the outboard motor sucked in from a water intake port (not shown) of the lower casing 16 by a cooling water pump 62 driven by the drive shaft 18. The cooling water is introduced upward to the engine 10 via the cooling water suction pipe 63, and the engine cooling water after cooling the engine 10 is guided to the waterway 52 via the support plate 42. There is.

According to such a configuration, the engine oil that has become hot after lubricating each part of the engine 10 is returned to the oil pan 34, and this oil is again forced to be sent to the engine 10 from the screen 44 via the oil suction pipe 45. be done.

Exhaust gas from the engine 10 passes through the exhaust pipe 36 and is introduced into the expansion chamber 3 without contacting the outer wall of the oil pan 34, where it is expanded and muffled.

At high speeds, the air flows from the lower outlet of the expansion chamber 38, passes through the passage of the lower casing 16, and is discharged into the sea from the exhaust outlet 40 that opens into the water. At low speeds, the air flows from the expansion chamber 38, passes through the throttle passage 56, and enters the sub-expansion chamber 58. The air is discharged into the air through the exhaust outlet 60.

The water sucked in as cooling water is pumped upward from the cooling water suction pipe 63 to the engine 10 to cool the engine.

After the engine has been cooled down, the cooling water drains first through the exhaust pipe 36.
The water is introduced into the passage 52 around the exhaust pipe 36 and cools the exhaust air passing therethrough. After that, a part of this cooling waste water falls into the water reservoir 54 around the expansion chamber 38, and
The other part falls into the expansion chamber 38. As a result, the exhaust gas within the expansion chamber is directly and indirectly cooled. Expansion chamber 38
The water that falls into the sea returns to seawater from below. A small amount of the water that has entered the water reservoir 54 is discharged downward from the drain hole 55, but since the amount of water supplied is large, it remains here and is effectively used to drain the expansion chamber 38.
cooling the outer wall of the Here, it is preferable to provide a notch (not shown) at the upper end of the water reservoir 54 so that the water accumulated in the water reservoir 54 overflows and returns to the sea surface along the inner wall of the upper casing 12. The water collected in this water reservoir 54 is
Even if water splashes due to an external force transmitted from the sea surface to an outboard motor or the like, exhaust pressure, etc., since the upper part thereof is blocked by the lid body 48, splashes of water containing salt will adhere to the oil pan 34. Therefore, corrosion of the oil pan can be reliably prevented.

Particularly in this embodiment, the expansion chamber 38 is isolated by the lid 48, and the sub-expansion chamber 5, through which exhaust air at low speeds passes, is also separated by the partition wall 5.
Since the exhaust gas is isolated from the oil pan 34 by 7, the exhaust gas does not come into direct contact with the oil pan 34, and therefore the oil pan 34 can be prevented from being heated due to contact with high-temperature exhaust gas.

In order to prevent the water that has entered the expansion chamber 38 from flowing backward, it is preferable to provide a horizontal hole 65 in one side wall of the portion of the exhaust pipe 36 that extends into the expansion chamber 38.

Next, a second embodiment of the present invention is shown in FIGS. 5 and 6, and the difference between this embodiment and the first embodiment described above is that the air is discharged from the throttle passage 56 of the expansion chamber 38 at low speeds. The point is that the exhaust gas is not isolated from the outer wall of the oil pan 34, but is expanded in a larger sub-expansion chamber to muffle the sound, and then is discharged from the exhaust outlet 60. That is, the partition wall 57 shown in FIG. 2 is unnecessary. However, the expansion chamber 38 is still closed by the lid 48, so the relatively high temperature exhaust gas at high speeds does not come into direct contact with the outer wall of the oil pan 34.

In this embodiment, the exhaust air at low speeds is removed from the oil pan 34.
However, since the sub-expansion chamber is large due to the absence of the partition wall 57, the exhaust gas is sufficiently expanded and cooled, and the oil pan 34 is not heated abnormally by the exhaust gas. The cooling water entering the expansion chamber 38 flows downward, and even if the water droplets splash near the throttle passage 56, the throttle passage 56 is throttled and the downstream passage of the throttle passage 56 is placed at the end of the lid 48. By integrally forming the water separation projecting wall 66 for lowering one end of the oil pan 34, it is possible to reliably prevent splashes of cooling water from adhering to the outer wall of the oil pan 34.

As shown in FIG. 7, by providing a weir 68 on the lid body 48, the cooling waste water descending from the waterway 52 is introduced only into the water reservoir 54 around the expansion chamber 38, and no water flows into the expansion chamber 38. It is also possible to prevent it from entering. In this way, it is possible to more reliably prevent water containing salt from adhering to the oil pan 34.

〔effect〕

As explained above, according to the present invention, the engine cooling water and the oil pan are separated, so even if the oil pan outer wall continues to be warmed by the high temperature oil that lubricates the engine, the oil pan outer wall will be exposed to salt. It has the excellent effect of preventing the formation of crystals and corrosion.

In particular, a water reservoir is formed around the exhaust expansion chamber, and at least this water reservoir is covered by the lid.
Even if the water in this reservoir splashes due to external forces transmitted to the outboard motor from the sea surface, sudden acceleration/deceleration of the outboard motor, exhaust pressure, etc., the water droplets can be reliably prevented from adhering to the outer wall of the oil pan.

[Brief explanation of drawings]

FIG. 1 is a side view showing the overall structure of a four-stroke outboard motor according to the present invention, and FIG. Figure 3 is a cross-sectional view taken along line ■-■ in Figure 2, and Figure 4 is a cross-sectional view taken along line IV-IV in Figure 2.
5 is a cross-sectional view of essential parts showing the second embodiment of the present invention, FIG. 6 is a cross-sectional view taken along line Vl-Vl in FIG. 5, and FIG. 7 is a cross-sectional view of the third embodiment of the present invention. FIG. 2 is a cross-sectional view of main parts showing an example. 10--Engine 12--Upper casing 34--Oil pan 36--Exhaust pipe 38.58--Expansion chamber 60--Exhaust outlet 8--Lid body water passage 54. Water reservoir

Claims (2)

[Claims] (1) An engine is mounted on the casing of the propulsion unit, an oil pan is housed near the top of the casing, and an exhaust outlet opening into the water is formed at the bottom of the casing.
In a 4-stroke outboard motor in which the engine and the exhaust outlet are communicated through an exhaust passage near the oil pan, engine cooling drainage is introduced around the outer periphery of the exhaust passage, and the engine cooling drainage and the oil pan are separated. Outboard motor exhaust system. (2) The exhaust passage is composed of an exhaust pipe that extends downward from the engine through the vicinity of the oil pan, and an exhaust expansion chamber that communicates with the exhaust pipe formed below the oil pan. The oil pan is introduced through a cooling water passage defined around the circumference and isolated from the oil pan into a water reservoir defined at least around the exhaust expansion chamber, and a lid is attached above the water reservoir. 2. The exhaust passage for a four-stroke outboard motor according to claim 1, wherein the exhaust passage and the water reservoir are isolated from each other.