JP3216087B2 - Breather structure of outboard motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breather structure for an outboard motor.

[0002]

2. Description of the Related Art Generally, an engine of an outboard motor is a vertical engine in which a crankshaft is disposed vertically, and an oil pan is provided below the engine.

[0003] Oil lubricating the crankshaft in the crank chamber and the piston in the cylinder is returned to the oil pan through a crank chamber side oil return passage between the crank chamber and the oil pan. The oil that has lubricated the valve mechanism in the cam chamber is returned to the oil pan via the cam chamber-side oil return passage between the cam chamber and the oil pan.

Generally, blow-by gas leaked into a crank chamber from a gap between a piston and a cylinder, as in the invention described in Japanese Patent Application Laid-Open No. Hei 4-91311, is guided directly to a cam chamber via a breather passage in a cylinder body. At the same time, it is indirectly guided to the cam chamber via the oil pan upper space. The blow-by gas introduced into the cam chamber via the two paths as described above is discharged into the atmosphere from a breather chamber arranged in communication with the cam chamber or sent to a silencer.

[0005]

However, since the breather passage which directly connects the crank chamber and the cam chamber is formed substantially horizontally, the oil agitated in the crank chamber during the operation of the engine is supplied with blow-by gas. Riding the flow of
It flows into the cam chamber via the breather passage. For this reason, the amount of oil returned from the crank chamber to the oil pan decreases, the oil level of the oil pan decreases, and there is a possibility that engine seizure or the like due to poor suction of oil may occur.

The above problem can be solved by eliminating the substantially horizontal breather passage. But in this case,
There is a possibility that the blow-by gas leaked into the crank chamber cannot be sufficiently discharged due to a shortage of the breather passage.

The present invention has been made in consideration of the above circumstances, and provides an outboard motor which can satisfactorily discharge blow-by gas and can avoid problems such as engine seizure due to insufficient oil in an oil pan. It is intended to provide a breather structure.

[0008]

According to the present invention, an oil pan is provided at a lower portion of an engine in which a crankshaft is disposed vertically, and oil lubricated in a crank chamber, a cam chamber and the like passes through an oil return passage to the oil pan. In the breather structure of the outboard motor, which is returned to the pan, a breather chamber is communicated with the cam chamber, and blow-by gas leaked into the crank chamber is led to the breather chamber via the cam chamber, the upper space of the oil pan And the cam chamber are communicated by a blow-by gas dedicated passage, and the crank chamber is connected to only the blow-by gas dedicated passage or the other oil return passage only through the one oil return passage and the oil pan upper space. Through the cam chamber.

[0009]

According to the outboard motor breather structure of the present invention, the crank chamber communicates with the cam chamber via the oil return passage and the oil pan upper space, and only through the passage for the blow-by gas or the oil return passage. Therefore, the blow-by gas leaked into the crank chamber always flows through the oil return passage to the upper space of the oil pan, and then flows through the blow-by gas dedicated passage or the oil return passage to reach the cam chamber. Therefore, the oil after lubricating the crank chamber is always returned into the oil pan along the flow of the blow-by gas, and is not guided to the cam chamber. For this reason, sufficient oil can always be ensured in the oil pan, and problems such as engine seizure due to insufficient oil in the oil pan can be avoided.

Further, the blow-by gas leaked into the crank chamber is guided to the upper space of the oil pan and then to the cam chamber through a dedicated blow-by gas passage or an oil return passage. Sufficiently secured, it is possible to discharge blow-by gas satisfactorily.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial sectional view showing an engine of an outboard motor to which an embodiment of a breather structure for an outboard motor according to the present invention is applied. FIG. 2 is a sectional view taken along the line II-II.

The engine 11 of the outboard motor 10 is mounted on a propulsion unit 10A via an exhaust guide 12. The engine 11 is covered with a cowling 13 and protected from water and the like.

The crankshaft 14 of the engine 11 is disposed vertically, and a piston 15 is disposed so as to be able to reciprocate in the horizontal direction. The crankshaft 14 is rotatably accommodated in a crank chamber 18 surrounded by a cylinder body 16 and a crankcase 17. The piston 15 is housed in a cylinder 16 </ b> A of a cylinder body 16, and is connected to a crankshaft 14 via a connecting rod 19.
Linked to

A cylinder head 20 and a head cover 21 are sequentially joined to the cylinder body 16, and a combustion chamber 50 is formed in the cylinder head 20. An intake valve 53 and an exhaust valve 54 open and close the intake port 51 and the exhaust port 52 communicating with the combustion chamber 50, respectively.

In a cam chamber 22 surrounded by the cylinder head 20 and the head cover 21, a camshaft 23 and a rocker arm 24 are arranged together with an intake valve 53 and an exhaust valve 54. Cam 25 of camshaft 23
Drives the intake valve 53 and the exhaust valve 54 via the rocker arm 24.

A cam driven pulley 26 is fixed to the camshaft 23, and a cam drive pulley 27 is fixed to the crankshaft 14. A cam drive belt 28 is wound around the cam driven pulley 26 and the cam drive wheel 27, and the cam shaft 23 is rotated by the crank shaft 14. The cam driven pulley 26, the cam drive pulley 27, and the cam drive belt 28 are arranged on the upper surface S of the engine 11, that is, on the upper surfaces of the cylinder head 20, the cylinder body 16, and the crankcase 17. The intake valve 53, the exhaust valve 54, the camshaft 23, the rocker arm 24, and the cam 25 constitute a valve mechanism.

An oil pump 29 is provided at the lower end of the camshaft 23 of the valve mechanism. On the other hand, an oil pan 30 is suspended from the exhaust guide 12. The oil pan 30 is formed integrally with the propulsion unit 10A. Oil pump 29 based on rotation of camshaft 23
The oil stored in the oil pan 30 lubricates between the rocker arm 24 and the cam 25 in the cam chamber 22 via the oil strainer 31 by the drive of the. Further, the oil lubricates between the crankshaft 14 and the connecting rod 19 in the crank chamber 18, between the cylinder 16A and the piston 15, and the like.

The oil after lubricating the inside of the cam chamber 22 is returned to the oil pan 30 through the cam chamber side oil return passage 32 as shown by an arrow A. The oil that has lubricated the inside of the crank chamber 18 and the cylinder 16A is returned into the oil pan 30 through the crank chamber side oil return passage 33 as shown by the arrow A. The inlet side of the cam chamber side oil return passage 32 communicates with the lowermost part of the cam chamber 22, and the crank chamber side oil return passage 3
The inlet side of 3 is communicated with the lowermost part of the crank chamber 18, that is, a position facing the crank web 34 (balance weight) at the lowermost position. Further, the cam chamber side oil return passage 32
Each outlet side of the oil return passage 33 and the crank chamber side is partitioned by a partition wall 35.

A passage 36 exclusively for blow-by gas is provided upright from the partition wall 35, extends substantially horizontally, is connected to the cam chamber 22, and communicates the interior of the cam chamber 22 with the upper space 37 of the oil pan 30. This blow-by gas exclusive passage 36
Is a cam chamber side oil return passage 32 in the cam chamber 22.
Above the connection position. That is, in the cam chamber 22, the outlet side of the blow-by gas dedicated passage 36 is connected to a portion above the oil surface 38 when the outboard motor 10 is tilted when the oil is excessively injected into the oil pan 30. The blow-by gas dedicated passage 36 is an internal pipe formed as a passage in the cylinder body 16 and the cylinder head 20.

A breather chamber 39 is disposed above the cam chamber side oil return passage 32. This breather room 39
Is disposed below the upper surface S of the engine 11 and behind the outboard motor 10. The breather chamber 39 communicates with the cam chamber 22 and is connected to a silencer 41 via a breather hose 40 as shown in FIG. The silencer 41 forms an intake system of the engine 11 together with the carburetor 42, and supplies air to the carburetor 42. The carburetor 42 generates an air-fuel mixture and guides the air-fuel mixture to the intake port 51 of the engine 11.

Therefore, the piston 15 and the cylinder 16A
The blow-by gas leaked into the crank chamber 18 from between
As shown by an arrow B in FIG. 1, all of the space above the upper space 3 of the oil pan 30 passes through a crank chamber side oil return passage 33.
7 flows into. A part of the blow-by gas introduced into the oil pan upper space 37 is separated from the oil component in the gas while flowing in the blow-by gas dedicated passage 36 as shown by an arrow C in FIG. This oil component flows down into the oil pan 30, and only approximately the gas component is guided into the cam chamber 22. Further, the remaining blow-by gas introduced into the oil pan upper space 37 is separated into gas and liquid through the cam chamber side oil return passage 32 in the same manner as described above, and is introduced into the cam chamber 22.

The blow-by gas that has flowed into the cam chamber 22 is led to a breather chamber 39, where the blow-by gas is further separated into gas and liquid in the breather chamber 39. be introduced. On the other hand, the oil separated in the breather chamber 39 is supplied to the cam chamber 2
2 and the oil pan 3 through the cam chamber side oil return passage 32.
Returned to 0.

According to the above embodiment, the crank chamber 18 is
The cam chamber 22 passes only through the passage of the blow-by gas exclusive passage 36 or the cam chamber-side oil return passage 32 through the crank chamber-side oil return passage 33 and the oil pan upper space 37.
And a breather passage 43 (FIG. 2) that directly connects the crank chamber 18 and the cam chamber 22 is not formed in the cylinder body 16. For this reason, the blow-by gas that has leaked into the crank chamber must be removed from the crank chamber side oil return passage 3.
After flowing into the oil pan upper space 37 through the third passage 3, the blow-by gas exclusive passage 36 or the cam chamber side oil return passage 3
2 flows to the cam chamber 22. Therefore, the crank chamber 18
The oil after lubricating the inside is always returned into the oil pan 30 along the flow B of the blow-by gas, and is not guided to the cam chamber 22. For this reason, since sufficient oil can always be ensured in the oil pan 30, it is possible to reliably avoid problems such as engine seizure due to insufficient oil in the oil pan 30.

The blow-by gas leaked into the crank chamber 18 is led to the upper space 37 of the oil pan and then to the cam chamber 22 through the dedicated blow-by gas passage 36 or the oil return passage 32 on the cam chamber side. In addition, the discharge path for the blow-by gas is sufficiently ensured, and the blow-by gas can be discharged well.

Further, as shown in FIG. 2, the breather passage 43 for directly connecting the crank chamber 18 and the cam chamber 22 is not formed in the cylinder body 16, so that the side wall of the cylinder body 16 is Can be set to the center side of Therefore, the carburetor 42 arranged adjacent to the side wall of the cylinder body 16 can be arranged closer to the center side of the cylinder body 16, so that the size of the engine 11 can be reduced.

[0026]

As described above, according to the breather structure for an outboard motor according to the present invention, blow-by gas can be satisfactorily discharged, and problems such as engine seizure due to insufficient oil in the oil pan can be reliably avoided. be able to.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing an engine of an outboard motor to which an embodiment of a breather structure for an outboard motor according to the present invention is applied.

FIG. 2 is a sectional view taken along line II-II.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Outboard motor 11 Engine 14 Crankshaft 18 Crank chamber 22 Cam chamber 30 Oil pan 32 Cam chamber side oil return path 33 Crank chamber side oil return path 36 Blow-by gas dedicated path 37 Oil pan upper space 39 Breather chamber

Claims (1)

(57) [Claims] An oil pan is provided at a lower portion of an engine in which a crankshaft is disposed vertically, and oil lubricating a crank chamber and a cam chamber is returned to the oil pan via an oil return passage, and the cam is rotated. A breather chamber is communicated with the chamber, and blow-by gas leaked into the crank chamber is led to the breather chamber through the cam chamber. The crank chamber is communicated with a dedicated passage, and the crank chamber is communicated with the cam chamber via only the oil return passage and the oil pan upper space, the blow-by gas dedicated passage or the other oil return passage only. A breather structure for an outboard motor, characterized in that: