JPS58178818A - Four cycle internal-combustion engine - Google Patents

Abstract

PURPOSE:To eliminate a lubrication oil to make induced circulation through a crankshaft and to stagnate in a crankcasing, by providing a rib having an oil guiding surface inclined downwardly relative to a tangential line in parallel with a rotating direction of a crankshaft. CONSTITUTION:A crankcasing 21 which is built to partition a crank chamber 28 has a rib 66 arranged at an inner surface 2 of an approximate intermediate of upper and lower sides thereof, the rib projecting from opposite corners of the inner surface so as to surround a web pinched by upper and lower crank pins therebetween. Each rib 66 is provided with a lubrication oil guding surface 67 which is inclined downwardly relative to a tangential line in parallel with a rotating direction of the crankshaft 29. That is, a lubrication oil making induced circulation with a rotation of the crankshaft 29 is guided to pass over the guiding surface 67 of the rib 66, and its speed components in the circulating direction are converted into downward speed components, and thereby forcibly making the lubrication oil to fall downwardly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a four-stroke internal combustion engine, and particularly to a four-stroke internal combustion engine in which a crankshaft is vertically disposed within a crank chamber.

Conventionally, in four-stroke internal combustion engines in which the crankshaft is vertically placed, such as in outboard motors, lubricating oil that slips in the crankshaft bearing and the large end bearing of the connecting rod prevents the rotation of the crankshaft. There is a tendency for it to be attached to the inner surface of the crankshaft chamber and accumulate after being entrained by the engine. Therefore, the lubricating oil does not return to the oil pan quickly after lubrication, and the temperature of the oil rises excessively, leading to early deterioration.In order to ensure a sufficient amount of circulating oil, it is necessary to increase the capacity of the oil pan. is occurring.

The present invention enables lubricating oil to circulate around the crankshaft and to reduce the accumulation of lubricating oil in the crank chamber in a four-stroke internal combustion engine in which the crankshaft is vertically placed in a two-cylinder chamber. The purpose is to provide a cycle internal combustion engine.

In order to achieve the above object, the present invention provides a four-stroke internal combustion engine in which the crankshaft is placed vertically in the crank chamber. A reso is provided with an oil guide surface that slopes downward.

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

FIG. 1 is a side view showing an outboard motor to which an internal combustion engine according to an embodiment of the present invention is applied, FIG. 2 is a sectional view showing main parts of the internal combustion engine, and FIG. ■-A cross-sectional view along the I line,
FIG. 4 is a view taken along line IV'' in FIG. 2.

A gauging 14 is supported on a stern plate 11 of the hull via a clamp bracket 12 and a swivel bracket 13. A plate-shaped intermediate member 15 is provided on the upper part of the casing 14.
An internal combustion engine 16 is mounted via. internal combustion engine 1
The output of the propeller 6 is transmitted to the propeller 19 via a drive shaft 17 vertically installed in the casing 14 and a forward/reverse switching mechanism 18, making the propeller 19 capable of rotating forward or backward.

As shown in FIGS. 2 and 3, the internal combustion engine 16 is a water-cooled four-cycle two-cylinder internal combustion engine, and its outer shell is formed by a cylinder case 20, a crankcase 21, a cylinder head 22, and a head cover 23. are doing.

A pair of upper and lower cylinders are placed horizontally in the cylinder case 20, and a piston 24 is arranged in each cylinder so as to be able to reciprocate in the horizontal direction.

A space defined by the cylinder case 20 and the cylinder head 22 on the top surface side of the piston 24 is a combustion chamber 25 . A spark plug, an intake port opened by the intake valve 26, and an exhaust port opened by the exhaust valve 2T are arranged in a portion of the cylinder head 22 facing the combustion chamber 25.

Further, a space defined by the upper cylinder coupe 20 and the crank case 21 on the back side of the piston 24 is defined as a crank chamber 28 . In the crank chamber 28, a Y/L shaft 29 is vertically disposed, supported by a bearing portion formed at the mating surface of the cylinder case 20 and the crank case 21. The crankshaft 29 has a crank pin 31 between its webs 3o, and a connecting rod 3 connected to the crank pin 31.
The two large ends 33 are connected to each other. The small end of the connecting rod 32 is connected to the piston 24 by a piston pin 34. That is, the crankshaft 29 is connected to the combustion chamber 2
The piston 24 rotates according to the reciprocating motion of the piston 24 based on the explosive force within the piston 5, and can apply rotational force to the drive shaft 17.

A space defined by the cylinder head 22 and head cover 23 is a cam chamber 35. A camshaft 36 is vertically disposed in the cam chamber 35, and the upper end of the camshaft 36 is directly supported by the cylinder head 22, and the lower end is connected to the cylinder via a housing 38 of a lubricating oil pump 37, which will be described later. It is indirectly supported by the head 22. The camshaft 36 has
An intake cam 39 and an exhaust cam 40 are formed. The intake cam 39 and the exhaust cam 40 are capable of opening the intake valve 26 and the exhaust valve 27 via a valley rocker arm 42 supported by each rocker shaft 41, respectively. A driven wheel 43 is fixed to the upper end of the camshaft 36 that protrudes from the cam chamber 35, and a driving wheel 44 is fixed to the upper end of the crankshaft 29 that protrudes from the crank chamber 28. A belt 45 is wound around the drive wheel 44, and the camshaft 36 can be driven one rotation by 290% rotation of the crankshaft.

As described above, the housing 38 of the lubricating oil bonder 37 is fixedly arranged on the lower surface of the cylinder head 22 coaxially with the camshaft 36. A pump chamber 46 is formed in the lubricating oil pump 37 , and an impeller 48 that is integrated with a connecting shaft 47 that hangs down from the lower end of the camshaft 36 is disposed in the pump chamber 46 . A suction passage 49 is opened in the lower part of the pump chamber 46, and a discharge passage 5 is opened in the upper part of the suction passage 49.
° is open.

An oil pan 51 is suspended and fixed to substantially the center shaft of the lower surface of the intermediate member 15. Suction passage 49 of the lubricating oil pump 37
The intermediate member 15 communicates with the oil M52 and the oil passage 52 formed in the cylinder head 22 and the cylinder case 20.
The oil pan 51 is
It is said that it is possible to communicate with the lubricating oil. That is, when the internal combustion engine 16 is operating, the lubricating oil pump 37 is driven together with the rotation of the camshaft 36, so that the lubricating oil in the oil pan 51 can be pumped to the discharge passage 50 side.

The lubricating oil pumped by the lubricating oil pump 37 is sent from the discharge passage 50 to the lower front wr 54 that is formed toward the crankshaft 29 on the lower surface side of the cylinder head 22 and cylinder case 20, and also to Oil is supplied to a lower front passage 55 formed in the direction connecting the crankshaft 29 and the camshaft 36 on the two sides of the head 22 and the cylinder case 20. In addition,
The lower front passage 54 and the lower front passage 55 are connected to each other by a communication oil passage (not shown) that branches from the middle of the lower front passage 54 and extends in the vertical direction on the side surface of the cylinder case 20.

The lubricating oil sent to the lower front passage 54 is transmitted to the crankshaft 29
The oil is supplied to the bearing portion sealed by an oil seal 56 at the lower end side of the crankshaft 29, and lubricates the bearing portion. After lubricating the big end bearing part formed with the part 33, it is scattered into the crank chamber 28. Also, Kamiike lol! t55 crankshaft 291111
The lubricating oil flowing toward the crankshaft 29 is supplied to the bearing portion sealed by the oil seal 59 on the upper end side of the crankshaft 29,
- After lubricating the bearing part described in H and also lubricating the big end bearing part formed by the crank pin 31 and the big end part 33 of the connecting rod 32 through the oil passage 61 bored in the crankshaft 29, the crank chamber Scattered to 28. Crank chamber 28 as above
The lubricating oil scattered inside moves downward within the crank chamber 28 and returns into the oil pan 51 via a return oil passage 62 formed by the cylinder case 20 and the intermediate member 15. Furthermore, the lubricating oil flowing toward the camshaft 36 in the lower front passage 55 is supplied to the oil seal 63 at the upper end side of the camshaft 36.
The bearing portion sealed by
Lubricate the cam surface of the exhaust cam 40.

After lubricating the camshaft 36, the lubricating oil moves downward in the cam chamber 35, passes through the return oil passage 65 formed in the cylinder case 20 and the cylinder head 22, and returns to the oil pan 5.
It returns to within 1.

Here, at the inner surface 2 position of the crankcase 21 which defines the crank chamber 28, approximately in the middle in the vertical direction, there are projecting from both corners of the inner surface toward the crankshaft 29 side, and a crank pin 31 below the crankcase 28 is provided. Rizo 66 is arranged so as to surround the web 30 to be sandwiched. The valley groove 66 is provided with a lubricating oil guide surface 67 that is inclined downward with respect to the substantially tangential direction of rotation of the crankshaft 29 . That is, the lubricating oil that rotates as the crankshaft 290 rotates is guided by the lubricating oil guide surface 67 of the lip 66, and the speed component in the direction of rotation is converted into a downward speed component.

Note that in the internal combustion engine 16, the cylinder case 2
0 and the cylinder head 22 are formed with a pressure communication passage 68 that communicates the crank chamber 28 and the cam chamber 35 with each other. The pressure communication passage 68 alleviates pressure fluctuations in the crank chamber 28 due to the reciprocating motion of the piston 24, and
The blow-by gas from the engine to the crank chamber 28 can be discharged to the carburetor side via a not-shown solide connected to the cam chamber 35.
The lubricating oil can be smoothly returned from the cam chamber 35 to the oil pan 51 by maintaining a good pressure balance with the oil pan 51.

Next, the operation of the above embodiment will be explained.

When the internal combustion engine 16 is operating, the rotation of the crankshaft 29 causes
When the camshaft 36 is driven by the valve E7 and the lubricating oil pump 31 is driven, the lubricating oil in the oil pan 51 is transferred to the lubricating oil pump 3.
7, it is force fed to the lower front passage 54 and the lower front passage 55. The fc lubricating oil forced into the lower front passage 54 lubricates the lower bearing of the crankshaft 29, passes through oil #Nt58, lubricates the big end bearing formed by the crank pin 32 and the big end 33, and then enters the crank chamber. Scattered within 28. In addition, a part of the lubricating oil force-fed to the lower front passage 55 is transferred to the crankshaft 29
It lubricates the upper bearing of the crankshaft and the big end bearing formed by the crank pin 31 and the big end 33 through the oil passage 61, and then scatters into the crank chamber 28.

The lubricating oil scattered in the crank chamber 28 is rotated in the direction of rotation of the crankshaft 290.

However, the lubricating oil that rotates as the crankshaft 29 rotates is guided by the lubricating oil guide surface 67 of the reso 66, so that its speed component in the direction of rotation is changed to a downward speed component, and the lubricating oil is forced downward. Forced to fall. In addition, the lubricating oil that does not fall downward and adheres to the inner surface of the crankcase 21 after being rotated with the rotation of the crankshaft 29 is given a downward velocity component as described above immediately before its attachment. It quickly flows downward along the inner surface of the crankcase 21 based on the downward velocity component. t' That is, the lubricating oil after lubricating around the crankshaft 29 in the crank chamber 28 is quickly dropped downward in the crank chamber 28, and is smoothly returned to the oil pan 51 via the return oil w562. Therefore, cooling of the lubricating oil after lubrication is promoted, early deterioration can be prevented, and the need to increase the capacity of the oil pan 51 more than necessary in order to secure the amount of circulating oil is eliminated.

As described above, the four-stroke internal combustion engine according to the present invention is
Since a rig is provided inside the crank chamber with a lubricating oil guide surface that slopes downward with respect to the substantially tangential direction of the crankshaft rotation, the velocity component of the lubricating oil that rotates along with the rotation of the crankshaft is reduced to a downward velocity. By converting the lubricating oil into components, it is possible to quickly drop the lubricating oil downward, which has the effect of reducing the lubricating oil's entrainment around the crankshaft and the resulting accumulation of lubricating oil in the crank chamber. has.

[Brief explanation of drawings]

FIG. 1 is a side view showing an outboard motor to which an internal combustion engine according to an embodiment of the present invention is applied, FIG. 2 is a sectional view showing main parts of the internal combustion engine, and FIG. (2) A sectional view taken along the line -1lI, and FIG. 4 is a cross-sectional view taken along the line IV-PL/ in FIG. 16... Internal combustion engine, 20... Cylinder case,
21°° crankcase, 28... crank chamber, 29°... crankshaft, 66°... reso, 67...
...Lubricating oil guide surface. Agent Patent Attorney Osamu Shiokawa Figure 1 Figure 2

Claims (1)

[Claims] (1) A four-stroke internal combustion engine in which the crankshaft is vertically placed in the crank chamber is provided with an oil guide surface that protrudes from the inner surface of the crank chamber toward the crankshaft and slopes downward with respect to the substantially tangential direction of the crankshaft rotation. A four-stroke internal combustion engine characterized by being provided with a lip.