JPS58178819A - Four cycle internal-combustion engine - Google Patents

Abstract

PURPOSE:To make a lubrication oil return quickly from a crankcase into an oil pan, by opening an oil drain passage communicating with the oil pan through a portion of a crankcase inner surface opposing to a tangential line in parallel with the revolving direction of a crankshaft. CONSTITUTION:An oil drain passage 66 is opened through a portion of an inner surface of a cylinder casing 20 opposing to a tangential line in parallel with a revolving direction of a crankshaft, the cylinder casing 20 partitioning a crankcase 28. The oil drain passage 66 is communicated with an oil pan via a port 67 bored through the cylinder casing 20 for inserting an oil level gauge therethrough. That is, the oil drain passage 66 serves to guide a lubrication oil making an induced circulation through the crankshaft 29 to the port 67 for its draining to the oil pan.

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, the lubricating oil that lubricates the bearing of the crankshaft and the large end bearing of the connecting rod is
When the crankshaft rotates, or after the rotation, rC tends to adhere to and accumulate on the inner surface of the crank chamber. Therefore, the lubricating oil does not return to the oil pan quickly after lubrication, causing the oil temperature to rise excessively and causing early deterioration, and it is necessary to increase the total capacity of the oil pan in order to ensure sufficient circulation oil. It is occurring.

SUMMARY OF THE INVENTION An object of the present invention is to provide a four-stroke internal combustion engine in which a crankshaft is vertically placed in a crank chamber, in which lubricating oil in the crank chamber can be quickly returned to an oil pan.

In order to achieve the above object, the present invention provides an oil pan in a four-stroke internal combustion engine in which the crankshaft is vertically placed in the crank chamber, at a portion of the inside of the crank chamber that faces substantially tangentially to the rotation of the crankshaft. A communicating oil discharge passage is opened.

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 the main parts of the internal combustion engine, and FIG. FIG. 4 is a sectional view taken along the line IV--F in FIG. 2.

A casing 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 gauging 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 disposed within the casing 14 and a forward/reverse switching mechanism 18, allowing the propeller 19 to rotate forward or backward.

As shown in FIGS. 2 and 3, the internal combustion engine 16 is
It is a water-cooled four-stroke 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.

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 240 is a combustion chamber 25 . A spark plug, an intake boat opened by an intake valve 26, and an exhaust boat opened by an exhaust valve 27 are disposed in a portion of the cylinder head 22 facing the combustion chamber 25.

In addition, the cylinder case 20 and the crank case 2
A space defined by 1 on the back side of the piston 24 is defined as a crank chamber 28. A crankshaft 29 supported by a bearing formed at the mating surface of the cylinder case 20 and the crankcase 21 is vertically disposed in the crank chamber 28, and the lower end of the crankshaft 29 is connected to the upper end of the drive shaft 17. are connected. A crankshaft 29Fi has a crankbin 31 between its webs 30, and a connecting rod 32 is attached to the crankbin 31.
The large end portions 33 of the two 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 25.
The piston 24 rotates in accordance with the reciprocating motion of the piston 24 based on the explosive force within the piston 24, thereby making it possible to 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 respective rocker arms 42 supported by a valley rocker shaft 41K. 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 when the crankshaft 290H rotates, the camshaft 36 is rotated once.
It can be rotated.

As described above, the housing 38 of the lubricating oil pump 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.
0 is open.

An oil pan 51 is suspended and fixed to substantially the center shaft of the lower surface of the intermediate member 15. Above +14? The suction passage 49 of the v-oil pump 37 is connected to the cylinder head 22 and the cylinder case 2.
The lubricating oil in the oil pan 51 can be communicated with the oil wt 52 formed in the oil pan 51 via a suction pipe 53 that communicates with the oil passage 52 and is vertically installed on the intermediate member 15 . That is, when the internal combustion engine 16 is operating, the lubricating oil pump 37
6 rotates, and enables the lubricating oil in the oil pan 51 to be pumped to the discharge path 50111I.

The lubricating oil pumped by the lubricating oil pump 37 is sent from the discharge passage 50 to the lower passage 54 where the same groove is formed in the crankshaft 29 on the lower surface side of the cylinder head 22 and cylinder case 20. Oil is supplied to a lower front passage 55 formed on the upper surface side of the cylinder head 22 and cylinder case 20 in a direction connecting the crankshaft 29 and the camshaft 36. Note that the lower oil passage 54 and the lower front passage 55 are communicated with each other by a communication oil passage (not shown) that branches from the middle of the lower oil passage 54 and extends vertically on the side surface of the cylinder case 20.

The lubricating oil sent to the lower oil passage 54 is transmitted to the crankshaft 29
The oil is supplied to the bearing section sealed by an oil seal 56 on the lower +lai side, and lubricates the bearing section. After lubricating the big end bearing part formed with the big end part 33, it is scattered into the crank chamber 28. In addition, the crankshaft 291 of the lower front passage 55
The lubricating oil directed toward the crankshaft 29 is supplied to a bearing portion sealed by an oil seal 59 on the upper end side of the crankshaft 29, and lubricates the bearing portion.
After lubricating the big end bearing formed by the crank pin 31 and the big end 33 of the connecting rod 32 through an oil passage 61 drilled in the oil passage 61 , the oil is scattered into the crank chamber 28 . The lubricating oil scattered in the crank chamber 28 as described above moves downward in the crank chamber 28 and returns to the oil pan 51 through the return oil passage 62 formed by the cylinder case 20 and the intermediate member 15. It looks like this. Also, camshaft 3 of Kamiike # & 55
The lubricating oil flowing toward the camshaft 36 lubricates the bearing portion sealed by the oil seal 63V′C on the upper end side of the camshaft 36.
Thereafter, it flows downward along the outer peripheral surface of the camshaft 36 and lubricates the cam surfaces of the intake cam 39 and 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, an oil discharge passage 66 is opened at a portion of the inner surface of the cylinder case 20 that defines the crank chamber 28 and faces substantially tangentially to the rotation of the crankshaft 290. The oil discharge passage 66 valves an oil level insertion hole 67 formed in the cylinder case 20.
It is communicated with the oil pan 51. That is, the oil discharge passage 66 introduces lubricating oil that circulates around the crankshaft 29 and supplies it to the oil pan 5 through the oil level insertion hole 67.
1 can be discharged.

Note that for 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 is configured to moderate pressure fluctuations in the crank chamber 28 due to the reciprocating movement of the hinge 24, and to communicate blow-by gas from the combustion chamber 25 to the crank chamber 28 with the cam chamber 35. In addition, the pressure balance between the crank chamber 28 and the cam chamber 35 is maintained at the skin hole, and the cam chamber 35
This enables smooth return of lubricating oil from the oil pan 51 to the oil pan 51.

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

When the internal combustion engine 16 is operating, due to the rotation of the crankshaft 29,
When the lubricating oil pump 37 is driven via the camshaft 36, the lubricating oil in the oil pan 51 is transferred to the lubricating oil bonder 37.
is forcedly fed to the lower oil passage 54 and lower front passage 55 by driving. The lubricating oil forced into the lower oil passage 54 is transferred to the crankshaft 29
After lubricating the lower bearing of the crankshaft 29 and the big end bearing formed by the crank pin 31 and the big end 33 through the oil passage 58, it scatters into the crank chamber 28 and rotates as the crankshaft 29 rotates. In addition, a part of the lubricating oil forced into the upper pond passage 55 lubricates the upper bearing of the crankshaft 29 and also lubricates the big end bearing between the crank pin 31 and the big end 33 through the oil passage 61. Thereafter, it scatters into the crank chamber 28 and is carried around by the crankshaft 29.

However, in the above embodiment, the crankshaft 290
The oil discharge passage 66 opens in the direction in which the lubricating oil moves as it rotates, and a portion of the lubricating oil flows to the crankshaft 29.
After being carried around, the oil immediately jumps into the oil discharge passage 66 and returns to the oil pan 51 through the oil level insertion hole 67. Note that the remaining lubricating oil falls and returns to the oil wr.
62 returns to the oil pan 51. Therefore, the lubricating oil after lubricating around the crankshaft 29 is transferred to the oil discharge path 6.
6, the oil quickly returns to the oil pan 51, promoting its cooling and preventing early deterioration.
The purpose is to eliminate the need to increase the capacity of the oil pan 51 in order to secure the amount of circulating oil.

As shown in (2) below, the four-stroke internal combustion engine according to the present invention has the following features:
An oil discharge passage that communicates with the oil pan is opened on the inside of the crankshaft chamber facing approximately tangentially to the rotation of the crankshaft, so lubricating oil circulating along with the crankshaft immediately passes through the oil discharge passage to the oil pan. This has the effect that the lubricating oil in the crank chamber can be quickly returned to the oil pan.

[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. FIG. 4 is a sectional view taken along the line ■--III in FIG. 2. 16... Internal combustion engine, 28... Crank chamber, 29
...Crankshaft, 51...Oil pan, 66.
・Oil drain path. Agent Patent Attorney Osamu Shiokawa Figure 1 Figure 2

Claims (1)

[Claims] (1) In a four-stroke internal combustion engine in which the crankshaft is vertically placed in the crank chamber, an oil discharge passage communicating with the oil pan is opened in a portion of the inside of the crank chamber that faces approximately tangentially to the rotation of the crankshaft. A 4-stroke internal combustion engine featuring: