JPH0151645B2 - - 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 [Field of Industrial Application] 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.

[Prior Art] Conventionally, in a four-stroke internal combustion engine in which the crankshaft is vertically placed, such as in an outboard motor,
The lubricating oil that lubricates the bearing portion of the crankshaft and the large end bearing portion of the connecting rod tends to rotate along with the rotation of the crankshaft or, after the rotation, adheres to and stagnates on the inner surface of the crank chamber.

[Problems to be solved by the invention] Therefore, the lubricating oil does not return to the oil pan quickly after lubrication, and the oil temperature rises excessively and deteriorates early, and it is difficult to ensure a sufficient amount of circulating oil. Therefore, it is necessary to increase the oil pan capacity.

In a four-stroke internal combustion engine in which the crankshaft is vertically placed in the crank chamber, the present invention has been developed to prevent lubricating oil from moving around the crankshaft and to accumulate the lubricating oil in the crank chamber in a wide area around the crankshaft. The aim is to ensure a reduction in

[Means for Solving the Problems] The present invention provides a four-stroke internal combustion engine in which the crankshaft is vertically placed in the crank chamber, in which the crankshaft protrudes from the inner surface of the crank chamber toward the crankshaft, and extends in a substantially tangential direction to the rotation of the crankshaft. A plurality of ribs each having an oil guide surface slanting downward are provided substantially parallel to each other at a plurality of positions spaced apart in the rotational direction of the crankshaft.

[Operation] According to the present invention, a plurality of ribs substantially parallel to each other are arranged in parallel at a plurality of positions spaced apart in the rotational direction of the crankshaft on the inner surface of the crank chamber around the crankshaft. Therefore, as the vertical crankshaft rotates, the rotational speed component of the lubricating oil that travels along the entire circumference around the crankshaft is converted into a downward speed component by the lubricating oil guide surface of each rib, and the lubricating oil This causes the object to quickly fall downward.

At this time, in the present invention, since a plurality of ribs that are substantially parallel to each other are provided in parallel at a plurality of positions spaced apart in the rotational direction of the crankshaft, the lubricating oil is accompanied by the above-mentioned lubricating oil falling effect. It can be applied to a wide area around the rotating crankshaft.

Therefore, in a four-stroke internal combustion engine in which the crankshaft is vertically placed in the crank chamber, the lubricating oil is circulated around the crankshaft and the lubricating oil is accumulated in the crank chamber in a wide area around the crankshaft. It can be definitely reduced by

[Embodiment] 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 is a sectional view taken along the - line in FIG. 2, and FIG. 4 is a sectional view taken along the - line in FIG. 2.

A clamp bracket 1 is attached to the stern plate 11 of the hull.
2. A casing 14 is supported via a swivel bracket 13. An internal combustion engine 16 is connected to the upper part of the casing 14 via a plate-shaped intermediate member 15.
is installed. The output of the internal combustion engine 16 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 a water-cooled four-stroke two-cylinder internal combustion engine,
A cylinder case 20, a crank case 21, a cylinder head 22, and a head cover 23 form the outer shell. 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 portion of the cylinder head 22 facing the combustion chamber 25 includes an ignition plug, an intake port opened by an intake valve 26, and an exhaust valve 27.
An exhaust port is provided which is opened by the valve. Further, a space defined by the cylinder case 20 and the crank case 21 on the back side of the piston 24 is defined as a crank chamber 28 . A crankshaft 29 is vertically disposed in the crank chamber 28 and is supported by a bearing formed at the mating surface of the cylinder case 20 and the crankcase 21.
The upper end of the drive shaft 17 is connected to the lower end of the drive shaft 17 . The crankshaft 29 has a crank pin 31 between its webs 30, and a large end 33 of a connecting rod 32 is connected to the crank pin 31. The small end of the connecting rod 32 is connected to the piston 24 by a piston pin 34. That is, the crankshaft 29 rotates according to the reciprocating motion of the piston 24 based on the explosive force within the combustion chamber 25, and
It is possible to apply rotational force to.

A space defined by the cylinder head 22 and head cover 23 is a cam chamber 35. A camshaft 36 is placed vertically in the cam chamber 35, and the camshaft 36
has its upper end directly supported by the cylinder head 22, and its lower end is connected to a lubricating oil pump 37, which will be described later.
cylinder head 22 through the housing 38 of
is indirectly supported. An intake cam 39 and an exhaust cam 40 are formed on the camshaft 36. The intake cam 39 and the exhaust cam 40 connect to the intake valve 26 and the exhaust valve 27 via rocker arms 42 supported by rocker shafts 41, respectively.
The valve can be opened. 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 one half rotation of the crankshaft 29.

As mentioned 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 4 is provided at the bottom of the pump chamber 46.
9 is opened, and a discharge passage 5 is provided at the top thereof.
0 is open.

An oil pan 51 is suspended and fixed approximately at the center of the lower surface of the intermediate member 15. Above lubricating oil pump 3
The suction passage 49 of No. 7 lubricates the oil pan 51 through an oil passage 52 formed in the cylinder head 22 and the cylinder case 20, and a suction pipe 53 that communicates with the oil passage 52 and hangs vertically on the intermediate member 15. It is said that it is possible to communicate with oil. That is, the internal combustion engine 16
During operation, 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 path 50 side.

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

The lubricating oil sent to the lower oil passage 54 is supplied to the bearing portion sealed by the oil seal 56 on the lower end side of the crankshaft 29, and lubricates the bearing portion as well as being drilled into the crankshaft 29. The crank pin 31 and the connecting rod 3 are connected to each other through the provided oil passage 58.
After lubricating the big end bearing part formed with the big end part 33 of No. 2, the lubricant is scattered into the crank chamber 28. Further, the lubricating oil flowing toward the crankshaft 29 side of the upper oil passage 55 is supplied to the bearing portion sealed by the oil seal 59 on the upper end side of the crankshaft 29, and lubricates the bearing portion and also lubricates the crankshaft 29 side. After lubricating the big end bearing formed by the crank pin 31 and the big end 33 of the connecting rod 32 through the oil passage 61 drilled in the oil passage 29, the oil is scattered into the crank chamber 28. The lubricating oil scattered within the crank chamber 28 as described above moves downward within the crank chamber 28 and enters the oil pan 51 via the return oil passage 62 formed by the cylinder case 20 and the intermediate member 15. It is starting to return to . Further, the lubricating oil flowing toward the camshaft 36 in the upper oil passage 55 lubricates the bearing portion sealed by the oil seal 63 on the upper end side of the camshaft 36, and then flows downward along the outer peripheral surface of the camshaft 36. and lubricates the cam surfaces of the intake cam 39 and exhaust cam 40. After lubricating the camshaft 36, the lubricating oil moves downward within the cam chamber 35 and returns to the oil pan 51 via a return oil passage 65 formed in the cylinder case 20 and cylinder head 22. There is.

Here, at two positions on the inner surface of the crankcase 21, which defines the crank chamber 28, approximately in the middle in the vertical direction, there are holes that protrude from both corners of the inner surface toward the crankshaft 29 side and are held between the upper and lower crank pins 31. web 3
A rib 66 is arranged to surround 0. Each rib 66 is provided at two positions separated from each other in the rotational direction of the crankshaft 29 and substantially parallel to each other. Each rib 66 is provided with a lubricating oil guide surface 67 that slopes downward with respect to the substantially tangential direction of rotation of the crankshaft 29 . That is, the lubricating oil that rotates as the crankshaft 29 rotates is transferred to the lubricating oil guide surface 6 of the rib 66.
7, and the velocity component in the co-rotating direction can be converted into a downward velocity component.

In the internal combustion engine 16, a pressure communication passage 68 is formed in the cylinder case 20 and the cylinder head 22 to communicate the crank chamber 28 and the cam chamber 35 with each other. The pressure communication path 68 is
Pressure fluctuations in the crank chamber 28 caused by the reciprocating motion of the piston 24 can be alleviated, and blow-by gas from the combustion chamber 25 to the crank chamber 28 can be discharged to the carburetor side via a breather (not shown) that is communicated with the cam chamber 35. At the same time, the pressure balance between the crank chamber 28 and the cam chamber 35 is maintained well, and lubricating oil can be smoothly returned from the cam chamber 35 to 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 the lubricating oil pump 37 to flow through the camshaft 36.
When the is driven, the lubricating oil in the oil pan 51 is
By driving the lubricating oil pump 37, the lower oil passage 5
4 and upper oil passage 55. The lubricating oil sent under pressure to the lower oil passage 54 lubricates the lower bearing of the crankshaft 29, and after passing through the oil passage 58 and lubricating the large end bearing formed by the crank pin 32 and the large end 33, the lubricating oil is transferred to the crank chamber. Scattered within 28. In addition, a part of the lubricating oil forced into the upper oil passage 55 lubricates the upper bearing of the crankshaft 29 and also lubricates the big end bearing formed by the crank pin 31 and the big end 33 through the oil passage 61. After that, it scatters into the crank chamber 28. The lubricating oil scattered inside the crank chamber 28 is
It rotates along with the direction of rotation of the crankshaft 29.

However, the lubricating oil that rotates as the crankshaft 29 rotates is guided by the lubricating oil guide surface 67 of the rib 66, so that the 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. At this time, two ribs 66 that are substantially parallel to each other are formed at two positions separated in the rotational direction of the crankshaft 29.
Since they are arranged in parallel, the above-mentioned lubricating oil falling effect can be exerted over a wide area around the crankshaft 29 where the lubricating oil rotates. That is, after lubricating the area around the crankshaft 29 in the crank chamber 28, the lubricating oil is quickly dropped downward in the crank chamber 28, passes through the return oil path 62, and reaches the oil pan 51.
Therefore, the entrainment of lubricating oil around the crankshaft 29 and the accompanying accumulation of lubricating oil in the crank chamber 28 can be reliably reduced in a wide area around the crankshaft 29. . This promotes cooling of the lubricating oil after lubrication, making it possible to prevent early deterioration, and eliminating the need to increase the capacity of the oil pan 51 more than necessary in order to ensure the amount of circulating oil.

[Effects of the Invention] As described above, according to the present invention, in a four-stroke internal combustion engine in which the crankshaft is vertically placed in the crank chamber, the lubricating oil can be circulated around the crankshaft and the lubrication inside the crank chamber can be improved. Oil accumulation can be reliably reduced in a wide area around the crankshaft.

[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. 4 is a cross-sectional view taken along the line -, and FIG. 4 is a sectional view taken along the line - in FIG. 16... Internal combustion engine, 20... Cylinder case, 21
...Crank case, 28...Crank chamber, 29...Crankshaft, 66...Rib, 67...Lubricating oil guide surface.

Claims (1)

[Claims] 1. In a four-cycle internal combustion engine in which the crankshaft is vertically disposed in the crank chamber, a plurality of oil guide surfaces protrude from the inner surface of the crank chamber toward the crankshaft and are inclined downward with respect to a substantially tangential direction of the rotation of the crankshaft. A four-stroke internal combustion engine characterized in that the ribs are provided substantially parallel to each other at a plurality of positions spaced apart in the rotational direction of the crankshaft.