JPH0565851A - Oil pan of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent leakage of lubrication oil from a crank chamber to the outside. CONSTITUTION:A bottom bearing cap 14 which supports the bottom part of a crank shaft which extends in the longitudinal direction of a engine main body is integrally formed on an oil pan 1. An engine cylinder is slantly arranged and the top face 1a of the oil pan 1 is also slantly arranged. Bottom wall faces 23, 24 of the bottom bearing cap 14 which supports the crank shaft between cylinders are extended slantly upward opposed to each other from the bottom end part 22 of the bottom bearing cap 14 in the lateral direction of the engine main body. Communication spaces 27, 28 are formed so as to communicate the bottom bearing cap wall bottom faces 23, 24 to crank chambers arranged between inner wall faces of the oil pan 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil pan for an internal combustion engine.

[0002]

2. Description of the Related Art A crankcase compression type 2-cylinder 2-cycle engine is known in which a crank chamber formed for each cylinder is separated by a bearing supporting a crankshaft (Japanese Utility Model Publication No. 1-95508). reference).

[0003]

However, without utilizing the compression action in the crankcase, fresh air is supplied into the combustion chamber by, for example, a supercharger, and an oil pan filled with lubricating oil is used to lubricate the crankshaft and the like. When the crankcases are installed, when the crank chambers are separated from each other, as in the above-described two-cycle engine, the separation wall narrows the volume of the oil pan, and thus the size of the oil pan is large in order to hold a sufficient amount of oil. Raises the problem that must be increased. Furthermore, when the crank chambers are separated from each other, the pressure in the crank chamber periodically increases as the piston moves up and down. However, when the pressure in the crank chamber periodically rises when an oil pan filled with lubricating oil is attached, the lubricating oil leaks out around the piston and the like, thus increasing the consumption amount of lubricating oil. The problem arises.

[0004]

In order to solve the above problems, according to the present invention, in an oil pan integrally formed with a lower bearing cap for supporting a lower portion of a crankshaft extending in a longitudinal direction of an engine body, an engine cylinder is provided. The lower wall surface of the lower bearing cap, which supports the crankshaft between the cylinders, is slanted upward from the lower end of the lower bearing cap in the lateral direction of the engine body to the opposite side. A communication space is formed between the lower wall surface of each of the lower bearing caps and the inner wall surface of the oil pan that extend toward each other and that communicate with the adjacent crank chambers.

[0005]

Even if the oil pan is filled with a sufficient amount of lubricating oil, the crank chambers are communicated with each other through the communication space, so that the pressure in each crank chamber does not fluctuate so much.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a two-cylinder two-cycle engine.
Referring to FIG. 1, 1 is an oil pan, 2 is a cylinder block, 3 is a crankshaft, and 4 is a cylinder block 2.
A piston that reciprocates inside, a connecting rod that connects the crankshaft 3 and the piston 4, a cylinder head, a combustion chamber formed between the piston 4 and the cylinder head 6, a combustion chamber 7 A fuel injection valve for injecting fuel toward the fuel cell, 9 is an air supply valve, and 10 is an exhaust valve. Air is pushed into the combustion chamber 7 via a charge valve 9 by a supercharger (not shown), and fuel is injected from the fuel injection valve 8 into the air supplied into the combustion chamber 7.

As can be seen from FIG. 1, the engine cylinders are arranged in an inclined manner, and the cylinder block 2 has a lower end surface 2a which is perpendicular to the cylinder axis. Therefore, the top surface 1a of the oil pan 1 coupled to the cylinder block lower end surface 2a is also inclined with respect to the cylinder axis. As shown in FIG. 1, the oil pan 1 is filled with lubricating oil, and the lubricating oil lubricates the joint portion of the crankshaft 3 and the connecting rod 5. The lubricating oil G in the oil pan 1 is sucked up by an oil pump (not shown) through the oil passage 11, and the lubricating oil discharged from the oil pump is jetted from the oil jet 12 toward the lower surface of the piston 4.

FIG. 2 is a plan view of the oil pan 1 from which the cylinder block 2 of FIG. 1 is removed, and FIGS.
Shows cross-sectional views taken along lines III-III and IV-IV of FIG. 2, respectively. Referring to FIGS. 2 to 4, three lower bearing caps 13, 14, 15 that support the lower portion of the crankshaft 8 are integrally formed on the oil pan 1. One of the lower bearing caps 13 located on the outer side is an end wall 16 of the oil pan 1 as shown in FIG.
The other lower bearing cap 15 positioned outside is also integrally formed with the end wall of the oil pan 1 like the lower bearing cap 13. On the other hand, an intermediate lower bearing cap 14 is provided to support the lower portion of the crankshaft 3 between a pair of cylinders, and as shown in FIG. Crank chambers 17 and 18 are formed respectively.

As shown in FIG. 4, the intermediate lower bearing cap 14 has a short sectional shape as a whole, and a pair of bearing cap bolt holes 19 extending in the cylinder axial direction are provided in the lower bearing cap 14.
20 is formed. One of the tops of the lower bearing caps 14 is connected to the top surface 1a of the oil pan 1 via a thin beam 21, and the side wall surface of the lower bearing cap 14 located on the opposite side of the beam 21 is made of the oil pan 1. It is integrally connected to the side wall surface.

The lower bearing cap 14 has a lowermost end 22 which is located at the bottom.
The lower wall surfaces 23 and 24 of the No. 4 extend obliquely upward from the lower end portion 22 in the lateral direction of the engine body on opposite sides.
The outer portion of the lower wall surface 24 is connected to the side wall of the oil pan 1 in the vicinity of the bolt hole 19 so that the lower open end of the one bolt hole 19 is exposed to the outside of the oil pan 1. In the embodiment shown in FIG. 4, the lower opening end of the other bolt hole 20 is exposed to the inside of the oil pan 1, so that the bottom of the oil pan 1 is aligned with the bolt hole 20 for inserting a bearing cap bolt. The bolt insertion hole 25 is formed. The bolt insertion hole 25 is closed by an oil drain plug after the lower bearing cap 14 is fixed to the upper bearing cap (not shown) integrally formed with the cylinder block 2 with a bearing cap bolt. On the other hand, in the embodiment shown in FIG. 5, the lower end of the bolt hole 20 is exposed to the outside of the oil pan 1, that is, the bearing cap bolt inserted into the bolt hole 20 is tightened from the outside of the oil pan 1. As can be seen, the bottom wall of the oil pan 1 is integrally formed with a tubular portion 26 extending from the bottom wall of the oil pan 1 to the lower wall surface 24 of the lower bearing cap 14. Note that FIG.
As shown in FIGS. 2, 4 and 5, a pair of engine mount brackets 29 and auxiliary equipment support brackets 30 are integrally formed on both sides of the oil pan 1.

In both of the embodiments shown in FIGS. 4 and 5, the crank chambers 17, 18 are communicated with each other between the lower wall surface 23 of the lower bearing cap 14 and the rib 21 and the side wall surface of the oil pan 1. A space 27 is formed, and a lower wall surface 24 of the lower bearing cap 14 is further formed.
Between the crank chamber 17 and the side wall surface of the oil pan 1,
A communication space 28 that communicates 18 with each other is formed.
As shown in FIGS. 4 and 5, the oil pan 1 is filled with the lubricating oil G, but since the lower end portion 22 of the lower bearing cap 14 is spaced from the bottom portion of the oil pan 1, the entire internal volume of the oil pan 1 is reduced. Lubricating oil G
Can be effectively used to hold.

On the other hand, even if the oil pan 1 is filled with the lubricating oil G, communication spaces 27 and 28 are formed above the liquid surface of the lubricating oil G, so that the crank chambers 17 and 18 are formed.
Are always communicated by these communication spaces 27, 28. By the way, in the two-cylinder two-cycle engine, when the piston 4 of one cylinder descends and the volume of the crank chamber 17 of that cylinder decreases, the piston 4 of the other cylinder rises and the volume of the crank chamber 18 of that cylinder decreases. It is increasing.
Therefore, as described above, when the crank chambers 17 and 18 are constantly communicated with each other through the communication spaces 27 and 28, the pressure in the crank chambers 17 and 18 is maintained at a substantially constant pressure without becoming extremely high. It Thus, the crank chamber 1
A large amount of lubricating oil G does not leak to the inside of the combustion chamber 7 through the periphery of the piston 4 due to the pressure increase in the insides of 7 and 18.
In addition, a large amount of lubricating oil passes through the other parts of the crank chamber 1
It will not leak from the inside of 7,18.

[0013]

The lubricating oil can be prevented from leaking from the oil pan to the outside.

[Brief description of drawings]

FIG. 1 is a side sectional view of a two-cycle engine.

FIG. 2 is a plan view of the oil pan shown in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a plan view taken along line IV-IV in FIG.

5 is a sectional view of another embodiment showing the same section as FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Oil pan 3 ... Crank shaft 13, 14, 15 ... Lower bearing cap 17, 18 ... Crank chamber 22 ... Lower end part 23, 24 ... Lower wall surface 27, 28 ... Communication space G ... Lubricating oil

Claims (1)

[Claims] 1. An oil pan integrally formed with a lower bearing cap for supporting a lower portion of a crankshaft extending in a longitudinal direction of an engine body, in which an engine cylinder is tilted and a top surface of the oil pan is tilted. The lower wall surface of the lower bearing cap that supports the crankshaft extends obliquely upward from the lower end of the lower bearing cap toward the lateral direction of the engine main body, and diagonally upward. An oil pan for an internal combustion engine in which a communication space is formed between the wall surface and the inner wall surface of the oil pan so that adjacent crank chambers can communicate with each other.