JPS6040843Y2 - internal combustion engine crankcase - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crankcase structure for an internal combustion engine.

As noise countermeasures for internal combustion engines, conventional methods include indirect methods of covering the outside of the engine with a sound insulating cover, as well as connecting the joint between the crankcase and oil pan with a vibration-proof structure to suppress noise caused by oil pan resonance. , methods of reducing noise from the engine itself are being adopted.

However, the reciprocating motion of the piston, explosive force, etc. are rigidly transmitted to the crankcase through the clearance of the crankshaft bearing metal, and the vibration noise emitted by the crankcase skirt peripheral wall acting as a speaker is a major noise source.
Suppressing the vibration noise of the crankcase is an extremely effective noise reduction measure, as it also reduces the resonance noise of the oil pan with the crankcase. There were no measures taken to reduce vibration and noise.

The present invention was devised in view of the above-mentioned conventional circumstances, and the present invention has been developed for an internal combustion engine crank which has a structure in which the side wall of the crankcase is formed into a vibration-proof structure to obtain a good noise reduction function, and at the same time, the weight of the crankcase can be reduced. It provides a case.

The present invention will be described in detail below based on embodiments shown in the drawings.

In the internal combustion engine according to the present invention shown in FIG. 1, a cylinder block main body 2 having a cylinder head 1 connected to its upper end surface is divided into a cylinder block part 2A in a narrow sense forming a cylinder peripheral wall, a crankshaft bearing part 2a, A crankcase portion 2B forming a peripheral wall thereof is integrally formed with the crankcase portion 2B, and an oil pan 3 is attached to the lower end of the crankcase portion 2B as will be described later.

In this configuration, the crankcase portion 2B of the cylinder block body 2 has the following shape.

That is, since the front and rear end walls of the crankcase portion 2B that bear the crankshaft ends are required to have a large degree of rigidity, they are shaped like completely closed plates, but the side wall portions border the cylinder block portion 2A. It has a comb-shaped structure in which a plurality of oil pan mounting legs 2b are arranged hanging down from the upper edge at intervals in the longitudinal direction.

The upper edge flange portion 3a of the oil pan 3 is connected to the oil pan mounting foot 2b by tightening bolts.

Furthermore, the upper edge of the side wall portion of the crankcase portion 2B is formed into a flange portion 2c that protrudes outward from the hanging portion of the mounting foot 2b, and the flange portion 2c and the oil flange portion 2c that is formed to similarly project outward from the mounting foot. Upper edge flange portion 3a of pan 3
A side panel 4 covering the outside of the mounting leg 2b is airtightly fitted and fixed to the upper and lower edges of the mounting leg 2b via anti-vibration rubber 5, respectively.
The side wall of the crankcase has a sealed structure.

With this configuration, only the oil pan mounting foot 2b vibrates in the side wall portion of the crankcase portion 2B due to the transmission of vibrations from the crankshaft and the cylinder block portion 2A, and the panel 4 forming the entire side wall portion vibrates. Since vibration transmission from the cylinder block body 2 is well insulated by the vibrating rubber 5 and resonance is suppressed, noise emanating from the outer wall of the crankcase can be significantly reduced.

Furthermore, since the panel 4 may be made of a plate material that is thinner than the wall thickness of the cylinder block body 2, the weight of the engine can be reduced compared to the conventional type in which the crankcase is formed only from the cylinder block body.

In particular, the panel 4 can also be made of a synthetic resin material, in which case the engine can be made even lighter.

In addition, the vibration of the panel 4 itself can be suppressed by strengthening the rigidity by providing the panel 4 with reinforcing ribs 4a as shown in FIG. , more effective noise reduction function can be obtained, and at the same time,
Since the same rigidity and strength can be obtained with thinner panels, weight reduction can also be promoted.

In FIG. 4, both side walls of the cylinder block crankcase portion are formed by screwing and fastening the upper ends of separately formed oil pan mounting legs 2b to the upper edge flange portion 2C.

In addition, although not shown in the drawings, an internal combustion engine may also be used in which the crankcase, in which the oil pan mounting foot, crankshaft bearing, and front and rear end walls are integrally molded, is molded separately from the cylinder block that constitutes the cylinder peripheral wall, and the two are fastened together. Of course, the present invention can be applied.

Also, since the oil pan contacts the side wall of the crankcase only through the oil pan mounting foot, vibration transmission can be sufficiently reduced with this configuration alone. 3 and anti-vibration rubber 7
If a vibration insulating structure is provided in which the oil pan 3 is interposed, resonance vibration noise of the oil pan 3 can be more effectively prevented.

As explained above, according to the present invention, the side wall portion of the crankcase portion of the cylinder block main body, which is a major source of noise, is made into a frame structure with only the mounting feet for attaching the oil pan left and other parts open. Since the side surfaces of the cylinder block are covered with the cylinder block body and vibration-insulated panels, the noise emitted from the crankcase can be significantly reduced, and at the same time, the engine can be made lighter.

[Brief explanation of the drawing]

1A to 1C show a basic embodiment of an internal combustion engine equipped with a vibration isolator according to the present invention, A is a side view, and B is a side view of FIG.
Figure 2A and B are front views and B-B arrow views showing embodiments of the panel used in the vibration isolator according to the present invention; The figure is a cross-sectional view showing another embodiment of the same panel as above, FIG. 4 is an enlarged cross-sectional view of a main part showing another embodiment of the present invention, and FIG. 5 is a cross-section of a main part showing another embodiment of the present invention. It is an enlarged view. 2...Cylinder block body, 2B...
・Crankcase part, 2b... Oil pan mounting foot, 2c... Flange part, 3... Oil pan, 3a... Upper edge flange part, 4・・・・・・
...Side panel, 5...Vibration-proof rubber.

Claims (2)

[Scope of utility model registration request] (1) An aggregate part having a comb-tooth structure on both side walls of the cylinder block crankcase part, which has a plurality of mounting feet for attaching an oil pan hanging down from an upper edge flange part integral with the cylinder block body, and the aggregate part a block body covering the outside of the block body and a separately molded panel, and the panel is placed between an upper edge flange portion integral with the block body and an oil pan upper edge flange portion connected to the mounting foot. A crankcase for an internal combustion engine, characterized in that the crankcase is fitted and attached via a vibration isolating member. (2) The crankcase for an internal combustion engine according to claim 1, wherein the oil pan is connected to the mounting foot via a vibration isolating member.