JPH0238053Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a bearing beam that supports a crankshaft, mainly in an automobile engine.

(Prior Art and Problems to be Solved) One of the causes of noise in automobile engines is vibration from the block skirt and oil pan due to vibration of the cylinder block.

In order to reduce this vibration noise, it is possible to increase the rigidity of the cylinder block and suppress the vibrations caused by the explosive torque that the crankshaft receives, but this would require a significant increase in weight, such as thickening the cylinder block, which would reduce fuel efficiency. This creates a new problem: deterioration of efficiency.

Therefore, various proposals have been made to effectively increase the rigidity of the cylinder block while suppressing an increase in weight. Bearing beams are attracting attention because of their enhanced environmental protection (see ``Second Report on Automobile Pollution Prevention Technology'' published by the Environment Agency in May 1981).

As shown in FIGS. 1 and 2, the bearing cap 3 that forms a pair with the bearing portion 2 of the cylinder block 1 is connected to each other by a beam member 4 to improve rigidity. The purpose is to increase the bending strength in the vertical direction, which occurs in the cylinder block 1 as shown by the imaginary line in FIG.

To this end, as shown in FIG. 3, the beam member 4, which interconnects the lower center of the bearing cap 3, is generally cast integrally with the bearing cap 3 using the same material.

By the way, recently, the above-mentioned block skirt part 5
The biggest cause of opening/closing vibrations, such as The inventor's experiments have revealed that this is the original vibration.

Therefore, as shown in FIGS. 4 and 5, the present applicant proposed a so-called double-barrel type bearing in which both bottom corners of the bearing cap 3 are connected to each other by two beam portions 4A and 4B. proposed a beam (see Japanese Unexamined Patent Publication No. 1983-99248).

According to this, the strength of the bearing cap 3 to fall in the direction of the crankshaft is increased, and at the same time, the torsional strength about the crank rotation center is significantly improved, and the bending strength about the cylinder bore axis is also increased.

As a result, torsion and left/right bending vibration of the bearing part 2 (bulk head) which is integrated with the bearing cap 3 are suppressed as much as possible, so this bearing part 2
The opening/closing vibration (membrane vibration) of the block skirt portion 5 using this as a node is effectively prevented.

However, in such a conventional double-barrel type bearing beam, two beam members 4
Since A and 4B are simply arranged in parallel, it is still insufficient to suppress the bending vibration of the cylinder block 1, which will be described later, and therefore there is a problem that a sufficient noise reduction effect cannot be obtained. It was hot.

In other words, since the transmission is attached to the rear end of the cylinder block 1, or its mounting seat is provided, the rear end has relatively high bending rigidity, but the bending rigidity decreases toward the front, which is the free end. .

Therefore, in a four-cylinder engine, for example, the cylinder block 1 has a vibration mode curve A in FIG. Large amplitude left and right bending vibrations occurred near the bearings 2 and 3 at the front end), and this bending vibration had a large effect on the vibration noise of the cylinder block 1 and the like.

The present invention aims to solve these conventional problems.

(Means for Solving the Problems) To this end, the present invention provides a bearing cap that supports the crankshaft and pairs with the bearing portion disposed between each cylinder of the cylinder block.
In a double-barrel type bearing beam that is connected to each other by two beam members at both bottom corners, the interval between the two beam members is formed to be large at the center.

(Function) With the above configuration, the rigidity near the center of the cylinder block, which is prone to bending vibrations, is greatly improved, so the amount of noise generated due to bending vibrations of the cylinder block is effectively reduced.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

In this invention, as illustrated in FIG. Since it is an inline 4-cylinder engine, the third bearing cap 3
Shaping is performed so that the distance H' in the vicinity of ) is larger.

By doing this, the bending stiffness of the bearing beam in the left and right direction is significantly improved due to the stiffness improvement effect of the curved beam and the law that the bending stiffness of the beam is proportional to the square of the distance from the neutral axis of bending (engine center). do.

For this reason, in the lateral bending vibration caused by the transmission mounting structure in the cylinder block 1 mentioned above, the lateral vibration near the third or central bearing part, which was the antinode, is significantly suppressed. Ru. As a result, together with the effect of the twin-barrel type bearing beam described above, the level of noise not only from the cylinder block 1 itself but also from the covers attached to it is significantly reduced.

(Effects of the invention) As explained above, according to the invention, the interval between the two beam members constituting the twin-barrel bearing beam can be increased in the central part where the horizontal bending vibration of the cylinder block has a large amplitude. Since it is formed, the left and right bending rigidity of the cylinder block can be greatly improved, and this, combined with the effect of the twin-barrel bearing beam, has the effect of significantly reducing engine noise.

[Brief explanation of the drawing]

Fig. 1 is a side view of a conventional device, Fig. 2 is a sectional view taken along the line - - in Fig. 1, Fig. 3 is a perspective view of the bearing beam, Fig. 4 is a longitudinal sectional front view of another conventional device, and Fig. 5 6 is a bottom view of the entire cylinder block, and FIG. 6 is an explanatory diagram showing the vibration mode of the cylinder block. 7th
The figure is an overall bottom view of one embodiment of the present invention. 1... Cylinder block, 3... Bearing cap, 4A, 4B... Beam member,... Neutral shaft.

Claims (1)

[Scope of utility model registration request] In a double-barrel type bearing beam, a bearing cap, which pairs with a bearing part arranged between each cylinder of a cylinder block and supports a crankshaft, is connected to each other at both bottom corners by two beam members, A bearing beam characterized in that the distance between the two beam members is formed to be large at the center.