JPS6319577Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an engine in which noise due to resonance is reduced by increasing the rigidity of the cylinder block.

Most conventional engines have a journal bearing that supports the crankshaft in the lower part of the cylinder block, so the lower part has lower rigidity than the upper part. For this reason, when the cylinder pressure acts on the lower part of the cylinder block through the bearing during operation, resonance occurs in the low frequency range, causing noise. Conventionally, attempts have been made to reduce the noise caused by resonance by installing a damping plate at the bottom of the cylinder block or by increasing the strength of the bearing, but these methods are not very effective in the low frequency range and have a complicated structure. It had drawbacks such as being expensive.

This invention was made with the aim of eliminating such drawbacks, and by making the main cap that supports the journal bearing almost wedge-shaped and tightening it to the cylinder block from the lower part of the cylinder block, the rigidity of the lower part of the cylinder block was dramatically increased. The present invention provides an engine that has been improved to effectively reduce noise, particularly in the low frequency range.

This invention will be explained in detail below with reference to an illustrated embodiment. In the figure, reference numeral 1 denotes a cylinder block in which a plurality of cylinder liners 2 are arranged in a straight line, a cylinder head 3 is attached to the upper part, and an oil pan 4 is attached to the lower part. A semicircular bearing mounting hole 1a having a center b on the center line a of the cylinder liner 2 is formed in the lower side of the cylinder block 1, and a crankshaft ( (none of which are shown) is supported.

Further, from the lower part of the shaft mounting hole 1a to the skirt portion 1b of the cylinder block 1, a horizontal line C intersects on the center line a of the cylinder liner 2 and passes through the center b of the crankshaft, and the shaft mounting hole 1
It forms an oblique mating surface 1c along a line e that passes through the intersection d with a and reaches the lower part of the skirt portion 1b, and the main cap 5 is attached to the fixing tool 6 from below the cylinder block 1 on these mating surfaces 1c. installed by. The main cap 5 is approximately wedge-shaped with a mating surface 5a that matches the mating surface 1c of the cylinder block 1, and has a semicircular shaft mounting hole 5b that matches the shaft mounting hole 1a of the cylinder block 1 at the top. Among the fasteners 6 for attaching the main cap 5 to the cylinder block 1, the two fasteners 6a located on both sides of the shaft mounting holes 1a and 5b are longer in length, and are attached to the crankshaft. The short fixing devices 6b located on both sides of the main cap 5 and the skirt portion 1b of the cylinder block 1 firmly fix the main cap 5 and the skirt portion 1b of the cylinder block 1, thereby increasing the rigidity of the lower part of the cylinder block 1. It has the effect of increasing the

As described in detail above, this invention is based on the fact that the main cap 5, which supports the crankshaft via a bearing, is firmly attached to the lower part of the cylinder block 1 in a substantially wedge-shaped manner from below the cylinder block 1 by means of a fixing device 6. Therefore, the rigidity of the lower part of the cylinder block 1, especially the skirt part 1b, is increased compared to the conventional one, so the vibration of the skirt part 1b can be significantly reduced, improving the durability of the skirt part 1b and reducing noise in the low frequency range. In addition to preventing the occurrence of
By removing the fixing member 6, the main cap 5 can be easily removed, so that bearings and the like can be easily replaced.

In addition, by tightening the fixing tool 6 during assembly, the main cap 5 is automatically aligned with the mating surface 1c of the cylinder block 1, so assembly is easy and the mating surface 1c is attached to the outside of the cylinder block 1. 5a and the fixing device 6 are not exposed, so there is no need to consider sealing or the like.

[Brief explanation of the drawing]

The drawing is a sectional view showing an embodiment of this invention. 1 is a cylinder block, 1a is a bearing mounting hole, 1b is a skirt portion, 1c is a mating surface, 2 is a cylinder liner, 5 is a main cap, and 6 is a fixing device.

Claims (1)

[Claims for Utility Model Registration] (1) At the lower part of the cylinder block 1, a mating surface 1c is formed diagonally from the bearing mounting hole 1a to the lower end of the skirt portion 1b, and these mating surfaces 1c
A wedge-shaped main cap 5 is attached from below the cylinder block 1 over almost the entire mating surface 1c, and the cylinder block 1 and skirt portion 1 are attached from the bottom side of the main cap 5.
An engine in which the main cap 5 is tightened and fixed to the cylinder block 1 using fasteners 6a and 6b screwed into the cylinder block 1. (2) A horizontal line c that intersects the mating surface 1c of the cylinder block 1 on the centerline a of the cylinder liner 2 and passes through the center b of the crankshaft and the bearing mounting hole 1
The engine according to claim 1, which is formed along a line e passing through the intersection point d of point a and reaching the lower part of the skirt portion 1b.