JPS5922271Y2 - cylinder for internal combustion engine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cylinder (including a cylinder liner and a sleeve) used in an internal combustion engine.

As is well known, in the sliding relationship between the piston ring and the cylinder, it is important to shorten the break-in time, prevent scuffing from occurring in the early stages of operation, and reduce lubricant consumption in the steady wear region. There has been a strong desire to reduce friction and exhibit excellent wear resistance, and research and development have been carried out on cylinders and piston rings in order to meet this demand.

As one of the results of this research, as shown in Fig. 1 and Fig. 1a, in the cylinder, grinding defects 2 by honing are provided on the inner circumferential surface 11 of the cylinder so as to intersect with each other, and a diamond-shaped sliding surface portion is provided. There is a cylinder 1 provided with a so-called plateau portion 3, which is widely used as a relatively excellent cylinder and has proven its superiority.

However, the intersection angle α at which the grinding defects due to honing in the cylinder shown in FIGS. 1 and 1a intersect is,
Usually 10 to 30 degrees in half-width (hereinafter all angles are shown in half-width)
and are provided at the same angle on the entire inner circumferential surface of the cylinder.

For this reason, it contained defects as shown below and was not fully satisfactory.

In other words, the operating conditions on the inner circumferential surface of the top dead center portion and the inner circumferential surface of the bottom dead center portion due to the reciprocating movement of the piston on the inner circumferential surface of the cylinder are completely different. As a result of research conducted by the present inventor, it has become clear that grinding defects with the same intersection angle are applied to the surface, leading to an increase in lubricant consumption.

On the other hand, many ideas have been made to improve the conformability of cylinders whose inner circumferential surfaces are coated with porous chrome plating.
Patent Application No. 35-44367 (Special Publication No. 38-31 Sho.
52), as seen in cylinder liners for internal combustion engines, there is a cylinder liner in which a porous surface is provided only at the bottom dead center of the cylinder by mechanical processing.

Although this cylinder liner is good in terms of its technical concept, in actual use, since the surface of the cylinder other than the bottom dead center is smooth and has a chrome-plated surface, it is difficult to lift an appropriate amount of lubricating oil upwards by the piston ring. In addition, the top dead center of the cylinder is smooth and has a chrome-plated surface, which causes the oil film to break.In addition, the desired effect cannot be expected when the engine rotates at low speeds, and scuffing occurs as a result. It had the flaws mentioned above.

In view of the above-mentioned circumstances, the present invention aims to provide a cylinder that skillfully solves both of the above-mentioned deficiencies.

Hereinafter, the cylinder of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 2 to 2b, the inner circumferential surface 41 of the cylinder 4 of the present invention is completely free from grinding damage caused by rehoning.
are provided to intersect with each other and have a plateau portion 3, but its feature is that, as shown in FIG. The angle θ is set within the range of 5 to 25°, and the intersection angle θ1 of the grinding damage 2 of the inner circumferential surface 43 of the top dead center portion is set within the range of 30 to 48°, as shown in Fig. 2b. It is in.

Of course, it is impossible to manufacture the inner circumferential surfaces 42 and 43 of the top and bottom dead center parts within the above-mentioned predetermined ranges using a honing machine commonly used in the past. Although it requires integration and some improvements, it can be easily improved by those with ordinary technology.

In this way, since the cylinder of the present invention is manufactured using a honing machine incorporating a continuously variable transmission, the inner circumferential surface 44 of the intermediate portion between the inner circumferential surface 43 of the top dead center portion and the inner circumferential surface 42 of the bottom dead center portion
is a transitional stage from the intersecting angle formed on the inner circumferential surfaces 42 and 43 of the upper and lower dead center portions, therefore, the intersecting angle formed on the inner circumferential surface of the intermediate portion 44
．． The intersection angle is forced to be intermediate between the intersection angles formed at 43.

Since the cylinder 4 of the present invention is constructed as described above, a large amount of lubricating oil is retained on the inner peripheral surface of the bottom dead center portion of the cylinder during operation.

That is, since the intersection angle θ of the grinding damage formed on the inner circumferential surface 42 of the bottom dead center portion is set to 5 to 25 degrees, the lubricating oil is not likely to fall toward the oil pan and is well retained. .

In this case, setting the crossing angle to 5° or less is difficult in manufacturing, and if it exceeds 25°, the lubricating oil retention property decreases and the desired effect cannot be obtained, so the crossing angle should be 5 to 2.
It is necessary to set it within a range of 5°.

As mentioned above, the lubricating oil held on the inner circumferential surface of the bottom dead center portion is formed so that the intersection angle gradually increases as it approaches the inner circumferential surface of the top dead center portion as the piston ring rises with the upward stroke of the piston. The lubricating oil is carried toward the inner circumferential surface of the top dead center through the grinding process, so the lubricating oil is effectively carried by the upward movement of the piston ring.
This effectively acts on the lubrication of the inner peripheral surface of the top dead center portion, which is the most severe area, and thereby significantly prevents the lubricating oil film from being worn out in this area, thereby preventing the occurrence of scuffing.

In addition, the excess lubricating oil is transferred through grinding disease as the piston ring moves during the downward stroke of the piston.
It is quickly scraped off in the direction of the oil pan.

Therefore, since lubricating oil is significantly prevented from flowing into the combustion chamber and being burned, many negative effects such as an increase in lubricating oil consumption and carbon sticking are prevented.

As described above, in the present invention, the intersection angle θ1 of the grinding damage formed on the inner circumferential surface 43 of the top dead center portion is set to 30 to 48° in order to maximize the effects.

That is, when the lubricating oil is scraped off toward the oil pan through grinding disease, the lubricating oil cannot be quickly scraped off due to the movement of the piston ring accompanying the lower limit stroke of the piston at 30 degrees or less, and therefore, the lubricating oil Flowing into the combustion chamber causes negative effects such as increased lubricating oil consumption and carbon stick, and on the other hand, it is difficult to form an angle of 48° or more, so the intersection angle is in the range of 30 to 48°. It is necessary to set it within.

As is clear from the above description, the cylinder of the present invention is designed to be most suitable for the operating conditions of the inner peripheral surfaces of the top and bottom dead centers of cylinders that suffer from cross-grinding disease due to honing. By using a treated cylinder, it has far superior performance compared to conventional cylinders of this type, and its effects are extremely large.

The depth of grinding disease caused by honing and its proportion to the total are determined by each organization.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional cylinder, FIG. 1a is an enlarged view of part A in FIG. FIG. 2b of section B shows an enlarged view of section C, respectively. Explanation of symbols 4... Cylinder of the present invention, 41...
...Inner peripheral surface, 42...Bottom dead center inner peripheral surface, 4
3...Top dead center portion inner circumferential surface, 44...Intermediate portion inner circumferential surface, 2...Grinding disease, 3...Plateau portion.

Claims (1)

[Claims for Utility Model Registration] In a cylinder in which grinding defects due to honing are provided on the inner circumferential surface of the cylinder in an intersecting manner and having a plateau portion, the grinding defects are provided with respect to a straight line that intersects at right angles to the axis of the cylinder. The intersection angle θ at the inner peripheral surface of the dead center portion due to the reciprocating motion of the piston is set to 5 to 25 degrees, and the intersection angle θ at the inner peripheral surface of the top dead center portion is set to 0.30 to 48 degrees, and The inner circumferential surface of the intermediate portion between the inner circumferential surface of the dead center portion and the inner circumferential surface of the bottom dead center portion is the intersection angle θ1 of the inner circumferential surfaces of the upper and lower dead center portions.
．． Crossing angle (5 to 25°) accompanying the transition process from θ to (
30 to 48°).