JPS597018B2 - cylinder liner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the lubrication performance of cylinder liners for internal combustion engines and other reciprocating engines.

FIG. 1 shows the cylinder litchi and piston parts of an internal combustion engine that are normally used, where 1 is a cylinder liner, 2 is a piston ring, 3 is a piston, and 4 is a cylinder oiling hole.

Figure 2 shows the cylinder liner 1 and piston ring 2 in Figure 1.
This is an enlarged view of the sliding part.The surface of the cylinder liner is wave-like along the sliding direction, and 5 indicates the convex part of the cylinder liner, and 6 indicates the concave part of the cylinder liner. .

These uneven parts can be displayed as shown in Fig. 3, where the interval between the protrusions or recesses (in Fig. 3, the protrusions) is the pinch of the wave, and the height H from the tip of the protrusion to the bottom of the recess is the depth of the wave. They are called respectively.

Lubrication between the cylinder liner and piston rings is achieved by discharging cylinder oil from multiple oil fill holes 4 drilled around the circumference of the cylinder liner 1 as shown in Figure 1. Due to the need to ensure oil retention on the cylinder liner wall surface, a wave-shaped cylinder liner is generally used, as shown in FIGS. 5 and 6.

The pinch of this wave is usually 2-20 mm, and the depth of the wave is usually 0.005-0. 1 rran
In most cases, cylinder liner sliding surfaces have the same pinch and depth surface shapes.

Note that at the dead center, the piston ring is of course in a position corresponding to the dead center of the piston, and if the piston shakes or the piston ring 2 is twisted within the ring groove γ, the piston ring will be at a position corresponding to the dead center of the piston, as shown in Fig. 4. The corner 8 of the piston ring and the convex portion 5 of the cylinder liner tend to come into contact with the so-called edge, and to avoid this, the ratio P/B of the pinch P of the cylinder liner wave to the width B in the sliding direction of the piston ring is usually set as follows. 0.
It is selected to be 5 or less.

Furthermore, since the piston rings of internal combustion engines are subject to unsteady and severe conditions such as ring back pressure, sliding speed, and temperature, the oil film is particularly susceptible to rupture near the dead center.

If this oil film rupture at the dead center (even if an oil film is formed, the oil film rupture occurs due to roughness rather than surface roughness) continues to a position near the center of the stroke where the sliding speed is high, the gap between the piston ring and cylinder liner surface Scuffing occurs, and if the vehicle continues to be operated in this condition, the damage will become even more extensive, and not only will the vehicle be unable to operate, but it will also become inoperable.

Even if oil film rupture at the dead center is unavoidable, as the sliding speed increases, it is important to make the oil film as thick as possible in order to prevent scuffing.

On the other hand, in conventionally used cylinder liners, all the sliding surfaces of cylinder 2 liner have the same pinch, so the load capacity of the oil film is not large in the zone where the sliding speed is high, causing scuff-in. The drawback was that it was easy to do.

An object of the present invention is to improve the formation of an oil film in the sliding direction of a cylinder liner having a wave-like surface shape, to prevent the occurrence of scuffing between the cylinder liner and piston ring as described above, and to prevent the occurrence of scuffing between the cylinder liner and piston ring. Our objective is to provide a cylinder liner that improves reliability.The feature is that the wave-shaped pinch engraved on the cylinder liner surface changes along the sliding direction, and the piston ring is placed at the top and bottom dead center of the piston. The pinch at the corresponding position is the smallest, and the pinch near the center of the piston ring's sliding stroke is the largest.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 is a sectional view showing the main parts of a cylinder cage according to an embodiment of the present invention.

In the figure, 10 is a cylinder liner according to the present invention, 1
1, 12, and 13 represent the states in which the piston rings have moved, and 11 and 13 indicate when the piston rings are at positions corresponding to both the upper and lower dead centers of the piston (hereinafter, this position is referred to as the upper and lower dead centers), 12 shows the state when the piston ring is near the center of the sliding stroke.

The surface shape of the cylinder liner 10 is wavy along the piston ring sliding direction, and its depth is constant over the entire sliding area of the cylinder liner, but the pinches of the unevenness are irregularly spaced, and the pinches at the top and bottom dead centers are wavy. is small, and the pinch is large in the middle of the printing process.

That is, in the case of Fig. 5, if the pinch P1 of the cylinder liner wave is B and the width of the piston ring is B, then at both the top and bottom dead center, P/B = 0.5, and at the center of the sliding stroke, P/B =
It is set to 1.

As shown in Fig. 6, the thickness of the oil film between the cylinder liner convex part and the piston ring sliding surface is h, and first, during one stroke of the piston ring (during the downward stroke) when using a conventional cylinder liner. The change in oil film thickness is shown as follows:
It becomes the broken line A in the figure, and the difference between the minimum oil film thickness hmin and the maximum oil film thickness hm&X is given by Δho.

On the other hand, when the cylinder liner according to the present invention is used, the change in oil film thickness during one stroke of the piston ring (during the downward stroke) is shown by the solid line in Figure 1, and the minimum oil film thickness and maximum oil film thickness are The difference is given by Δhn, and this value is larger than the oil film thickness difference Δho.

Therefore, it can be said that the cylinder liner according to the present invention is more advantageous in terms of oil film formation than the conventional cylinder liner.

The reason for this will be explained in detail with reference to FIG.

In Fig. 8, the abscissa is the pitch P of the cylinder liner.
and the piston ring width B, the ordinate is the oil film h
This figure shows an example of the size of a and a in the same figure.

The continuous curve shows the so-called minimum oil film thickness hmin near the dead center where the sliding speed is low during one cycle, and b shows the oil film thickness hmaX near the center of the stroke where the sliding speed is high, and P/B respectively. It shows the oil film thickness when the value of is changed, and these relationships tend to be obtained both theoretically and experimentally.

First, in the conventional wave-shaped cylinder liner, the normal p/B<o. 50 conditions, the shape of P/B = 0.5 is the best condition for oil film formation in this zone.

In order to make the oil film thicker than the conventional one, it is most effective to set P/B larger than 0.5 and select p/B=1, but as mentioned above, Then, P/B must be <0.5 in order to avoid edge contact due to piston swing and piston ring twist.

On the other hand, near the center of the sliding stroke, the absolute value of the oil film thickness is larger than that at the dead center, so there are no unstable factors such as edge contact as shown in Figure 4. A value of P/B that maximizes the thickness, ie, P/B=1, can be selected.

From the above characteristics, P/B = 0. near the dead center such as the upper and lower parts of the cylinder liner. 5, and by arranging the pinches of the cylinder liner wave at irregular intervals along the sliding direction so that P/B=1 near the center of the stroke, an oil film like the one-dot chain line C in Fig. 8 can be created. A curve of thickness variation can be obtained.

If the above is expressed based on the sliding stroke of the piston ring,
As mentioned above, the conventional one is represented by curve A in FIG. 7, and the one according to the present invention is represented by curve A in FIG.

Therefore, the oil film according to the present invention is more effective in increasing the oil film thickness than the conventional oil film.

In addition, with the cylinder liner according to the present invention, the maximum oil film thickness hmaX at the center of the stroke is larger than the conventional one, so the squeezing effect of the oil film is ensured, and as a result, the oil film thickness at the dead center is also thicker than the conventional one. Become.

As mentioned above, the cylinder liner according to the present invention allows for a thicker oil film during the entire stroke compared to conventional cylinder liners, which not only prevents the occurrence of scuffing but also allows the initial rubbing to be completed in a short period of time. , it can also contribute to reducing operating costs.

FIG. 9 and FIG. 10 each show other embodiments.

Fig. 9 shows a cylinder liner with a wavy surface shape and a smooth part 17, and Fig. 10 shows a cylinder liner with a wavy surface but with an upwardly convex part 18. The pinches are arranged at unequal intervals, and the operation and effect are the same as in the embodiment described above.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the cylinder liner and piston of an internal combustion engine, Fig. 2 is an enlarged sectional view showing the piston ring sliding surface of the cylinder liner in Fig. 1, and Fig. 3 is a sectional view showing the pinch and height of the wave. FIG. 4 is an explanatory diagram showing edge contact, FIG. 5 is a sectional view showing the main parts of a cylinder liner according to an embodiment of the present invention, and FIG. 6 is a diagram showing the cylinder liner convex portion and piston ring circumference. An explanatory diagram showing the thickness of the oil film between the
Fig. 7 is a diagram showing the change in oil film thickness during one stroke of the piston ring, and Fig. 8 is a diagram showing the ratio P/B of the pinch P of the unevenness of the cylinder liner to the piston ring width B and the oil film thickness h. A diagram showing the relationship, FIG. 9 is an explanatory diagram showing another embodiment according to the present invention, and FIG. 10 is an explanatory diagram showing still another embodiment according to the present invention. 10...Cylinder liner, 11, 12, 13
... Piston ring, 14 ... Convex part,
15... Concavity.

Claims (1)

[Claims] 1. In a case where the piston ring sliding surface of the inner cylinder 2 is an uneven surface formed in a wavy manner along the sliding direction of the piston ring, the pinch of the unevenness of the sliding surface can be corrected to the piston top and bottom dead center of the piston ring. A cylinder liner characterized in that it is narrowest at a position where the piston ring moves, and widest at a position near the center of a piston ring's sliding stroke.