JPS5933881Y2 - Piston for internal combustion engine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a piston for an internal combustion engine.

In general, the gap between pistons for internal combustion engines constantly changes as they move up and down within the cylinder.

Then, as the gap becomes smaller, the pressure of the lubricating oil increases during this gap, resulting in so-called oil leakage, which increases the amount of lubricating oil consumed.

For this reason, in order to alleviate the pressure increase due to the decrease in the clearance of the lubricating oil that has reached the compression ring left behind by the oil ring, it has been proposed to It is known that the step-shaped notch d communicating with the ring groove bVc is uniformly provided over the entire circumference to improve lubricant consumption due to oil drainage.

Tokoro Rikihisa: Reducing the diameter of the land directly below the ring groove in a piston increases the opening area of the ring abutment by the same amount, increasing the flow rate of the proby gas. In this piston, this tendency is exacerbated because the land portion C is cut out over the entire circumference.

In other words, even if the ring rotates during the vertical movement of the piston and the position of its abutment moves, the notches d are cut uniformly around the entire circumference, so the opening area becomes large 11, and the proby gas continues to blow through. Become.

This not only causes deterioration of the lubricating oil, but also, in extreme cases, can lead to ring sticking or even seizure of the piston.

By the way, since the piston is connected to the crankshaft via a connecting rod, during its vertical movement, inertia and combustion pressure cause it to move in the anti-thrust direction during the upward stroke, and in the thrust direction during the downward stroke. to reduce the gap with the cylinder.

That is, the gap between the cylinder and the surface perpendicular to the piston pin that receives side pressure is reduced.

On the other hand, since the force acting in the direction of the piston pin is small, the reduction in the clearance is small.

Therefore, it can be said that the increase in lubricating oil pressure is greater on the surface perpendicular to the piston pin that receives lateral pressure than on the surface in the direction of the piston pin, so a notch for pressure buffering is provided on this surface, and other piston pins are In terms of direction, if this is eliminated or made smaller, the flow rate of the proby gas will be reduced when the ring rotates and its abutment is located on this plane.

The present invention was developed in view of the above points, and aims to reduce the flow rate of proby gas in a piston designed to reduce lubricating oil consumption due to oil drainage.One embodiment is shown in Figs. 2 and 3 below. This is explained by:

1 is a piston, 2Fi is its land portion, 3 is a skirt portion, and the land portion 2 has a first pressure ring groove 4a, a second pressure culling groove 4b, and an oil ring groove 4c, and the skirt portion 3 has a piston pin hole 5. is formed.

Reference numeral 6 denotes a stepped notch cut out in the upper part of the land portion 2a directly below the first compression ring groove 4a so as to communicate with the ring groove 4a, and the cutout amount of the notch 6 passes through the piston axis C. Axis line Y'-Y' parallel to piston pin axis Y-Y (
In this figure, the axis Y-Y and Y'-Y' coincide with each other.
) is formed so that it gradually increases in size as it goes in the direction of the axis XX passing through the piston axis C at right angles to the piston axis C.

That is, the amount of the notch gradually decreases from the surface receiving the lateral pressure to the surface perpendicular thereto.

When the piston 1 with the above configuration is inserted into a cylinder and operated, the piston 1 moves in the thrust direction and anti-thrust direction during upward and downward movements, reducing the gap between the surface of the piston 1 that receives side pressure and the cylinder, thereby reducing the oil ring. This is to increase the pressure of the lubricating oil that has been left behind by the compression ring and has risen near the compression ring.

However, since the piston 1 is provided with the stepped notch 6 on the first compression ring groove 4a side of the land portion 2a, the pressure increase of the lubricating oil is alleviated.

Therefore, it is possible to prevent oil from rising due to pressure increase.

Also, during the vertical movement of the piston, the ring rotates within the ring groove 4, but when the first compression ring rotates within the ring groove 4a and moves from the direction of the side receiving surface to the direction perpendicular thereto, Since the amount of the stepped notch 6 gradually decreases, the opening area of the ring mating opening also gradually decreases.

Accordingly, the flow rate of the proby gas also decreases accordingly.

As described above, according to the present invention, the notch 6 at the upper part of the land portion 2a immediately below the first compression ring groove 4a is gradually reduced in depth from the surface receiving lateral pressure to the surface perpendicular thereto. Since the gap between the piston 1 and the cylinder is made smaller, it is possible to reduce the pressure increase of the lubricating oil on the surface receiving side pressure where the gap between the piston 1 and the cylinder becomes smaller.

Furthermore, as the first compression ring rotates in the ring groove 4a during the vertical movement of the piston 1 and the abutment moves toward the piston pin, the opening area decreases accordingly. The flow rate of the proby gas is reduced compared to a piston with uniform notches throughout.

Therefore, deterioration of the lubricating oil can be reduced, and thereby the lubricating oil replacement interval can also be extended.

Fig. 4 shows another embodiment, in which the end of the notch 6 is set near the middle between the axes Y-Y and X-X, and the cut is made on the surface that receives the side pressure where the lubricating oil pressure increases most. A notch 6 is provided, and in this case, the riding portion on the surface in the direction of the piston pin is the same as a normal piston without a notch, so that the flow rate of the proby gas can be further reduced.

In this embodiment, the notch 6 provided in the land portion 2a directly below the first compression ring has been described, but the notch 6 is intended to alleviate the pressure increase of the lubricating oil that is left behind by the oil ring and rises. Therefore, it is sufficient that the land is located above the oil ring, and the location can be determined depending on the situation.

[Brief explanation of drawings]

Fig. 1 is a front view showing a conventional piston, Fig. 2 is a sectional view taken along line A-A in Fig. 1, Fig. 3 is a front view showing an actual case of the present invention, and Fig. 4 is B in Fig. 3. -B sectional view, FIG. 5 shows another embodiment and shows the same cross section as FIG. 3. 1: Piston, 4a: First compression ring groove, 2a: Land portion directly below the first compression ring groove, 6: Notch.

Claims (1)

[Scope of utility model registration request] A piston having a notch communicating with the ring groove on the upper side of the land immediately below the compression ring groove, wherein the notch is formed except in an axial direction parallel to the piston pin axis passing through the piston axis. Engine piston.