JPS6123636Y2 - - Google Patents

Description

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

The purpose of this invention is especially for supercharged engines,
This aims to prevent piston ring scuffing that occurs when the cylinder internal pressure is high, and to reduce oil consumption.

As shown in FIG. 1B, the piston rings are fitted as pressure rings 3a and 3b into grooves 2a and 2b provided on the outer peripheral surface of the piston 1. Since the cylinder _{pressure P 1 is high when the piston 1 starts its explosive stroke, that is, descending from the top dead center, the pressure ring 3a is pressed downward by this cylinder pressure P 1 and} pressed against the lower surface of the groove 2a. However, since the cylinder internal pressure _P1 decreases as the piston 1 descends, the downward pressing force of the pressure ring 3a decreases. Therefore, the pressure ring 3a has a force that pushes up the pressure ring 3a due to the upward inertial force accompanying the descent of the piston 1, the frictional force generated between the pressure ring 3a and the cylinder wall, and the pressure P ₂ in the space 4 below the pressure ring 3a. acts. Therefore, when the cylinder internal pressure P ₁ approaches the same pressure as the pressure P ₂ in the lower space 4 and the pressure difference becomes small, the pressure ring 3a closes in the groove 2.
It moves from the bottom surface of a to the top surface and is pressed. At that time, in a general engine, the cylinder pressure P ₁ and the lower space pressure are as shown by the solid line in the curve diagram in Figure 1A.
Since the pressure ring _3a does not come into close contact with the upper surface of the groove 2a, the gas in the lower space 4 immediately flows back toward the combustion chamber, and the pressure P ₂ in the lower space 4 decreases, causing the gas to flow toward the crank chamber. This reduces gas leakage, and thereby returns to the lower surface of the groove 2a when the inertial force becomes downward (when the crank rotation angle is about 75 degrees). Therefore, the pressure ring 3a is mainly formed by the groove 2a.
Since the temperature of the bottom surface of the groove 2a is lower than that of the top surface, the temperature of the pressure ring 3a is also low, and as shown in FIG. 2, the temperature distribution on the top and bottom surfaces of the pressure ring is almost symmetrical. There is no twisting due to thermal deformation, and therefore there is no problem of scuffing.

However, in the case of a supercharged engine, for example, the cylinder pressure _P1 increases as shown by the broken line in FIG. 1A. Correspondingly, the lower space pressure P ₂ also increases. Therefore, when the piston 1 descends, the pressure ring 3a
is pressed more strongly against the upper surface of the groove 2a, preventing the gas in the lower space 4 from returning toward the combustion chamber. As a result, the behavior of the pressure ring 3a becomes as shown in the ring behavior line 5 shown in Figure 3A, until the pressure ring 3a comes into close contact with the upper surface of the groove 2a and the cylinder internal pressure _P1 becomes high again at point D. During most of one cycle of engine operation, the pressure ring 3 is
a is in close contact with the upper surface of the groove 2a. Also,
The gas pressure in the lower space 4 is high and a large amount of gas leaks from the lower ring 3b into the crank chamber. If a large amount of high-temperature gas leaks from the crank chamber and is released into the outside air, unburned gas may pollute the atmosphere, or carbon particles from the unburned gas may mix with the oil in the oil pan, causing the oil to deteriorate. This has the disadvantage of causing staining or early deterioration.

Furthermore, the pressure ring 3a has the groove 2a as described above.
Since the piston 1 is in close contact with the high-temperature upper surface of the piston 1, the heat of the high-temperature piston 1 is conducted to the upper surface of the pressure ring 3a through the contact surface, and the upper surface of the pressure ring 3a is A temperature difference occurs between the lower surface and the lower surface, and as a result, the pressure ring 3a generates thermal strain and deforms as shown in FIG. 4B. This thermal deformation of the pressure ring 3a creates a problem in that the oil adhering to the inner wall of the cylinder due to the reverse taper is swept up toward the combustion chamber and burned, thereby increasing oil consumption. Furthermore, since the outer circumferential surface of the pressure ring 3a partially contacts the inner wall surface of the cylinder, heat conduction to the cylinder wall surface, which is cooled by cooling water, is inhibited and the heat dissipation effect deteriorates, causing the ring itself to become hot and cause scuffing. This has problems such as easily interfering with piston cooling.

The present invention is a piston ring provided in order to eliminate the above-mentioned problems, and its gist is that in a piston for an internal combustion engine having at least two or more pressure rings, the top ring of the pressure rings is located on the side of the combustion chamber. A groove is provided in the upper surface in the radial direction to allow the gas in the space between the pressure rings to flow out to the combustion chamber side when the piston descends, and even when the pressure ring is in close contact with the upper surface of the groove, this groove This allows the gas in the lower space to flow back into the combustion chamber and suppresses heat conduction on the upper surface of the pressure ring.

An embodiment of the present invention will be explained with reference to FIGS. 5 to 9.

The piston ring according to the present invention, that is, the pressure ring 3a, which is a top ring among pressure rings having two or more, has a plurality of holes on the upper surface on the combustion chamber side to cause gas between the pressure rings to flow out to the combustion chamber side when the piston descends. A groove 6 is provided in the radial direction.

The ring behavior of the pressure ring 3a of the present invention having the above structure is shown in the ring behavior line 7 shown in FIG.
As shown, the intake and exhaust stroke 7a and the crank rotation angle a-
The pressure ring 3a is lifted up between 7b and 7b, and is located on the lower surface of the groove 2a during the other strokes.

The effect is explained in Figure 9 B and C.
Even if the pressure ring 3a is in close contact with the upper surface of the groove 2a as shown in FIG. 9B, the lower space 4 and the combustion chamber are in communication with each other through the groove 6. Therefore, the gas in the lower space 4 immediately flows back to the combustion chamber side through the groove 6, reducing the lower space pressure _P2 . Therefore, as shown in Fig. 9A, it rises between crank rotation angles a and b, but immediately descends at point b, and remains in close contact with the lower surface of the groove 2a, as shown in Fig. 9C. .

As described above, the present invention has the following effects due to the simple structure in which a radial groove is provided on the upper surface of the pressure ring.

The gas in the lower space is caused to flow back into the combustion chamber through the concave groove, and this backflow of gas reduces the pressure in the lower space.
P ₂ decreases and the pressure ring comes into close contact with the bottom surface of the groove, eliminating gas leakage into the crank chamber and preventing unburned impurities such as carbon from entering the oil in the oil pan and preventing oil deterioration. Also, air pollution caused by the release of unburned gas into the outside air can be prevented.

Furthermore, since there is no conduction of high-temperature heat from the piston from the top surface of the groove, the temperature distribution on the top and bottom surfaces of the pressure ring is second to none.
As shown in the figure, it becomes almost symmetrical and no thermal deformation occurs. As a result, scuffing is also prevented, and oil on the cylinder wall is no longer swept up into the combustion chamber, reducing oil consumption.
Furthermore, since the outer circumferential surface of the pressure ring is normally in close contact with the cylinder wall surface, good heat conduction to the cylinder wall surface is obtained, ensuring a heat dissipation effect.

[Brief explanation of the drawing]

Figure 1 A and B are explanatory diagrams of the relationship between cylinder internal pressure and lower space pressure in general engines and supercharged engines, Figure 2 is a heat distribution diagram of the pressure ring, and Figure 3 A and B are pressure rings in the supercharged engine. Figure 4A is a thermal distribution diagram of the pressure ring, Figure 4B is a thermal deformation diagram of the pressure ring, Figure 5 is a plan view of the piston ring according to the present invention, Figure 6 is a side view of the same, FIG. 7 is an enlarged sectional view taken along the - line in FIG. 5, FIG. 8 is an enlarged sectional view taken along the - line in FIG. 5, and FIGS. 3a...pressure ring, 6...concave groove.

Claims (1)

[Scope of utility model registration request] In a piston of an internal combustion engine having at least two or more pressure rings, gas in the space between the pressure rings flows out to the combustion chamber side when the piston descends, on the upper surface of the top ring in the pressure ring on the combustion chamber side. A piston ring characterized by having a concave groove in the radial direction.