JPH094711A - Pressure ring for engine - Google Patents

Abstract

PURPOSE: To provide a pressure ring of engine which can reduce excessive oil consumption at the beginning of operation without lowering a blowby gas sealing function even if a piston diameter and a piston speed are increased. CONSTITUTION: A pressure ring 5 is fitted closely into a pressure ring groove provided recessedly in a piston. It forms its barrel top part P on the outer peripheral surface to a piston head side from a center position G in the height direction of the pressure ring 5. Also the surface near the barrel top part P is made in a rough flat surface 10, and an upper arc surface 11 and a lower arc surface 12 are formed at the upper and lower sides of the rough flat surface. Then an oil retaining groove 13 is engraved in the lower arc surface 12 in peripheral direction, and a distance (d) between the lower top end part 14 of the oil retaining groove 13 and the outermost periphery part of the rough flat surface 10 is set at a friction width which is produced within running-in operation at the beginning of the operation of an engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine piston ring, and more particularly to a pressure ring fitted in a pressure ring groove formed in a piston.

[0002]

2. Description of the Related Art As an example of a conventional pressure ring, the outer peripheral surface of the pressure ring is formed into a barrel shape, and an oil film of lubricating oil is formed between the outer peripheral surface of the pressure ring and the inner peripheral surface of the cylinder to form an oil-tight seal. In order to maintain a good condition, FIG.
As shown in (A), an oil sump groove 32 is circumferentially formed in the contact portion between the pressure ring 5 and the inner peripheral surface of the cylinder, that is, in the vertical center of the pressure ring 5, so that the pressure ring 5 is not worn. There are things I tried to reduce.

In this structure, when the pressure ring 5 is twisted as the piston moves up and down, the uniformity of the oil film layers formed above and below the contact portion between the pressure ring 5 and the inner peripheral surface of the cylinder is impaired, and the pressure is reduced. The upper and lower portions of the contact portion communicate with each other through the oil sump groove 32 formed in the contact portion of the ring 5, the gas sealing state due to the oil film is broken, the blow-by gas amount increases, and the oil rise increases. There is a problem.

FIG. 5 (B) is a view for explaining the state, showing the state of the contact surface between the outer peripheral surface of the pressure ring 5 and the inner peripheral surface of the cylinder, and the pressure associated with the vertical movement of the piston. Due to the twisting of the ring 5, the contact portion 30 becomes wavy, and the upper and lower portions of the contact portion 30 communicate with each other via the oil sump groove 32 (indicated by an arrow 33 in FIG. 5B).
Things happen.

To address this problem, the applicant of the present invention has
No. 38457 discloses the following engine pressure ring 5. FIG. 6 (A) is an actual flat 3-3845.
It is a partially broken sectional view of the pressure ring 5 disclosed in No. 7. In the same figure, a pressure ring groove 3 is provided in the ring forming region above the piston 1, and a pressure ring 5 is fitted in the pressure ring groove 3. The outer peripheral surface of the pressure ring 5 is formed in a barrel shape, and its substantially vertical center is formed as a standard contact surface 31 with the cylinder inner peripheral surface 34. Further, an oil sump groove 32 is formed in the circumferential direction in a portion closer to the cylinder bottom than the standard contact surface 31.

According to such a pressure ring 5, as shown in FIG.
Even if the contact portion 30 undulates due to the twist of the pressure ring 5 as shown in (B), the oil sump groove 32 is formed on the cylinder bottom side of the contact portion 30, so that the oil sump groove 3 is formed.
The upper and lower sides of the contact portion 30 do not communicate with each other via the contact point 2, and the oil-tight state can be maintained.

[0007]

However, when the conventional structure shown in Japanese Utility Model Laid-Open No. 3-38457 is applied to a pressure ring fitted to a piston having a large outer diameter and a high piston speed, the two-stage structure described later will be described. A hit occurs,
There is a problem that the amount of oil rises at the beginning of engine operation and the shape of the outer peripheral surface of the pressure ring is significantly impaired.

The occurrence of this problem will be further described.
When the outer diameter of the piston becomes large, a large tension is required on the pressure ring 5 in order to apply a force for making pressure contact with the inner peripheral surface 34 of the cylinder over the entire circumference. Therefore, when the outer diameter of the piston increases, the contact pressure between the cylinder inner peripheral surface 34 and the outer peripheral surface of the pressure ring 5 increases. Further, in the arc-shaped barrel shape shown in FIG. 6, since the cylinder inner peripheral surface 34 and the standard contact surface 31 of the pressure ring 5 are substantially point-contacted (linear in the circumferential direction), the contact points are contacted at the initial stage of engine operation. The pressure increases considerably. Moreover, since the outer peripheral surface of the pressure ring 5 is substantially arcuate, the pressure ring 5 starts from the contact point.
Tend to tilt (twist) due to frictional force,
In addition, when the piston speed exceeds, for example, 10 m / sec, the frictional force further increases, resulting in a two-step hit.

7A and 7B are views for explaining the relationship between the inclination of the pressure ring and two stages, FIG. 7A shows the state of the pressure ring 5 when stopped, and FIG. 7B shows the piston. FIG. 7C is a diagram showing a state in which the pressure ring 5 is tilted by + θ due to the frictional resistance when the piston is lowered, and FIG. 7C is a diagram showing a state in which the pressure ring 5 is inclined by −α by the frictional resistance when the piston is raised.
FIG. 7 (D) shows the pressure ring 5 worn by two steps.
It is a figure which shows the shape of.

As can be seen from FIGS. 7 (A) to 7 (C), as the piston diameter increases and the piston speed increases, the contact surface when ascending and the contact surface when descending become different, and It is easy for a step to occur. Further, when the two-stage contact occurs, the lubricating oil 35 accumulated in the oil sump groove 32 when the piston descends as shown in FIG.
4 is lubricated and the lubricating oil 35 applied to the cylinder inner peripheral surface 34 is scraped up toward the upper side of the cylinder inner peripheral surface 34 when the piston rises, as shown in FIG. 7C. It will increase significantly.

Further, as can be seen from FIG. 7 (D), when the two-stage contact becomes severe, the preset barrel shape is deformed due to wear to form the upper wear surface 36 and the lower wear surface 37, and the pressure ring. There is also a problem that the predesigned function of 5 cannot be exhibited.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and in a pressure ring applied to a piston having a large outer diameter and a large piston speed, it is possible to reduce oil rising at the initial stage of operation. An object of the present invention is to provide a pressure ring that can reliably perform gas sealing even if the pressure ring is twisted.

[0013]

An engine pressure ring according to claim 1 for achieving the above object is provided, for example, in FIG.
Referring to FIG. 2, the pressure ring 5 is fitted in the pressure ring groove 3 provided in the piston 1 of the engine, and the barrel top portion P on the outer peripheral surface of the pressure ring 5 has a height higher than that of the pressure ring 5. It is formed closer to the piston head side than the center position G in the depth direction, and the vicinity of the barrel top P is defined as a substantially flat area (generally flat surface 10). It is formed in a curved surface area (upper circular arc surface 11, lower circular arc surface 12), and an oil sump groove 13 is engraved in the circumferential direction in a convex curved surface area (lower arc surface 12) on the cylinder bottom side. The distance d between the cylinder bottom side tip portion (lower tip portion 14) and the outermost peripheral portion of the substantially flat surface 10 is set to the wear width that occurs within the familiar running time at the beginning of engine operation, and the oil sump groove is completed after the familiar running time. 13's Linda bottom tip (lower tip 14) is characterized by being set so as to contact the inner circumferential surface cylinder (liner surface 15).

[0014]

According to the pressure ring of claim 1, the pressure ring 5
By forming the barrel top portion P on the outer peripheral surface of the pressure ring 5 closer to the piston head side than the center position G in the height direction, for example, when the vicinity of the barrel top portion P is formed into a substantially flat surface 10 by a method such as lapping, Lower arc surface 12
It is possible to form the substantially flat surface 10 having a predetermined width L without cutting the oil sump groove 13 formed in the substantially flat surface 10.
In addition, since the vicinity of the barrel top P is a substantially flat surface 10,
The area of the outer peripheral portion of the pressure ring 5 that contacts the liner surface 15 can be increased, the contact pressure can be reduced, and since two points do not hit as in the conventional case, it is possible to prevent the two-step contact from occurring. Therefore, FIG.
It is possible to reduce the oil rise in the initial stage of engine operation as described in (C), and to suppress the deformation of the outer peripheral surface of the pressure ring 5 due to the two steps as shown in FIG. 7D. it can.

Further, the distance d between the lower tip portion 14 of the oil sump groove 13 and the outermost peripheral portion of the substantially flat surface 10 is set to a wear width that occurs within the familiar running time at the beginning of engine operation, and after the familiar running time ends. Since the lower end 14 of the oil sump groove 13 abuts on the inner peripheral surface of the cylinder, the lubricating oil in the oil sump groove 13 must be supplied to the contact surface before mirror surface lubrication occurs in the latter stage of the leveling operation. Therefore, the gas sealing function can be sufficiently exerted in the pressure ring 5 after the break-in operation. Further, since the oil sump groove is formed on the lower side of the central portion, the oil sump groove 13 is formed as described with reference to FIG.
Since the upper and lower portions of the contact portion do not communicate with each other via the, the oil-tight state can be favorably maintained.

[0016]

As described in detail in the above operation, according to the invention of claim 1, when the pressure ring is applied to a piston having a large outer diameter and a large piston speed, (a) the oil sump groove is formed. It is possible to form a substantially flat area of a predetermined width on the outer peripheral surface of the pressure ring without affecting the formation, (b) it is possible to reduce the oil rise at the initial stage of engine operation, and (c) by two steps The deformation of the pressure ring can be reduced. (D) The lubricating oil in the oil sump groove can be supplied to the contact surface before mirror surface lubrication occurs in the latter stage of the leveling operation, and the gas sealing function is sufficient after the leveling operation. It has a unique effect that it can be demonstrated to the full.

[0017]

Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments. 1 and 2 are views for explaining an engine pressure ring according to the present invention, and FIG.
FIG. 1B is a partially cutaway front view of the piston, FIG. 1B is an enlarged cross-sectional view for explaining the outer shape of the pressure ring.

As shown in FIG. 1 (B), the piston 1 has two pressure ring grooves 3 and one oil scraping ring groove 4 provided in a ring forming region 2 at the upper part thereof, and the pressure ring Groove 3
The pressure ring 5 in the oil scraping ring groove 4
Are fitted respectively. As shown in FIG. 2 (A), the outer peripheral surface of the pressure ring 5 fitted in the pressure ring groove 3 has the barrel top P formed closer to the piston head side than the center position G in the height direction of the pressure ring 5, Substantially flat surface 10 formed by cutting off the vicinity of the barrel top P almost vertically
And an upper arc surface 11 on the piston head side of the substantially flat surface 10 and a lower arc surface 12 on the cylinder bottom side of the substantially flat surface 10. An oil sump groove 13 is formed in the lower arc surface 12 in the circumferential direction.

The outer peripheral surface of the pressure ring 5 is formed by first forming a barrel surface having a radius R with the center thereof shifted upward so that the barrel top P is located above the center position G of the pressure ring 5 in the height direction. It is formed on the side, and then industrial chrome plating is applied to the entire barrel-shaped outer peripheral surface to a thickness of approximately 0.15 m.
A substantially flat surface 10 is formed by applying it over m and lapping. Then, the oil sump groove 13 is formed on the lower arc surface 12. With such a configuration, even when the oil sump groove 13 is formed on the lower arc surface 12, as shown in FIG.
The width L of the substantially flat surface 10 shown in FIGS. 2A and 2B can be easily secured.

Further, even if the substantially flat surface 10 is worn due to friction with the liner surface 15, the substantially flat surface 10 as the contact surface is located on the upper side of the oil sump groove 13, so that the oil sump groove 13 is formed. Can be prevented from being scraped by wear within the distance d. In addition, by using the barrel surface of the radius R with the center shifted upward, the position of the lower arc surface 12 where the oil sump groove 13 is formed can be positioned considerably behind when viewed from the substantially flat surface 10. It is possible to prevent the shape of the oil sump groove 13 from being deformed due to wear at the beginning of operation.

Further, the distance d between the lower tip portion 14 of the oil sump groove 13 and the outermost peripheral portion of the substantially flat surface 10 is about 100 hours to 1000 at the initial stage of engine operation (it depends on the type of engine.
The wear width is set within the familiar operating time. Further, the width L of the substantially flat surface 10 is set so that the width worn during the familiar running time is d. The distance d and the length L are set by an actual experiment in the engine of each model.

When the engine is first operated with the pressure ring 5 attached, the substantially flat surface 10 and the liner surface 15 are in contact with each other as shown in FIG. 2 (A). FIG.
FIGS. 2B and 2C are views showing an example of a state in which the substantially flat surface 10 is worn, and FIG. 2B is a liner when the substantially flat surface 10 is worn in parallel with the original substantially flat surface 10. FIG. 2C shows a contact state with the surface 15, and FIG. 2C shows a contact state with the liner surface 15 when the wear is performed in a state slightly inclined with respect to the original substantially flat surface 10 (shown by an angle φ). FIG.

Although the wear width is drawn large in FIGS. 2B and 2C for the sake of clarity, as shown in FIG. 2B, the total height h of the pressure ring is 3 mm and the width s of the pressure ring is s. Is 5 mm, the distance d is 0.005 mm to 0.0
It is about 08 mm. The width L of the substantially flat surface 10 is about 0.6 mm to 1.0 mm.

2B and 2C, the distance d and the length L are set so that the lower tip 14 of the oil sump groove 13 contacts the liner surface 15 at the end of the engine run-in operation. The settings are the same, as shown in Fig. 2 (B),
2C shows that the wear shown in FIGS. 2B and 2C may occur depending on the state of the inner peripheral surface of the cylinder and the pressure ring 5.

FIG. 3 is a flow chart for explaining the adapting action of the pressure ring 5 to the liner surface 15. In step SP1, a substantially flat surface 10 is obtained with a small amount of lubricating oil.
Is in contact with the liner surface 15, and the engine is run-in, and the flat surface 10 is worn by the distance d at the end of the run-in in step SP2.
After the run-in operation in 3, the lower tip portion 14 of the oil sump groove 13 directly contacts the liner surface 15 and the lubricating oil is supplied to the contact surface.

According to this embodiment, as compared with the conventional pressure ring 5 shown in FIG.
Since the contact area is widened, the contact pressure is reduced, and the contact is made on the surface, so that the pressure ring 5 is less likely to tilt. Therefore, it is possible to prevent the occurrence of extreme two-step hits, reduce the oil rise, and prevent the shape of the pressure ring 5 from being significantly impaired. Further, during the initial run-in operation, as shown in step SP1 of FIG. 3, the engine is operated with a small amount of lubricating oil, so that the oil consumption at the initial operation can be reduced.

Before the pressure ring 5 and the liner surface 15 are mirror-lubricated due to wear in the initial stage of operation, the liner surface 15
Since the distance d is set so that the lower tip portion 16 of the oil sump groove 13 comes into contact with the oil sump groove 13, after the break-in operation is finished,
The necessary minimum oil film can be generated on the contact surface by the lubricating oil in the oil sump groove 13, and the pressure ring 5 and the liner surface 15 can be formed.
The oil-tightness of the oil is not impaired, and blow-by gas and oil rise can be reduced.

[0028]

[Embodiment 2] FIG. 4 is a longitudinal sectional view showing the outer peripheral structure of a pressure ring according to the present invention. The second embodiment is different from the first embodiment in that the upper arc surface 11 and the lower arc surface 12 in the first embodiment have an upper first convex curved surface 17 and a lower arc surface 12 whose curvature change is larger than that of an arc. The point of replacing the first convex curved surface 18 with each other, the point of replacing the substantially flat surface 10 of the first embodiment with the second convex curved surface 19 having a much smaller curvature than the first convex curved surfaces 17 and 18, and the lower first The length of the convex curved surface 18 is set to the upper first convex curved surface 1
It is only a point that is larger than the length of 7.

In the second embodiment as well, the oil sump groove 13
Is formed on the lower first convex curved surface 18, and the position of the barrel top P is formed on the upper side with respect to the center position G in the height direction. Similar to the first embodiment, the second convex curved surface 19 also makes a substantially flat contact in the second embodiment, so that it is possible to prevent the occurrence of an extreme two-step contact, and it is possible to suppress the oil rise amount. A good airtight state can be maintained at the end of the break-in operation, and the expansion gas can be prevented from leaking from the combustion chamber to the crankcase.

[Brief description of drawings]

FIG. 1 is a view for explaining a pressure ring according to a first embodiment, and FIG. 1 (A) is a cross-sectional view of a main part taken out,
FIG. 1B is a partially cutaway front view of the piston.

2A to 2C are enlarged cross-sectional views of a pressure ring according to the first embodiment of the present invention.

FIG. 3 is a flow chart for explaining the action of applying the pressure ring of the present invention to the liner surface.

FIG. 4 is an enlarged sectional view showing the shape of a pressure ring according to a second embodiment of the present invention.

5A is a cross-sectional view of a conventional pressure ring, FIG.
(B) is a figure for explaining the problem.

FIG. 6 (A) is a sectional view of a pressure ring already proposed by the present applicant, and FIG. 6 (B) is a diagram for explaining its effect.

7 (A) to 7 (D) are views for explaining problems when the pressure ring diameter is increased and the piston speed is increased.

[Explanation of symbols]

1 ... Piston, 3 ... Pressure ring groove, 5 ... Pressure ring, 1
0 ... substantially flat surface, 11 ... upper arc surface, 12 ... lower arc surface, 1
3 ... Oil sump groove, 14 ... Lower tip, 15 ... Liner surface, 1
7 ... upper 1st convex curved surface, 18 ... lower 1st convex curved surface, 19 ... 2nd convex curved surface, P ... barrel top part, G ... height direction center position of a pressure ring.

Claims (1)

[Claims] 1. A pressure ring (5) fitted in a pressure ring groove (3) recessed in a piston (1) of an engine, wherein a barrel top (P) on an outer peripheral surface of the pressure ring (5) is provided. The pressure ring (5) is formed closer to the piston head than the center position (G) in the height direction, and the vicinity of the barrel top (P) is defined as a substantially flat area (10) (19), which is closer to the substantially flat area (10). Also the area on the piston head side and the area on the cylinder bottom side are convex curved surface areas (11) (1
2) Formed on (17) and (18), and engraving the oil sump groove (13) in the circumferential direction on the convex curved surface area (12) (18) on the cylinder bottom side, the cylinder bottom side of the oil sump groove (13) The distance (d) between the tip portion (14) and the outermost peripheral portions of the substantially flat regions (10) and (19) is set to the wear width that occurs within the familiar running time at the beginning of engine operation, and the oil sump is stored after the familiar running time ends. A pressure ring for an engine, characterized in that the tip (14) of the groove (13) on the cylinder bottom side is set to abut on the cylinder inner peripheral surface (15).