Piston ring

Abstract

The invention provides a piston ring, and relates to the technical field of piston rings. The piston ring comprises an opening and a position opposite to the opening, the lower surface of the piston ring is an inclined plane inclined relative to a plane perpendicular to the axis of the piston ring, and on the plane where the axis of the piston ring is located, the inclination angle of the inclined plane at the opening position is smaller than that at the position opposite to the opening. The lower surface of the piston ring is the inclined plane, and the angle of the inclined plane at the opening position is smaller than the angle of the inclined plane at the position opposite to the opening, so that enough space is formed between the lower surface of the piston ring near the opening position and the ring groove for oil storage, and the abrasion at the position is reduced; abrasion of different positions of the lower surface of the piston ring is basically consistent, and therefore the service life of the piston ring is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of piston rings, in particular to a piston ring. Background Art

[0002] High burst pressure and high power will be one of the main features of the next generation of engine technology upgrades. However, high burst pressure and power put forward more stringent requirements on engine performance. As one of the core components of the engine, the engine piston ring will face the challenges of higher blowby volume and oil consumption performance requirements. High burst pressure will cause wear problems on the lower surface of a ring. Analysis shows that the contact pressure of the lower surface has a greater impact on the wear of the lower surface. When the contact pressure is large, the friction force on the lower surface will also increase accordingly. During the operation of the engine, this continuous friction will continue to act on the lower surface, causing the material on the lower surface to be gradually worn and consumed. Over time, the degree of wear will continue to deepen, which may affect the overall performance and service life of the engine piston ring. If the contact pressure is at a high level for a long time, the wear rate of the lower surface will be significantly accelerated, which may cause the engine's sealing to decrease, affecting the engine's power output and fuel economy.

[0003] After studying a large number of worn piston ring samples, it was found that after the piston ring has been running for a long time under high explosion pressure conditions, the lower surface of the ring is close to the piston ring opening, which makes it difficult to form an oil film between the ring and the ring groove, and cannot form effective lubrication, resulting in severe wear. On the opposite side of the opening, the oil film will not be destroyed, and the lower surface of the ring is almost not worn. In the prior art, the wear problem is solved by the technical means of tilting the lower surface of the piston ring. The inclination angle design of the lower surface has a great influence on the contact pressure of the lower surface. A small inclination angle design of the lower surface is good for the wear of the lower surface, but is not conducive to controlling the amount of blowby and oil consumption. A large inclination angle of the lower surface is harmful to the wear of the lower surface, but is beneficial to controlling the amount of blowby and oil consumption. However, the wear and blowby problems corresponding to different positions of the piston ring are different. At present, the inclination angle of the lower surface of the top ring in the prior art is fixed, so that the wear of different positions of the lower surface of the piston ring still cannot change according to the different positions of the piston ring, and the wear at the opening is still serious. Summary of the invention

[0004] An object of the first aspect of the present invention is to provide a piston ring to solve the problem in the prior art that the lower surface of the piston ring has a fixed inclination angle, which causes severe wear on the lower surface of the opening side of the piston ring.

[0005] In particular, the present invention provides a piston ring, which has an opening and a position opposite to the opening, and the lower surface of the piston ring is an inclined surface inclined relative to a plane perpendicular to the axis of the piston ring, on the plane where the axis of the piston ring is located; the inclination angle of the inclined surface at the opening position is smaller than the inclination angle of the inclined surface at the position opposite to the opening.

[0006] Optionally, the piston ring is symmetrically arranged on both sides of a line from the opening to a position opposite to the opening;

[0007] The lower surface includes, on both sides of the connecting line, first areas located on both sides of the opening and second areas located on both sides of a position opposite to the opening;

[0008] The inclination angle of the first area is a fixed value α1;

[0009] The inclination angle of the second area is a fixed value α2;

[0010] Among them, α1<α2.

[0011] Optionally, the angle of the arc where the first area is located is less than or equal to 30°.

[0012] Optionally, the lower surface further includes at least one transition region on both sides of the connecting line, the at least one transition region is located between the first region and the second region, and the inclination angle of the inclined surface of the at least one transition region is a fixed value α3; wherein α1<α3<α2.

[0013] Optionally, there are multiple transition areas, and the inclination angle of each transition area is a fixed value α3n, wherein α1<α3n<α2; the inclination angle of the transition area from the first area to the second area gradually increases, that is, α31<α32……<α3n.

[0014] Optionally, the lower surface of the piston ring is formed as an arc-shaped surface at a position close to the outer peripheral surface.

[0015] Optionally, a ratio of a distance from a starting position of the arc-shaped surface to the outer peripheral surface to a width value of the lower surface is less than or equal to 50%.

[0016] Optionally, the ratio gradually decreases from the opening position to a position opposite to the opening.

[0017] Optionally, the piston ring is symmetrically arranged on both sides of a line from the opening position to a position opposite to the opening;

[0018] The lower surface includes a first area located on the side of the opening and a second area located on the side opposite to the opening on both sides of the connecting line;

[0019] The ratio is a fixed value λ1 in the first region;

[0020] The ratio is a fixed value λ2 in the second region;

[0021] Among them, 50%≥λ1>λ2.

[0022] Optionally, the lower surface further includes at least one transition region on both sides of the connecting line, the at least one transition region is located between the first region and the second region, and the ratio is a fixed value λ3 in the transition region; wherein 50% ≥ λ1>λ3>λ2.

[0023] Optionally, a height of a connection between the arc-shaped surface and the outer peripheral surface is less than or equal to 100 um.

[0024] Optionally, the height of the connection between the arc-shaped surface and the outer peripheral surface gradually decreases from the opening position to a position opposite to the opening position.

[0025] Optionally, the height of the connection between the arc-shaped surface and the outer peripheral surface in the first area is a fixed value h1;

[0026] The height of the connection between the arc surface and the outer peripheral surface is a fixed value h2 in the second area;

[0027] Among them, 100um≥h1>h2.

[0028] Optionally, a height of a connection between the arc-shaped surface and the outer peripheral surface in the transition region is a fixed value h3; wherein 100um≥h1>h3>h2.

[0029] In this embodiment, the lower surface of the piston ring is formed as an inclined surface, and the inclination angle α of the inclined surface at the opening position is smaller than the inclination angle at the position opposite to the opening, so that there is enough space between the lower surface of the piston ring and the ring groove near the opening position for oil storage, thereby reducing the wear at this location, making the wear at different locations on the lower surface of the piston ring basically consistent, thereby improving the service life of the piston ring.

[0030] In this solution, the first area d1 and the second area d2 are arranged on both sides of the connecting line of the piston ring, and the first area d1 is near the opening 1, and the second area d2 is near the opposite side of the opening. The inclination angle of the first area d1 is a fixed value α1, and the inclination angle of the second area d2 is a fixed value α2. The inclination angles of the first area d1 and the second area d2 are designed to be fixed values, which reduces the wear near the opening of the piston ring on the one hand, and facilitates the processing of the piston ring on the other hand.

[0031] In this solution, a transition area is set between the first area and the second area, and the inclination angle of the transition area d3 is between the first area d1 and the second area d2. The main purpose of the transition area d3 is to allow the inclination angles of the first area d1 and the second area d2 to transition gradually, so as to avoid excessive changes in the inclination angles of different areas, which may affect the performance of the piston ring.

[0032] This solution forms a curved surface at the position from the lower surface to the outer peripheral surface, so that a gap is formed between the curved surface of the lower surface and the bottom of the piston ring groove, so that the lubricating oil enters from the position between the curved surface and the piston ring groove to other positions of the lower surface, thereby increasing the lubrication between the piston ring and the piston ring groove, reducing friction, and thus reducing wear.

[0033] This solution can eliminate this difference by gradually reducing the ratio from the opening position to the position opposite to the opening position, so that the amount of lubricating oil entering the lower surface of the piston ring at each position of the piston ring is not much different.

[0034] This solution designs the height h of the connection between the arc surface and the outer peripheral surface. When the height h is too low, the lubricating oil cannot enter between the lower surface and the piston ring groove, so it cannot be lubricated well, resulting in dry friction between the piston ring and the piston ring groove, and the piston ring is also worn. If the height h is too high, too much lubricating oil will enter, which will eventually lead to poor sealing performance. The height of the connection between the arc surface and the outer peripheral surface of this solution cannot be higher than 100um to achieve a balance between wear and lubrication, further reducing wear.

[0035] In this solution, the height of the connection between the arc surface and the outer peripheral surface from the opening position to the position opposite to the opening position gradually decreases, so that the lubricating oil can more easily enter between the lower surface and the piston ring groove at the opening position, reducing the wear at the opening position, and making the wear at different positions of the entire piston ring uniform and small.

[0036] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0038] Figure 1 is a schematic structural diagram of a piston ring according to a specific embodiment of the present invention;

[0039] Figure 2 is in accordance with Figure 1 A schematic cross-sectional view after cutting along the cutting line AA in FIG.

[0040] Figure 3 is in accordance with Figure 1 A schematic cross-sectional view after cutting along the cutting line BB in FIG.

[0041] Figure 4 is a schematic structural diagram of a piston ring according to a specific embodiment of the present invention;

[0042] Figure 5 is a schematic cross-sectional view of a piston ring disposed at a piston ring groove according to a specific embodiment of the present invention;

[0043] Figure 6 is a schematic cross-sectional view of a piston ring according to another specific embodiment of the present invention.

[0044] Description of reference numerals:

[0045] Piston ring 100; lower surface 110; arc surface 111; opening 120; inner peripheral surface 130; outer peripheral surface 140; piston ring groove 200. DETAILED DESCRIPTION

[0046] In the description of this embodiment, it should be understood that the terms "length", "width", "height", "up", "down", "left", "right", "vertical", "horizontal", "bottom", "inside" and "outside" etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0047] As a specific embodiment of the present invention, Figure 1-Figure 3As shown, this embodiment provides a piston ring 100, which has an opening 120 and a position opposite to the opening 120. The lower surface 110 of the piston ring 100 is an inclined surface that is inclined relative to a plane perpendicular to the axis L of the piston ring 100, and on the plane where the axis L of the piston ring 100 is located, the inclination angle α of the inclined surface at the position of the opening 120 is smaller than the inclination angle of the inclined surface at the position opposite to the opening 120. Preferably, the inclination angle α of the inclined surface at the opening position gradually increases from the position of the opening 120 to the position opposite to the opening 120 (e.g., Figure 3 and Figure 4 shown).

[0048] Specifically, the lower surface 110 of the piston ring 100 in this embodiment is formed as an inclined surface, and the angle a between the section line after sectioning the plane where the axis L of the piston ring 100 is located and the axis L is an acute angle, that is, when the piston ring is placed horizontally, the connection between the inclined surface and the inner peripheral surface 130 is higher than the height of the connection between the inclined surface and the outer peripheral surface 140. The inclination angle α of the inclined surface of this embodiment is greater at the position of the opening 120 than the inclination angle of the inclined surface at the position opposite to the opening 120, and more preferably, the inclination angle gradually increases from the position of the opening 120 to the position opposite to the opening 120, so that the lower surface 110 of the piston ring 100 near the position of the opening 120 has enough space between the ring groove for oil storage, so that the wear at this position is reduced, and the wear of different positions of the lower surface 110 of the piston ring 100 is basically consistent, thereby improving the service life of the piston ring 100.

[0049] In addition, the inclination angle is set to an angle where the space is insufficient to provide sufficient space for blowby gas. When the piston ring 100 is under high load, at least a portion of the lower surface 110 of the piston ring 100 is always in contact with the piston ring groove 200. The sealing function of the piston ring 100 is ensured by the high explosion pressure. Therefore, in this embodiment, the lower surface 110 of the piston ring 100 is formed as an inclined surface and the change in the angle of the inclined surface can greatly reduce the amount of blowby gas.

[0050] As a specific embodiment of the present invention, Figure 4 As shown, the piston ring 100 of this embodiment is symmetrically arranged about a line M from the opening 120 to a position opposite to the opening 120. The lower surface 110 includes a first area d1 adjacent to the opening 120 and a second area d2 located on the side of the position opposite to the opening 120 on both sides of the line M. The inclination angle of the first area d1 is a fixed value α1. The inclination angle of the second area d2 is a fixed value α2; wherein α1<α2.

[0051] Specifically, in this embodiment, the piston ring 100 is symmetrical about the opening 120 and the connecting line M at the position opposite to the opening 120. In this embodiment, the first area d1 and the second area d2 are set on both sides of the connecting line M of the piston ring 100, and the first area d1 is near the opening 120, and the second area d2 is near the opposite side of the opening 120. The inclination angle of the first area d1 is a fixed value α1, and the inclination angle of the second area d2 is a fixed value α2. The inclination angles of the first area d1 and the second area d2 are designed to be fixed values, which, on the one hand, reduces the wear near the opening 120 of the piston ring 100, and on the other hand, facilitates the processing of the piston ring 100.

[0052] As a specific embodiment of the present invention, the angle of the arc where the first area d1 of this embodiment is located is less than or equal to 30°. Specifically, for example, the angle of the arc where the first area d1 is located can be 10°, 20° or 30°, excluding 0°. Preferably, the angle of the arc where the first area d1 of this embodiment is located is 20-30°, ensuring that all areas with severe wear are designed with a smaller inclination angle.

[0053] As a specific embodiment of the present invention, the lower surface 110 of this embodiment also includes at least one transition area d3 on both sides of the connecting line M, at least one transition area d3 is located between the first area d1 and the second area d2, and the inclination angle of the inclined surface of at least one transition area d3 is a fixed value α3; wherein α1<α3<α2.

[0054] Specifically, the inclination angle of the transition area d3 is between the first area d1 and the second area d2. The main purpose of the transition area d3 is to allow the inclination angles of the first area d1 and the second area d2 to transition gradually to avoid excessive changes in the inclination angles of different areas that may affect the performance of the piston ring 100.

[0055] As a specific embodiment of the present invention, the angle of the arc where all transition areas d3 located on both sides of the symmetry axis M of the piston ring 100 of this embodiment are less than or equal to 20°. For example, the angle of the arc where the transition area d3 is located is 0°, 10° or 20°. The angle can be designed according to actual needs. Generally speaking, the angle of the arc where the transition area d3 is located does not exceed the angle of the arc where the first area d1 is located.

[0056] As a specific embodiment of the present invention, the number of transition areas d3 in this embodiment is multiple, and the inclination angle of each transition area d3 is a fixed value α3n, wherein α1<α3n<α2; the inclination angle of the transition area d3 from the first area d1 to the second area d2 gradually increases, that is, α31<α32……<α3n.

[0057] Specifically, the number of transition areas d3 in this embodiment can be multiple, and the inclination angle of each transition area d3 can be a constant value. However, since the transition area d3 is designed to gradually transition the inclination angles of the first area d1 and the second area d2, the inclination angle of the transition zone close to the first area d1 is smaller than the inclination angle close to the second area d2, and the inclination angles of multiple transition areas d3 gradually change and transition, so that the transition of the inclination angle is smoother.

[0058] As a specific embodiment of the present invention, Figure 5 As shown, the position from the lower surface 110 to the outer peripheral surface 140 of the piston ring 100 of this embodiment is formed as an arc surface 111.

[0059] Specifically, during the operation of the piston ring 100, the wear of the lower surface 110 is closely related to the lubrication effect. After the lower surface 110 is formed into an inclined surface, the lower surface 110 located near the outer peripheral surface 140 is in close contact with the bottom of the piston ring groove 200, so that the lubricating oil is not easy to enter, resulting in serious wear of the lower surface 110 of the piston ring 100. From the perspective of the piston ring interface section, this embodiment is provided with an arc surface 111 at the position from the lower surface 110 to the outer peripheral surface 140, so that the piston ring rolls along the arc when it is twisted under high pressure, replacing the non-rounded design in the prior art, reducing friction and wear. A gap is formed between the lower surface 110 and the bottom of the piston ring groove 200 at the arc surface 111, so that the lubricating oil enters from the position between the arc surface 111 and the piston ring groove 200 to other positions of the lower surface 110, thereby increasing the lubrication between the piston ring 100 and the piston ring groove 200, reducing friction, and thus reducing wear.

[0060] As a specific embodiment of the present invention, Figure 6 As shown, in this embodiment, the ratio of the distance L1 between the starting position of the arc surface 111 and the outer peripheral surface 140 to the width L2 of the lower surface 110 is less than or equal to 50%.

[0061] Specifically, the ratio of the distance L1 from the starting position of the arc surface 111 to the outer peripheral surface 140 to the width L2 of the lower surface 110 can be 50%, 40%, 30% or 10%, etc. Specifically, the ratio cannot be equal to 0. The ratio can be designed according to actual conditions.

[0062] Specifically, in this embodiment, the ratio of the distance L1 from the starting position of the arc surface 111 to the outer peripheral surface 140 to the width value L2 of the lower surface 110 is designed to be less than or equal to 50%. This can avoid the instability of the piston ring 100 due to the excessive width of the arc surface 111, which in turn causes the outer peripheral surface 140 of the piston ring 100 to fit unstable with the cylinder liner, resulting in poor sealing performance between the outer peripheral surface 140 of the piston ring 100 and the cylinder liner, and poor sealing performance between the lower surface 110 of the piston ring 100 and the bottom of the piston ring groove 200.

[0063] As a specific embodiment of the present invention, the ratio from the position of the opening 120 to the position opposite to the position of the opening 120 in this embodiment gradually decreases. Specifically, since the piston ring 100 has a greater mobility at the position of the opening 120, it is more difficult for the lubricating oil to enter the lower surface 110 at the position of the opening 120 than at the position opposite to the opening 120. Therefore, this embodiment can eliminate this difference by gradually reducing the ratio from the position of the opening 120 to the position opposite to the opening 120, so that the amount of lubricating oil entering the lower surface 110 of the piston ring 100 at each position is not much different.

[0064] As a specific embodiment of the present invention, the ratio of this embodiment is a fixed value λ1 in the first region d1 and a fixed value λ2 in the second region d2, wherein λ1>λ2.

[0065] Specifically, this embodiment designs different ratios at different positions of the piston ring 100. Specifically, the ratio of the first area d1 near the opening 120 is a fixed value λ1, and the ratio of the second area d2 is a fixed value λ2. In order to ensure that the amount of lubricating oil entering the first area d1 and the second area d2 is not much different, λ1>λ2, and 50%≥λ1>λ2. Designing the ratio of the first area d1 to a fixed value and the ratio of the second area d2 to a fixed value can reduce the difficulty of processing the piston ring 100.

[0066] As a specific embodiment of the present invention, the ratio of this embodiment is a fixed value λ3 in the transition region d3; wherein, 50%≥λ1>λ3>λ2.

[0067] Specifically, in this embodiment, the ratio of the transition area d3 between the first area d1 and the second area d2 is also to form the transition area d3 due to the different starting positions of the arc surface 111, so as to avoid a sudden change in the starting positions of the arc surface 111 of the first area d1 and the second area d2, which may cause a sudden change in the performance of the piston ring 100, and further cause a sudden change in the amount of lubricating oil entering the lower surface 110 of the piston ring 100, thereby ultimately causing unstable operation of the piston ring 100.

[0068] Of course, as a specific embodiment, the transition area d3 on one side of the connecting line M of the piston ring 100 of this embodiment can be one or more. When there are multiple transition areas d3, the ratio of each area is a fixed value, and the ratio gradually decreases from the first area d1 to the second area d2, that is, 50% ≥ λ1> λ31> λ32...> λ3n> λ2. Designing multiple transition areas d3 can make the transition between the first area d1 and the second area d2 smoother.

[0069] As a specific embodiment of the present invention, the height h of the connection between the arc surface 111 and the outer peripheral surface 140 in this embodiment is less than or equal to 100 um.

[0070] Specifically, the height of the connection between the arc surface 111 and the outer peripheral surface 140 in this embodiment has a great relationship with the pressure between the lower surface 110 and the contact surface, and the pressure has a great relationship with the wear. Generally speaking, the height of the connection between the arc surface 111 and the outer peripheral surface 140 and the contact surface pressure between the lower surface 110 and the piston ring groove 200 are almost linearly related. The greater the height, the lower the contact surface pressure. On the contrary, the smaller the height, the greater the contact surface pressure.

[0071] In this embodiment, the height h of the connection between the arc surface 111 and the outer peripheral surface 140 is designed. When the height h is too low, the lubricating oil cannot enter between the lower surface 110 and the piston ring groove 200, so that lubrication cannot be performed well, resulting in dry friction between the piston ring 100 and the piston ring groove 200, and the piston ring 100 is also worn. If the height h is too high, too much lubricating oil will enter, which will eventually lead to poor sealing performance. In this embodiment, the height of the connection between the arc surface 111 and the outer peripheral surface 140 cannot be higher than 100um to achieve a balance between wear and lubrication, further reducing wear.

[0072] As a specific embodiment of the present invention, the height h of the connection between the arc surface 111 and the outer peripheral surface 140 of this embodiment gradually decreases from the position of the opening 120 to the position opposite to the position of the opening 120.

[0073] Specifically, since it is difficult for the lubricating oil of the piston ring 100 to enter between the lower side surface and the piston ring groove 200 near the opening 120, the piston ring 100 is worn more near the opening 120, so better lubrication is needed to balance the wear. In this embodiment, the height of the connection between the arc surface 111 and the outer peripheral surface 140 from the opening 120 to the position opposite to the opening 120 is gradually reduced, so that the lubricating oil can more easily enter between the lower surface 110 and the piston ring groove 200 at the opening 120, reducing the wear at the opening 120, so that the wear at different positions of the entire piston ring 100 is uniform and small.

[0074] As a specific embodiment of the present invention, the height of the connection between the arc surface 111 and the outer peripheral surface 140 in the first area d1 is a fixed value h1; the height of the connection between the arc surface 111 and the outer peripheral surface 140 in the second area d2 is a fixed value h2; wherein 100μm≥h1>h2.

[0075] Specifically, the height of the connection between the arc surface 111 and the outer peripheral surface 140 in the first area d1 and the second area d2 of the present embodiment is a fixed value, which can reduce the difficulty of processing the piston ring 100. In addition, the height of the connection between the arc surface 111 and the outer peripheral surface 140 in the first area d1 is greater than that in the second area d2, which can make it easier for lubricating oil to enter the first area d1, thereby ensuring that the wear of the first area d1 is reduced, so that the wear of the first area d1 and the second area d2 are not much different, and both are small.

[0076] As a specific embodiment of the present invention, the height of the connection between the arc surface 111 and the outer peripheral surface 140 in the transition area d3 of this embodiment is a fixed value h3; wherein, 100 μm ≥ h1> h3> h2.

[0077] Specifically, the height of the arc surface 111 in the transition area d3 of the present embodiment is also a fixed value, and 100μm≥h1>h3>h2, ensuring a smooth transition of the height h of the arc surface 111 in the transition area d3 from the first area d1 to the second area d2, thereby avoiding sudden changes in the height h in different areas that may cause unstable performance of the piston ring 100.

[0078] Specifically, the transition area d3 of this embodiment can be one or more transition areas d3. When there are multiple transition areas d3, the height h of the connection between the arc surface 111 and the outer peripheral surface 140 of each transition area d3 is a fixed value, and the height h of the transition area d3 from the first area d1 to the second area d2 gradually decreases, that is, 100μm≥h1>h31>h32>……>h31>h2, so that the height h of different areas of the piston ring 100 transitions more smoothly.

[0079] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A piston ring, characterized in that: The piston ring has an opening and a position opposite to the opening. The lower surface of the piston ring is an inclined surface inclined relative to a plane perpendicular to the axis of the piston ring. On the plane where the axis of the piston ring is located, the inclination angle of the inclined surface at the opening position is smaller than the inclination angle of the inclined surface at the position opposite to the opening.

2. The piston ring according to claim 1, characterized in that: The piston rings are symmetrically arranged on both sides of a line from the opening to a position opposite to the opening; The lower surface includes, on both sides of the connecting line, first areas located on both sides of the opening and second areas located on both sides of a position opposite to the opening; The inclination angle of the first area is a fixed value α1; The inclination angle of the second area is a fixed value α2; Among them, α1<α2.

3. The piston ring according to claim 2, characterized in that: The angle of the arc where the first area is located is less than or equal to 30°.

4. The piston ring according to claim 2, characterized in that: The lower surface also includes at least one transition area on both sides of the connecting line, the at least one transition area is located between the first area and the second area, and the inclination angle of the inclined surface of the at least one transition area is a fixed value α3; wherein α1<α3<α2.

5. The piston ring according to claim 4, characterized in that: There are multiple transition areas, and the inclination angle of each transition area is a fixed value α3n, wherein α1<α3n<α2; the inclination angle of the transition area from the first area to the second area gradually increases, that is, α31<α32……<α3n.

6. The piston ring according to claim 1, characterized in that The lower surface of the piston ring is formed into an arc-shaped surface at a position close to the outer peripheral surface.

7. The piston ring according to claim 6, characterized in that The ratio of the distance between the starting position of the arc-shaped surface and the outer peripheral surface to the width of the lower surface is less than or equal to 50%; The ratio gradually decreases from the opening position to a position opposite to the opening.

8. The piston ring according to claim 7, characterized in that The piston ring is symmetrically arranged on both sides of a line from the opening position to a position opposite to the opening; The lower surface includes a first area located on the side of the opening and a second area located on the side opposite to the opening on both sides of the connecting line; The ratio is a fixed value λ1 in the first region; The ratio is a fixed value λ2 in the second region; Among them, 50%≥λ1>λ2.

9. The piston ring according to claim 8, characterized in that The lower surface further includes at least one transition region on both sides of the connecting line, wherein the at least one transition region is located between the first region and the second region, and the ratio is a fixed value λ3 in the transition region; wherein 50% ≥ λ1>λ3>λ2.

10. The piston ring according to claim 9, characterized in that The height of the connection between the arc surface and the outer peripheral surface is less than or equal to 100um; The height of the connection between the arc surface and the outer peripheral surface gradually decreases from the opening position to a position opposite to the opening position.

11. The piston ring according to claim 10, characterized in that The height of the connection between the arc surface and the outer peripheral surface in the first area is a fixed value h1; The height of the connection between the arc surface and the outer peripheral surface is a fixed value h2 in the second area; Among them, 100um≥h1>h2.

12. The piston ring according to claim 11, characterized in that The height of the connection between the arc surface and the outer peripheral surface in the transition area is a fixed value h3; wherein 100um≥h1>h3>h2.

Images