Piston rings and internal combustion engines
By designing a piston ring substrate with a specific structure and applying a protective coating, the wear problem of the piston groove in the internal combustion engine was solved, resulting in reduced wear and extended service life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- MAHLE INT GMBH
- Filing Date
- 2024-09-24
- Publication Date
- 2026-06-30
AI Technical Summary
The wear mechanisms caused by conventional piston rings in the piston groove of internal combustion engines are known to include stepped wear, flared wear, and planar wear. Existing technologies that improve the strength of piston groove materials are costly and difficult to implement.
Design a piston ring with a ring-shaped substrate having a specific structured interrupted facet and chamfer, and coat the substrate with a protective coating, including a DLC coating or a ceramic material, to reduce wear.
It significantly reduces piston groove wear, improves piston ring service life and anti-seize properties, reduces the coefficient of friction, and enhances sliding performance.
Smart Images
Figure CN119687194B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a piston ring for an internal combustion engine, and an internal combustion engine having such a piston ring. Background Technology
[0002] The known wear mechanisms caused by conventional piston rings in the piston grooves of internal combustion engines include stepped wear, flared wear, and planar wear.
[0003] One well-known solution to reduce this type of wear is to increase the strength of the piston groove material, for example, by laser hardening the piston. However, this has proven to be a very expensive and difficult-to-implement solution. Summary of the Invention
[0004] Therefore, the object of the present invention is to provide an improved piston ring that can reduce wear in the piston groove that houses the piston ring.
[0005] This objective is achieved through the subject matter of this invention. Preferred embodiments are the subject matter of the technical solution of this invention.
[0006] The piston ring for an internal combustion engine according to the invention comprises an annular base having a central longitudinal axis extending axially, and the annular base extending circumferentially around the central longitudinal axis in a direction perpendicular to the axial direction. The base has a circumferentially interrupted structure forming a joining structure. The interrupted structure or joining structure is defined circumferentially by a first and a second joining side of the base. An end face of the base, axially oriented relative to the axial direction, surrounds a radially outer surface portion extending perpendicular to the central longitudinal axis. This surface portion merges radially into a radially inner surface portion. This radially inner surface portion is arranged at an obtuse angle to the central longitudinal axis. According to the invention, the radially measured extension of the radially outer surface portion is a maximum of 0.3 mm. Such a maximum extension significantly reduces wear on the piston grooves.
[0007] Furthermore, the (first) edge formed between the first mating side and the end face has a (first) chamfer, the (first) chamfer having an axial extension dimension of at most 0.16 mm, preferably about 0.06 mm, measured axially. Additionally, the (first) chamfer has a circumferential extension dimension of at most 0.16 mm, preferably about 0.05 mm. This edge design further reduces piston groove wear. Furthermore, a protective coating is arranged on the outer periphery of the annular substrate.
[0008] Preferably, the substrate can be stainless steel, and the substrate can contain 10-17% chromium.
[0009] In a preferred embodiment, the (second) edge formed between the second mating side and the axial end face has a second chamfer, the second chamfer having an axial extension dimension of at most 0.16 mm, preferably about 0.06 mm, measured axially, and an extension dimension of at most 0.16 mm, preferably about 0.05 mm, measured circumferentially.
[0010] According to another preferred embodiment, to reduce adhesive wear, i.e., material transfer from the piston groove material to the underside of the piston ring, an additional protective coating made of polymer, Cr electroplating, or DLC film is disposed on the axial end face of the annular substrate of the piston ring. The coating material may include a polymer or consist of such a polymer, metallic chromium, or a carbon-based film. Polymer-based coating materials may contain WC (tungsten carbide) particles.
[0011] Particularly advantageous is that the protective coating includes or is a DLC coating. This DLC coating not only possesses very high hardness but also an exceptionally low coefficient of friction, which is particularly beneficial for piston rings in internal combustion engines, for example, by improving anti-seize properties. Particularly preferably, more than 50% of the bonds formed in the amorphous carbon of the DLC protective coating are sp2 hybrid bonds. These provide favorable sliding properties for the sliding element. Alternatively or additionally, in this variant, 20% to 45% of the bonds formed in the amorphous carbon of the DLC protective coating are sp3 bonds. Since the mechanical properties of sp3 bonds determine the highest wear resistance of the DLC protective coating, this selected proportion of bond type ensures the high hardness and excellent low-friction characteristics of the DLC protective coating.
[0012] In another preferred embodiment, the coating material of the protective coating may include or be composed of ceramic materials, particularly nitride-based PVD ceramic coatings. The coating material may be, for example, PVD chromium nitride (CrN), chromium aluminum nitride (CrAlN), chromium aluminum nitride multilayer (CrAlN / CrAlN), chromium nitride and niobium nitride multilayer (NbN / CrN), or diamond-like carbon (DLC) films, with the aim of improving wear resistance and extending the service life of the piston rings.
[0013] With further advantageous improvements, an adhesion-promoting layer containing or composed of chromium (Cr) can be sandwiched between the protective coating and the substrate. This can significantly improve the adhesion between the protective coating and the piston ring substrate.
[0014] Of particular advantage is that the thickness of the additional protective coating can be between 5 μm and 40 μm, preferably between 15 μm and 30 μm.
[0015] According to a further advantageous improvement, the axial end face has two textured portions that extend circumferentially from the center position of the joint structure relative to the circumference by a maximum 35°, preferably about 25°.
[0016] In this further improvement, the end face has a texture in each of the two textured sections. This texture provides additional protection against wear to the area around the engagement structure of the piston rings, which are subjected to particularly high mechanical loads when used in internal combustion engines.
[0017] Particularly preferably, each of the two textures can be formed by multiple grooves, which are preferably arranged in a grid pattern on the surface of the end face, preferably having a rounded shape, and particularly preferably having a circular geometry. Textures formed in this way can be produced in a particularly simple manner, especially by irradiation with a laser beam.
[0018] In another preferred embodiment, at least one, preferably several, particularly preferably all grooves have a depth perpendicular to the surface that is between 5µm and 20µm, preferably between 8µm and 12µm, and preferably about 10µm. In this embodiment, at least one, preferably several, particularly preferably all grooves have a groove diameter that is between 30µm and 90µm, preferably between 50µm and 70µm, and preferably about 60µm.
[0019] A particularly advantageous feature is that the proportion of the surface covered by the grooves in the two textured sections can be between 15% and 35%.
[0020] The present invention also relates to an internal combustion engine for a motor vehicle, the internal combustion engine having at least one cylinder surrounding a combustion chamber, in which a piston is adjustably arranged. At least one annular groove is formed on the outer periphery of the piston, in which the piston ring according to the invention can be partially arranged or partially received, such that the piston ring is supported on both the cylinder and the piston. Therefore, the advantages of the piston ring according to the invention are transferred to the internal combustion engine according to the invention. The axial end face of the piston ring in the at least one annular groove is axially opposite to the combustion chamber.
[0021] In a preferred embodiment of the internal combustion engine according to the present invention, a first annular groove, a second annular groove, and a third annular groove are axially spaced on the outer periphery of the piston. The first annular groove is axially oriented towards the combustion chamber, and the second annular groove is axially arranged between the first and third annular grooves. The piston rings according to the present invention are arranged in the first annular groove.
[0022] Other important features and advantages of the present invention will become apparent from the technical solutions, the accompanying drawings, and the description of the drawings with reference to the drawings.
[0023] It should be understood that the above features, as well as the features that will still be explained below, can be used not only in the combinations indicated in each case, but also in other combinations or individually, without departing from the scope of the invention. Attached Figure Description
[0024] Examples of preferred embodiments of the invention are shown in the accompanying drawings and explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical parts.
[0025] The attached diagram schematically illustrates:
[0026] Figure 1 An axial plan view of an example piston ring according to the present invention is shown.
[0027] Figure 2 It shows Figure 1 A partial perspective view of the piston rings in the image.
[0028] Figure 3a , 3b Plan views of the outer periphery 11 of the piston ring along the radial direction R in the regions of the first and second mating sides of the mating structure are shown respectively.
[0029] Figure 4 A rough schematic diagram of the surface texture of the two side regions of the joint structure is shown.
[0030] Figure 5 An axial longitudinal sectional view of an example of an internal combustion engine according to the invention, having piston rings according to the invention, is shown. Detailed Implementation
[0031] Figure 1 A simplified top view along the axial direction A is shown for an example of a piston ring 1 for an internal combustion engine according to the present invention. Figure 2 yes Figure 1 A partial perspective view of the piston rings.
[0032] according to Figure 1 and Figure 2 The piston ring 1 includes an annular base 2 having a central longitudinal axis M extending along an axial direction A, and the annular base also extending circumferentially around the central longitudinal axis M in a direction U perpendicular to the axial direction A. Furthermore, a radial direction R extends perpendicular to the axial direction A and is orthogonally perpendicular to the circumferential direction U away from the central longitudinal axis M.
[0033] The substrate of the substrate 2 can be stainless steel, and the chromium content in the substrate can be 10% to 17%.
[0034] according to Figure 1The substrate 2 has an interruption structure 4 along the circumferential direction U that forms the joining structure 3. The interruption structure or joining structure 3 is defined along the circumferential direction U by the first joining side surface 5a and the second joining side surface 5b of the substrate 2.
[0035] from Figure 2 As can be seen in the perspective view, the end face 6 of the substrate 2 is axially oriented relative to the axis A, and the end face 6 includes a radially outer surface portion 7 extending perpendicular to the central longitudinal axis M. The radially outer surface portion 7 merges radially inward along the radial direction R of the substrate 2 into a radially inner surface portion 8. The radially inner surface portion 8 is arranged at an obtuse angle α relative to the central longitudinal axis M. Therefore, the radially outer surface portion 7 and the radially inner surface portion 8 are arranged at an obtuse angle θ to each other. According to the present invention, the maximum extension dimension r1 of the radially outer surface portion 7, measured along the radial direction R, is 0.3 mm.
[0036] Figure 3a and 3b A top view of the outer periphery 11 of the substrate 2 in the region of the first joint side 5a and the second joint side 5b is shown along the radial direction R.
[0037] Therefore, it is formed on the first joint side 5a (as shown in the image). Figure 3a The first edge 12a between the first chamfer (shown) and the end face 6 has a first chamfer 9a, the axial extension dimension x1 of the first chamfer, measured axially, is at most 0.16 mm, preferably about 0.06 mm. Furthermore, the extension dimension y1 of the first chamfer 9a, measured circumferentially U, is at most 0.16 mm, preferably about 0.05 mm. Correspondingly, a second mating side surface 5b (see...) is formed... Figure 3b The second edge 12b between the first chamfer 1a and the axial end face has a second chamfer 9b. The axial extension dimension x2 of the second chamfer, measured axially, is at most 0.16 mm, preferably about 0.06 mm, and the radial extension dimension y2 of the second chamfer, measured circumferentially, is at most 0.16 mm, preferably about 0.05 mm. Preferably, the first chamfer 9a and the second chamfer 9b can be as follows: Figure 3a and Figure 3b It is formed in the same way as shown.
[0038] according to Figure 1 , Figure 2 A protective coating 10a is arranged on the outer periphery 11 of the annular substrate 2. The coating material of the protective coating 10a can be a ceramic material. In this example, the protective coating 10a is formed by a DLC layer. A chromium (Cr) adhesion promoting layer 13 can be sandwiched between the protective coating 10a and the substrate 2.
[0039] An additional protective coating 10b is provided on the axial end face 6 of the annular substrate 2. The coating material of the additional protective coating includes polymer, chromium (Cr) plating, or DLC film. The thickness of the additional protective coating 10b can be between 5 μm and 40 μm, preferably between 15 μm and 25 μm. When the piston ring 1 in the internal combustion engine is working, the axial end face 6 can be the lower surface facing away from the combustion chamber.
[0040] In addition, such as Figure 1 As shown, the axial end face 6 may have two textured portions 14a and 14b, which respectively begin from the first joint side 5a and the second joint side 5b and extend along the circumferential direction U with circumferential angles β1 and β2 of up to 35°, preferably about 25°, said circumferential angles β1 and β2 starting from the center position 3.1 of the joint structure 3 relative to the circumferential direction U (see...). Figure 1 ).
[0041] The two textured parts 14a and 14b have Figure 4 The textures 15a and 15b are roughly reproduced. Figure 4 Each of the two textures 15a and 15b is formed by multiple grooves 16, which are arranged in a grid pattern on the surface of the end face 6 and have annular or circular geometry, such as... Figure 4 As shown. The surface proportions of the two textured portions 14a and 14b covered by the groove 16 can both be between 15% and 30%. Figure 4 (Not shown in the image). The groove diameter D of each groove is between 30 μm and 90 μm, preferably between 50 μm and 70 μm, and particularly preferably about 60 μm. Independently, the depth of each groove 16, measured perpendicular to the surface, is between 5 μm and 20 μm, preferably between 8 μm and 12 μm, and preferably about 10 μm.
[0042] Figure 5 The application of the aforementioned piston ring 1 in an internal combustion engine 20 is illustrated. The internal combustion engine 20 includes a cylinder 21 surrounding a combustion chamber 22, and... Figure 5 The diagram shows a partial longitudinal cross-sectional view of the internal combustion engine along axis A. The combustion chamber 22 includes cylindrical piston rings 1. A cylindrical piston 23 is arranged in the combustion chamber 22 and is adjustable along axis A. Three annular grooves 25a, 25b, and 25c are axially spaced on the outer periphery 24 of the piston 23. The first annular groove 25a of the three annular grooves 25a-25c is axially oriented towards the combustion chamber 22. The third annular groove 25c of the three annular grooves 25a-25c is axially opposite to the combustion chamber 22. Therefore, the second annular groove 25b of the three annular grooves 25a-25c is axially arranged between the first annular groove 25a and the third annular groove 25c.
[0043] like Figure 5As shown, each of the three annular grooves 25a, 25b, and 25c can be provided with a corresponding piston ring 26a, 26b, or 26c, which is radially inwardly supported on the piston 22 and radially outwardly supported on the cylinder 21 of the internal combustion engine.
[0044] The piston ring 26a arranged in the first annular groove 25a is the piston ring 1 according to the invention as described above, which serves as a compression ring. The axial end face 6 of the piston ring 1 is arranged axially away from the combustion chamber 2 in the first annular groove 25a.
Claims
1. A piston ring (1) for an internal combustion engine (20), - The piston ring has an annular base (2) having a central longitudinal axis (M) extending along an axial direction (A), and the annular base extending circumferentially about the central longitudinal axis (M) along a circumferential direction (U) perpendicular to the axial direction (A). The piston ring also has an interruption structure (4) along the circumferential direction (U) forming a joining structure (3), the joining structure being defined along the circumferential direction (U) by a first joining side (5a) and a second joining side (5b) of the base (2). - in, The axial end face (6) of the substrate (2) includes a radially outer surface portion (7), which extends perpendicularly to the central longitudinal axis (M) and merges radially inward along the radial (R) direction of the substrate (2) into a radially inner surface portion (8), which is arranged at an obtuse angle (α) to the central longitudinal axis (M). - The radial extension dimension (r1) of the radially outer surface portion (7) measured along the radial direction (R) is a maximum of 0.3 mm. - The first edge (12a) formed between the first joining side surface (5a) and the end face (6) has a first chamfer (9a), the axial extension dimension (x1) of the first chamfer (9a) measured along the axial direction (A) being a maximum of 0.16 mm, and the extension dimension (y1) measured along the circumferential direction (U) being a maximum of 0.16 mm. - A protective coating (10a) is arranged on the outer periphery (11) of the annular substrate (2).
2. The piston ring according to claim 1, Its features The second edge (12b) formed between the second joint side surface (5b) and the end face has a second chamfer (9b), the axial extension dimension (x2) of the second chamfer measured along the axial direction is a maximum of 0.16 mm, and the circumferential extension dimension (y2) of the second chamfer measured along the circumferential direction (U) is a maximum of 0.16 mm.
3. The piston ring according to claim 1 or 2, Its features The protective coating (10a) is made of ceramic material or is composed of ceramic material.
4. The piston ring according to claim 1 or 2, Its features are, The protective coating (10a) includes a nitrided PVD ceramic coating or a nitrided PVD ceramic coating, or includes a DLC layer or a DLC layer.
5. The piston ring according to claim 1 or 2, Its features An additional protective coating (10b) is disposed on the axial end face (6) of the annular substrate (2), the additional protective coating comprising a polymer as a coating material, or the coating material of the additional protective coating comprising a polymer, Cr electroplating or DLC film.
6. The piston ring according to claim 1 or 2, Its features An adhesion promoting layer (13) is sandwiched between the protective coating (10a) and the substrate (2), the adhesion promoting layer (13) containing chromium (Cr) or composed of chromium (Cr).
7. The piston ring according to claim 1 or 2, Its features The thickness of the additional protective coating (10b) is between 5 μm and 40 μm.
8. The piston ring according to claim 1 or 2, Its features - The axial end face (6) has two textured portions (14a, 14b), which are respectively extended from the center position (3.1) of the joint structure (3) relative to the circumferential direction (U) by a circumferential angle (β1, β2) of up to 35°. - The axial end face (6) has texture (15a, 15b) in each of the two textured portions (14a, 14b).
9. The piston ring according to claim 8, Its features Each of the two textured portions (14a, 14b) is formed by a plurality of grooves (15) having a rounded geometry and arranged in a grid pattern on the surface of the axial end face (6).
10. The piston ring according to claim 9, Its features - The depth of at least one groove (15), measured perpendicular to the surface, is between 5 μm and 20 μm, and / or - The groove diameter (D) of at least one groove (15) is between 30 μm and 90 μm.
11. The piston ring according to claim 9 or 10, Its features The proportion of the surface area of the two textured portions (14a, 14b) covered by the groove (15) is between 15% and 35%.
12. The piston ring according to claim 1, Its features The piston ring (1) is a compression ring, and the axial extension dimension (x1) of the first chamfer (9a) measured along the axial direction (A) is 0.06 mm, and the extension dimension (y1) measured along the circumferential direction (U) is 0.05 mm.
13. The piston ring according to claim 2, Its features The axial extension dimension (x2) of the second chamfer, measured along the axial direction, is 0.06 mm, and the circumferential extension dimension (y2) of the second chamfer, measured along the circumferential direction (U), is 0.05 mm.
14. The piston ring according to claim 7, Its features The thickness of the additional protective coating (10b) is between 15 μm and 30 μm.
15. The piston ring according to claim 8, Its features The circumferential angle (β1, β2) is 25°.
16. The piston ring according to claim 9, Its features The groove (15) has a circular geometry.
17. The piston ring according to claim 10, Its features - The depth of the plurality of grooves (15) measured perpendicular to the surface is between 8 μm and 12 μm, and / or - The groove diameter (D) of the multiple grooves (15) is between 50 μm and 70 μm.
18. The piston ring according to claim 17, Its features - The depth of all grooves (15) measured perpendicular to the surface is 10 μm, and / or - The groove diameter (D) of all grooves (15) is 60 μm.
19. An internal combustion engine for motor vehicles (20). - The internal combustion engine has at least one cylinder (21) surrounding a combustion chamber (22), and a piston (23) is movably arranged in the combustion chamber. - in, At least one annular groove (25a, 25b, 25c) is formed on the outer periphery (24) of the piston (23), and a piston ring (1) according to any of the preceding claims is partially arranged in the annular groove (25a, 25b, 25c) so that the piston ring is supported on both the cylinder (21) and the piston (23). - The axial end face (6) of the piston ring (1) is arranged in at least one annular groove (25a, 25b, 25c) and is axially away from the combustion chamber (22).
20. The internal combustion engine according to claim 19, Its features - On the outer periphery (24) of the piston (23), a first annular groove (25a), a second annular groove (25b), and a third annular groove (25c) are arranged axially spaced from each other. The first annular groove (25a) is axially oriented toward the combustion chamber (22), and the second annular groove (25b) is axially arranged between the first annular groove (25a) and the third annular groove (25c). - wherein the piston ring (1) according to any one of claims 1 to 18 is arranged at least in the first annular groove (25a).
21. The internal combustion engine according to claim 20, Its features The piston ring (1) is arranged in the first annular groove (25a) and the second annular groove (25b).