Low-friction wear-resistant two-stroke engine cylinder bore mirror honing structure

Abstract

The utility model relates to an engine technical field, especially a low friction wear -resisting two -stroke engine cylinder hole mirror honing structure, including cylinder base body, the cylinder bore inner wall of cylinder base body is combined with superhard wear -resistant plating layer, superhard wear -resistant plating layer has the microcosmic oil storage texture formed by mirror level honing treatment, the utility model has the advantages that by the arithmetic average roughness Ra value of cylinder bore inner wall is controlled below 0.1mu m (preferably 0.06mu m~0.1mu m), reached " mirror level " smoothness, greatly reduced the running friction resistance of piston ring assembly, effectively reduced the mechanical loss, thereby directly improved the power output efficiency and fuel economy of engine, adopt the superhard wear -resistant plating layer (such as hard chromium plating layer) of vickers hardness up to HV 900-1000, and combined 30-40mu m's optimization thickness, endows the cylinder bore surface with very high abrasive wear and adhesion wear and tear ability, significantly prolonged the overhaul period and service life of cylinder even entire engine.

Description

Technical Field

[0001] This utility model relates to the field of engine technology, and in particular to a low-friction, wear-resistant two-stroke engine cylinder bore mirror honing structure. Background Technology

[0002] Two-stroke engines are widely used in small general-purpose machinery, motorcycles, models, and certain special vehicles due to their simple structure, high power output per liter, and high thrust-to-weight ratio. However, their inherent lubrication conditions are not as ideal as those of four-stroke engines, resulting in particularly prominent friction and wear problems in the cylinder, piston, and piston ring assemblies. This directly restricts further improvements in their reliability, lifespan, and performance.

[0003] Traditional two-stroke engine cylinder treatment solutions are mainly divided into two categories: one is to use cast iron cylinder liners, and the other is to apply a coating to the aluminum alloy cylinder block. The above two technologies have the following defects: (1) the surface roughness is not optimized to the ultra-low friction "mirror" level, resulting in high friction and oil consumption; (2) the hardness and thickness of the coating are overemphasized, without systematically co-designing it with the microstructure of the substrate that can provide the best oil film carrying capacity; (3) the key geometric accuracy (roundness, taper) of the cylinder bore is not strictly controlled, which affects the long-term stability and performance output of the engine. Therefore, there is an urgent need in this field for an innovative cylinder bore surface structure solution that can combine the wear resistance of the coating with the friction reduction of mirror-level low roughness, and comprehensively improve the performance and life of the two-stroke engine under the guarantee of extremely high geometric accuracy.

[0004] To address this issue, this utility model proposes a low-friction, wear-resistant cylinder bore mirror honing structure for a two-stroke engine, thus providing a solution. Utility Model Content

[0005] The purpose of this invention is to at least solve one of the aforementioned technical defects.

[0006] Therefore, one objective of this utility model is to propose a low-friction, wear-resistant cylinder bore mirror honing structure for a two-stroke engine, in order to solve the problems mentioned in the background art and overcome the shortcomings of the existing technology.

[0007] To achieve the above objectives, one embodiment of the present invention provides a low-friction, wear-resistant two-stroke engine cylinder bore mirror honing structure, including a cylinder substrate, wherein an ultra-hard wear-resistant coating is bonded to the inner wall of the cylinder bore of the cylinder substrate, and the ultra-hard wear-resistant coating has microscopic oil-retaining textures formed by mirror-level honing treatment.

[0008] Preferably, the Vickers hardness of the superhard wear-resistant coating is HV 900-1000, and the thickness is 30-40μm; the arithmetic mean roughness Ra value of the inner wall of the cylinder bore is not greater than 0.1μm, the roundness error is not greater than 0.006mm, and a positive taper is required throughout the entire length.

[0009] Preferably, the ultra-hard wear-resistant coating is a hard chrome coating, which is one of the above-mentioned solutions.

[0010] Preferably, the arithmetic mean roughness Ra of the inner wall of the cylinder bore is 0.06 μm to 0.1 μm, which is one of the above-mentioned solutions.

[0011] Preferably, in any of the above schemes, the microscopic oil-storing texture is a cross-laid structure with a cross-laid angle θ of 40° to 60°.

[0012] Preferably, the thickness of the ultra-hard wear-resistant coating is 30 μm to 40 μm, which is one of the above-mentioned solutions.

[0013] Preferably, the Vickers hardness of the superhard wear-resistant coating is HV 900-1000, which is one of the above-mentioned options.

[0014] Preferably, as described in any of the above embodiments, a first flange and a second flange are fixedly provided on the outer wall of the cylinder base.

[0015] Compared with the prior art, the advantages and beneficial effects of this utility model are as follows: 1. By controlling the arithmetic mean roughness Ra value of the cylinder bore inner wall to below 0.1μm (preferably 0.06μm~0.1μm), a "mirror-level" smoothness is achieved, which greatly reduces the operating friction resistance of the piston ring assembly, effectively reduces mechanical losses, and thus directly improves the engine's power output efficiency and fuel economy.

[0016] 2. It adopts an ultra-hard wear-resistant coating with a Vickers hardness of up to HV 900-1000 (such as hard chrome plating) and an optimized thickness of 30-40μm, which gives the cylinder bore surface extremely high resistance to abrasive wear and adhesive wear, significantly extending the overhaul cycle and service life of the cylinder and even the entire engine.

[0017] 3. The specific cross-hatching structure (hatching angle 40°-60°) formed by mirror honing creates a uniform and moderate microscopic oil-retaining texture. This structure can effectively retain lubricating oil on the cylinder bore surface, ensuring the formation of a continuous and stable oil film even under harsh lubrication conditions, avoiding dry friction, and is particularly suitable for two-stroke engines with inherently insufficient lubrication conditions.

[0018] 4. Strict control of cylinder bore roundness error (≤0.006mm) and requirement for full-length positive taper ensure that the piston rings and cylinder wall are always in optimal fit. This reduces air leakage, ensures stable compression pressure, which not only promotes smooth and efficient engine operation but also effectively controls oil consumption and exhaust emissions.

[0019] 5. The special flange structure set outside the cylinder block (the longitudinal and transverse extension lines of the first and second flanges are perpendicular) enhances the rigidity and deformation resistance of the cylinder block, ensuring that the key geometric accuracy of the cylinder bore is maintained under high load conditions, and further improving the reliability of the engine.

[0020] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a three-dimensional schematic diagram of the cylinder block according to an embodiment of the present utility model; Figure 2 This is an axial sectional view of the cylinder block according to an embodiment of the present utility model; Figure 3 According to the embodiments of this utility model Figure 2 A magnified view of a portion of region A in the middle; Figure 4 This is a schematic diagram of the microstructure of a mirror-honed surface according to an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the cylinder bore roundness and taper requirements according to an embodiment of the present invention.

[0022] In the diagram: 1. Cylinder base, 2. Mirror-finish cylinder bore, 3. Cylinder bore before plating, 4. Ultra-hard wear-resistant plating. Detailed Implementation

[0023] like Figures 1 to 5 As shown, a low-friction, wear-resistant two-stroke engine cylinder bore mirror honing structure is provided. It includes a cylinder base 1, on which an ultra-hard wear-resistant coating 4 is bonded. The ultra-hard wear-resistant coating 4 has microscopic oil-retaining textures formed by mirror-level honing.

[0024] Furthermore, the Vickers hardness of the superhard wear-resistant coating 4 is HV 900-1000, and the thickness is 30-40μm; the arithmetic mean roughness Ra value of the inner wall of the cylinder bore is not greater than 0.1μm, the roundness error is not greater than 0.006mm, and a positive taper is required throughout the entire length.

[0025] Furthermore, the ultra-hard wear-resistant coating 4 is a hard chrome coating.

[0026] Furthermore, the arithmetic mean roughness Ra value of the inner wall of the cylinder bore is 0.06 μm to 0.1 μm.

[0027] Furthermore, the microscopic oil-storing texture is a cross-laid structure with a cross-laid angle θ of 40° to 60°.

[0028] Furthermore, the thickness of the ultra-hard wear-resistant coating 4 is 30 μm to 40 μm.

[0029] Furthermore, the Vickers hardness of the ultra-hard wear-resistant coating 4 is HV 900-1000.

[0030] Furthermore, a first flange and a second flange are fixedly provided on the outer wall of the cylinder base. The longitudinal extension line of the first flange and the transverse extension line of the second flange are arranged perpendicularly to provide good resistance to deformation of the cylinder base and enhance the overall rigidity and strength.

[0031] This utility model provides a low-friction, wear-resistant, two-stroke engine cylinder bore mirror honing structure, the preparation method of which includes the following steps: S1. Cylinder base preparation: An aluminum alloy cylinder block blank is provided, with the cylinder bore machined to near the final size, leaving machining allowance for subsequent plating and honing. The cylinder block is then subjected to routine cleaning and degreasing to ensure the surface is free of contaminants. Alkaline solution ultrasonic cleaning is then performed to thoroughly remove oil and particles. Acid pickling activation is then performed to remove the extremely thin oxide layer on the surface, exposing fresh aluminum grains. Finally, the cylinder block is rinsed with running water and dried to ensure the surface is absolutely clean and free of any contamination. This step is crucial for ensuring the bonding strength between the plating and the substrate.

[0032] S2. Coated with an ultra-hard wear-resistant layer: An ultra-hard wear-resistant coating was prepared on an activated mirror substrate using electrochemical deposition technology. The coating was electroplated hard chromium with a thickness controlled between 90 and 120 μm and a Vickers hardness between 900 and 1000.

[0033] S3. Coarse honing: The cylinder bore is rough-honed using a resin-bonded diamond honing rod. The main purpose is to remove machining marks, correct the geometry, and initially obtain the desired cross-hatching pattern. In this example, a honing rod with a mesh size of 80-120 is selected, the honing head speed is 200-300 rpm, the reciprocating speed is 15-25 m / min, and the honing cross angle is approximately 50°-70°. After this step, the surface roughness Ra value is controlled at 1.0-1.5 μm.

[0034] S4. Semi-fine honing: In this step, a 220-240 mesh honing bar is used, with a higher rotation speed (250-400 rpm) and a lower reciprocating speed (10-20 m / min) to produce a finer, shallower texture and remove the microscopic peaks generated after coarse honing. The honing cross angle is adjusted to 40°-60°. After this step, the surface roughness Ra value is significantly reduced to 0.3-0.6 μm, laying the foundation for the next step of mirror honing.

[0035] S5. Fine honing (mirror honing): This is the core step in obtaining the final surface morphology of the substrate. A 600-mesh honing bar is used, and the machining is carried out with a high rotation speed (300-500 rpm), a low reciprocating speed (5-15 m / min), and a low honing pressure. The purpose of this step is no longer cutting, but polishing and smoothing the surface. After this step, the inner wall surface of the cylinder bore achieves a mirror-like finish, and its arithmetic mean roughness Ra value is no greater than 0.1 μm.

[0036] S6. Geometric precision control (throughout the entire process): This invention places particular emphasis on controlling the final geometric accuracy of the cylinder bore. During honing (especially steps S4 and S5), a high-precision online pneumatic gauge or CNC honing machine is required for real-time feedback and compensation. The roundness error of the cylinder bore on any cross-section should be ≤ 0.006 mm, and the cylinder bore should be a positive taper throughout its entire length.

[0037] This level of geometric precision ensures a uniform fit between the piston rings and the cylinder wall, preventing localized wear and blow-by.

[0038] S7. Post-processing and inspection: After the cylinder bore has been honed, it is necessary to clean it. The surface roughness is checked using a white light interferometer or a high-precision surface profiler. The roundness and taper are checked using a high-precision inner diameter pneumatic gauge. The hardness of the coating is checked using a microhardness tester. Qualified products can be assembled and used.

Claims

1. A low-friction, wear-resistant two-stroke engine cylinder bore mirror honing structure, comprising a cylinder base, characterized in that: The cylinder bore inner wall of the cylinder substrate is coated with an ultra-hard wear-resistant coating, which has a microscopic oil-retaining texture formed by mirror-level honing.

2. The low-friction, wear-resistant two-stroke engine cylinder bore mirror honing structure according to claim 1, characterized in that: The Vickers hardness of the superhard wear-resistant coating is HV 900-1000, and the thickness is 30-40μm; the arithmetic mean roughness Ra value of the inner wall of the cylinder bore is not greater than 0.1μm, the roundness error is not greater than 0.006mm, and a positive taper is required throughout the entire length.

3. The low-friction, wear-resistant two-stroke engine cylinder bore mirror honing structure according to claim 1, characterized in that: The ultra-hard wear-resistant coating is a hard chrome coating.

4. The low-friction, wear-resistant two-stroke engine cylinder bore mirror honing structure according to claim 1, characterized in that: The arithmetic mean roughness Ra value of the inner wall of the cylinder bore is 0.06 μm to 0.1 μm.

5. The low-friction, wear-resistant two-stroke engine cylinder bore mirror honing structure according to claim 1, characterized in that: The microscopic oil-storage texture is a cross-laid structure with a cross-laid angle θ of 40° to 60°.

6. The low-friction, wear-resistant two-stroke engine cylinder bore mirror honing structure according to claim 1, characterized in that: The thickness of the ultra-hard wear-resistant coating is 30 μm to 40 μm.

7. The low-friction, wear-resistant two-stroke engine cylinder bore mirror honing structure according to claim 1, characterized in that: The Vickers hardness of the ultra-hard wear-resistant coating is HV 900-1000.

8. The low-friction, wear-resistant two-stroke engine cylinder bore mirror honing structure according to claim 1, characterized in that: The cylinder base is fixedly provided with a first flange and a second flange on its outer wall.

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