Forced lubrication structure of two-stroke air cylinder body

Abstract

A piston matched with the air cylinder body is at least provided with two piston rings and comprises an air cylinder body lubricating oil channel, and the air cylinder body lubricating oil channel obliquely extends to an air cylinder hole wall in the air cylinder body from the outer side wall of the air cylinder body and penetrates through the air cylinder hole wall to form a first notch. The first notch is configured to be matched with the position, away from a combustion chamber, of the piston ring when the piston is located at the lower dead center, so that engine oil entering through the cylinder body lubricating oil channel can reach the piston ring, and the effect of lubricating the cylinder hole is achieved. Directional lubrication of a friction pair is achieved, the problems that in a traditional lubrication mode, engine oil is distributed dispersedly, and coverage of an effective lubrication area is insufficient are solved, engine oil conveyed in a directional mode can rapidly form a stable oil film on a cylinder hole wall, dry friction and boundary friction between a piston ring and the cylinder wall are remarkably reduced, and the service life of the piston ring is prolonged. And faults such as cylinder scoring and scratching are reduced from the source.

Description

Technical Field

[0001] This invention relates to the field of two-stroke heavy oil small piston engine technology, and in particular to a forced lubrication structure for a two-stroke cylinder block. Background Technology

[0002] In existing technologies, two-stroke heavy-oil small piston engines possess irreplaceable application advantages in scenarios such as small drones, portable special power units, and micro emergency power generation equipment due to their combination of high power density, lightweight structure, and heavy-oil fuel economy. These small engines require compact installation space; compared to large two-stroke heavy-oil engines, their internal structure design is more refined, and they must achieve stable power output within a limited volume. To address the issue of high heavy-oil viscosity and insufficient atomization in the combustion chamber of small engines, the industry commonly employs air-assisted injection technology. Through precise mixing and injection of high-pressure air and heavy-oil, fuel atomization is effectively improved, combustion efficiency is enhanced, and the power performance of small engines at low displacement is ensured, meeting the adaptability requirements of small equipment for power systems. However, at the same time, the high relative motion frequency between the piston and cylinder wall in two-stroke heavy-oil small piston engines, along with the concentrated localized high temperatures generated by heavy-oil combustion, places higher demands on the uniformity and timeliness of lubrication system supply. Whether a continuous and stable lubricating oil film can be formed on the cylinder wall directly determines the engine's operational reliability and service life.

[0003] However, existing lubrication systems in small two-stroke heavy-oil piston engines mostly employ splash lubrication or simple pressure lubrication structures. Limited by the compact internal space of these small engines, the design of lubrication channels often suffers from issues such as restricted paths and unreasonable oil outlet positions, making it difficult for the lubricating oil to form a continuous and uniform protective oil film on the cylinder wall. Especially during the piston's reciprocating motion, the bottom dead center area often experiences localized lubrication deficiencies due to untimely or uneven lubrication supply; furthermore, the high temperatures generated by heavy-oil combustion accelerate the deterioration of the lubricating oil in this area, further exacerbating frictional losses between the piston rings and the cylinder wall, easily leading to cylinder scoring failures. Such failures not only interrupt small engine research and development testing and increase development costs, but also severely affect the reliability of small equipment in mission execution, becoming a key bottleneck restricting the technological optimization and industrial application of small two-stroke heavy-oil piston engines.

[0004] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0005] The purpose of this invention is to propose a forced lubrication structure for a two-stroke cylinder block to solve the technical problem of insufficient lubrication in the prior art, which leads to cylinder scoring.

[0006] Therefore, this invention proposes a forced lubrication structure for a two-stroke cylinder block.

[0007] Preferably, the present invention may also have the following technical features:

[0008] A forced lubrication structure for a two-stroke cylinder block, wherein the piston adapted to the cylinder block is provided with at least two piston rings, and includes a cylinder block lubrication oil passage. The cylinder block lubrication oil passage extends obliquely from the outer wall of the cylinder block to the cylinder bore wall inside the cylinder block and penetrates the cylinder bore wall to form a first notch. The first notch is configured such that when the piston is at bottom dead center, the first notch matches the position of the piston ring away from the combustion chamber, so that the oil entering through the cylinder block lubrication oil passage can reach the piston ring to achieve the function of lubricating the cylinder bore.

[0009] Preferably, the piston ring includes a first piston ring and a second piston ring, the second piston ring being located away from the combustion chamber, and the first notch matching the position of the second piston ring.

[0010] Preferably, the piston rings include a first piston ring, a second piston ring, and a third piston ring, wherein the first notch is configured such that when the piston is at bottom dead center, the first notch matches the position of the second or third piston ring.

[0011] Preferably, the piston ring is disposed in the piston ring groove, the width of the first notch is H, and the groove width of the piston ring groove is h, such that h≤H≤1.5h.

[0012] Preferably, it also includes an oil tank, which is located outside the engine housing and stores oil. An oil pump is used to pump the oil to the lubrication passage of the cylinder block.

[0013] Preferably, the oil pump is an electronic oil pump, and the oil supply speed of the electronic oil pump is adjusted by an ECU.

[0014] Preferably, the cylinder block lubrication passage includes a horizontal oil passage and an inclined oil passage. The horizontal oil passage extends from the end face of the cylinder block near the housing towards the side near the cylinder head. The inclined oil passage extends from the end of the horizontal oil passage away from the housing towards the cylinder bore and penetrates the cylinder bore wall to form the first notch. Engine oil can enter from the horizontal oil passage, pass through the inclined oil passage, and finally reach the piston ring away from the combustion chamber from the first notch at the lower end of the inclined oil passage.

[0015] Preferably, the end of the inclined oil passage away from the cylinder bore penetrates the outer wall of the cylinder body, and a plug is provided at the penetration point.

[0016] Preferably, a guide sleeve is provided at one end of the horizontal oil passage near the housing. The guide sleeve has a hollow structure, and part of the guide sleeve is disposed in the cylinder body and part of the housing body.

[0017] Preferably, a sealing gasket is provided on the end face of the cylinder body adjacent to the housing.

[0018] The beneficial effects of this invention compared to the prior art include:

[0019] 1. The cylinder block lubrication passage of the forced lubrication structure of the present invention extends from the outer wall of the cylinder block to the cylinder bore wall inside the cylinder block and penetrates the cylinder bore wall to form a first notch. When the piston is at the bottom dead center, the first notch matches the position of the piston ring away from the combustion chamber, so that the oil entering through the cylinder block lubrication passage can reach the piston ring to achieve the function of lubricating the cylinder bore and realize directional lubrication of the friction pair, avoiding the problems of dispersed oil distribution and insufficient coverage of effective lubrication area in traditional lubrication methods.

[0020] 2. The forced lubrication structure of this invention delivers engine oil in a directional manner, which can quickly form a stable oil film on the cylinder bore wall, significantly reducing dry friction and boundary friction between the piston rings and the cylinder wall. This reduces the occurrence of failures such as cylinder scoring and scratches from the root cause. It is especially suitable for the harsh working conditions of high-frequency reciprocating motion of two-stroke engines. For equipment such as drones that have extremely high requirements for the stability of the power system, this structure can ensure continuous and effective lubrication under complex working conditions such as high altitude and variable load, reducing the risk of engine downtime caused by lubrication failure and extending the continuous operation time and service life of the equipment.

[0021] 3. The width of the first notch in the forced lubrication structure of the present invention is greater than or equal to the width of the piston ring groove, and less than or equal to 1.5 times the width of the piston ring groove. This ensures that the oil delivered through the cylinder block lubrication passage can meet the lubrication requirements of the cylinder bore while avoiding excessive friction between the first notch and the piston due to excessive size. This structure can reduce unnecessary wear on the piston, thereby extending the overall service life of the piston and improving the long-term stability of the engine.

[0022] 4. The segmented design of the horizontal and inclined oil passages in the forced lubrication structure of this invention allows for flexible planning of the oil passage path according to the overall structural characteristics of the cylinder block. This facilitates the extension of the horizontal oil passage from the end face near the housing to adapt to the overall assembly layout of the engine, while also shortening the inclined oil passage path. The inclined oil passages can be precisely guided to the target lubrication area on the cylinder bore wall, and can also effectively avoid interference with other functional structures inside the cylinder block (such as cooling channels, bolt holes, etc.), thereby improving space utilization. Attached Figure Description

[0023] Figure 1 This is a first structural schematic diagram of a specific embodiment of the present invention.

[0024] Figure 2 This is a second structural schematic diagram of a specific embodiment of the present invention.

[0025] Figure 3 This is a specific embodiment of the present invention. Figure 2 A sectional view taken along the MM section.

[0026] Figure 4 This is a schematic diagram of the first oil circuit according to a specific embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of the second oil circuit according to a specific embodiment of the present invention.

[0028] Figure 6 This is a schematic diagram of the third oil circuit in a specific embodiment of the present invention.

[0029] Explanation of reference numerals in the attached drawings: 1-Cylinder block lubrication passage; 101-Horizontal oil passage; 102-Inclined oil passage; 103-First cylinder block lubrication passage; 104-Second cylinder block lubrication passage; 2-Cylinder block; 21-Cylinder bore; 22-Cylinder bore wall; 23-First notch; 24-Exhaust port; 3-Piston; 31-Piston ring groove; 4-Piston ring; 41-First piston ring; 42-Second piston ring; 5-Oil tank; 6-Tank; 61-Tank oil passage; 7-Oil pump; 8-Plug; 9-Guide sleeve; 10-Combustion chamber; 11-Oil filter; 12-Oil inlet; 13-Cylinder head. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to specific embodiments and the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope or application of the present invention.

[0031] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein the same reference numerals denote the same parts unless otherwise specifically stated.

[0032] Example 1:

[0033] A forced lubrication structure for a two-stroke cylinder block 2 includes a piston 3 fitted with at least two piston rings 4. Specifically, the forced lubrication structure includes a cylinder block lubrication passage 1. The lubrication passage 1 extends obliquely from the outer wall of the cylinder block 2 to the cylinder bore wall 22 within the cylinder block 2, penetrating the cylinder bore wall 22 to form a first notch 23. This first notch 23 is configured such that when the piston 3 is at bottom dead center, it matches the position of the piston ring 4 furthest from the combustion chamber 10, allowing the engine oil entering through the cylinder block lubrication passage 1 to reach the piston ring 4, thereby lubricating the cylinder bore 21. This embodiment uses two piston rings 4 as an example. Figures 1-6 As shown, the piston ring 4 includes a first piston ring 41 and a second piston ring 42. The piston ring 4 furthest from the combustion chamber 10 is the second piston ring 42. The first notch 23 is matched with the position of the second piston ring 42. It can be understood that when the engine is working, the piston 3 will reciprocate. When the piston 3 moves to the bottom dead center, the first notch 23 is directly opposite the second piston ring 42. After the piston 3 reaches the bottom dead center, it will move to the top dead center again. Due to the elasticity of the piston ring 4 itself and the thrust of the piston 3, the second piston ring 42 will "lift" the oil on the cylinder bore wall 22 and evenly coat it on the surface of the cylinder bore wall 22, forming a thin and continuous oil film.

[0034] The cylinder block lubrication passage 1 of the aforementioned forced lubrication structure extends from the outer wall of the cylinder block 2 to the cylinder bore wall 22 inside the cylinder block 2 and penetrates the cylinder bore wall 22 to form a first notch 23. When the piston 3 is at the bottom dead center, the first notch 23 matches the position of the piston ring 4 away from the combustion chamber 10, so that the oil entering through the cylinder block lubrication passage 1 can reach the piston ring 4 to achieve the function of lubricating the cylinder bore 21, realize directional lubrication of the friction pair, and avoid the problems of dispersed oil distribution and insufficient coverage of effective lubrication area in traditional lubrication methods. The directional delivery of engine oil can quickly form a stable oil film on the cylinder bore wall 22, significantly reducing dry friction and boundary friction between the piston ring 4 and the cylinder bore wall 22. This reduces the occurrence of failures such as cylinder scoring and scratches from the root cause. It is especially suitable for the harsh working conditions of high-frequency reciprocating motion of two-stroke engines. For equipment such as drones that have extremely high requirements for the stability of the power system, this structure can ensure continuous and effective lubrication under complex working conditions such as high altitude and variable load, reducing the risk of engine downtime caused by lubrication failure and extending the continuous operation time and service life of the equipment.

[0035] Specifically, such as Figure 3 and 6As shown, it also includes an oil tank 5, which is located outside the engine housing 6. The oil tank 5 stores engine oil, and an oil pump 7 draws the engine oil to the cylinder block lubrication passage 1. An oil filter 11 is also installed between the oil tank 5 and the oil pump 7, meaning that the oil filter 11 is upstream of the oil pump 7. The oil filter 11 uses micropores in its filter paper to intercept any impurities (such as metal shavings, carbon deposits, gum, or other external contaminants) that may be mixed in with the engine oil before the oil pump 7. The filtered clean engine oil enters the oil pump 7, which can prevent the gears inside the oil pump 7 from wearing due to impurities, thus extending the life of the oil pump 7, and preventing impurities from entering the cylinder block lubrication passage 1 with the engine oil and scratching the piston rings 4 or the cylinder bore wall 22. This embodiment takes a two-cylinder engine as an example. Figure 5 and 6 As shown, two cylinder block lubrication oil passages 1 are provided, including a first cylinder block lubrication oil passage 103 and a second cylinder block lubrication oil passage 104. Oil from the oil pump 7 enters the cylinder block 2 through the oil inlet 12 and then splits into three oil paths: a first cylinder block lubrication oil path, a second cylinder block lubrication oil path, and a bearing lubrication oil path. The oil from the first and second cylinder block lubrication oil paths leads to the first cylinder block lubrication oil passage 103 and the second cylinder block lubrication oil passage 104, respectively. Specifically, the oil pump 7 is an electronic oil pump, and the ECU adjusts the oil supply speed of the electronic oil pump to ensure that the amount of oil reaching the piston rings 4, which are far from the combustion chamber, is appropriate. Of course, a small amount of excess oil will enter the combustion chamber and be burned directly as the piston 3 reaches top dead center.

[0036] In some examples of this embodiment, the piston ring 4 is disposed in the piston ring groove 31, the width of the first notch 23 is H, and the groove width of the piston ring groove 31 is h, such that h≤H≤1.5h, so that the oil delivered through the cylinder block lubrication passage 1 can meet the lubrication requirements of the cylinder bore 21, and avoid the first notch 23 being too large, which would cause excessive friction with the piston 3. This structure can reduce unnecessary wear on the piston 3, thereby extending the overall service life of the piston 3 and improving the long-term stability of the engine.

[0037] In some examples of this embodiment, such as Figure 3 and 5As shown, the cylinder block lubrication passage 1 includes a horizontal oil passage 101 and an inclined oil passage 102. The horizontal oil passage 101 extends from the end face of the cylinder block 2 near the housing 6 towards the cylinder head 13. The inclined oil passage 102 extends from the end of the horizontal oil passage 101 away from the housing 6 towards the cylinder bore 21 and penetrates the cylinder bore wall 22, forming the first notch 23. Engine oil can enter from the horizontal oil passage 101, pass through the inclined oil passage 102, and finally reach the piston ring 4 away from the combustion chamber 10 from the first notch 23 at the lower end of the inclined oil passage 102. Specifically, for ease of processing, the end of the inclined oil passage 102 away from the cylinder bore 21 penetrates the outer wall of the cylinder block 2, and a plug 8 is provided at the penetration point to prevent dust and other debris from entering the cylinder bore 21 and thus affecting the normal operation of the engine. The segmented design of the horizontal oil passage 101 and the inclined oil passage 102 allows for flexible planning of the oil passage path according to the overall structural characteristics of the cylinder block 2. This facilitates the extension of the horizontal oil passage 201 from the end face near the housing 6 to fit the overall engine assembly layout, while also shortening the path of the inclined oil passage 102. The inclined oil passage 102 precisely guides the oil passage to the target lubrication area of ​​the cylinder bore wall 22 (that is, when the piston 3 is at the bottom dead center, the first notch 23 and the second piston ring 42 are matched). It also effectively avoids interference with other functional structures inside the cylinder block 2 (such as cooling channels, bolt holes, etc.), thus improving space utilization. A plug 8 is provided at the end of the inclined oil passage 102 that is away from the cylinder bore 21 and penetrates the outer side wall of the cylinder body 2. This simplifies the machining process of the cylinder body lubrication oil passage 1. The horizontal oil passage 101 and the inclined oil passage 102 can be drilled separately, and then the opening at the beginning of the inclined oil passage 102 can be sealed by the plug 8, without the need for a complicated one-piece molding process. At the same time, the removability of the plug 8 facilitates the cleaning or maintenance of the oil passage in the later stage, reducing maintenance costs.

[0038] In some examples of this embodiment, a guide sleeve 9 is provided at one end of the horizontal oil passage 101 near the housing 6. The guide sleeve 9 has a hollow structure, and part of it is disposed inside the cylinder block 2 and part of it is disposed inside the housing 6. Here, the guide sleeve 9 serves a positioning function and also serves to facilitate the flow of engine oil. In specific installation, the guide sleeve 9 can be first placed in the housing oil passage 61, and then the cylinder block lubrication oil passage 1 on the cylinder block 2 can be matched with the guide sleeve 9. Specifically, the guide sleeve 9 is in transition fit with the horizontal oil passage 101. The structure of the guide sleeve 9 at the starting end of the horizontal oil passage 101, by partially embedding into the cylinder block 2 and partially embedding into the housing 6, can accurately position the docking position of the cylinder block lubrication oil passage 1 and the housing oil passage 61, avoiding poor oil passage connection or leakage due to misalignment during assembly. It is especially suitable for the high-precision assembly requirements in the compact structure of the engine. The pre-installation method of first assembling the guide sleeve 9 onto the oil passage 61 of the housing simplifies the assembly process of the cylinder block 2 and the housing 6, eliminating the need for repeated calibration of the oil passage position and reducing assembly time. Simultaneously, the tolerance of the transition fit can accommodate certain machining errors, improving the assembly qualification rate in mass production. For the high-frequency vibration conditions of UAV engines, the dual positioning function of the guide sleeve enhances the structural rigidity of the oil passage connection between the cylinder block 2 and the housing 6, reducing relative displacement caused by vibration, preventing oil passage leakage or wear due to loosening after long-term use, and extending the service life of the lubrication system.

[0039] Specifically, a sealing gasket (not shown in the figure) is provided on the adjacent end face of the cylinder block 2 and the housing 6. The sealing gasket provided on the adjacent end face of the cylinder block 2 and the housing 6 can effectively prevent oil leakage from the mating gap between the two. Especially under the conditions of vibration and temperature change during engine operation, it can compensate for the micro-unevenness or assembly error of the mating surface through its own elasticity, ensuring the sealing of the lubrication system and avoiding insufficient lubrication or environmental pollution caused by oil loss.

[0040] In some other examples of this embodiment, the cylinder block lubrication passage 1 is an inclined passage that extends from the end face of the cylinder block 2 near the housing 6 toward the cylinder bore 21 and penetrates the cylinder bore wall 22 to form the first notch 23. This structure requires the cylinder block 2 to have a sufficiently thick wall.

[0041] Example 2:

[0042] This embodiment provides a forced lubrication structure for a two-stroke cylinder block. The difference between this embodiment and Embodiment 1 lies only in the provision of three piston rings 4: a first piston ring, a second piston ring, and a third piston ring. The first notch 23 is configured such that when the piston 3 is at bottom dead center, the first notch 23 matches the position of either the second or third piston ring. In this embodiment, it is sufficient to ensure that the first notch 23 does not match the first piston ring. If the first notch 23 matches the first piston ring, the cylinder block lubrication oil passage 1 is too close to the exhaust port 24, and the engine oil can easily drain away directly, failing to lubricate the cylinder bore.

[0043] Those skilled in the art will recognize that numerous variations are possible with respect to the above description, and the embodiments and figures are merely for describing one or more specific implementations.

[0044] Although exemplary embodiments of the invention have been described and illustrated, those skilled in the art will understand that various changes and substitutions can be made thereto without departing from the spirit of the invention. Furthermore, many modifications can be made to adapt specific situations to the doctrine of the invention without departing from the central concepts of the invention described herein. Therefore, the invention is not limited to the specific embodiments disclosed herein, but may include all embodiments and equivalents that fall within the scope of the invention.

Claims

1. A forced lubrication structure for a two-stroke cylinder block, wherein the piston adapted to the cylinder block is provided with at least two piston rings, characterized in that: The cylinder block includes a lubrication passage that extends obliquely from the outer wall of the cylinder block to the cylinder bore wall inside the cylinder block and penetrates the cylinder bore wall to form a first notch. The first notch is configured such that when the piston is at bottom dead center, the first notch matches the position of the piston ring away from the combustion chamber, so that the oil entering through the cylinder block lubrication passage can reach the piston ring to lubricate the cylinder bore.

2. The forced lubrication structure for a two-stroke cylinder block according to claim 1, characterized in that: The piston rings include a first piston ring and a second piston ring, with the second piston ring located away from the combustion chamber, and the first notch matching the position of the second piston ring.

3. The forced lubrication structure for a two-stroke cylinder block according to claim 1, characterized in that: The piston rings include a first piston ring, a second piston ring, and a third piston ring, wherein the first notch is configured such that when the piston is at bottom dead center, the first notch matches the position of the second or third piston ring.

4. The forced lubrication structure for a two-stroke cylinder block according to claim 1, characterized in that: The piston ring is disposed in the piston ring groove, the width of the first notch is H, and the groove width of the piston ring groove is h, such that h≤H≤1.5h.

5. The forced lubrication structure for a two-stroke cylinder block according to claim 1, characterized in that: It also includes an oil tank, which is located outside the engine housing. The oil tank stores oil, and an oil pump draws the oil to the lubrication passage of the cylinder block.

6. The forced lubrication structure for a two-stroke cylinder block according to claim 5, characterized in that: The oil pump is an electronic oil pump, and the oil supply speed of the electronic oil pump is adjusted by an ECU.

7. The forced lubrication structure for a two-stroke cylinder block according to claim 5, characterized in that: The cylinder block lubrication passage includes a horizontal oil passage and an inclined oil passage. The horizontal oil passage extends from the end face of the cylinder block near the housing towards the side near the cylinder head. The inclined oil passage extends from the end of the horizontal oil passage away from the housing towards the cylinder bore and penetrates the cylinder bore wall to form the first notch. Engine oil can enter from the horizontal oil passage, pass through the inclined oil passage, and finally reach the piston ring away from the combustion chamber from the first notch at the lower end of the inclined oil passage.

8. The forced lubrication structure for a two-stroke cylinder block according to claim 7, characterized in that: The inclined oil passage extends through the outer wall of the cylinder body at one end away from the cylinder bore, and a plug is provided at the penetration point.

9. The forced lubrication structure for a two-stroke cylinder block according to claim 7, characterized in that: A guide sleeve is provided at one end of the horizontal oil passage near the housing. The guide sleeve has a hollow structure and is partially disposed within the cylinder body and partially disposed within the housing.

10. The forced lubrication structure for a two-stroke cylinder block according to claim 5, characterized in that: A sealing gasket is provided on the end face of the cylinder block adjacent to the housing.

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