A marine low-speed engine cylinder liner oil injection device

Abstract

The application discloses a marine low-speed engine cylinder liner oil injection device, and aims to solve the problems of poor lubrication in the piston top dead center area and uneven distribution of oil film in the prior art. The technical scheme of the application comprises the following steps: an oil injection hole is arranged at a position 1 / 8 of the height of the piston stroke from the top of the cylinder liner, and an oil injection device is fixedly arranged in the oil injection hole, wherein the oil injection device is provided with a one-way horizontal injection hole, and the injection direction is the same as the tangent direction of the rotation of the gas spiral vortex in the cylinder. When the oil is injected, the cylinder oil is horizontally injected into the inner wall of the cylinder liner through the one-way horizontal injection hole, and is uniformly spread to form a continuous oil film under the action of the centrifugal force of the gas vortex. The application significantly improves the lubrication effect in the top dead center area, improves the uniformity of the oil film, reduces the wear of the cylinder liner and the consumption of the cylinder oil, and has the advantages of simple structure and suitability for new machine manufacturing and in-service machine modification.

Description

Technical Field

[0001] This invention relates to the field of marine low-speed engine technology, specifically to a marine low-speed engine cylinder liner oil injection device. Background Technology

[0002] As the primary propulsion source for large merchant ships, the lubrication between the cylinder liner and piston rings of marine low-speed two-stroke engines is crucial to the engine's reliability, economy, and emissions performance. Currently, mainstream cylinder lubrication systems employ mechanically or electronically controlled lubricators, which inject cylinder oil into the inner wall of the cylinder liner at regular intervals and in measured quantities through lubrication devices located on the oil injection holes of the cylinder liner.

[0003] In traditional cylinder lubrication systems, the oil injection device is typically located at the cylinder liner oil injection hole, approximately one-third of the piston stroke. As the piston moves upward and its first piston ring reaches the oil injection hole, the device simultaneously injects cylinder oil horizontally from both holes on either side. The piston ring then spreads the oil, forming a lubricating film. As the piston continues to move upward, this film is carried to the top dead center region.

[0004] However, existing technologies have the following main shortcomings: 1. The oil injection point is far from the piston's top dead center. As the piston moves upward, the oil film gradually becomes thinner. When the piston reaches top dead center, the oil film is at its thinnest, resulting in insufficient lubrication and severe wear of the cylinder liner near the high temperature and high pressure area of ​​the piston's top dead center.

[0005] 2. In the oil film scraping method, the oil film is not evenly distributed on the same plane. Summary of the Invention

[0006] This invention aims to overcome the technical defects of existing marine low-speed engine cylinder liner lubrication systems, such as the oil injection point being too far from the piston's top dead center, resulting in an excessively thin oil film in the top dead center area, and the reliance on piston rings to scrape the oil film, leading to uneven oil film distribution. It provides an oil injection device and its arrangement that can significantly improve the lubrication effect in the piston's top dead center area, enhance oil film uniformity, and reduce cylinder liner wear and cylinder oil consumption. The technical solution adopted in this invention is as follows: A marine low-speed engine cylinder liner oil injection device, comprising: The cylinder liner has multiple oil injection holes on its side wall; The oil injection structure is fixedly installed in each of the oil injection holes.

[0007] The oil injection hole is located on the cylinder liner wall at a distance of 1 / 8 of the piston stroke from the top of the cylinder liner. This position is significantly higher than the traditional 1 / 3 stroke oil injection point, bringing the oil injection point closer to the high-temperature, high-pressure region of the piston's top dead center. The oil injection structure has a one-way horizontal spray hole, the axis of which is perpendicular to the cylinder liner axis and located in a horizontal plane. The outer shell of the oil injection structure has an "UP" direction mark to indicate the installation direction and ensure the correct orientation of the spray hole. The oil injection structure is fixed to the oil injection hole of the cylinder liner via a threaded connection or flange connection. The spray direction of the one-way horizontal spray hole is the same as the rotational tangential direction of the spiral vortex of gas inside the engine cylinder. This spiral vortex is a rotating upward airflow formed by the air entering through the engine scavenging port after the exhaust valve is closed. During oil injection, the cylinder oil is sprayed horizontally along the tangential direction of the vortex, avoiding oil mist generated by opposing the vortex.

[0008] The oil inlet of the oil injection structure is connected to the output pipe of the external oiler, and the one-way horizontal spray hole is open towards the inner wall of the cylinder liner. When the oil injection time arrives, the cylinder oil is horizontally sprayed into the surface of the inner wall of the cylinder liner through the one-way horizontal spray hole, and under the action of centrifugal force of the gas spiral vortex, it spreads evenly along the circumference and axial direction of the inner wall of the cylinder liner, forming a continuous and stable lubricating oil film. This film-forming process does not rely on the mechanical oil scraping action of the piston rings.

[0009] The preferred timing for oil injection is when the piston moves upward and the upper edge of its first piston ring passes the center of the oil injection hole; or the engine electronic control system can perform oil injection based on the piston position sensor signal, after the exhaust valve is closed and the piston moves upward to the position of the oil injection hole.

[0010] The oil injection structure is evenly arranged at equal angles along the circumference of the cylinder liner, and the number of structures is preferably 6 or 8 depending on the cylinder diameter.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1) Because the oil injection hole is moved to 1 / 8 of the piston stroke, the injection point is closer to the piston's top dead center (TDC), resulting in a significant increase in oil film thickness when the piston reaches TDC. This solves the problem of excessively thin oil film in the TDC region in traditional designs. Tests show that cylinder liner wear near TDC can be reduced by 30% to 50%.

[0012] 2) The gas spiral vortex centrifugal force film distribution method is adopted to replace the traditional method of mechanical scraping by piston rings, so that the lubricating oil is more evenly distributed in the circumferential and axial directions on the inner wall of the cylinder liner, avoiding local excessive oil film thickness or absence, and reducing the oil film uniformity variation coefficient from 25% to below 8%.

[0013] 3) The jet direction of the unidirectional horizontal nozzle is the same as the vortex direction, which avoids the high-speed oil jet from colliding with the vortex to form oil mist, ensuring that most of the cylinder oil adheres to the cylinder wall in liquid form, thus improving lubrication effectiveness and cylinder oil utilization.

[0014] 4) Due to improved lubrication efficiency, there is no need to compensate for wear by excessive oil injection, which can reduce cylinder oil consumption by about 15%, thereby reducing operating costs and emissions.

[0015] 5) This invention only requires changing the position of the oil injection hole and using a one-way spray nozzle oil injection device, without making significant modifications to the main structure of the engine, resulting in low manufacturing costs and a short modification cycle.

[0016] 6) The location of the oil injection hole, the direction of the unidirectional spray hole of the oil injection device, and the direction of the spiral vortex of the gas inside the cylinder work together to form a "gas vortex coordinated film distribution system", which realizes efficient lubrication without mechanical contact and has significant technological progress. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the installation position of the marine low-speed engine cylinder liner oil injection device of the present invention in the cylinder liner height direction. Figure 2 This is a cross-sectional view of the installation arrangement of the cylinder liner oil injection device of the present invention on the horizontal section of the cylinder liner; Figure 3 This is a schematic diagram of the cylinder liner oil injection device of the present invention. Detailed Implementation To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0018] like Figure 1 As shown, this embodiment provides an arrangement of a cylinder liner oil injection device for a marine low-speed engine. The engine is a marine low-speed two-stroke diesel engine. Multiple oil injection holes are evenly spaced along the circumference of the cylinder liner (part 2) at a distance of 1 / 8 of the piston stroke from the top of the cylinder liner (i.e., the piston's top dead center). The number of oil injection holes is determined according to the cylinder diameter, preferably 6 or 8. An oil injection structure (part 1) is installed in each oil injection hole and fixed by threads or flanges.

[0019] like Figure 3 As shown, the outer shell of the oil injection structure (part 1) is marked with a direction mark "UP". During installation, it is necessary to ensure that the "UP" direction points to the top of the cylinder liner (i.e. the direction of the piston top dead center) so as to ensure that the axis of the one-way horizontal spray hole inside the oil injection device is in the horizontal plane and faces the preset direction.

[0020] like Figure 2 and Figure 3 As shown, the oil injection structure (component 1) includes a device body, an oil injection inlet, a one-way horizontal spray hole, and a mounting flange. The device body has an internal oil passage; one end is the oil injection inlet for connecting to the output pipeline of an external oil injector (such as an electronic or mechanical oil injector); the other end is a one-way horizontal spray hole, which is a single circular or slit-shaped hole with a diameter of 0.5~1.5 mm, preferably 0.8 mm.

[0021] The axis of the one-way horizontal nozzle is perpendicular to the axis of the cylinder liner (part 2) and lies in the horizontal plane. At the same time, the direction of this axis is consistent with the direction of the spiral vortex of gas inside the engine cylinder. Specifically, for this type of engine, the design of its scavenging port and exhaust valve causes a clockwise (viewed from top to bottom) rotating and rising vortex to be formed inside the cylinder. Therefore, the one-way horizontal nozzle of the oil injection device points in the clockwise tangential direction.

[0022] When the engine is running, the piston reciprocates within the cylinder liner (part 2). After the exhaust valve closes, a stable upward spiral vortex forms within the cylinder. When the piston rises to the position where its first piston ring passes the oil injection hole (or when the piston rises to the vicinity of the oil injection hole and the vortex has been established), the oil injector supplies cylinder oil to the oil injection structure (part 1) according to a preset timing and quantity. The cylinder oil passes through the oil inlet and the oil passage within the device, and is horizontally injected into the inner wall of the cylinder liner in the form of a high-speed jet from the one-way horizontal nozzle.

[0023] Because the injection direction is completely aligned with the direction of the spiral vortex of gas inside the cylinder, the injected cylinder oil will not violently collide with the vortex, thus avoiding the generation of oil mist and ensuring that most of the cylinder oil adheres to the inner wall surface of the cylinder liner in liquid form. Subsequently, under the centrifugal force of the spiraling upward vortex, the cylinder oil is evenly spread on the circumferential and axial areas of the inner wall of the cylinder liner, forming a continuous, uniform, and stable lubricating oil film.

[0024] As the piston continues to move upward to top dead center, the oil film maintains sufficient thickness and adhesion, providing good lubrication for the friction pair between the piston rings and cylinder liner, and significantly reducing wear in the high-temperature and high-pressure area at top dead center.

[0025] Using the oil injection device and arrangement described in Examples 1-3 above, a bench test was conducted on a certain type of 6-cylinder marine low-speed two-stroke engine. Test settings: engine speed 100 r / min, power 5000 kW, cylinder oil injection rate 0.8 g / kWh. Compared with traditional oil injection devices (oil injection holes located at 1 / 3 of the stroke, dual-hole horizontal symmetrical injection, and reliance on piston ring scraping), the solution of this invention achieves the following improvements: In the piston top dead center region (within ±20 mm from top dead center), the wear depth of the cylinder liner inner wall decreased from the original 0.15 mm / 1000h to 0.08 mm / 1000h, and the wear rate decreased by about 47%. The coefficient of variation (CV) of the oil film thickness at four circumferential measuring points decreased from 25% to 8%, indicating a significant improvement in the uniformity of oil film distribution. Cylinder oil consumption was reduced by 15%, and blue smoke in the exhaust was significantly reduced.

[0026] Figure 3 The "UP" marking on the oil injection structure (part 1) indicates not only the vertical installation orientation but also implicitly suggests the direction of the horizontal nozzle. During actual installation, the operator should first screw the oil injection device into the cylinder liner's oil injection hole to the appropriate preload, then fine-tune the device body to align the direction of the unidirectional horizontal nozzle with the direction of the vortex flow within the cylinder, and finally tighten it. For engines with different rotation directions (such as left-hand or right-hand engines), an oil injection device with mirror-symmetrical nozzle directions should be selected to ensure that the injection direction is always the same as the vortex direction.

[0027] To further improve lubrication, the timing of oil injection can be precisely controlled using the engine's electronic control system. Preferably, an injection command is issued when the piston position sensor detects that the piston has moved upwards and is within ±5 mm of the injection port. Simultaneously, the injection pulse width is adjusted according to engine load and speed, typically between 5 and 20 ms. This timing ensures that cylinder oil is injected when the swirl is strongest and the piston rings have not yet completely sealed the injection port, which is beneficial for oil film formation and spread.

[0028] For large cylinders (with an inner diameter exceeding 600 mm), eight lubrication structures (part 1) can be evenly arranged circumferentially. Each lubrication device is independent of the others, but the lubrication timing and volume are managed uniformly by the same controller. The controller can fine-tune the lubrication volume of each lubrication device based on parameters such as exhaust temperature and explosion pressure of each cylinder to achieve uniform lubrication within the cylinder.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A cylinder liner oil injection device for a marine low-speed engine, characterized in that, include: The cylinder liner has multiple oil injection holes on its side wall; The oil injection structure is fixedly installed in each of the oil injection holes; The oil injection hole is located on the cylinder liner wall at a distance of 1 / 8 of the piston stroke from the top of the cylinder liner; The oil injection structure has a one-way horizontal spray hole, the axis of which is perpendicular to the axis of the cylinder liner and located in the horizontal plane, and the spray direction of the one-way horizontal spray hole is the same as the rotation tangential direction of the spiral vortex of gas in the engine cylinder. The oil inlet of the oil injection structure is connected to the output pipeline of the external oil injector, and the one-way horizontal spray hole is open towards the inner wall of the cylinder liner. When oil is injected, the cylinder oil is horizontally sprayed into the inner wall surface of the cylinder liner through the one-way horizontal nozzle, and spreads evenly along the circumference and axial direction of the inner wall of the cylinder liner under the centrifugal force of the gas spiral vortex, forming a continuous lubricating oil film.

2. The marine low-speed engine cylinder liner oil injection device according to claim 1, characterized in that: The structure is arranged evenly at equal angles along the circumference of the cylinder liner, and the number of such structures is 6 or 8.

3. The marine low-speed engine cylinder liner oil injection device according to claim 1, characterized in that: The unidirectional horizontal nozzle is a single nozzle, which is circular or slit-shaped, with a diameter of 0.5 mm to 1.5 mm.

4. The marine low-speed engine cylinder liner oil injection device according to claim 1, characterized in that: The outer shell of the oil injection structure is provided with an installation direction mark, which is marked with the word "UP". When installing, the mark points to the top of the cylinder liner to ensure that the injection direction of the one-way horizontal nozzle is consistent with the direction of the spiral vortex of the gas in the cylinder.

5. The marine low-speed engine cylinder liner oil injection device according to claim 1, characterized in that: The oil injection structure is fixed to the oil injection hole of the cylinder liner via a threaded connection or a flange connection.

6. The marine low-speed engine cylinder liner oil injection device according to claim 1, characterized in that: The oil injection timing of the oil injection structure is as follows: oil injection begins when the piston moves upward and the upper edge of its first piston ring passes the center position of the oil injection hole.

7. The marine low-speed engine cylinder liner oil injection device according to claim 1, characterized in that: The timing of the oil injection is determined by the engine electronic control system based on the piston position sensor signal, and oil injection is performed when the exhaust valve is closed and the piston moves up to the position of the oil injection hole.

8. The marine low-speed engine cylinder liner oil injection device according to claim 1, characterized in that: The gas spiral vortex is a rotating upward airflow formed by the air entering the engine scavenging port after the exhaust valve is closed; the injection direction of the unidirectional horizontal nozzle is the same as the tangential velocity direction of the rotating upward airflow in the plane where the oil injection hole is located, so as to avoid the oil jet from colliding with the vortex and generating oil mist.

9. The marine low-speed engine cylinder liner oil injection device according to claim 1, characterized in that: For engines rotating in opposite directions, oil injection devices with mirror-symmetrical nozzle directions are configured to ensure that the injection direction is always consistent with the direction of the cylinder swirl.

10. The marine low-speed engine cylinder liner oil injection device and its arrangement according to any one of claims 1 to 9, characterized in that: The location of the oil injection hole in the cylinder liner, the direction of the unidirectional horizontal spray hole in the oil injection structure, and the direction of the gas spiral vortex together constitute a gas vortex cooperative film distribution system. This system can achieve uniform oil film distribution without relying on the mechanical scraping of the piston rings.

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