Integrated lubricating oil tank for two-stroke heavy oil unmanned aerial vehicle engine

Abstract

The invention provides an integrated lubricating oil tank for a two-stroke heavy oil unmanned aerial vehicle engine, and belongs to the field of engine lubricating system design. Aiming at the problems of serious bubble accumulation, impurity pollution, closed loop failure, insufficient system redundancy and the like of the traditional two-stroke heavy oil engine lubricating oil tank, the lubricating oil tank integrates the structures of a lubricating oil tank shell, a defoaming layer, an oil suction pipe, a cover plate, a vent valve, an oil suction filter, an engine oil level gauge, an oil discharge port and the like. Return oil of a front gear chamber, a rear gear chamber and an oil pump is received through three oil inlets, most foam is eliminated through a defoaming layer after engine oil enters an oil tank, impurities are filtered through an oil suction filter, and then the engine oil is conveyed to a lubricating point position through an oil suction pipe; the vent valve is used for balancing air pressure inside and outside the oil tank, the engine oil level gauge can monitor oil quantity, and the oil discharge port facilitates impurity discharge. According to the design, full coverage of multiple lubricating point positions is achieved, lubricating reliability is improved, the unmanned aerial vehicle can adapt to complex working conditions, and meanwhile the risk that impurities intrude into a main oil way during maintenance is reduced.

Description

Technical Field

[0001] This invention belongs to the field of engine lubrication system design, and more specifically, relates to an integrated lubrication tank for a two-stroke heavy oil unmanned aerial vehicle engine. Background Technology

[0002] my country's development system for heavy-oil piston engines for aviation is still incomplete, with few mature products, and there is a long-term reliance on imported products, especially in the field of heavy-oil engines for aviation. In the lubrication system of two-stroke heavy-oil engines, traditional lubrication oil tanks have the following significant drawbacks:

[0003] Severe foam accumulation: Traditional oil tanks lack a dedicated defoaming structure. During the engine oil return process, the oil is prone to generating a large amount of foam due to factors such as impact and turbulence, which leads to a decrease in lubrication efficiency and increases the risk of oil pump cavitation, affecting the stable operation of the engine.

[0004] Impurity contamination and closed-loop failure: Most existing lubrication systems use external filters, which not only increases the complexity of pipeline connections, but also requires disassembling the oil pipe when replacing the filter element. During the operation, external impurities can easily enter the main oil circuit, damaging the cleanliness of the lubrication system and aggravating engine wear.

[0005] Insufficient system redundancy: Traditional oil tanks are mostly single-input designs, which are difficult to adapt to the oil return requirements of multiple lubrication points (such as front gear chamber, rear gear chamber, oil pump, etc.) in complex models. They cannot maximize the efficiency of the oil tank. In equipment with extremely high reliability requirements, such as drones, a single point of failure can easily affect the overall lubrication system. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides an integrated lubricating oil tank for a two-stroke heavy oil unmanned aerial vehicle engine.

[0007] An integrated lubricating oil tank for a two-stroke heavy oil unmanned aerial vehicle (UAV) engine includes a lubricating oil tank shell, a lubricating oil tank cover, a lubricating oil tank defoaming layer, a lubricating oil tank suction pipe, a suction filter, a vent valve, an oil level gauge, and a drain port. The lubricating oil tank shell has a hollow structure, with its upper part welded to the lubricating oil tank suction pipe, its middle part welded to the lubricating oil tank defoaming layer, and its lower part welded to the drain port. The lubricating oil tank cover is fitted onto the top of the lubricating oil tank shell and fastened with bolts. The lubricating oil tank shell has three oil inlets. It has one oil outlet and three oil inlets connected to the front gear chamber, rear gear chamber, and oil pump, respectively. The oil outlet is connected to the lubricating oil tank suction pipe. The oil suction filter is welded to the tail of the lubricating oil tank suction pipe. The lubricating oil tank defoaming layer is located inside the lubricating oil tank shell and separates its internal space. The oil entering the lubricating oil tank shell is defoamed by the lubricating oil tank defoaming layer, filtered by the oil suction filter, and then sucked out by the lubricating oil tank suction pipe. The vent valve and oil level gauge are both installed on the lubricating oil tank cover plate. The vent valve is used to balance the air pressure inside and outside the lubricating oil tank.

[0008] Preferably, of the three oil inlets, the oil inlet has an Rc1 / 8 tapered thread, and the oil inlet, oil outlet, and oil outlet all have an Rc1 / 4 tapered thread.

[0009] Preferably, the lubricating oil tank cover plate and the lubricating oil tank shell are connected by threads, and the connection is sealed with adhesive.

[0010] Preferably, the drain port is secured by an Rc1 / 8 tapered bolt.

[0011] Preferably, the lubricating oil tank cover plate is fastened to the lubricating oil tank shell by three M6×1 bolts and nuts.

[0012] Preferably, the defoaming layer of the lubricating oil tank can eliminate more than 95% of the foam in the engine oil entering the outer shell of the lubricating oil tank.

[0013] Preferably, the oil suction filter is used to filter impurities in the engine oil and is coaxially arranged with the oil suction pipe of the lubricating oil tank.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. Enhance the redundancy and reliability of the lubrication system: Adopting a "three-input, one-output" oil circuit design, the three oil inlets are respectively connected to the front gear chamber, the rear gear chamber, and the oil pump return oil, achieving full coverage of multiple lubrication points, meeting the lubrication needs of complex models, effectively improving system redundancy, and reducing the risk of single-point failure.

[0016] 2. Highly efficient oil foam elimination: Through the built-in anti-foaming layer of the lubricating oil tank, more than 95% of oil foam can be eliminated, solving the problems of reduced lubrication efficiency and pump cavitation caused by foam in traditional oil tanks, ensuring stable lubrication performance of the oil and extending engine service life.

[0017] 3. Optimize impurity filtration and maintenance safety: The oil suction filter is integrated with the lubricating oil tank suction pipe, reducing the pipeline complexity caused by external filters; during maintenance, there is no need to disassemble the main oil circuit pipe, and impurities can be discharged simply through the drain port, reducing the risk of impurities entering during maintenance and ensuring the closed-loop cleanliness of the lubrication system.

[0018] 4. Adaptable to complex operating conditions of drones: The oil tank cover is connected to the outer shell by threads and sealed with glue. With the help of the vent valve to balance the internal and external air pressure, it can ensure that the oil does not leak under complex attitudes such as drone inverted flight and side flight. At the same time, the oil level can be conveniently monitored by the oil level gauge, which improves the adaptability of the system and the convenience of operation. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of the lubricating oil tank shell in this invention;

[0021] Figure 3 This is the simulation process of the present invention. Figure 1 ;

[0022] Figure 4 This is the simulation process of the present invention. Figure 2 .

[0023] In the diagram, the correspondence between the component names and the attached drawing numbers is as follows: 1. Lubricating oil tank outer shell; 2. Lubricating oil tank defoaming layer; 3. Lubricating oil tank suction pipe; 4. Lubricating oil tank cover plate; 5. Vent valve; 6. Suction filter; 7. Oil level gauge; 8. Drain port. Detailed Implementation

[0024] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0025] Please see Figures 1-4 This invention provides an integrated lubricating oil tank for a two-stroke heavy oil unmanned aerial vehicle engine, the overall structure and assembly relationship of which are as follows:

[0026] The integrated multi-functional lubricating oil tank of this invention mainly consists of a lubricating oil tank shell 1, a lubricating oil tank defoaming layer 2, a lubricating oil tank suction pipe 3, a lubricating oil tank cover plate 4, a vent valve 5, a suction filter 6, an oil level gauge 7, and an oil drain port 8. The material selection and assembly process of each component are as follows:

[0027] 1. Core component materials and specifications:

[0028] The outer shell of the lubricating oil tank 1 is made of 45 steel and is a hollow columnar structure with a wall thickness of 3mm. The inner wall is phosphated for rust prevention. Its internal space is divided into an "outer oil return zone" and an "inner oil suction zone" by the lubricating oil tank defoaming layer 2. The outer oil return zone is used to receive the return oil from various lubrication points, and the inner oil suction zone is used to temporarily store the treated clean oil.

[0029] Lubricating oil tank defoaming layer 2: It is made of stainless steel woven mesh (80 mesh) and polytetrafluoroethylene film, with a thickness of 5mm. It has oil-loving and gas-repellent properties, which can effectively break the air bubbles in the oil while allowing the oil to penetrate.

[0030] Lubricating oil tank suction pipe 3: Made of seamless steel pipe (φ10mm×1mm), one end extends to the bottom of the lubricating oil tank shell 1 (5mm away from the bottom to avoid sucking in sediment impurities), and the other end passes through the lubricating oil tank cover plate 4 as an oil outlet, which is connected to the oil suction end of the engine oil pump.

[0031] Oil suction filter 6: It is a copper-based sintered filter element with a filtration accuracy of 10μm. It is fixed to the tail of the oil suction pipe 3 of the lubricating oil tank by argon arc welding, with a coaxiality error of ≤0.5mm, ensuring that all the oil enters the oil suction pipe after being filtered.

[0032] Lubricating oil tank cover plate 4: Made of aluminum alloy (6061-T6), 8mm thick, with anodized surface treatment. It has a pre-drilled hole for vent valve 5 (φ8mm), a hole for oil level gauge 7 (φ12mm), and an oil outlet through hole (to cooperate with the lubricating oil tank suction pipe 3).

[0033] Vent valve 5: This is a one-way pressure balancing valve with an opening pressure set at ±5kPa. It is made of brass and is fixed to the lubricating oil tank cover plate 4 via a threaded connection. It is used to balance the air pressure inside and outside the oil tank.

[0034] Oil level gauge 7: It adopts a stainless steel graduated scale (range 0-500mL, accuracy 10mL), and a nitrile rubber float is installed at the lower end. It is fixed to the lubricating oil tank cover plate 4 through a sealing threaded seat, which can directly read the oil level in the oil tank.

[0035] Drain port 8: A brass ball valve (diameter Rc1 / 8), welded to the lower part of the lubricating oil tank shell 1 by argon arc welding. The valve stem end is fitted with an Rc1 / 8 tapered bolt for periodically draining sediment from the bottom of the oil tank. The upper part of the lubricating oil tank shell 1 is fixed to the lubricating oil tank suction pipe 3 by carbon dioxide gas shielded welding, with a weld height of 2mm. The middle part of the shell is fixed to the lubricating oil tank defoaming layer 2 by spot welding (4 weld points evenly distributed around the circumference), ensuring that the edge of the defoaming layer is tightly fitted to the inner wall of the shell, without any oil short-circuit channel. After the lower part of the shell is welded to the drain port 8, a water pressure test is required (0.2MPa, pressure held for 3 minutes without leakage).

[0036] The lubricating oil tank cover 4 is fastened to the top of the lubricating oil tank shell 1 by 3 M6×1 bolts and nuts. The bolts are evenly distributed around the circumference (120° spacing). The contact surface between the cover and the shell is coated with silicone rubber sealant (0.5mm thick). After curing, a sealing ring is formed to ensure that the oil does not leak under complex attitudes such as inverted flight and side flight of the drone.

[0037] Oil circuit design and interface specifications:

[0038] 1. Layout of oil inlet and outlet:

[0039] like Figure 2 As shown, the side wall of the lubricating oil tank shell 1 has three oil inlets and one oil outlet, with the following specific specifications:

[0040] Oil inlet 1: Located on the upper part of the outer casing, it adopts Rc1 / 8 tapered thread and is connected to the oil return line of the front gear chamber of the engine, responsible for receiving the oil return from the front gear chamber;

[0041] Oil inlet 2: Located in the middle of the outer casing, it uses an Rc1 / 4 tapered thread and is connected to the oil return line of the engine rear gear chamber;

[0042] Oil inlet 3: Located at the bottom of the housing, it uses an Rc1 / 4 tapered thread and is connected to the engine oil pump return line;

[0043] Oil outlet: Integrated into the end of the oil suction pipe 3 that passes through the oil tank cover plate 4, using Rc1 / 4 tapered thread, and connected to the oil suction pipe of the engine oil pump.

[0044] All threaded joints are coated with thread sealant (PTFE) to ensure sealing performance and facilitate later disassembly and maintenance.

[0045] Work process:

[0046] When the engine is running, the circulation process and core functions of the lubricating oil tank are as follows:

[0047] 1. Oil return collection and defoaming treatment:

[0048] The return oil from the front gear chamber, rear gear chamber, and oil pump enters the outer oil return zone of the lubricating oil tank shell 1 through oil inlet 1, oil inlet 2, and oil inlet 3, respectively. Since the return oil has a certain pressure (0.1-0.3MPa), the oil will generate a large amount of foam after entering the outer layer due to the impact (the initial foam volume can reach 30%-40%).

[0049] Foamy engine oil flows downwards under gravity. When it passes through the defoaming layer 2 in the lubrication tank, the foam is cut and broken by the mesh structure of the defoaming layer. At the same time, the polytetrafluoroethylene film absorbs the air bubbles in the engine oil, reducing the foam volume ratio to below 5% (meeting the lubrication system's requirements for engine oil air content). The defoamed engine oil penetrates through the defoaming layer and enters the inner oil absorption zone.

[0050] 2. Filtration and oil suction circulation:

[0051] When the oil in the inner oil suction zone passes through the oil suction filter 6, impurities such as metal shavings and colloids are filtered out (filtration efficiency ≥98%), and the clean oil enters the lubricating oil tank suction pipe 3.

[0052] When the engine oil pump is working, it draws clean engine oil from the inner oil suction area through the oil suction pipe and delivers it to each lubrication point (front gear chamber, rear gear chamber, etc.) to complete the lubrication cycle.

[0053] 3. Implementation of auxiliary functions:

[0054] Pressure balancing: When the oil pump is working, the oil circuit is pressurized, and a pressure difference (up to ±10kPa) can easily occur inside and outside the oil tank. When the pressure difference exceeds the opening pressure of the vent valve 5 (±5kPa), the vent valve will automatically open to balance the air pressure through airflow, thus preventing the oil tank shell from deforming due to pressure difference or the oil from cavitation due to negative pressure.

[0055] Oil level monitoring: The oil level in the tank can be read in real time via the oil level gauge 7. When the oil level is lower than the minimum mark (100mL), it will prompt that oil needs to be added to avoid insufficient lubrication.

[0056] Impurity discharge: After every 50 hours of engine operation, the Rc1 / 8 tapered bolt of the drain port 8 can be opened to discharge impurities (such as metal shavings, sludge, etc.) that have settled at the bottom of the oil tank. This does not require disassembling the oil pipe and reduces the risk of impurities entering the main oil circuit during maintenance.

[0057] Simulation verification:

[0058] To verify the effectiveness of the defoaming layer 2 in the lubricating oil tank, the oil flow process was simulated using fluid simulation software (operating conditions: rated speed of a two-stroke heavy oil UAV engine of 4000 r / min, return oil flow rate of 5 L / min). The results are as follows:

[0059] Figure 3 The display shows that after the engine oil enters the outer oil return zone, it all flows to the defoaming layer 2 of the lubricating oil tank. There is no short-circuit phenomenon of "skipping the defoaming layer and directly entering the inner layer", ensuring that all engine oil has undergone defoaming treatment.

[0060] Figure 4In the test, the air volume fraction (foam percentage) was 0.3-0.4 before passing through the defoaming layer (red area), and dropped to below 0.05 after passing through the defoaming layer (blue area), which is consistent with the actual test results, proving that the defoaming layer can eliminate more than 95% of the foam.

[0061] Figure 2 In the middle, the bottom is the oil outlet, the top is the first oil inlet, the left is the second oil inlet, and the right is the third oil inlet.

[0062] This embodiment integrates functions such as oil return treatment, defoaming, filtration, and air pressure balancing, solving problems such as foam accumulation, impurity contamination, and insufficient system redundancy in traditional lubricating oil tanks. It is suitable for the complex lubrication needs of two-stroke heavy oil UAV engines.

[0063] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. An integrated lubricating oil tank for a two-stroke heavy oil unmanned aerial vehicle engine, characterized in that: It includes a lubricating oil tank shell (1), a lubricating oil tank cover plate (4), a lubricating oil tank defoaming layer (2), a lubricating oil tank suction pipe (3), a suction filter (6), a vent valve (5), an oil level gauge (7), and an oil drain port (8); the lubricating oil tank shell (1) is a hollow structure, with its upper part welded to the lubricating oil tank suction pipe (3), its middle part welded to the lubricating oil tank defoaming layer (2), and its lower part welded to the oil drain port (8); The lubricating oil tank cover plate (4) covers the top of the lubricating oil tank shell (1) and is fastened by bolts; the lubricating oil tank shell (1) is provided with three oil inlets and one oil outlet. The three oil inlets are respectively connected to the front gear chamber, the rear gear chamber and the oil pump, and the oil outlet is connected to the lubricating oil tank suction pipe (3); the suction filter (6) is welded to the tail of the lubricating oil tank suction pipe (3), and the lubricating oil tank defoaming layer (2) is located inside the lubricating oil tank shell (1) and separates its internal space, so that the oil entering the lubricating oil tank shell (1) is defoamed by the lubricating oil tank defoaming layer (2) and filtered by the suction filter (6), and then sucked out by the lubricating oil tank suction pipe (3); the vent valve (5) and the oil level gauge (7) are both installed on the lubricating oil tank cover plate (4), and the vent valve (5) is used to balance the air pressure inside and outside the lubricating oil tank.

2. The integrated lubricating oil tank for a two-stroke heavy oil UAV engine as described in claim 1, characterized in that, Of the three oil inlets, oil inlet one has an Rc1 / 8 tapered thread, while oil inlet two, oil inlet three, and the oil outlet all have an Rc1 / 4 tapered thread.

3. The integrated lubricating oil tank for a two-stroke heavy oil UAV engine as described in claim 2, characterized in that, The lubricating oil tank cover plate (4) is threadedly connected to the lubricating oil tank shell (1), and the connection is sealed with glue.

4. The integrated lubricating oil tank for a two-stroke heavy oil UAV engine as described in claim 3, characterized in that, The drain port (8) is secured by an Rc1 / 8 tapered bolt.

5. The integrated lubricating oil tank for a two-stroke heavy oil UAV engine as described in claim 4, characterized in that, The lubricating oil tank cover plate (4) is fastened to the lubricating oil tank shell (1) by three M6×1 bolts and nuts.

6. The integrated lubricating oil tank for a two-stroke heavy oil UAV engine as described in claim 5, characterized in that, The defoaming layer (2) of the lubricating oil tank can eliminate more than 95% of the foam in the oil entering the outer shell (1) of the lubricating oil tank.

7. The integrated lubricating oil tank for a two-stroke heavy oil UAV engine as described in claim 6, characterized in that, The oil suction filter (6) is used to filter impurities in the engine oil and is coaxially arranged with the oil suction pipe (3) of the lubricating oil tank.

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