Double-layer high-pressure oil pipe for engine

Abstract

The utility model discloses a double -deck high -pressure oil pipe for engine, aims at solving the deficiency of traditional single -deck high -pressure oil pipe on structural strength, sealing reliability. The high -pressure oil pipe contains oil pipe subassembly, fixed pipe clamp, end connection nut and protection sheath. Oil pipe subassembly is " inner layer delivery pipe + outer layer protection pipe " coaxial double -deck structure, and inner layer delivery pipe selects alloy steel pipe, can bear high -pressure fuel impact, and outer layer protection pipe forms clearance with inner layer pipe, constitutes anti -leakage double -screen, and outer layer pipe still is " galvanization + passivation " treatment to promote anticorrosion capacity. Sealing aspect, and oil pipe and oil atomizer, common rail pipe, oil pump connecting part all adopt double -sealed structure, and like oil atomizer end is " spherical surface head sticking + fluorine rubber sealing washer " seal, and pump end adopts enhanced fluorine rubber sealing washer and to the sticking surface mirror surface polishing. The first, second double -tube pipe clamp of fixed structure is equipped. The utility model has the advantages of multilayer protection, sealing reliable, anti -vibration anticorrosion etc.

Description

Technical Field

[0001] This utility model relates to the field of engine fuel system technology, specifically to a double-layer high-pressure oil pipe for engines. Background Technology

[0002] In the field of engine technology, high-pressure fuel lines, as the core delivery component of the fuel system, are responsible for accurately delivering the high-pressure fuel output from the fuel pump to the common rail, and then distributing it to the injectors of each cylinder. As engines upgrade towards higher power and higher fuel pressure, traditional single-layer high-pressure fuel lines have gradually revealed many technical defects, making it difficult to meet the stringent operating conditions.

[0003] From a structural reliability perspective, traditional single-layer high-pressure fuel lines rely solely on a single pipe wall to withstand the impact of high-pressure fuel. Over long-term use, this can easily lead to pipe wall cracking or end seal failure due to material fatigue and vibration wear. Especially during engine operation, the high-pressure fuel line experiences high-frequency vibrations from the cylinder block. If the fixing structure is not properly designed, the fuel line can easily sway significantly, further exacerbating wear on the end sealing surface and causing high-pressure fuel leakage.

[0004] In terms of sealing performance, traditional high-pressure oil pipes are often connected to oil pumps, common rails, and injectors using a "single metal sealing surface" or "simple O-ring seal" structure. The reliability of this seal is easily affected by assembly precision, vibration, and temperature changes. For example, the metal-to-metal seal between the oil pipe end and the injector connecting rod can fail if torque is not properly controlled during assembly, or if scratches appear on the sealing surface due to impurities after long-term use. Furthermore, ordinary rubber O-rings are prone to aging and hardening under the high temperature and high pressure of the engine compartment, losing elasticity and further increasing the risk of leakage.

[0005] For specialized applications such as marine engines and heavy-duty commercial vehicle engines, high-pressure fuel lines face even greater challenges. Marine engines operate for extended periods in the high-humidity, high-salt-spray marine environment, where the anti-corrosion treatments on the outer surface of traditional fuel lines are prone to failure, leading to thinning of the pipe wall due to corrosion and a shortened service life. Simultaneously, the amplitude of turbulence and vibration during ship navigation is greater than that of land vehicles, placing higher demands on the vibration fatigue resistance of fuel lines. Traditional single-layer fuel lines have limited vibration resistance and are prone to problems such as pipe bending and loosening of joints after long-term use, affecting the stability of fuel delivery.

[0006] In summary, existing high-pressure oil pipes have significant shortcomings in terms of structural strength, sealing reliability, vibration fatigue resistance, and adaptability to special environments, making it difficult to meet the usage requirements of modern engines, especially high-power, high-oil-pressure engines and marine engines. Therefore, it is necessary to design a high-pressure oil pipe structure with double-layer protection, enhanced sealing, vibration resistance, and adaptability to multiple scenarios to solve the above-mentioned technical problems. Utility Model Content

[0007] In view of the above-mentioned defects in the prior art, the double-layer high-pressure oil pipe for engines provided by this utility model solves the problems of traditional high-pressure oil pipes in terms of pressure resistance, sealing, vibration resistance and environmental adaptability through the design concept of "structural reinforcement + sealing upgrade + adaptation optimization".

[0008] This utility model proposes a double-layer high-pressure fuel pipe for an engine, including a fuel pipe assembly and end connecting nuts. The fuel pipe assembly forms a high-pressure fuel delivery link of "fuel pump-common rail-injector", including a first cylinder double-layer high-pressure fuel pipe assembly, a second cylinder double-layer high-pressure fuel pipe assembly, a third cylinder double-layer high-pressure fuel pipe assembly, and a fourth cylinder double-layer high-pressure fuel pipe assembly for connecting the common rail to the injectors of each cylinder, and a pump rail I double-layer high-pressure fuel pipe assembly and a pump rail II double-layer high-pressure fuel pipe assembly for connecting the fuel pump to the common rail. The fuel pipe assembly has a coaxial double-layer structure, including an inner layer and an outer layer, with a gap between the inner and outer layers. The end connecting nuts include an injector end nut, a rail end nut, and a pump end nut.

[0009] Preferably, the inner layer is an alloy steel pipe, the outer layer is a seamless steel pipe, the gap is 0.4-0.6 mm, the surface of the oil pipe assembly is provided with a zinc passivation layer with a coating thickness of greater than or equal to 8 μm, and the cleanliness of the inner hole of the oil pipe assembly meets the requirement that the maximum particle size is less than or equal to 205 μm.

[0010] Preferably, it also includes a fixing clamp, which includes a first double-pipe clamp and a second double-pipe clamp. Both types of clamps are U-shaped clamps and bolted, and are adapted to the preset mounting holes of the engine cylinder block. The first double-pipe clamp is a structure with a welded nut that can be fixed to the engine cylinder block by welding, and the second double-pipe clamp is a nutless structure that needs to be bolted to fit the preset threaded hole of the cylinder block.

[0011] Preferably, it also includes protective sleeves, which include a pump end sleeve and a rail end sleeve, both made of oil-resistant rubber. The pump end sleeve is fitted on the outside of the pump end nut, and the rail end sleeve is fitted on the outside of the rail end nut, and the inner walls of both are tightly fitted to the outer walls of the corresponding nuts.

[0012] Preferably, the end connecting nut is made of carbon structural steel and the inner wall thread accuracy grade is 6H; the injector end nut is adapted to the injector interface size, the rail end nut is adapted to the common rail interface, the pump end nut is adapted to the oil pump interface, and the inner sealing groove depth of the pump end nut is increased by 0.2mm compared with the rail end nut.

[0013] Preferably, the connection between the oil pipe assembly and the injector adopts a double sealing structure of spherical head fitting and fluororubber sealing ring; the end of the inner delivery pipe is processed into a spherical head, which fits tightly with the conical sealing seat of the injector interface to form a main seal; the inner side of the injector end nut is provided with a stepped sealing groove, and a fluororubber annular sealing ring with a temperature resistance range of -20℃ to 200℃ is installed in the groove to form an auxiliary seal.

[0014] Preferably, the connection between the oil pipe assembly and the common rail pipe adopts a double sealing structure of spherical head fitting and O-ring rubber seal; the spherical head at the end of the inner delivery pipe cooperates with the inner sealing cavity of the rail end nut to form a main seal; a nitrile rubber O-ring is installed at the gap between the outer side of the inner sealing cavity of the rail end nut and the annular sealing boss of the common rail pipe interface to form an auxiliary seal.

[0015] Preferably, the connection between the oil pipe assembly and the oil pump adopts a double sealing structure of mirror-polished bonding and reinforced fluororubber sealing ring; the bonding surface of the inner delivery pipe and the oil pump interface is mirror-polished, and the surface roughness Ra is less than or equal to 0.8μm; a reinforced fluororubber sealing ring with added carbon fiber and improved compressive strength is installed in the sealing groove inside the pump end nut.

[0016] The beneficial effects of this utility model include:

[0017] (1) Multi-layer protection enhances safety level. Double-layer pipe wall constructs "leakage prevention double barrier": The inner delivery pipe is made of high-strength alloy steel pipe, which can directly withstand the impact of high-pressure fuel, avoiding direct leakage caused by fatigue cracking of a single pipe wall; The outer protective pipe forms a gap of 0.4-0.6mm with the inner pipe. Even if there is a slight leakage in the inner pipe, the leaked fuel will be temporarily stored by the outer pipe and will not directly seep into the engine compartment or contact high-temperature components.

[0018] (2) At the connection points of the oil pipe and the injector, common rail and oil pump, a dual structure of "metal bonding seal + rubber sealing ring seal" is designed. For example, the injector end forms the main seal by the tight fit between the inner tube spherical head and the injector conical sealing seat, and with the auxiliary seal of the fluororubber annular sealing ring, it can effectively resist the influence of assembly torque deviation, vibration impact and temperature change on sealing performance; the pump end adopts an enhanced fluororubber sealing ring for high oil pressure characteristics, and the bonding surface is mirror polished to further reduce the probability of leakage under high oil pressure conditions and ensure that there is no leakage throughout the fuel delivery process.

[0019] (3) Pipe clamps are used to suppress vibration and wear. The spacing of the first and second double pipe clamps is adapted to the engine cylinder block hole positions. Through the "U-shaped clamp + bolt fixing" structure, the vibration displacement of the oil pipe can be controlled to a minimum. The pipe clamp with the weld nut is directly welded to the cylinder block and is adapted to the high-frequency vibration area at the injector end. The pipe clamp without the nut is locked with the pre-set threaded hole in the cylinder block and is adapted to the stable area at the common rail and oil pump end. The two types of pipe clamps work together to avoid the oil pipe from being worn more severely at the end sealing surface due to high-frequency shaking and to extend the service life of the sealing components.

[0020] (4) The outer protective pipe is treated with "galvanizing + passivation" with a coating thickness of ≥8μm. It can resist the high temperature and humidity in the engine compartment and the salt spray corrosion in marine scenarios, and avoid the pipe wall from rusting and thinning, thus extending the service life of the oil pipe in harsh environments such as marine or heavy commercial vehicles. The oil-resistant rubber sleeves at the pump end and rail end can prevent dust and coolant from entering the connection gap, avoid impurities from wearing the seals, and further improve the structural reliability.

[0021] This utility model discloses a double-layer high-pressure oil pipe for engines, which has the advantages of multi-layer protection, reliable sealing, vibration resistance and corrosion resistance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a double-layer high-pressure oil pipe according to an embodiment of the present invention. Figure 1 ;

[0023] Figure 2 This is a schematic diagram of a double-layer high-pressure oil pipe according to an embodiment of the present invention. Figure 2 ;

[0024] Figure 3 This is a schematic diagram of the pump end and rail end sheaths in an embodiment of this utility model.

[0025] Explanation of reference numerals in the attached drawings: 1-First cylinder double-layer high-pressure oil pipe assembly; 2-Second cylinder double-layer high-pressure oil pipe assembly; 3-Third cylinder double-layer high-pressure oil pipe assembly; 4-Fourth cylinder double-layer high-pressure oil pipe assembly; 5-Pump rail I double-layer high-pressure oil pipe assembly; 6-Pump rail II double-layer high-pressure oil pipe assembly; 7-First double-pipe clamp; 8-Second double-pipe clamp; 9-Injector end nut; 10-Rail end nut; 11-Pump end nut; 12-Pump end sleeve; 13-Rail end sleeve. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] This utility model provides a double-layer high-pressure fuel line for engines, designed to enhance pressure resistance and leak prevention through a double-layer structure. It also utilizes standardized connection components and fixing structures to adapt to the assembly requirements of the fuel pump, common rail, and injectors in the engine fuel system. Figures 1-3 As shown, its specific structure and assembly relationship are as follows:

[0028] I. Overall Composition and Core Components

[0029] This double-layer high-pressure oil tubing includes tubing assemblies, fixing clamps, end connecting nuts, and protective sleeves. Each component is precisely assembled through a modular design, as detailed below:

[0030] 1. Fuel Line Assembly: This assembly comprises six sets of components: cylinder 1 (double-layer high-pressure fuel line assembly 1), cylinder 2 (double-layer high-pressure fuel line assembly 2), cylinder 3 (double-layer high-pressure fuel line assembly 3), cylinder 4 (double-layer high-pressure fuel line assembly 4), pump rail I (double-layer high-pressure fuel line assembly 5), and pump rail II (double-layer high-pressure fuel line assembly 6). These six sets of components correspond to different fuel delivery paths in the engine. Cylinders 1-4 (double-layer high-pressure fuel line assemblies 1-4) connect the common rail to the injectors of each cylinder. Pump rail I and II (double-layer high-pressure fuel line assemblies 5-6) connect the fuel pump to the common rail, forming a complete high-pressure fuel delivery chain: "fuel pump → common rail → injector".

[0031] 2. Fixing Structure: Equipped with a first double-pipe clamp 7 and a second double-pipe clamp 8, both types of clamps employ a "U-shaped clamping + bolt fixing" structure. The clamp spacing is adapted to the pre-set mounting holes in the engine block. The first double-pipe clamp 7 has a "welded nut" structure and can be directly fixed to the engine block by welding, used to fix the fuel line assembly near the injector end. The second double-pipe clamp 8 has a "nutless" structure and requires bolt fixing to the pre-set threaded holes in the engine block, used to fix the fuel line assembly near the common rail and fuel pump end. The combined effect of the two types of clamps restricts the vibration displacement of the fuel lines during engine operation, preventing seal failure caused by high-frequency vibration.

[0032] 3. End Connection Components: These include three types of specialized nuts: injector end nut 9, rail end nut 10, and pump end nut 11. All are manufactured using high-quality carbon structural steel as specified in GB / T 699 standard, and the outer surface of each nut must be permanently marked with the manufacturer's code, the last four digits of the corresponding oil pipe assembly part number, and the production date, facilitating future traceability and maintenance. Injector end nut 9 is compatible with injector interface sizes, rail end nut 10 is compatible with common rail interfaces, and pump end nut 11 is compatible with oil pump interfaces. All three types of nuts have precision threads on their inner walls, with a thread accuracy grade of 6H, ensuring a tight fit with the corresponding connection object.

[0033] 4. Protective sleeves: These include pump end sleeve 12 and rail end sleeve 13, both made of oil-resistant rubber with an oil resistance rating conforming to GB / T 1690 standard. They are respectively fitted onto the outer side of the pump end nut 11 and the rail end nut 10. The inner wall of the protective sleeve fits tightly against the outer wall of the nut, effectively preventing external dust, coolant, and oil from entering the connection gap between the nut and the oil pipe, avoiding wear of the seals due to impurity accumulation. Simultaneously, it buffers vibration and impact between the nut and the connected object, extending the service life of the sealing structure.

[0034] II. Double-layer tubing main structure design

[0035] Each double-layer high-pressure oil pipe assembly adopts a coaxial double-layer structure of "inner delivery pipe + outer protective pipe". The specific parameters and material selection are as follows:

[0036] 1. Inner delivery pipe: As the direct delivery channel for high-pressure fuel, its inner diameter is designed to be 3mm to meet the high-pressure fuel flow requirements of the engine. The outer diameter is 6.35mm. The material can be alloy steel pipe with yield strength ≥800MPa, tensile strength ≥950MPa, and elongation ≥12%, which meets the GB / T 3087 standard. It can withstand a test pressure of ≥30MPa, and the pressure test duration is ≥5min. There should be no leakage, cracking or permanent deformation during the test, which ensures the structural stability under the high oil pressure conditions of the engine.

[0037] 2. Outer Protective Pipe: Sleeve over the inner delivery pipe, made of seamless steel pipe of 20# steel, conforming to GB / T 8163 standard. The gap between its inner diameter and the outer diameter of the inner delivery pipe is controlled at 0.4-0.6mm. This avoids direct friction between the inner and outer pipes during vibration and also forms a "temporary storage space for leaked fuel" in case of leakage from the inner pipe. Furthermore, both ends of the outer protective pipe are welded to the inner steps of the corresponding end nuts. The welding is done using argon arc welding, and non-destructive testing is performed after welding. Penetration testing conforms to JB / T 4730.5 standard to ensure weld sealing and prevent leaked fuel from overflowing from the ends of the outer pipe.

[0038] 3. Cleanliness and Surface Treatment: The cleanliness of the inner bore of each oil pipe assembly must meet the requirement of "maximum particle size ≤ 205μm," and can be tested according to the method specified in GB / T 14039 standard to prevent impurities from entering the fuel system and causing injector blockage. The outer surface of the outer protective pipe is treated with "galvanizing + passivation," conforming to GB / T 13912 standard, with a coating thickness ≥ 8μm, which can effectively improve corrosion resistance and adapt to the harsh environment of high temperature and high humidity in the engine compartment.

[0039] III. Sealing Structure and Connection Method

[0040] To ensure leak-free high-pressure fuel delivery, the double-layer high-pressure fuel line features targeted sealing structures at different connection points, as detailed below:

[0041] 1. Connection between fuel line and injector: A stepped sealing groove is provided on the inner side of the injector end nut 9. A circular sealing ring made of fluororubber is installed in the groove, with a temperature resistance range of -20℃ to 200℃. When the injector end nut 9 is tightened with the injector high-pressure connecting rod, the sealing ring is compressed to a state of "fitting the bottom surface of the sealing groove and tightly wrapping the outer wall of the connecting rod", forming the first seal. At the same time, the end of the inner delivery pipe is machined into a "spherical head", which fits tightly with the "conical sealing seat" of the injector interface, forming the second seal. The double sealing structure can effectively prevent high-pressure fuel from leaking from the connection gap.

[0042] 2. Connection between the oil pipe and the common rail pipe. The inner side of the rail end nut 10 is designed with a "double-layer sealing cavity." The inner side of the cavity mates with the spherical end cap of the inner delivery pipe to form the main seal, while the outer side mates with the "annular sealing boss" of the common rail pipe interface. An "O-ring" made of nitrile rubber, with oil resistance meeting HG / T2579 standards, is installed at the gap between the sealing boss and the rail end nut 10 to form an auxiliary seal. Furthermore, the rail end sleeve 13, after being fitted onto the outside of the rail end nut 10, has its end tightly fitted against the outer wall of the common rail pipe, further preventing external impurities from entering the sealing area and improving sealing reliability.

[0043] 3. Connection between oil pipe and oil pump: The structural design of pump end nut 11 is similar to that of rail end nut 10. However, considering the high oil pressure characteristics of the oil pump outlet (which is usually higher than the common rail pressure), the depth of its inner sealing groove is increased by 0.2mm, and the sealing ring is made of "reinforced fluororubber," which can be reinforced with carbon fiber, increasing the compressive strength by 30%. At the same time, the contact surface between the inner delivery pipe and the oil pump interface is "mirror polished," with a surface roughness Ra≤0.8μm, reducing the contact gap and lowering the risk of leakage.

[0044] IV. Assembly and Usage Requirements

[0045] 1. Assembly Process: Before assembly, check that the markings on each component match their assembly positions. For example, check the connection between the pump rail I double-layer high-pressure oil pipe assembly 5 and the oil pump and common rail I. Clean any impurities from the inner bore of the oil pipe and the connection interface. During assembly, pre-tighten the nuts to the connected objects to a pre-tightening torque of 15-20 N·m. Finally, tighten them to the specified torque using a torque wrench (25-30 N·m for injector end nut 9, 30-35 N·m for rail end nut 10, and 35-40 N·m for pump end nut 11) to ensure full compression of the sealing structure. Finally, place the protective sleeve on the outside of the corresponding nut.

[0046] 2. Inspection Requirements: After assembly, each double-layer high-pressure oil pipe assembly must undergo an "air tightness test" (test pressure 20MPa, pressure holding for 5 minutes, pressure drop ≤0.5MPa) and a "visual inspection" (checking for cracks at welds and damage to the protective sheath). If used in marine engines, a ship inspection certificate conforming to CCS or LR classification society standards must also be provided as per the order requirements to ensure the product complies with marine safety regulations.

[0047] 3. Maintenance Requirements: During use, the pipe clamp fixation status and the integrity of the protective sleeve should be checked regularly, such as every 1000 working hours. If the sleeve is found to be damaged or the nut is loose, the sleeve should be replaced in time and the nut should be tightened again to the specified torque. When the oil pipe assembly reaches its design service life, such as 8000 working hours, it should be replaced as a whole to avoid safety hazards caused by material fatigue.

[0048] The high-pressure oil pipe structure of this utility model has the characteristics of double-layer protection, enhanced sealing, vibration resistance and adaptability to multiple scenarios.

[0049] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A double-layer high-pressure oil pipe for an engine, characterized in that, The system includes a tubing assembly and end connecting nuts. The tubing assembly forms a high-pressure fuel delivery link of "fuel pump-common rail-injector". It includes a first cylinder double-layer high-pressure tubing assembly (1), a second cylinder double-layer high-pressure tubing assembly (2), a third cylinder double-layer high-pressure tubing assembly (3), and a fourth cylinder double-layer high-pressure tubing assembly (4) for connecting the common rail to the injectors of each cylinder, and a pump rail I double-layer high-pressure tubing assembly (5) and a pump rail II double-layer high-pressure tubing assembly (6) for connecting the fuel pump to the common rail. The tubing assembly has a coaxial double-layer structure, including an inner layer and an outer layer, with a gap between the inner and outer layers. The end connecting nuts include an injector end nut (9), a rail end nut (10), and a pump end nut (11).

2. The double-layer high-pressure oil pipe for an engine according to claim 1, characterized in that, The inner layer is an alloy steel pipe, the outer layer is a seamless steel pipe, the gap is 0.4-0.6mm, and the surface of the oil pipe assembly is provided with a zinc passivation layer with a coating thickness of greater than or equal to 8μm; the cleanliness of the inner hole of the oil pipe assembly meets the requirement that the maximum particle size is less than or equal to 205μm.

3. The double-layer high-pressure oil pipe for an engine according to claim 1, characterized in that, It also includes a fixing clamp, which includes a first double pipe clamp (7) and a second double pipe clamp (8). Both types of clamps are U-shaped clamps and bolts for fixing, and are adapted to the preset mounting holes of the engine cylinder block. The first double pipe clamp (7) is a structure with a welded nut that can be fixed to the engine cylinder block by welding, and the second double pipe clamp (8) is a structure without a nut that needs to be bolted to fit the preset threaded hole of the cylinder block.

4. The double-layer high-pressure oil pipe for an engine according to claim 1, characterized in that, It also includes protective sleeves, which include pump end sleeve (12) and rail end sleeve (13), both made of oil-resistant rubber. The pump end sleeve (12) is fitted on the outside of the pump end nut (11), and the rail end sleeve (13) is fitted on the outside of the rail end nut (10). The inner walls of both are tightly fitted to the outer walls of the corresponding nuts.

5. The double-layer high-pressure oil pipe for an engine according to claim 1, characterized in that, The end connecting nut is made of carbon structural steel and the inner wall thread accuracy grade is 6H; the injector end nut (9) is adapted to the injector interface size, the rail end nut (10) is adapted to the common rail pipe interface, the pump end nut (11) is adapted to the oil pump interface, and the inner sealing groove depth of the pump end nut (11) is increased by 0.2mm compared with the rail end nut (10).

6. The double-layer high-pressure oil pipe for an engine according to claim 1, characterized in that, The connection between the oil pipe assembly and the injector adopts a double sealing structure of spherical head fitting and fluororubber sealing ring; the end of the inner delivery pipe is processed into a spherical head, which fits tightly with the conical sealing seat of the injector interface to form the main seal; the inner side of the injector end nut (9) is provided with a stepped sealing groove, and a fluororubber annular sealing ring with a temperature resistance range of -20℃ to 200℃ is installed in the groove to form an auxiliary seal.

7. The double-layer high-pressure oil pipe for an engine according to claim 1, characterized in that, The connection between the oil pipe assembly and the common rail pipe adopts a double sealing structure of spherical head fitting and O-ring rubber seal; the spherical head at the end of the inner delivery pipe cooperates with the inner sealing cavity of the rail end nut (10) to form the main seal; at the gap between the outer side of the inner sealing cavity of the rail end nut (10) and the annular sealing boss of the common rail pipe interface, a nitrile rubber O-ring seal is installed to form an auxiliary seal.

8. The double-layer high-pressure oil pipe for an engine according to claim 1, characterized in that, The connection between the oil pipe assembly and the oil pump adopts a double sealing structure of mirror polishing and reinforced fluororubber sealing ring; the mating surface of the inner delivery pipe and the oil pump interface is mirror polished and the surface roughness Ra is less than or equal to 0.8μm; the inner sealing groove of the pump end nut (11) is equipped with a reinforced fluororubber sealing ring with added carbon fiber and improved compressive strength.

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