Connecting structure of plastic flange parts for air inlet system of aero-engine

Abstract

The invention belongs to the field of mechanical parts, and relates to a connecting structure of a plastic flange part for an aero-engine air inlet system, which comprises well-designed screw hole layout, high-precision screw torque loading control, a self-locking gasket assembly and a structural stress release design adapted to high and low temperature environments. And the stability, the sealing performance and the environmental adaptability of the connecting structure are remarkably improved. The structure not only effectively solves the problem of stress concentration of the plastic part in high and low temperature environments, but also enhances the sealing performance and stress dispersion capability of the connection through the innovative design of the gasket assembly, thereby ensuring the reliable operation of the air inlet system of the aero-engine under various working conditions. The air inlet system has the beneficial effects that the safety and durability of the air inlet system of the aero-engine are remarkably improved, the maintenance cost is reduced, and powerful technical support is provided for development of the aviation industry.

Description

Technical Field

[0001] The invention belongs to the field of mechanical parts and relates to a connection structure of plastic flange parts for an aero-engine air intake system. Background Art

[0002] With the continuous development and growth of the UAV industry and low-altitude economy at home and abroad, aviation piston engines are widely equipped in UAVs due to their unique advantages. This type of power system is not only compact in structure, high in power-to-weight ratio, and economical, but also a complex technology that integrates multiple disciplines and professions. In order to achieve the complex comprehensive performance of its design, many parts of its power system will adopt different structures, materials and processing technologies, but there are differences in the relative expansion of parts of different materials, and the matching accuracy of the system will change with the change of ambient temperature, and even the structural parts will be damaged. However, the engine will face the test of complex and changeable environment with different flight altitudes, flight areas and weather conditions, mainly due to the influence of high and low temperature alternating loads. Nylon plastic parts with higher surface hardness are more sensitive to stress in low temperature environments, and the size of brittle materials should be controlled as much as possible.

[0003] Pursuing lightweight design principles is an important indicator of aviation power systems, and highly integrated precision power systems have high requirements for connection reliability. However, plastic structural parts with advantages such as low thermal conductivity, light weight and easy molding can not only ensure the adaptability of precision transmission systems to changes in ambient temperature to a certain extent, but also improve the power-to-weight ratio of engines. Therefore, engineering plastics are widely used in the design of parts in the aerospace field due to their many advantages. However, such parts use conventional screw fasteners to match metal structural parts, and the complex flight environment under high and low temperature will greatly shorten their service life. Usually, the nylon shell in the assembly is connected with conventional screw assemblies and placed at an ambient temperature of -10℃ to 0℃. Due to the existence of local stress, cracks of varying degrees will occur in about 10 hours. Therefore, a series of inherent characteristics of plastic structural parts themselves determine that the conventional screw pre-tightening connection and combination connection process is no longer applicable. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a connection structure for plastic flange parts for aircraft engine intake systems, to solve the problem of safe use of plastic parts in complex flight environments, to avoid excessive tightening torque during component installation, and to avoid local squeezing of plastic parts by gasket edges, leading to damage to the plastic parts.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a connection structure of plastic flange parts for an aircraft engine intake system, comprising a plastic flange cover, a screw, a gasket assembly and a base, the plastic flange cover having at least three screw holes for the screws to pass through, the base having threaded holes corresponding to the plastic flange cover, the screws passing through the screw holes of the plastic flange cover and being screwed into the threaded holes of the base, for fastening the plastic flange cover to the base, the gasket assembly being located between the screw head and the plastic flange cover, for dispersing the pressure of the screw head on the plastic flange cover and preventing the screw from loosening; the contact surface between the screw head and the gasket assembly is a stepped surface, and the contact surface between the gasket assembly and the plastic flange cover is provided with an O-ring to ensure sealing and buffering.

[0006] Optionally, the number of screw holes of the plastic flange cover is 3 or 5, and the wall thicknesses corresponding to the screw holes are different. The screw holes are divided into stepped holes and through holes, and are designed to be continuously and evenly distributed along the circumference of the flange. Under low temperature conditions, the freedom of all through holes is released, and under high temperature, the expansion of the stepped holes is smaller than that of the through holes, so as to adapt to the shrinkage differences of plastic parts at different temperatures.

[0007] Optionally, both ends of the through hole and the small round hole of the stepped hole need to be chamfered, and the special force-bearing mode of the gasket assembly can avoid stress concentration on the surface of the plastic part during the assembly process.

[0008] Optionally, the screw hole positioning dimensions of the plastic flange cover have an upper deviation design to avoid stress damage in a low temperature environment and to improve the assembly accuracy of the flange while avoiding stress concentration in a high temperature environment.

[0009] Optionally, the gasket assembly includes a gasket, an inner O-ring and an outer O-ring, the inner O-ring and the outer O-ring are respectively arranged between the gasket and the plastic flange cover, and two O-grooves are opened at the bottom of the gasket; the upper surface of the gasket is stepped to form a stepped surface contact with the screw head.

[0010] Optionally, the gasket is made of stainless steel, and the roughness of the contact surface between the gasket and the screw is controlled, and a solid lubricant is applied to the contact portion between the screw head and the gasket to prevent relative sliding between the gasket assembly and the plastic flange cover during the screw tightening process.

[0011] Optionally, the surface roughness of the bottom surface of the screw head and the topmost surface of the step gasket is controlled below 0.8 microns.

[0012] Optionally, the stress distribution of the thread pair between the screw and the base in the working environment should be relatively uniform, the screw material is stainless steel, and the thread matching accuracy is medium matching accuracy at the assembly environment temperature (20±5)°C.

[0013] Optionally, the surface roughness of the thread pair is controlled below 1.6 microns to avoid jamming under high and low temperature environments.

[0014] The beneficial effects of the present invention are:

[0015] 1) Improve connection stability: Through the structural stress release design, the present invention effectively solves the connection failure and parts safety problems caused by stress concentration of plastic flange parts in high and low temperature environments, and significantly improves the stability and reliability of the connection structure.

[0016] 2) Enhanced sealing and stress dispersion: The innovative application of self-locking gasket components not only enhances the sealing performance of the connection, but also reduces the stress concentration phenomenon in the metal-plastic connection area by dispersing stress, thereby improving the overall strength and durability of the connection structure.

[0017] 3) Strong adaptability: The connection structure design of the present invention fully considers the influence of high and low temperature environments. Through sophisticated design and innovative component application, the structure can maintain good connection performance and stability under different temperature conditions, and has strong environmental adaptability and broad application prospects.

[0018] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0020] Figure 1 It is the overall connection schematic diagram of the present invention;

[0021] Figure 2 It is a schematic diagram of the connection method of the plastic flange cover of the present invention;

[0022] Figure 3 is a schematic diagram of a gasket of the present invention;

[0023] Figure 4 for Figure 3 AA section view;

[0024] Figure 5 for Figure 4 Left view of;

[0025] Figure 6 It is a schematic diagram of the plastic flange cover of the present invention;

[0026] Figure 7 It is a schematic diagram of a screw of the present invention.

[0027] Reference numerals: plastic flange cover 1 , screw 2 , gasket assembly 3 , gasket 31 , inner O-ring 32 , outer O-ring 33 , base 4 , through hole 5 , stepped hole 6 . DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0029] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0030] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0031] See also Figure 1 to Figure 7 , which is a connection structure of plastic flange parts for an aircraft engine intake system, specifically comprising a plastic flange cover 1, a screw 2, a gasket assembly 3 and a base 4.

[0032] Plastic flange cover 1: Figure 6 As shown, the plastic flange cover 1 has three screw holes, one of which is a through hole 5 and the other two are stepped holes 6. These screw holes are designed continuously along the circumference of the flange to adapt to the shrinkage differences of plastic parts at different temperatures. Chamfers are provided at both ends of the threaded hole of the through hole 5 to avoid stress concentration on the surface of the plastic part during assembly. The positioning dimensions of the screw holes have an upper deviation design to avoid stress damage in low temperature environments and avoid stress concentration in high temperature environments.

[0033] In this embodiment, the material is transparent PC.

[0034] Screw 2: As Figure 7 As shown, the screw 2 is made of stainless steel, and the surface roughness of the bottom surface of the head and the surface of the gasket component in contact therewith are controlled to be less than 0.8 microns. The screw 2 passes through the screw hole of the plastic flange cover 1 and is screwed into the threaded hole of the base 4 to fasten the plastic flange cover 1 to the base 4.

[0035] In this embodiment, the stress distribution of the thread pair between the screw 2 and the base 4 is relatively uniform under the working environment, the thread matching accuracy is medium at the assembly environment temperature (20±5)°C, and the surface roughness of the thread pair is controlled below 1.6 microns to avoid sticking under high and low temperature environments.

[0036] In this embodiment, the screw thread is half-thread, which prevents the connected plastic flange from expanding under high temperature conditions and being scratched by the thread.

[0037] Gasket assembly 3: As Figures 3 to 5 As shown, the gasket assembly 3 includes a gasket 31, an inner O-ring 32 and an outer O-ring 33. The gasket 31 is made of stainless steel, and it is forbidden to use carbon steel nickel plating to reduce the surface accuracy. Its upper surface is stepped to form a stepped surface contact with the head of the screw 2. The inner O-ring 32 and the outer O-ring 33 are respectively arranged between the gasket 31 and the plastic flange cover 1, and two O-shaped grooves are opened at the bottom of the gasket 31 to ensure sealing and buffering. The roughness of the contact surface between the gasket 31 and the screw 2 is controlled, and a solid lubricant is applied to the contact part between the head of the screw 2 and the gasket 31 to prevent relative sliding between the gasket assembly 3 and the plastic flange cover 1.

[0038] In this embodiment, the solid lubricant may be graphite.

[0039] In this embodiment, the roughness of the upper surface of the gasket is controlled to be below Ra0.8, and the roughness of the lower surface is controlled to be within Ra1.6.

[0040] In this embodiment, the O-ring may use fluororubber as a base material to ensure that it has stable mechanical properties and service life in an environment of -50°C to 100°C.

[0041] Base 4: Base 4 has threaded holes corresponding to the plastic flange cover 1, which are used to cooperate with the screws 2 to achieve a fastening effect. The material and structural design of base 4 must meet the working environment and performance requirements of the aircraft engine intake system.

[0042] In this embodiment, the base thread is a metal thread, preferably brass or stainless steel.

[0043] In this embodiment, the base thread accuracy should be medium accuracy, and the surface roughness should be controlled within Ra1.6.

[0044] Assembly process:

[0045] The inner O-ring 32 and the outer O-ring 33 are respectively installed in the corresponding O-ring grooves of the gasket 31 to form a gasket assembly 3.

[0046] Place the gasket assembly 3 over the screw hole of the plastic flange cover 1 , and ensure that the inner O-ring 32 and the outer O-ring 33 are in close contact with the plastic flange cover 1 .

[0047] The screw 2 is passed through the screw hole of the plastic flange cover 1 and screwed into the threaded hole of the base 4 until the head of the screw 2 is in close contact with the gasket 31 of the gasket assembly 3 .

[0048] Tighten screw 2 according to the specified tightening torque to ensure the tightness and sealing of the connection structure.

[0049] In this embodiment, during the implementation of the technology, the preload force required for the connection is ensured by adjusting the compression amount of the O-ring.

[0050] Through actual testing and application verification, the connection structure of the present invention has shown excellent performance in the air intake system of an aircraft engine. Specifically, it is embodied in:

[0051] The connection stability is significantly improved, effectively solving the problem of connection failure caused by stress concentration in plastic flange parts under high and low temperature environments.

[0052] The sealing performance is good and there is no gas leakage, which ensures the normal operation of the engine.

[0053] The stress dispersion effect is significant, which reduces the stress concentration phenomenon in the connection area between metal and plastic and improves the overall strength and durability of the connection structure.

[0054] It has strong adaptability and can maintain good connection performance and stability under different temperature conditions, meeting the stringent requirements of aircraft engine intake systems.

[0055] In summary, the connection structure of plastic flange parts for aircraft engine intake systems of the present invention has significant technical advantages and broad application prospects.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A connection structure of plastic flange parts for an aircraft engine intake system, characterized in that: The invention comprises a plastic flange cover, a screw, a washer assembly and a base, wherein the plastic flange cover has at least three screw holes for screws to pass through, the base has threaded holes corresponding to the plastic flange cover, the screws pass through the screw holes of the plastic flange cover and are screwed into the threaded holes of the base, so as to fasten the plastic flange cover to the base, and the washer assembly is located between the screw head and the plastic flange cover, so as to disperse the pressure of the screw head on the plastic flange cover and prevent the screw from loosening; The contact surface between the screw head and the washer assembly is a stepped surface, and the contact surface between the washer assembly and the plastic flange cover is provided with an O-ring to ensure sealing and buffering.

2. The connection structure of plastic flange parts for an aircraft engine air intake system according to claim 1, characterized in that: The number of screw holes of the plastic flange cover is 3 or 5, and the wall thickness corresponding to the screw holes is different. The screw holes are divided into stepped holes and through holes, which are designed to be continuously and evenly distributed along the circumference of the flange. The freedom of all through holes is released under low temperature conditions. At high temperatures, the expansion of the stepped holes is smaller than that of the through holes to adapt to the shrinkage differences of plastic parts at different temperatures.

3. The connection structure of plastic flange parts for an aircraft engine air intake system according to claim 2, characterized in that: Both ends of the through holes and stepped holes need to be chamfered, and the special force-bearing mode of the gasket assembly can avoid stress concentration on the surface of the plastic parts during the assembly process.

4. The connection structure of plastic flange parts for an aircraft engine air intake system according to claim 1, characterized in that: The screw hole positioning dimensions of the plastic flange cover have an upper deviation design to avoid stress damage in low temperature environments and to avoid stress concentration in high temperature environments while improving the positioning accuracy of the flange end cover.

5. The connection structure of plastic flange parts for an aircraft engine air intake system according to claim 1, characterized in that: The gasket assembly includes a gasket, an inner O-ring and an outer O-ring, wherein the inner O-ring and the outer O-ring are respectively arranged between the gasket and the plastic flange cover, and two O-grooves are opened at the bottom of the gasket; The upper surface of the gasket is arranged in steps to form a step surface contact with the screw head.

6. The connection structure of plastic flange parts for an aircraft engine air intake system according to claim 5, characterized in that: The gasket is made of stainless steel, and the roughness of the contact surface between the gasket and the screw is controlled. At the same time, solid lubricant is applied to the contact portion between the screw head and the gasket to prevent relative sliding between the gasket assembly and the plastic flange cover during the assembly process.

7. The connection structure of plastic flange parts for an aircraft engine air intake system according to claim 6, characterized in that: The surface roughness of the bottom surface of the screw head and the top surface of the step gasket is controlled below 0.8 microns.

8. The connection structure of plastic flange parts for an aircraft engine air intake system according to claim 1, characterized in that: The stress distribution of the thread pair between the screw and the base in the working environment should be relatively uniform. The screw is made of stainless steel, and the thread matching accuracy is medium at the assembly environment temperature (20±5)℃.

9. The connection structure of plastic flange parts for an aircraft engine air intake system according to claim 8, characterized in that: The surface roughness of the thread pair is controlled below 1.6 microns to avoid jamming in high and low temperature environments.

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