Borescope plug with heat insulation, cooling and aligning functions

Abstract

The invention provides a borescope plug with heat insulation, cooling and aligning functions, and belongs to the field of aero-engine structural design, the borescope plug comprises a plug cylinder, a mounting hole is formed in the plug cylinder, an annular interlayer is arranged on the outer side wall of the plug cylinder, a threaded section used for being matched with a casing threaded hole is arranged on the outer side of the annular interlayer, and the mounting hole is formed in the mounting hole. An air guide hole communicated with the mounting hole is formed in the end head of the plug cylinder body; the heat insulation cotton is arranged in the annular interlayer and is limited through a blocking ring; the spring, the round plug and the plug body are sequentially arranged in the mounting hole of the plug barrel and limited in the mounting hole through the limiting clamping ring; wherein the plug body is of a double-end ball structure, one side of the plug body forms a ball joint structure under the limiting action of the plug barrel and the round plug, the other side of the plug body and the guide blade observation hole form a ball cone sealing structure, and cold air is introduced into the mounting hole through the air guide hole, so that the temperature of the spring is reduced.

Description

Technical Field

[0001] The present application belongs to the field of aircraft engine structure design, and in particular relates to a borescope plug with heat insulation cooling and centering functions. Background Art

[0002] During the service of aircraft engines, borescope inspections are performed regularly on the engine rotor and stator blades and other flow path parts to timely detect and track the damage to the flow path parts. To ensure the accessibility of the borescope, an observation hole is set on the engine casing. When the engine is working normally, the observation hole is blocked with a plug to prevent flow path gas leakage.

[0003] There are two common types of borescope plugs on current aircraft engine turbine cases: one is a pin-type plug and the other is a compression spring-type plug. The former inserts the plug pin into the observation hole to block the flow gas; the latter is a plug that is pressed tightly against the observation hole under the action of a compression spring to prevent gas leakage.

[0004] like Figure 1 The pin-rod plug structure schematic diagram shown in the figure shows that due to the non-concentricity of the observation holes of the casing 12, guide vanes 13 and other parts, in order to ensure the smooth assembly of the plug 11, the pin part of the plug 11 and the observation hole are designed to be clearance-matched, and the clearance is generally not less than 0.5mm. Due to the existence of the clearance, gas leakage is inevitable, the sealing effect is poor, and the working temperature of the casing 12 and other parts will increase, affecting the service life.

[0005] like Figure 2 As shown in the schematic diagram of the compression spring plug structure, the temperature of the high-temperature alloy cylindrical spring 24 for long-term stable operation is below 500°C, which cannot adapt to the higher operating temperature of the turbine components. After working in a high-temperature environment for a period of time, the spring 24 will relax, and the sealing effect of the plug 21 will weaken. It needs to be replaced regularly, resulting in a high replacement rate of parts. In addition, the traditional compression spring plug has poor self-aligning function. When the concentricity of the observation holes of the casing 21 and the guide vane 22 is large, it is easy to get stuck and there is a problem of inability to completely seal. Summary of the invention

[0006] The purpose of the present application is to provide a borescope plug with heat insulation cooling and centering functions to solve or alleviate at least one problem in the background technology.

[0007] The technical solution of the present application is: a borescope plug with heat insulation cooling and centering functions, comprising:

[0008] A plug cylinder, wherein a mounting hole is provided inside the plug cylinder, an annular interlayer is provided on the outer wall of the plug cylinder, a threaded section for cooperating with a threaded hole of a casing is provided on the outer side of the annular interlayer, and an air bleed hole communicating with the mounting hole is provided at the end of the plug cylinder;

[0009] Thermal insulation cotton, which is arranged in the annular interlayer and is limited by a blocking ring;

[0010] A spring, a round plug and a plug body, wherein the spring, the round plug and the plug body are sequentially arranged in the mounting hole of the plug cylinder and are limited in the mounting hole by a limiting collar;

[0011] Among them, the plug body is a double-headed ball structure, one side of the plug body forms a ball joint structure under the limiting action of the plug cylinder and the round plug, and the other side of the plug body forms a spherical cone sealing structure with the guide blade observation hole, and cold air is introduced into the mounting hole through the air duct, thereby reducing the temperature of the spring.

[0012] In an optional embodiment of the present application, the annular interlayer is obtained by electrospark machining.

[0013] In an optional embodiment of the present application, the material of the thermal insulation wool is selected from alkali-free glass wool or high-silica wool.

[0014] In an optional implementation manner of the present application, the plugging ring and the plug cylinder are fixed by welding.

[0015] In an optional implementation manner of the present application, the spring is a cylindrical spring.

[0016] In an optional embodiment of the present application, in the double spherical structure of the plug body, the spherical head structure located in the plug cylinder is a spherical structure larger than a semicircle, and the spherical head structure used to seal the guide blade observation hole is a spherical structure smaller than a semicircle.

[0017] In an optional embodiment of the present application, the mounting holes of the round plug, the plug body and the plug cylinder are clearance-fitted, and the clearance is no greater than 0.05 mm.

[0018] In an optional embodiment of the present application, the guide blade observation hole that cooperates with the ball head structure on one side of the plug body is provided with a cone angle, and the cone angle α>ψ, where ψ is the friction angle, ψ=tanμ, and μ is the static friction coefficient of the contact surface.

[0019] The borescope plug provided in the present application can reduce the heat conduction of the external gas of the borescope plug to the spring in the mounting hole of the plug cylinder, strengthen the heat exchange of the mounting hole where the spring is located, reduce the temperature in the cavity, and effectively prevent the gas from entering the mounting hole where the spring is located. Ultimately, it can effectively reduce the working temperature of the spring, ensure the long-term working stability of the spring, and can adapt to the situation where the casing observation hole and the guide vane observation hole are obviously not concentric. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0021] Figure 1 It is a schematic diagram of the pin-type plug structure in the prior art.

[0022] Figure 2 It is a schematic diagram of the structure of a compression spring plug in the prior art.

[0023] Figure 3 This is a schematic diagram of the borescope plug structure of the present application.

[0024] Figure 4 Schematic diagram of installing thermal insulation cotton on the plug cylinder in this application.

[0025] Figure 5 This is a schematic diagram of the exploded state of the borescope plug structure in this application.

[0026] Figure 6 This is a schematic diagram of the borescope plug in this application being installed on the casing.

[0027] Figure 7 Schematic diagram of the cooling process of the borescope plug in this application.

[0028] Figure 8 Schematic diagram of the borescope plug centering process in this application.

[0029] Fig. 9 Schematic diagram of the contact angle between the plug body and the guide blade in this application.

[0030] Reference numerals:

[0031] 30-Bore detector plug

[0032] 31-plug cylinder

[0033] 311-Annular sandwich

[0034] 312-thread segment

[0035] 313-Mounting hole

[0036] 314-Air vent

[0037] 315-Ring groove

[0038] 32-Spring

[0039] 33-Insulation cotton

[0040] 34-Blocking Circle

[0041] 35-Round plug

[0042] 36-Plug body

[0043] 37-Snap ring

[0044] 41-Receiver

[0045] 42-Guide blades DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0047] In order to ensure that the compression spring of the plug can work stably for a long time under a higher working temperature environment, ensure that the sealing effect of the plug is long-term and effective, and at the same time make the plug have a good centering function, when there is obvious eccentricity between the casing and the guide vane observation holes, the assemblability and gas sealing effect of the plug can also be guaranteed. The present application provides a borescope plug with thermal insulation cooling and centering functions.

[0048] like Figure 3 As shown, the borescope plug 30 provided in the present application includes: a plug cylinder 31, a spring 32, thermal insulation cotton 33, a plug ring 34, a round plug 35, a plug body 36 and a retaining ring 37.

[0049] like Figure 4 As shown, the plug cylinder 31 is provided with a mounting hole 313 inside, and an annular groove 315 is provided on the inner wall surface of the end of the mounting hole 313. The outer wall of the plug cylinder 31 is processed into an annular sandwich 311 by a specific processing method, and the processing method can be selected from electric spark processing. The heat insulation cotton 33 is filled in the annular sandwich 311, and the plugging ring 34 is arranged at the outlet of the annular sandwich 311, which can be fixed to the plug cylinder 31 by fillet welding H, thereby forming a heat insulation structure of the mounting hole 313.

[0050] In some embodiments of the present application, the material of the thermal insulation wool 33 may be alkali-free glass wool, high-silica wool, etc.

[0051] The outer side of the annular interlayer 311 of the plug cylinder 31 is provided with a threaded section 312, which can be used to cooperate with the observation hole thread on the casing (not shown). Further, the top of the plug cylinder 31 is provided with an air inlet 314 connected to the mounting hole 313, which can introduce cooling air from the outside.

[0052] In some embodiments of the present application, the spring 32 is a cylindrical spring.

[0053] The plug body 36 is a double ball head structure. One end of the plug body 36 is set under the limiting action of the plug cylinder 31 and the round plug 35 to form a ball joint structure. The roughness of the ball joint matching surface is controlled within Ra0.8 to reduce the friction resistance of the joint movement. The other end of the plug body 36 is used to block the guide blade observation hole. In the preferred embodiment of the present application, the ball head structure located in the plug cylinder 31 is a spherical structure larger than a semicircle, and the ball head structure used to block the guide blade observation hole is a spherical structure smaller than a semicircle.

[0054] As shown in Figure 5, the spring 32, the round plug 35 and the plug body 36 are sequentially installed into the mounting hole 313 in the plug cylinder 31, and the spring 32, the round plug 35 and the plug body 36 are limited in the mounting hole 313 by the retaining ring 7 installed in the annular groove 315 at the end of the plug cylinder 31.

[0055] In the present application, the clamping ring 37 is an open structure and can be installed in the annular groove 315 of the plug cylinder 31 by shrinking the outer diameter through an auxiliary tool.

[0056] In the preferred embodiment of the present application, in order to ensure the freedom of movement of the ball joint of the plug body 36 and prevent the gas from entering the mounting hole 313 where the spring 32 is located, the round plug 35, the plug body 36 and the inner hole of the plug cylinder 31 are matched with a small clearance, and the matching clearance is selected within 0.05mm.

[0057] like Figure 6 As shown, the outer wall of the plug cylinder 1 is provided with a threaded section 312, and the top end is a hexagonal head structure. During assembly, the borescope plug 30 is screwed into the threaded hole of the casing 41 by a socket wrench. After the borescope plug 30 is assembled in place, the plug body 36 moves up and the spring 32 is compressed. Under the action of the spring 32, the lower end of the plug body 36 is pressed against the observation hole of the guide blade 42 to form a spherical-conical contact seal.

[0058] It should be noted that the size and compression of the spring 32 should be selected to ensure that the plug body 36 is not pushed open by the gas pressure in the flow channel.

[0059] like Figure 7As shown, the borescope plug provided by the present application can reduce the heat conduction of the external gas of the borescope plug to the spring 32 in the mounting hole 313 by setting an annular interlayer 311 on the outside of the plug cylinder 1, and the annular interlayer 311 is equipped with heat insulation cotton 33, which can reduce the heat conduction of the external gas of the borescope plug to the spring 32 in the mounting hole 313; by setting the air duct 314 at the top of the plug cylinder 31, the external engine air with a lower external temperature can be introduced, thereby strengthening the heat exchange of the mounting hole where the spring 32 is located and reducing the temperature in the cavity; by the round plug 35, the plug body 36 and the mounting hole 313 in the plug cylinder 31 with a small gap, the gas can be effectively prevented from entering the mounting hole where the spring 32 is located. Through the above-mentioned combined effect, the working temperature of the spring 32 can be effectively reduced, and the long-term working stability of the spring 32 can be ensured.

[0060] like Figure 8 As shown, the plug body 36 in the borescope plug 30 of the present application is a double ball head structure, the upper end of which forms a ball joint structure under the limiting action of the plug cylinder 31 and the round plug 35, and the lower end forms a ball-cone sealing structure with the guide vane observation hole. When the casing 41 and the guide vane 42 observation holes are not concentric, during the process of screwing the borescope plug 30, the lower end of the plug body 36 first partially contacts the guide vane 42 observation hole. When the borescope plug 30 continues to be screwed in, under the action of the tightening force, the ball joint at the upper end of the plug body 36 rotates, so that the lower end of the plug body 36 is completely in contact with the guide vane 42 observation hole to form a ball-cone seal. Since the ball joint is a rolling friction pair, it has small rotation resistance, strong self-aligning effect, and is not easy to get stuck, and can adapt to the situation where the casing observation hole and the guide vane observation hole are obviously not concentric.

[0061] As shown in Figure 9, during the tightening process of the borescope plug 30, in order to ensure that the spherical surface of the plug body 36 slides smoothly on the conical surface of the observation hole of the guide vane 42, the inclination angle α of the conical surface of the observation hole of the guide vane 42 should be reasonably selected, and the influence of the contact surface friction angle ψ should be considered. If the angle α of the conical surface of the observation hole is smaller than the friction angle ψ, a self-locking effect will occur, causing the spherical surface of the plug body 36 to be stuck on the conical surface of the observation hole, so in this application α>ψ. The friction angle calculation formula is ψ=tanμ, where μ is the static friction coefficient of the contact surface. For example, in one embodiment of the present application, the static friction coefficient of the contact surface is taken as 1 based on experience, the friction angle ψ is 45°, and the inclination angle α of the conical surface of the guide vane can be 55°.

[0062] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A borescope plug with heat insulation cooling and centering functions, characterized in that: include: A plug cylinder, wherein a mounting hole is provided inside the plug cylinder, an annular interlayer is provided on the outer wall of the plug cylinder, a threaded section for cooperating with a threaded hole of a casing is provided on the outer side of the annular interlayer, and an air bleed hole communicating with the mounting hole is provided at the end of the plug cylinder; Thermal insulation cotton, which is arranged in the annular interlayer and is limited by a blocking ring; A spring, a round plug and a plug body, wherein the spring, the round plug and the plug body are sequentially arranged in the mounting hole of the plug cylinder and are limited in the mounting hole by a limiting collar; Among them, the plug body is a double-headed ball structure, one side of the plug body forms a ball joint structure under the limiting action of the plug cylinder and the round plug, and the other side of the plug body forms a spherical cone sealing structure with the guide blade observation hole, and cold air is introduced into the mounting hole through the air duct, thereby reducing the temperature of the spring.

2. The borescope plug with heat insulation, cooling and centering functions as claimed in claim 1, characterized in that: The annular sandwich is obtained by electrospark machining.

3. The borescope plug with heat insulation, cooling and centering functions as claimed in claim 1, characterized in that: The material of the heat insulation wool is selected from alkali-free glass wool or high-silica wool.

4. The borescope plug with heat insulation, cooling and centering functions as claimed in claim 1, characterized in that: The plugging ring and the plug cylinder are fixed by welding.

5. The borescope plug with heat insulation, cooling and centering functions as claimed in claim 1, characterized in that: The spring is a cylindrical spring.

6. The borescope plug with heat insulation, cooling and centering functions as claimed in claim 1, characterized in that: In the double spherical structure of the plug body, the spherical head structure located in the plug cylinder is a spherical structure larger than a semicircle, and the spherical head structure used to seal the guide blade observation hole is a spherical structure smaller than a semicircle.

7. The borescope plug with heat insulation, cooling and centering functions as claimed in claim 1, characterized in that: The mounting holes of the round plug, the plug body and the plug cylinder are matched with clearance, and the clearance is no greater than 0.05 mm.

8. The borescope plug with heat insulation, cooling and centering functions as claimed in claim 6 or 7, characterized in that: The guide blade observation hole matched with the ball head structure on one side of the plug body is provided with a cone angle, wherein the cone angle α>ψ, wherein ψ is the friction angle, ψ=tanμ, and μ is the static friction coefficient of the contact surface.

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