Aircraft integral drive generator pressure switch dismounting tool

Abstract

The utility model provides a kind of aircraft overall drive generator pressure switch dismounting tool, belong to aviation maintenance tool technical field, the tool includes main part, its bottom is equipped with the clamping space for accommodating pressure switch component end lead protective sleeve, its upper end is equipped with the installation site for screw rod installation;Screw rod, detachably installed on the main part, extend along vertical direction, provide the guiding and stroke space of upper and lower sliding for rammer;Rammer, sleeve set on the screw rod can move up and down along the screw rod;At least one screw, with right thread mode installed on the main part, end extends into the clamping space, for providing clamping force by screwing.The dismounting tool provided by the utility model can efficiently and safely pull out pressure switch component from overall drive generator shell without damaging pressure switch component and other components of overall drive generator.

Description

Technical Field

[0001] This utility model relates to the field of aviation maintenance tool technology, and in particular to a tooling for disassembling the pressure switch of an aircraft integral drive generator. Background Technology

[0002] In modern civil aviation, the generators installed in mainstream fleets are all integral drive generators (IDGs). IDGs are driven by engine accessory gearboxes to provide power to the entire aircraft, meeting the power needs of flight control, lighting, avionics, and galley operations. The normal operation of IDGs is directly related to flight safety; therefore, monitoring their status is crucial.

[0003] To ensure the normal operation of the IDG, the manufacturer incorporated a pressure monitoring system during the production and design phase. This system continuously monitors the internal lubricating oil pressure to determine the IDG's performance. A pressure switch assembly, installed on a housing pipeline within the IDG, senses the lubricating oil pressure within the housing pipeline and transmits the pressure signal to the aircraft control mechanism via the on / off state of the switch, thus enabling real-time monitoring of the IDG's pressure status.

[0004] The core component of the pressure switch assembly is the pressure switch itself, which needs to be constantly immersed in lubricating oil during operation. During frequent takeoffs and landings, the IDG (Independent Aircraft Generator) continuously undergoes cycles of starting, running, and stopping, causing the pressure switch to actuate frequently. This high-frequency cyclical operation results in a relatively high failure rate for the pressure switch. Once the pressure switch malfunctions, maintenance personnel need to disassemble the pressure switch assembly for repair or replacement. Therefore, disassembly of the pressure switch assembly is a frequently performed and high-frequency operation in the routine maintenance and repair of the IDG.

[0005] The pressure switch assembly is sealed to the IDG housing piping via a sealing ring. Over time, this sealing ring can age and loosen, significantly increasing friction between the ring and the housing when disassembling and removing the pressure switch assembly, making it difficult to remove normally. Existing process manuals (such as the relevant sections of the Aircraft Maintenance Manual (AMM)) only vaguely state "disassemble the pressure switch assembly" without providing specific disassembly methods or operating procedures, nor offering any guidance on specialized tools.

[0006] In actual maintenance, the pressure switch assembly is fully embedded inside the IDG housing, with its upper surface located below the IDG housing end face. During installation, a retaining ring is installed at the upper end of the pressure switch, below the IDG housing end face, to secure the pressure switch assembly in place. During disassembly, maintenance personnel need to remove the retaining ring first. However, after removing the retaining ring, the outer surface of the pressure switch assembly is basically flush with or slightly lower than the IDG housing end face, offering no leverage point for pulling. Maintenance personnel cannot directly grasp the pressure switch assembly by hand for extraction.

[0007] The pressure switch assembly has a protective wire and a protective bushing at its end. This bushing is only about 2 cm high and is glued in place. Maintenance personnel attempted to pull the pressure switch assembly out by directly pulling the wire or the bushing, but due to the bushing's low height, effective force was difficult to apply in the confined working space around the IDG, and the bushing was prone to bending and deformation. More importantly, the wire is welded to the switch inside the pressure switch, resulting in low structural strength at the weld point. In numerous actual maintenance operations, it frequently occurred that the wire broke while the pressure switch assembly remained stuck inside the IDG housing. This not only damaged the pressure switch assembly but also increased the difficulty and cost of maintenance, and could even cause secondary damage due to the broken wire remaining inside the housing.

[0008] In summary, the existing disassembly methods for pressure switch components have the following significant drawbacks: (1) lack of effective process guidance and special tools; (2) no direct pulling point for pressure switch components; (3) direct pulling of the wires can easily lead to breakage of the solder joints and damage to the components; (4) the protective bushing is not high enough and is easy to bend, making it difficult to effectively transmit the pulling force.

[0009] These defects make the disassembly of the pressure switch assembly a prominent challenge in IDG maintenance. Therefore, there is an urgent need to design a special tooling to solve the technical difficulties of disassembling the pressure switch assembly. Utility Model Content

[0010] The purpose of this utility model is to overcome the above-mentioned defects in the prior art and provide a tooling for disassembling the pressure switch of an aircraft integral drive generator. This tooling can efficiently and safely pull the pressure switch assembly out of the integral drive generator housing without damaging the pressure switch assembly and other components of the integral drive generator.

[0011] To solve the above-mentioned technical problems, this utility model provides a disassembly tooling for the pressure switch of an aircraft integral drive generator, comprising: The main body has a clamping space at its bottom for accommodating the protective sleeve of the end wire of the pressure switch assembly, and a mounting position at its upper end for mounting the screw. The screw is detachably mounted on the main body and extends vertically to provide guidance and travel space for the hammer to slide up and down; The hammer, which has a hollow cylindrical structure, is sleeved on the screw and can move up and down along the screw. It is used to provide upward kinetic energy to pull out the pressure switch assembly by striking the main body or the upper end of the screw. At least one screw is installed on the body with a positive thread and its end extends into the clamping space for providing clamping force by screwing. A screw end protective sleeve, fixed to the end of the screw, is made of hard plastic material and has a knurled structure on its bottom to prevent punctures and maintain clamping force when clamping the wire protective sleeve; The clamping space is used to clamp the wire protective sleeve at the end of the pressure switch assembly. The height of the main body is configured such that the stroke of the hammer is sufficient to overcome the friction of the sealing ring to pull out the pressure switch assembly, while preventing the pressure switch assembly from being flung off and damaging other components due to excessive pulling.

[0012] Furthermore, the height of the main body is 4cm to 6cm.

[0013] Preferably, the height of the main body is 5cm.

[0014] Furthermore, the screw has a rectangular end cross-section, and a wrench is detachably fitted onto the rectangular end to extend the lever arm and tighten the screw by hand.

[0015] Furthermore, the wrench has an L-shaped or T-shaped structure, and one end of it is provided with a groove that matches the rectangular end of the screw.

[0016] Furthermore, the screw end protective sleeve is fixed to the screw end by adhesive bonding or interference fit, and the knurled pattern on its bottom is one or more combinations of straight knurling, mesh knurling, or diamond knurling.

[0017] Furthermore, the inner diameter of the hammer is clearance-fitted with the outer diameter of the screw, with a clearance of 0.1mm to 0.5mm, to ensure that the hammer slides smoothly along the screw without wobbling.

[0018] Furthermore, the upper end of the screw is provided with a stop structure to limit the maximum upward sliding displacement of the hammer. The stop structure is a nut, a retaining ring, or an integrally formed flange.

[0019] Furthermore, the main body is provided with at least two screws, which are symmetrically arranged along the clamping space to clamp the wire protective sleeve from both sides respectively.

[0020] Furthermore, the tightening torque of the screw when it clamps the wire protective sleeve is 55 to 65 pounds-in.

[0021] Preferably, the tightening torque of the screw when it clamps the wire protective sleeve is 60 psi.

[0022] This utility model provides a disassembly tool for the pressure switch of an aircraft integral drive generator, which has the following advantages and technical effects: 1. Highly adaptable, solving the unique disassembly challenges of embedded pressure switch assemblies and enabling non-destructive disassembly. This invention is the first to propose using the wire protection bushing as a reasonable stress point. Stress analysis verifies that the adhesive fixing mode of the wire protection bushing can withstand the pulling strength required for disassembling the pressure switch, thus effectively avoiding the risk of weld point breakage caused by directly pulling the wire.

[0023] 2. Reliable clamping without damaging components. By providing a hard plastic screw end protector with a knurled structure at its bottom, the metal screw is prevented from directly contacting and puncturing the wire protection bushing. Furthermore, the knurled structure increases the coefficient of friction, ensuring a secure, non-slip clamping grip at a tightening torque of 60 psi.

[0024] 3. High safety. This invention effectively limits the travel of the hammer by restricting the height of the main body within a suitable range (preferably 5cm), thereby controlling the magnitude of the impact force. This design ensures that the impact force is sufficient to overcome the friction of the sealing ring, while preventing excessive pulling that could cause the pressure switch assembly to suddenly fly off and damage surrounding components or injure operators.

[0025] 4. Highly efficient operation, shortening maintenance time. Using this tool, the pressure switch assembly can be quickly disassembled, avoiding the predicament of not being able to pull out the assembly due to the lack of an effective leverage point, greatly improving maintenance efficiency and reducing aircraft downtime.

[0026] 5. Simple structure, easy to maintain and promote. The screw adopts a detachable design, which facilitates component replacement and tooling maintenance during future promotion and application. The wrench adopts a special design and can be operated by hand without additional tools. Attached Figure Description

[0027] Figure 1 A schematic diagram of the overall structure of an aircraft integral drive generator pressure switch disassembly tooling provided for an embodiment of this utility model; Figure 2 A cross-sectional view of the wrench location when using a wrench to disassemble the pressure switch of the aircraft integral drive generator according to an embodiment of this utility model; Explanation of reference numerals in the attached drawings: 1-Main body, 2-Hammer, 3-Screw, 4-Screw, 5-Screw end protective sleeve, 6-Wrench. Detailed Implementation

[0028] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings. It should be noted that the following embodiments are only used to illustrate the technical solution of this utility model, and are not intended to limit the scope of protection of this utility model.

[0029] Example 1: like Figure 1 and Figure 2 As shown, the aircraft integral drive generator pressure switch disassembly tool provided by this utility model includes six main parts: body 1, hammer 2, screw 3, screw 4, screw end protective sleeve 5, and wrench 6.

[0030] The main body 1 is made of metal (such as aluminum alloy or structural steel) and has a roughly block or frame structure. The top of the main body 1 has a threaded hole or a smooth hole for mounting the screw 3. The lower end of the main body 1 forms the fixed wall of the clamping space. At least one threaded through hole is provided on the side wall of the main body 1 for mounting the screw 4. The height of the main body 1 is optimized and is 5cm in the preferred embodiment of this invention. This height is determined based on the following force analysis: the frictional force of the sealing ring between the pressure switch assembly and the IDG housing is measured to be approximately F_f; the mass of the hammer 2 is m; and the maximum impact velocity corresponding to the maximum allowable drop height H from the top of the main body 1 is v. Therefore, the impact kinetic energy provided by the hammer 2 is E=½mv². Calculations show that when the height of the main body 1 is 5cm, the effective stroke h of the hammer 2 is just sufficient to overcome the sealing ring frictional force F_f and smoothly pull out the pressure switch assembly, while preventing damage to other connecting parts on the IDG housing due to excessive impact force. If the height of the main body 1 is too large (e.g., exceeding 6cm), the stroke of the hammer 2 will be too large, the impact speed too high, and the impact force may damage the welding point or other connection structure between the pressure switch assembly and the wire; if the height of the main body 1 is too small (e.g., less than 4cm), the impact force will be insufficient to overcome the friction of the sealing ring, and the pressure switch assembly cannot be effectively pulled out. Therefore, the preferred range for the height of the main body 1 is 4cm to 6cm, with an optimal value of 5cm.

[0031] The screw 3 is made of high-strength alloy steel, and its lower end is fixed to the mounting hole on the top of the main body 1 by a threaded connection, interference fit, or other detachable method. The screw 3 extends vertically upward, and its outer diameter matches the inner diameter of the hammer 2. The length of the screw 3 determines the maximum stroke of the hammer 2. A stop structure (such as a tightened nut or an integrally formed flange) is provided at the upper end of the screw 3 to prevent the hammer 2 from slipping off the screw 3 when sliding upward. The detachable design of the screw 3 facilitates replacement when the threads are worn or damaged, and also provides convenience for the transportation and storage of the tooling.

[0032] The hammer 2 is a hollow cylindrical structure made of metal (such as steel or copper alloy). A through hole running axially through the center of the hammer 2 is provided, the diameter of which is slightly larger than the outer diameter of the screw 3 (the clearance is preferably 0.1mm to 0.5mm), allowing the hammer 2 to slide smoothly up and down along the screw 3 without significant wobbling or jamming. The mass of the hammer 2 is determined according to the required impact kinetic energy. In a preferred embodiment of this invention, the mass of the hammer 2 is such that when a maintenance worker pulls the hammer 2 upwards to the top of the main body 1 and releases it (or strikes it upwards), the resulting impact force is sufficient to overcome the friction of the sealing ring. The outer surface of the hammer 2 may be provided with knurled or anti-slip textures for easy gripping by the operator.

[0033] Screw 4 is a rectangular-end screw structure. The threaded section of screw 4 mates with the threaded through hole on the side wall of the main body 1, and is a positive thread design (i.e., the screw moves into the clamping space when turned clockwise). The end of screw 4 (the end that extends into the clamping space) has a rectangular cross-section, which is used to mate with wrench 6. The rectangular cross-section design allows wrench 6 to reliably transmit torque without slippage. The number of screws 4 can be one, two, or more. In a preferred embodiment of this utility model, two screws 4 are symmetrically arranged on the main body 1, clamping the wire protective sleeve from both sides to ensure the uniformity and symmetry of the clamping force.

[0034] The screw end protector 5 is made of a rigid plastic material (such as polyoxymethylene (POM), nylon, or polytetrafluoroethylene (PTFE). The screw end protector 5 is fixed to the end of the screw 4 by bonding, interference fit, or threaded connection. The bottom surface of the screw end protector 5 that contacts the wire protection sleeve has a knurled structure; the knurling pattern can be straight, mesh, diamond, or cross-knit. The knurling structure increases the coefficient of friction between the screw end protector 5 and the outer surface of the wire protection sleeve, preventing relative slippage during pull-out. Simultaneously, the use of rigid plastic material ensures that the screw end protector 5 has a certain degree of rigidity and wear resistance without causing indentations or punctures to the wire protection sleeve. The shape of the surface of the screw end protector 5 that contacts the wire protection sleeve can be adapted to the outer contour of the wire protection sleeve (such as an arc-shaped groove) to increase the contact area and further reduce local pressure.

[0035] Wrench 6 is a specialized hand tool with a groove at one end that fits the rectangular end of screw 4. Wrench 6 can be L-shaped, T-shaped, or straight-bar. Its function is to add an extended lever arm to the rectangular end of screw 4, allowing maintenance personnel to tighten screw 4 to the specified torque (60 psi) by hand without the need for additional tools such as wrenches. The lever arm length of wrench 6 is ergonomically designed to ensure sufficient torque for hand operation without causing inconvenience due to excessive length.

[0036] Example 2: In another embodiment, three or more screws 4 can be provided on the main body 1, evenly distributed along the circumference of the clamping space, to achieve multi-directional uniform clamping of the conductor protective sleeve. This multi-screw design is particularly suitable for situations where the outer diameter of the conductor protective sleeve is large or the shape is irregular.

[0037] Example 3: In another embodiment, a linear bearing or bushing can be added between the hammer 2 and the screw 3 to further reduce sliding friction resistance, improve the transmission efficiency of impact force, and make the movement of the hammer 2 more stable.

[0038] The present invention provides an embodiment of an aircraft integral drive generator pressure switch disassembly tool, the working principle and specific operation steps of which are as follows when disassembling the pressure switch assembly of the integral drive generator.

[0039] Step 1: Preparation. Confirm that the IDG is powered off and removed from the aircraft, or that safety measures have been taken. Remove the retaining ring at the top of the pressure switch assembly to expose the top surface of the pressure switch assembly and the wire protection sleeve at the end. Clean the work area to ensure the workspace is tidy.

[0040] Step 2: Install the tooling. Place the wire protection sleeve at the end of the pressure switch assembly into the clamping space between the main body 1 and the screw end protection sleeve 5. Fit the wrench 6 onto the rectangular end of the screw 4.

[0041] Step 3: Clamp the wire protection sleeve. Manually turn wrench 6 clockwise (causing screw 4 to rotate clockwise), moving screw 4 inward along the positive thread, pushing the screw end protection sleeve 5 towards the fixed wall surface of the body 1, thereby clamping the wire protection sleeve between the screw end protection sleeve 5 and the body 1. Continue turning to the specified tightening torque, i.e., 60 psi (permissible range 55 to 65 psi). At this point, the knurled structure at the bottom of the screw end protection sleeve 5 is in close contact with the outer surface of the wire protection sleeve, providing reliable frictional clamping force.

[0042] Step 4: Impact Pull-out Force. Hold hammer 2 and lift it upwards along screw 3 to the upper part of screw 3 (near the stop structure). Then release hammer 2 to allow it to fall freely along screw 3, impacting the upper end of body 1 (or the stop structure on screw 3), generating an upward impact force. This impact force is transmitted through body 1 to the wire protection sleeve in the clamping space, and then to the entire pressure switch assembly, overcoming the static friction between the sealing ring and the housing, causing the pressure switch assembly to move upwards. Repeat this operation several times, with the pressure switch assembly gradually moving outwards after each impact until it is completely pulled out.

[0043] Step 5: Remove the tooling. After pulling out the pressure switch assembly, turn wrench 6 counterclockwise to loosen screw 4 and remove the tooling from the wire protective sleeve. Check the pressure switch assembly and wires for damage and confirm that the disassembly process did not cause any additional damage.

[0044] Throughout the operation, because the height of the main body 1 is limited to 5cm (or within the range of 4-6cm), the maximum stroke of the hammer 2 is strictly limited, thus there is an upper limit to the impact force generated by each impact. This design ensures that even under multiple impacts, the pressure switch assembly will not suddenly accelerate and fly off due to excessive cumulative impact force. The removal process of the pressure switch assembly is a controlled and gradual process, effectively ensuring maintenance safety.

[0045] Furthermore, the use of a hard plastic screw end protector 5 for clamping ensures that the wire protector is not directly squeezed by the metal screw, preventing scratches or crushing of the screw end protector surface. The knurled structure ensures a sufficient coefficient of static friction between the screw end protector 5 and the wire protector at a clamping torque of 60 psi, preventing slippage during pull-out. Experiments have verified that under these clamping conditions, the wire protector can withstand a pulling force far greater than the force required to overcome the friction of the sealing ring, thus ensuring the reliability of the disassembly process.

[0046] This utility model provides an embodiment of an aircraft integral drive generator pressure switch disassembly tool, which achieves the following technical effects through the above technical solution: (1) For the first time, the wire protective sleeve of the pressure switch assembly was determined as a reasonable pulling force point. Through force analysis and experimental verification, the screw end protective sleeve of the glue-fixed structure can withstand the pulling strength required for disassembly, effectively avoiding the technical risk of the welding point breaking due to direct pulling of the wire. (2) By setting a protective sleeve at the end of the hard plastic screw and a knurled structure, reliable clamping force is provided while avoiding damage to the wire protective sleeve; (3) By optimizing the height of the main body (4-6cm, preferably 5cm), the effective stroke and impact force of the hammer are precisely controlled, which not only ensures the disassembly efficiency, but also prevents safety hazards caused by excessive pulling. (4) The design of using a positive thread screw and a special wrench allows maintenance personnel to operate by hand without additional tools, thus lowering the operating threshold; (5) The detachable screw design facilitates tooling maintenance and component replacement, which is beneficial for technology promotion and application; (6) The overall structure is simple, the manufacturing process is mature and the cost is low, making it suitable for widespread use in aviation maintenance units.

[0047] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although this utility model has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of protection claimed by this utility model.

Claims

1. A disassembly fixture for a pressure switch on an aircraft integral drive generator, characterized in that, include: The main body (1) has a clamping space at its bottom for accommodating the protective sleeve of the end wire of the pressure switch assembly, and the upper end of the main body (1) has a mounting position for the screw (3) to be installed. The screw (3) is detachably mounted on the main body (1) and extends vertically to provide guidance and travel space for the hammer (2) to slide up and down; The hammer (2) has a hollow cylindrical structure, is sleeved on the screw (3) and can move up and down along the screw (3), and is used to provide upward kinetic energy to pull out the pressure switch assembly by striking the main body (1) or the upper end of the screw (3); At least one screw (4) is installed on the body (1) in a positive thread manner, with its end extending into the clamping space, for providing clamping force by screwing; The screw end protective sleeve (5) is fixed to the end of the screw (4) and is made of hard plastic material. Its bottom is provided with a knurled structure to prevent puncture and maintain clamping force when clamping the wire protective sleeve. The clamping space is used to clamp the wire protection sleeve at the end of the pressure switch assembly. The height of the main body (1) is configured such that the stroke of the hammer (2) is sufficient to overcome the friction of the sealing ring to pull out the pressure switch assembly, while preventing the pressure switch assembly from being flung off and damaging other components due to excessive pulling.

2. The disassembly fixture according to claim 1, characterized in that, The height of the main body (1) is 4cm to 6cm.

3. The disassembly fixture according to claim 2, characterized in that, The height of the main body (1) is 5cm.

4. The disassembly fixture according to claim 1, characterized in that, The end section of the screw (4) is rectangular, and the wrench (6) is detachably sleeved on the rectangular end to extend the lever arm and tighten the screw (4) by hand.

5. The disassembly fixture according to claim 4, characterized in that, The wrench (6) has an L-shaped or T-shaped structure, and one end of it is provided with a groove that matches the rectangular end of the screw (4).

6. The disassembly fixture according to claim 1, characterized in that, The screw end protective sleeve (5) is fixed to the end of the screw (4) by bonding or interference fit, and the knurling pattern at the bottom is one or more combinations of straight knurling, mesh knurling or diamond knurling.

7. The disassembly fixture according to claim 1, characterized in that, The inner diameter of the hammer (2) is clearance-fitted with the outer diameter of the screw (3), with a clearance of 0.1 mm to 0.5 mm.

8. The disassembly fixture according to claim 1, characterized in that, The upper end of the screw (3) is provided with a stop structure to limit the maximum displacement of the hammer (2) sliding upward. The stop structure is a nut, a retaining ring or an integrally formed flange.

9. The disassembly fixture according to claim 1, characterized in that, The main body (1) is provided with at least two screws (4), which are symmetrically arranged along the clamping space to clamp the wire protective sleeve from both sides respectively.

10. The disassembly fixture according to claim 1, characterized in that, The screw (4) is tightened to a torque of 55 to 65 psi when it clamps the wire protective sleeve.

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