Auxiliary tool for oil pan discharge of main oil tank of Boeing B737NG aircraft

Abstract

An auxiliary tool for oil bottom discharge of a main oil tank of a Boeing B737NG airplane relates to the technical field of airplane maintenance tools, a lift valve is driven by a lift valve driving mechanism to slide upwards in a containing cavity of an oil discharge pipe by utilizing a piston, a valve core of a water discharge valve is gradually opened when the lift valve moves upwards, fuel oil is discharged from the water discharge valve, and the oil bottom discharge of the main oil tank of the Boeing B737NG airplane is realized. Due to the fact that the piston isolates the long hole I from the long hole II, fuel oil enters the oil storage cavity of the lifting valve from the long hole I, then flows out from the long hole II and finally flows into an oil barrel to be stored through the connecting pipe and the hose. A worker does not need to use an oil drainage rod to always prop the water drainage valve in the oil drainage process, the oil drainage efficiency is improved, and manpower is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft maintenance tools, and particularly to an auxiliary tool for draining the bottom oil of the main fuel tank of a Boeing B737NG aircraft. Background Art

[0002] The main fuel tanks of Boeing B737NG aircraft are located on both sides of the aircraft's wings, and their function is to store the fuel required for the aircraft to fly. Since the wings of the aircraft have anhedral angles (i.e., the wings are tilted upwards by about 7 degrees), a safety fuel quantity is reserved for each flight to ensure safety (i.e., the amount of fuel added to cope with emergencies is more than that consumed during normal flight, about 2 - 4 tons). However, water is inevitably mixed in the production process of fuel, and the density of water is greater than that of fuel. Therefore, water accumulates at the bottom layer of the root of the wing fuel tank. The accumulation of water and the organic nutrients of the fuel will breed microorganisms. Microbial contamination will cause the fuel pipeline to be blocked, and its excretions will also corrode the aircraft structure, endangering flight safety. Therefore, the manufacturer Boeing has installed a drain valve at the root of the wing fuel tank. Before each flight, the maintenance personnel operate the drain valve to discharge a certain amount of fuel (about 1 - 2L) to avoid the long-term accumulation of water. However, when the aircraft undergoes a major inspection, it is necessary to empty the fuel in the fuel tank and enter the interior for inspection. However, Boeing only gives a method for discharging the fuel quantity through the drain valve in the maintenance manual. This method of discharging the fuel quantity (generally referred to as the bottom oil) is very inefficient, and the time and labor costs are very high.

[0003] The method for draining the main fuel tank of a B737NG aircraft: 1) Clean the fuel drain rod, drain valve, and the skin near the valve; 2) Approach the main fuel tank drain valve as specified; 3) Place the oil collecting bucket under the drain valve, insert the end of the fuel drain rod into the oil collecting bucket, and align the top of the fuel drain rod with the top lift valve of the drain valve; 4) Push the fuel drain rod upwards to open the drain valve and discharge about 2 liters of fuel to check the condition; 5) Ensure that the drain valve is reset, wipe the area near the drain valve with a rag, and there is no fuel leakage. According to the entire discharge process, it can be seen that this method requires personnel to keep the drain valve in the lifted state through the fuel drain rod all the time, and the flow rate is small, which is not suitable for the situation of discharging a large amount of bottom oil. Summary of the Invention

[0004] In order to overcome the above-mentioned deficiencies in technology, the present invention provides an auxiliary tool for quickly emptying the fuel in the main fuel tank of an aircraft by using a drain valve.

[0005] The technical solution adopted by the present invention to overcome its technical problems is as follows: An auxiliary tool for draining the bottom oil of the main fuel tank of a Boeing B737NG aircraft, comprising: The drain pipe has openings at both its upper and lower ends and is internally provided with a sealed cavity. The upper end of the drain pipe is provided with external thread I, and the drain pipe is screwed into the screw hole at the drainage valve on the large wing skin of the Boeing B737NG aircraft through external thread I. The lifting valve has a cylindrical structure. The periphery of the lifting valve is airtight and internally provided with a sealed oil storage cavity. The piston is installed on the lifting valve. The lifting valve is slidably installed in the cavity of the drain pipe along the vertical direction through the piston. A long hole I communicating with the cavity is provided on the lifting valve above the piston, and a long hole II communicating with the cavity is provided on the lifting valve below the piston. The connecting pipe has external thread III at its upper end. The lower end of the drain pipe is provided with screw hole I, and the connecting pipe is screwed into screw hole I through external thread III. The lower end of the connecting pipe is connected to an oil barrel through a hose. The lifting valve driving mechanism is arranged on the drain pipe and is used to control the up and down movement of the lifting valve. When the lifting valve moves upward to the uppermost end, it pushes open the valve core of the drainage valve.

[0006] To improve the sealing performance, a sealing ring I is provided at the connection between the drain pipe and the large wing skin.

[0007] To improve the sealing performance, a sealing ring II is provided at the connection between the connecting pipe and the drain pipe.

[0008] For the convenience of connection, it further includes a groove provided on the connecting pipe and a sleeve sleeved on the connecting pipe. A screw passes through the sleeve and is inserted into the groove. A clamping groove is provided on the sleeve along the circumferential direction. The upper end of the hose is inserted into the sleeve, and a hose clamp locks and fixes the hose in the clamping groove. The lower end of the hose is inserted into the oil barrel.

[0009] Further, the above-mentioned lifting valve driving mechanism includes a branch pipe inclined downward at the lower end on the drain pipe, a pipe joint, a sliding rod axially inserted into the pipe joint, and a knob. The head end of the sliding rod contacts the lower end surface of the lifting valve. The upper end of the pipe joint is provided with external thread IV, and the pipe joint is threadedly connected to the branch pipe through external thread IV. The lower end of the pipe joint is provided with external thread II. A screw hole II is provided inside the knob, and the knob is screwed onto external thread II through screw hole II. The tail end of the sliding rod is coaxially rotatably connected to the knob through a rotational connection mechanism. A spring is sleeved on the lifting valve, its upper end is connected to the inner wall of the drain pipe, and its lower end is connected to the piston.

[0010] Preferably, the included angle between the axis of the above-mentioned branch pipe and the axis of the drain pipe is 45°.

[0011] To improve the service life, it further includes a ball head provided at the head end of the sliding rod, and the ball head contacts the lower end surface of the lifting valve.

[0012] To improve the sealing performance, a sealing ring IV is provided at the connection between the sliding rod and the pipe joint.

[0013] To improve the sealing performance, a sealing ring III is provided at the connection between the pipe joint and the branch pipe.

[0014] Furthermore, the above-mentioned rotational connection mechanism includes an installation groove provided at the end of the knob head. The installation groove communicates with the screw hole II through a through hole. A plug is provided at the tail end of the sliding rod, and the plug passes through the through hole. A washer is provided in the installation groove, and the washer is sleeved on the plug in the installation groove. A nut is provided in the installation groove, and the nut is screwed onto the plug in the installation groove.

[0015] The beneficial effects of the present invention are as follows: The lifting valve is driven by the lifting valve drive mechanism to slide upward by means of the piston in the cavity of the drain pipe. When the lifting valve moves upward, the valve core of the drain valve is gradually pushed open, and the fuel is discharged from the drain valve. Since the piston isolates the long hole I from the long hole II, the fuel enters the oil storage cavity of the lifting valve from the long hole I, then flows out from the long hole II, and finally flows into the oil barrel through the connecting pipe and the hose for storage. There is no need for the staff to use an oil drain rod to always hold down the drain valve during the oil draining process, which improves the oil draining efficiency and saves manpower. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a usage state diagram of the present invention; Figure 2 is a sectional structure diagram of the present invention; Figure 3 is a sectional structure diagram of the oil draining state of the present invention; Figure 4 is a sectional structure diagram of the branch pipe part of the present invention; In the figure, 1. oil barrel; 2. large wing skin; 3. drain valve; 4. drain pipe; 5. branch pipe; 6. pipe clamp; 7. knob; 8. hose; 9. external thread I; 10. sealing ring I; 11. lifting valve; 12. piston; 13. spring; 14. long hole I; 15. long hole II; 16. pipe joint; 17. sliding rod; 18. ball head; 19. external thread II; 20. screw hole I; 21. connecting pipe; 22. external thread III; 23. sealing ring II; 24. sleeve; 25. card slot; 26. groove; 27. screw; 28. external thread IV; 29. sealing ring III; 30. sealing ring IV; 31. screw hole II; 32. through hole; 33. plug; 34. washer; 35. nut. DETAILED DESCRIPTION OF THE INVENTION

[0017] The following further describes the present invention in conjunction with Figure 1 to Figure 4 the attached drawings.

[0018] An auxiliary tooling for the bottom drainage of the main fuel tank of a Boeing B737NG aircraft, comprising: a drain pipe 4, which has openings at both the upper and lower ends and is provided with a sealed cavity inside. The upper end of the drain pipe 4 is provided with an external thread I 9, and the drain pipe 4 is screwed into the screw hole at the drain valve 3 on the wing skin 2 of the Boeing B737NG aircraft through the external thread I 9. A lift valve 11, having a cylindrical structure, with the periphery of the lift valve 11 being airtight and provided with a sealed oil storage cavity inside; a piston 12, installed on the lift valve 11, and the lift valve 11 is slidably installed in the cavity of the drain pipe 4 along the vertical direction through the piston 12. A long hole I 14 communicating with the cavity is provided on the lift valve 11 above the piston 12, and a long hole II 15 communicating with the cavity is provided on the lift valve 11 below the piston 12; a connecting pipe 21, the upper end of which is provided with an external thread III 22, and the lower end of the drain pipe 4 is provided with a screw hole I 20. The connecting pipe 21 is screwed into the screw hole I 20 through the external thread III 22, and the lower end of the connecting pipe 21 is connected to an oil barrel 1 through a hose 8; a lift valve driving mechanism, arranged on the drain pipe 4, for controlling the up and down movement of the lift valve 11. When the lift valve 11 moves up to the uppermost end, it pushes open the valve core of the drain valve 3. When the aircraft needs to be reinspected and the fuel in the fuel tank needs to be emptied, the drain pipe 4 is installed at the drain valve 3 on the wing skin 2, and then the lift valve driving mechanism is used to drive the lift valve 11 to slide upward in the cavity of the drain pipe 4 by means of the piston 12. When the lift valve 11 moves upward, it gradually pushes open the valve core of the drain valve 3, and the fuel is discharged from the drain valve 3. Since the piston 12 isolates the long hole I 14 from the long hole II 15, the fuel enters the oil storage cavity of the lift valve 11 from the long hole I 14, then flows out from the long hole II 15, and finally flows into the oil barrel 1 through the connecting pipe 21 and the hose 8 for storage. It is not necessary for the staff to always hold the drain valve 3 with a fuel drain rod during the fuel draining process, which improves the fuel draining efficiency and saves manpower.

[0019] In an embodiment of the present invention, a sealing ring I 10 is provided at the connection between the drain pipe 4 and the wing skin 2. A sealing ring II 23 is provided at the connection between the connecting pipe 21 and the drain pipe 4. The sealing ring I 10 can improve the sealing performance at the connection between the drain pipe 4 and the drain valve 3, and the sealing ring II 23 can improve the sealing performance at the connection between the connecting pipe 21 and the drain pipe 4 to prevent oil leakage.

[0020] In one embodiment of the present invention, it further includes a groove 26 provided on the connecting pipe 21 and a sleeve 24 sleeved on the connecting pipe 21. A screw 27 passes through the sleeve 24 and is inserted into the groove 26. A clamping groove 25 is provided on the sleeve 24 along the circumferential direction. The upper end of the hose 8 is inserted onto the sleeve 24, and a pipe clamp 6 locks and fixes the hose 8 in the clamping groove 25. The lower end of the hose 8 is inserted into the oil barrel 1. By fixing the sleeve 24 at the outer end of the connecting pipe 21 and then using the pipe clamp 6 arranged in the clamping groove 25 to firmly fix the hose 8 and the sleeve 24, the reliability of use is improved.

[0021] In one embodiment of the present invention, the lift valve driving mechanism includes a branch pipe 5 inclined downward at the lower end on the drain pipe 4, a pipe joint 16, a slide bar 17 axially inserted into the pipe joint 16, and a knob 7. The head end of the slide bar 17 is in contact with the lower end surface of the lift valve 11. An external thread IV 28 is provided at the upper end of the pipe joint 16, and the pipe joint 16 is threadedly connected to the branch pipe 5 through the external thread IV 28. An external thread II 19 is provided at the lower end of the pipe joint 16. A screw hole II 31 is provided inside the knob 7, and the knob 7 is screwed onto the external thread II 19 through the screw hole II 31. The tail end of the slide bar 17 is coaxially and rotationally connected to the knob 7 through a rotational connection mechanism. A spring 13 is sleeved on the lift valve 11, its upper end is connected to the inner wall of the drain pipe 4, and its lower end is connected to the piston 12. When the knob 7 is rotated, the knob 7 will move axially when rotating on the external thread II 19. Since the slide bar 17 and the knob 7 are rotationally connected through a rotational connection mechanism, the slide bar 17 follows the knob 7 and moves along the axis of the branch pipe 5. Since the slide bar 17 is in contact with the bottom of the lift valve 11, when the slide bar 17 moves obliquely upward, it will push the lift valve 11 upward and compress the spring 13, and the lift valve 11 will push open the valve core of the drain valve 3. When the slide bar 17 moves obliquely downward, the spring 13 releases energy to drive the lift valve 11 to move downward to achieve reset, and the drain valve 3 closes.

[0022] In this embodiment, preferably, the included angle between the axis of the branch pipe 5 and the axis of the drain pipe 4 is 45°.

[0023] In this embodiment, it may further include a ball head 18 provided at the head end of the slide bar 17, and the ball head 18 is in contact with the lower end surface of the lift valve 11. Since the ball head 18 has a smooth spherical surface, when the slide bar 17 moves, the ball head 18 is in sliding friction contact with the lower end surface of the lift valve 11, reducing the frictional force, preventing excessive wear of the lift valve 11, and improving the service life.

[0024] In this embodiment, a sealing ring Ⅳ 30 is provided at the connection between the sliding rod 17 and the pipe joint 16. A sealing ring Ⅲ 29 is provided at the connection between the pipe joint 16 and the branch pipe 5. By providing the sealing ring Ⅳ 30, the sealing performance between the sliding rod 17 and the pipe joint 16 can be improved. By providing the sealing ring Ⅲ 29, the sealing performance between the pipe joint 16 and the branch pipe 5 can be improved, preventing the oil from overflowing.

[0025] In an embodiment of the present invention, the rotational connection mechanism includes an installation groove provided at the head end of the knob 7. The installation groove is connected to the screw hole Ⅱ 31 through a through hole 32. A plug 33 is provided at the tail end of the sliding rod 17. The plug 33 passes through the through hole 32. A washer 34 is provided in the installation groove. The washer 34 is sleeved on the plug 33 in the installation groove. A nut 35 is provided in the installation groove. The nut 35 is screwed onto the plug 33 in the installation groove. The sliding rod 17 rotates relative to the through hole 32 of the knob 7 through the plug 33. The axial limit is achieved by using the washer 34 and the nut 35 provided in the installation groove. When the knob 7 is rotated, the sliding rod 17 does not rotate relative to the knob 7 but moves axially along with the knob 7.

[0026] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An auxiliary tooling for the oil bottom discharge of the main fuel tank of Boeing B737NG aircraft, characterized in that: include: The oil drain pipe (4) has openings at both ends and a sealed cavity inside. The upper end of the oil drain pipe (4) is provided with an external thread I (9). The oil drain pipe (4) is screwed into a screw hole at a drain valve (3) on a large wing skin (2) of a Boeing B737NG aircraft through the external thread I (9). The lifting valve (11) is of cylindrical structure, the lifting valve (11) is sealed on all sides, and a sealed oil storage chamber is provided inside; A piston (12) is mounted on a lifting valve (11). The lifting valve (11) is slidably mounted in a cavity of the oil discharge pipe (4) in a vertical direction through the piston (12). The lifting valve (11) located at the upper end of the piston (12) is provided with a long hole I (14) communicating with the cavity. The lifting valve (11) located at the lower end of the piston (12) is provided with a long hole II (15) communicating with the cavity. A connecting pipe (21) having an external thread III (22) at its upper end, a screw hole I (20) at the lower end of the oil drain pipe (4), the connecting pipe (21) being screwed into the screw hole I (20) via the external thread III (22), and the lower end of the connecting pipe (21) being connected to the oil barrel (1) via a hose (8); The lifting valve driving mechanism is arranged on the oil discharge pipe (4) and is used to control the lifting valve (11) to move up and down. When the lifting valve (11) moves upward to the uppermost end, it pushes open the valve core of the drain valve (3).

2. The auxiliary tooling for oil bottom discharge of the main fuel tank of Boeing B737NG aircraft according to claim 1 is characterized in that: A sealing ring I (10) is provided at the connection between the oil drain pipe (4) and the large wing skin (2).

3. The auxiliary tooling for oil bottom discharge of the main fuel tank of Boeing B737NG aircraft according to claim 1 is characterized in that: A sealing ring II (23) is provided at the connection between the connecting pipe (21) and the oil drain pipe (4).

4. The auxiliary tooling for oil bottom discharge of the main fuel tank of Boeing B737NG aircraft according to claim 1 is characterized in that: It also includes a groove (26) provided on the connecting pipe (21) and a sleeve (24) sleeved on the connecting pipe (21); a screw (27) passes through the sleeve (24) and is inserted into the groove (26); a clamping groove (25) is provided on the sleeve (24) along a circumferential direction; the upper end of the hose (8) is inserted into the sleeve (24); the hose (8) is locked and fixed in the clamping groove (25) by a pipe clamp (6); and the lower end of the hose (8) is inserted into the oil drum (1).

5. The auxiliary tooling for oil bottom discharge of the main fuel tank of Boeing B737NG aircraft according to claim 1 is characterized in that: The lift valve driving mechanism comprises a branch pipe (5) arranged on the oil discharge pipe (4) at an angle downward, a pipe joint (16), a slide rod (17) inserted axially into the pipe joint (16), and a knob (7); the head end of the slide rod (17) contacts the lower end surface of the lift valve (11); the upper end of the pipe joint (16) is provided with an external thread IV (28); the pipe joint (16) is threadedly connected to the branch pipe (5) via the external thread IV (28); the lower end of the pipe joint (16) is provided with an external thread II (19); a screw hole II (31) is provided in the knob (7); the knob (7) is screwed onto the external thread II (19) via the screw hole II (31); the tail end of the slide rod (17) is coaxially rotatably connected to the knob (7) via a rotating connection mechanism; the spring (13) is sleeved on the lift valve (11); the upper end of the spring is connected to the inner wall of the oil discharge pipe (4); and the lower end of the spring is connected to the piston (12).

6. The auxiliary tooling for oil bottom discharge of the main fuel tank of Boeing B737NG aircraft according to claim 5 is characterized in that: The angle between the axis of the branch pipe (5) and the axis of the oil drain pipe (4) is 45°.

7. The auxiliary tooling for oil bottom discharge of the main fuel tank of Boeing B737NG aircraft according to claim 5 is characterized in that: It also includes a ball head (18) arranged at the head end of the slide rod (17), wherein the ball head (18) contacts the lower end surface of the lift valve (11).

8. The auxiliary tooling for oil bottom discharge of the main fuel tank of Boeing B737NG aircraft according to claim 5 is characterized in that: A sealing ring IV (30) is provided at the connection between the slide rod (17) and the pipe joint (16).

9. The auxiliary tooling for oil bottom discharge of the main fuel tank of Boeing B737NG aircraft according to claim 5, characterized in that: A sealing ring III (29) is provided at the connection between the pipe joint (16) and the branch pipe (5).

10. The auxiliary tooling for oil bottom discharge of the main fuel tank of Boeing B737NG aircraft according to claim 5, characterized in that: The rotating connection mechanism comprises a mounting groove arranged at the head end of the knob (7), the mounting groove being connected to the screw hole II (31) via a through hole (32), a plug (33) being arranged at the tail end of the slide rod (17), the plug (33) passing through the through hole (32), a washer (34) being arranged in the mounting groove, the washer (34) being sleeved on the plug (33) in the mounting groove, a nut (35) being arranged in the mounting groove, the nut (35) being screwed on the plug (33) in the mounting groove.

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