System for variable height wedges for pneumatic oil pressure shock absorbers

Abstract

The present invention relates to a maintenance system (1) for a pneumatic oil pressure damper (2), the system comprising wedges arranged to be assembled to form a plurality of wedge devices of different heights and each associated with a different temperature range, each wedge device is arranged so as to be mounted to a shock absorber by being positioned between one end (8) of the cylinder (4) into which the rod (5) is inserted and one end (9) of the rod (5) located outside the cylinder, such that when the shock absorber is compressed with the end of the cylinder or the end of the rod abutting against the wedge device, when the cavity (10) is filled up to the maximum, the cavity (10) is filled up to the maximum. The amount of oil in the chamber is equal to an amount optimized for oil temperatures included within a temperature range associated with the wedge device.

Description

Technical Field

[0001] This invention relates to pneumatic-hydraulic shock absorbers, and more particularly to pneumatic-hydraulic shock absorbers for aircraft landing gear. Background Technology

[0002] Aircraft landing gear is typically equipped with shock absorbers. These shock absorbers are usually pneumatic-hydraulic shock absorbers, consisting of a cylinder and a rod. The rod slides in a sealed manner within the cylinder, which contains pressurized gas and a damping hydraulic fluid (referred to as "oil" in this example).

[0003] The cylinder can be part of the landing gear bay. In this case, the rod carries the axle, on which the landing gear wheels are mounted. The shock absorber can also be made independently of the landing gear bay.

[0004] When an aircraft lands, the amount of oil in the shock absorbers depends on the oil temperature, which can cause the following problems. When an aircraft lands in cold regions (such as Canada and Russia), the oil temperature is low, and the oil level is also low. Therefore, when the landing gear wheels contact the ground upon landing, there is a risk that the shock absorber cylinders may abut against the end of the rod, resulting in an impact that could be felt by the aircraft's passengers. This problem is primarily related to the aircraft's main landing gear, whose wheels are the first to contact the ground and absorb the most energy during the impact of landing. Summary of the Invention

[0005] The purpose of this invention is to improve the comfort of aircraft passengers in a simple and economical way.

[0006] To achieve this goal, a maintenance system for hydraulic shock absorbers is proposed, comprising a cylinder consisting of an oil-containing chamber and a rod sliding within the cylinder. The maintenance system includes multiple gaskets or wedges arranged to be assembled to form multiple gasket assemblies of varying heights and each associated with a different temperature range. Each gasket assembly is arranged to be mounted to the shock absorber by being positioned between the rod-inserted end of the cylinder and the end of the rod located outside the cylinder, such that when the shock absorber is compressed, causing the cylinder end or the rod end to abut against the gasket assembly, the amount of oil in the chamber, when maximally filled, is equal to an amount optimized for the oil temperature within the temperature range associated with the gasket assembly.

[0007] Therefore, the maintenance system also includes multiple gasket devices of different heights, and each gasket device is associated with a different temperature range.

[0008] When maintaining a shock absorber, more specifically during the oil filling operation, the operator measures the oil temperature, selects a shim assembly whose temperature range includes the measured temperature, positions it on the shock absorber between the end of the cylinder and the end of the rod, and compresses the shock absorber to its maximum extent. Under these conditions, the amount of oil in the chamber is optimal relative to the measured temperature when the chamber is filled to its maximum extent.

[0009] This maintenance system can precisely adjust the oil level based on the oil temperature. The higher the temperature, the greater the oil level. Therefore, during cold landings, the reduced oil level in the shock absorbers due to temperature prevents the cylinder end from contacting the rod end.

[0010] This maintenance system is inexpensive and very simple and quick for operators to use: each gasket unit includes an indication of its associated temperature range. Operators simply need to measure the oil temperature and select the appropriate gasket unit.

[0011] This maintenance system is lightweight, reusable, and robust. If the shock absorbers are used for aircraft landing gear, they can reduce aircraft downtime during maintenance operations, which is highly beneficial to aircraft operators.

[0012] It is worth noting that this invention makes it possible to extend the service life of shock absorbers (and landing gear) by simplifying the maintenance and mechanical repair of shock absorbers (and landing gear).

[0013] The maintenance system according to claim 1, wherein the gasket assembly (13) includes a main gasket assembly (13a) and at least one secondary gasket assembly (13b, 13c, 13d), the main gasket assembly being associated with a minimum temperature range and including a separate main gasket (12a), and each secondary gasket assembly including the main gasket assembly and at least one secondary gasket (12b, 12c, 12d) stacked on the main gasket.

[0014] In addition, a maintenance system as described above is proposed, wherein each auxiliary gasket assembly further includes a main gasket assembly and a separate auxiliary gasket.

[0015] The present invention also provides a maintenance system as described above, wherein a main gasket includes a first bearing surface and a second bearing surface, the first bearing surface being arranged to be applied to a shock absorber receiving surface located near the end of the cylinder or the end of the rod, a secondary gasket being disposed on the second bearing surface, and the main gasket further includes a first retaining device arranged to position and retain the secondary gasket on the second bearing surface.

[0016] Furthermore, the present invention also proposes a maintenance system as described above, wherein the secondary gasket includes a second retaining device arranged to engage with a first retaining device to position and retain the secondary gasket on a second bearing surface of the primary gasket.

[0017] Furthermore, the present invention also proposes a maintenance system as described above, wherein a first retaining device includes a hole, a second retaining device includes a pin, and vice versa, the pin being intended to be positioned in the hole.

[0018] Furthermore, the present invention also proposes a maintenance system as described above, wherein at least one secondary pad includes a third retaining device arranged to position and retain another secondary pad on the secondary pad.

[0019] In addition, a maintenance system as described above is proposed, wherein the main gasket assembly further includes a strip and fasteners through which the strip passes, the strip being arranged to surround a rod or cylinder, and the fasteners being arranged to tighten the strip, thereby securing the main gasket assembly to the rod or cylinder.

[0020] In addition, a maintenance system as described above is provided, wherein the main gasket assembly includes a first protective element arranged to abut a rod or cylinder, and the first protective element is positioned between the rod or cylinder and the main gasket when the main gasket assembly is mounted on the shock absorber.

[0021] In addition, a maintenance system as described above is proposed, wherein the main gasket assembly includes a second protective element arranged as an abutment rod or cylinder, and when the main gasket assembly is mounted on the landing gear, the second protective element is positioned between the rod or cylinder and a fastener.

[0022] In addition, a maintenance system as described above is proposed, wherein the first protective element and / or the second protective element are made of polyoxymethylene.

[0023] In addition, a maintenance system as described above is proposed, wherein the shock absorber is a shock absorber for the landing gear of an aircraft.

[0024] In addition, a maintenance system as described above is proposed, wherein the cylinder is the landing gear bay, and wherein a rod carries at least one wheel of the landing gear, a main gasket assembly is arranged to be fixed to the rod, and the receiving surface is the upper surface of the radially protruding part of the rod.

[0025] In addition, a maintenance system as described above is proposed, wherein the radial protrusion has a through hole through which a connecting shaft passes, and the landing gear includes a compass joint, the lower branch of which is pivotally mounted relative to the rod via the connecting shaft.

[0026] Furthermore, the present invention also proposes a maintenance system as described above, wherein the main gasket assembly includes two lateral stops arranged such that, when the main gasket assembly is installed, a radial protrusion is positioned between the two lateral stops.

[0027] Furthermore, the present invention also proposes a method for maintaining a pneumatic hydraulic shock absorber using the maintenance system described above, the method comprising the following steps:

[0028] -Measure oil temperature;

[0029] - Select a gasket assembly that corresponds to the temperature range that includes the oil temperature, and install the gasket assembly on the shock absorber;

[0030] - Compression damper, causing the end of the cylinder or the end of the rod to abut against the gasket device;

[0031] - Ensure the shock absorbers are filled with as much oil as possible.

[0032] In addition, the present invention also proposes a maintenance method as described above, which further includes the following steps: fully compressing the shock absorber and emptying all the oil contained in the chamber of the shock absorber, then fully filling the chamber with new oil, and subsequently expanding the shock absorber.

[0033] Furthermore, the present invention also proposes a maintenance method as described above, wherein the compression of the shock absorber is performed by means of a jack, which can bring the end of the rod closer to the end of the cylinder.

[0034] Furthermore, the present invention also proposes a maintenance method as described above, wherein when the end of the cylinder or the end of the rod abuts against the gasket device, excess oil is discharged to ensure that the shock absorber is filled with oil to the maximum extent.

[0035] Furthermore, the present invention also proposes a maintenance method as described above, wherein the pneumatic hydraulic shock absorber is a shock absorber used for aircraft landing gear.

[0036] Furthermore, the present invention also proposes a landing gear assembly comprising an aircraft landing gear and a maintenance system as described above, and using the maintenance system to perform the maintenance method as described above in the landing gear.

[0037] The invention will be better understood in conjunction with the following description of specific and non-limiting embodiments thereof. Attached Figure Description

[0038] Please refer to the attached diagram, in which:

[0039] [ Figure 1 ] Figure 1 A schematic diagram of an aircraft landing gear equipped with a maintenance system is shown.

[0040] [ Figure 2 ] Figure 2 A perspective view and a front view of the main gasket assembly (including the main gasket) and three auxiliary gaskets;

[0041] [ Figure 3 ] Figure 3 A perspective view and a bottom view of the main gasket assembly;

[0042] [ Figure 4 ] Figure 4 A perspective view and an attached view of the main gasket assembly;

[0043] [ Figure 5 ] Figure 5 A three-dimensional view of a shock absorber with a main gasket installed under maximum compression.

[0044] [ Figure 6 ] Figure 6 It shows the relationship with Figure 5 A similar view, with a secondary gasket device;

[0045] [ Figure 7 ] Figure 7 It shows the relationship with Figure 5 A similar view, with a secondary gasket device;

[0046] [ Figure 8 ] Figure 8 It shows the relationship with Figure 5 A similar view, with a third auxiliary gasket device. Detailed Implementation

[0047] refer to Figure 1 This describes a specific, non-limiting embodiment of the invention, in which a maintenance system 1 is used to fill the pneumatic-hydraulic shock absorber 2 of the aircraft main landing gear 3 with oil. The pneumatic-hydraulic shock absorber 2 is a conventional shock absorber and has no distinguishing features compared to shock absorbers known to those skilled in the art.

[0048] The shock absorber 2 includes a cylinder 4 and a rod 5 that slides within the cylinder 4. In this example, the cylinder is the landing gear bay 3. The rod 5 carries a wheel axle 6, on which the wheels 7 of the landing gear 3 are mounted.

[0049] Cylinder 4 has a first end attached to the wing (not shown) and a second end 8 through which rod 5 is inserted into cylinder 4. Rod 5 includes a first end located inside cylinder 4 (not shown) and a second end 9 located outside cylinder 4.

[0050] In this example, only the second end 8 of cylinder 4 and the second end 9 of rod 5 will be involved, and these second ends 8 and 9 will be referred to simply as "ends".

[0051] The shock absorber 2 includes a chamber 10 and a filling valve 11, such as Figure 1 As shown schematically, chamber 10 contains oil. Chamber 10 is filled with oil and emptied via filling valve 11.

[0052] As mentioned above, the amount of oil in chamber 10 depends on the oil temperature, which may cause discomfort to passengers when landing in cold regions.

[0053] The maintenance system 1 is intended to ensure that after the operation of filling the chamber 10 of the shock absorber 2 with oil while the aircraft is on the ground, the amount of oil filled in the chamber 10 is optimal relative to the oil temperature at the time of filling.

[0054] The optimal amount is a predefined amount based on temperature, which ensures that regardless of the oil temperature at landing, even when landing in cold regions, the amount of oil in the chamber 10 of the shock absorber 2 is sufficient to prevent the travel of the rod 5 in the cylinder 4 during landing through the internal action of the shock absorber 2, without causing the end 8 of the cylinder 4 to abut against the end 9 of the rod 5.

[0055] Therefore, when the oil temperature is high, the chamber 10 of the shock absorber 2 will be filled with an additional amount of oil. Thus, in the case of a cold landing, although the amount of oil in the shock absorber 2 will decrease due to the temperature drop during filling and landing, the amount of oil is still sufficient to prevent the impact mentioned above.

[0056] refer to Figures 2 to 8 The maintenance system 1 includes multiple gaskets 12.

[0057] Gaskets 12 can be assembled to form gasket devices 13 of different heights, with each gasket associated with a different temperature range.

[0058] Each gasket assembly 13 can be mounted to the shock absorber 2 by positioning it between the end 8 of the cylinder 4 and the end 9 of the rod 5, and when the shock absorber 2 is compressed such that the end 8 of the cylinder 4 abuts against the gasket assembly 13, the amount of oil in the chamber 10 of the shock absorber 2, when the latter is filled to its maximum value, is equal to the amount optimized for the oil temperature within the temperature range associated with the gasket assembly 13.

[0059] When filling the shock absorber 2, the oil temperature is measured, and the shim device 13 used is a shim device associated with the temperature range that includes the oil temperature. When the shock absorber 2 is compressed such that the end 8 of the cylinder 4 abuts against the shim device 13, and the shock absorber 2 is filled to its maximum value, the amount of oil contained in the shock absorber 2 is the optimal amount of oil.

[0060] In this example, the gasket device 13 includes a main gasket device 13a and at least one auxiliary gasket device, which in this example are three auxiliary gasket devices: a first auxiliary gasket device 13b, a second auxiliary gasket device 13c, and a third auxiliary gasket device 13d.

[0061] The main gasket assembly 13a is associated with the lowest temperature range and includes a separate main gasket 12a.

[0062] Gasket 12 includes a main gasket 12a and at least one secondary gasket, which in this example includes a first secondary gasket 12b, a second secondary gasket 12c, and a third secondary gasket 12d.

[0063] Each sub-gasket assembly 13b, 13c, 13d includes a main gasket assembly 13a and at least one sub-gasket 12b, 12c, 12d stacked on the main gasket 12a. In this example, each sub-gasket assembly 13b, 13c, 13d includes a main gasket assembly 13a and individual sub-gaskets 12b, 12c, 12d.

[0064] Therefore, in this example, there are four different gasket devices: 13a, 13b, 13c, and 13d.

[0065] Main gasket assembly 13a (in) Figures 2 to 5 As can be seen in the image, this includes only the main gasket assembly 12a, which in this example has an associated temperature range of [-20°C; -5°C]. It should be noted that this temperature range is etched (in this example, etched) on the front side of the main gasket assembly 12a.

[0066] First gasket device 13b (in) Figure 6 As can be seen in the image, the device includes a main gasket assembly 13a (and a main gasket 12a) and a first auxiliary gasket assembly 12b. The first auxiliary gasket 12b is stacked on top of the main gasket 12a. The first auxiliary gasket assembly 13b is associated with a temperature range of [-5°C; +15°C]. It should be noted that this temperature range is etched (in this example, etched) on the front side of the first auxiliary gasket 12b.

[0067] Second auxiliary gasket device 13c Figure 7 As can be seen in the image, the device includes a main gasket assembly 13a (and a main gasket 12a) and a second auxiliary gasket 12c. The second auxiliary gasket 12c is stacked on top of the main gasket 12a. The temperature range associated with the second auxiliary gasket assembly 13c is [+15°C; +25°C]. It should be noted that this temperature range is etched (in this example, etched) on the front side of the second auxiliary gasket 12c.

[0068] The third gasket assembly 13d ( Figure 8 As can be seen in the image, the device includes a main gasket assembly 13a (and a main gasket 12a) and a third auxiliary gasket 12d. The third auxiliary gasket 12d is stacked on top of the main gasket 12a. The temperature range associated with the third auxiliary gasket assembly 13d is [+25°C; +40°C]. It should be noted that this temperature range is etched (in this example, etched) on the front side of the third auxiliary gasket 12d.

[0069] It can be seen that the height of the first gasket 12b is less than the height of the second gasket 12c, and the height of the second gasket 12c is less than the height of the third gasket 12d.

[0070] The higher the temperature range, the higher the height of the gasket assembly 13.

[0071] Therefore, when the chamber 10 is filled to its maximum value, the higher the oil temperature during filling, the higher the height of the gasket device 13 used, and the greater the amount of oil in the shock absorber 2.

[0072] It should be noted that the entire temperature range covers -20°C to +40°C, therefore maintenance operations on shock absorber 2 will not be permitted outside this temperature range.

[0073] Therefore, the main gasket assembly 13a includes the main gasket 12a.

[0074] The main gasket 12a has a central portion 22a and two lateral portions 22b. The central portion 22a includes two lateral fingers 22c, each extending from one side and the lower part of the central portion 22a. Each lateral portion 22b is secured to one of the lateral fingers 22c by two screws, and when the main gasket 12a is viewed from the front, the lateral portion 22b is positioned behind the lateral fingers 22c.

[0075] The main gasket 12a includes a first bearing surface 14, which is arranged to abut against a receiving surface 15 positioned near the end of the shock absorber close to the rod 5. Figure 5 and 7 (See in the middle).

[0076] In this configuration, the first bearing surface 14 is located on the first surface 16 of the main washer 12a, specifically on the lower surface of the main washer 12a when it is mounted onto the shock absorber 2. The first bearing surface 14 has two flat surfaces 14a and 14b. A lateral portion 22b protrudes downward relative to the bottom portion of the central portion 22a, thereby forming a recess 17 between the two flat surfaces 14a and 14b. This recess 17 provides access to the screw head when the main washer 12a is positioned on the receiving surface 15.

[0077] In this case, the receiving surface 15 is the upper surface of the radial protrusion 18 of the rod 5, which extends from the end 9 of the rod 5. In this example, the radial protrusion 18 is ear-shaped. The radial protrusion 18 has a perforation 19 (in... Figure 6 and 8 As can be seen in the image, the connecting shaft 20 passes through the through hole 19. The longitudinal direction of the connecting shaft 20 is parallel to the plane perpendicular to the sliding direction of the rod 5 in the cylinder 4.

[0078] Landing gear 2 includes a compass joint, which further includes an upper branch (not shown) and a lower branch 21 (in... Figure 6 and 8 (As can be seen in the image). Therefore, the compass joint allows rod 5 to slide in the sliding direction within cylinder 4, while preventing rod 5 from pivoting within cylinder 4.

[0079] The lower branch 21 of the compass connector is pivotally mounted relative to the rod 5 via a connecting shaft 20.

[0080] Each lateral portion 22b of the main gasket 12a includes a lateral stop 23. Thus, both lateral stops 23 are arranged at the ends of the main gasket 12a, on either side of the flat surfaces 14a and 14b of the first bearing surface 14, and they extend vertically from the first surface 16 of the main gasket 12a.

[0081] In order to mount the main gasket assembly 13a onto the shock absorber, the first bearing surface 14 of the main gasket 12a should be placed on the receiving surface 15 of the radial protrusion 18, such that the two lateral stops 23 are positioned on either side of the radial protrusion 18.

[0082] The lateral stop 23 forms a guide portion that aids in the positioning of the main washer 12a. The lateral stop 23 also impedes the pivoting of the main washer 12a relative to the rod 5.

[0083] The shape of the main gasket 12a ensures that each gasket assembly 13 remains in place during installation without the risk of tilting or tipping over.

[0084] The main gasket 12a also includes a second bearing surface 24.

[0085] The second bearing surface 24 is located on the second surface 25 of the main gasket 12a, which is opposite to the first surface 16. When the main gasket assembly 13a is mounted on the shock absorber 2, this surface is the top surface of the main gasket 12a. The second bearing surface 24 includes the upper surfaces of the central portion 22a and the lateral portion 22b of the main gasket 12a.

[0086] When using a main gasket assembly 13a that includes only the main gasket 12a, the second bearing surface 24 is the surface that abuts the end 8 of the cylinder 4 when the shock absorber 2 is compressed to its maximum extent.

[0087] When using the auxiliary gasket devices 13b, 13c or 13d, one of the auxiliary gaskets 12b, 12c or 12d is placed on the second bearing surface 24.

[0088] Each sub-gasket 12b, 12c, 12d includes a first bearing surface 26 (i.e., the first surface (lower surface) of the sub-gasket) and a second bearing surface 27 (i.e. formed on the second surface (upper surface) of the sub-gasket).

[0089] The second bearing surface 27 of each sub-gasket includes a first surface 27a and a second surface 27b. The upper and central portions of each sub-gasket are recessed, and surfaces 27a and 27b extend on both sides of the recess.

[0090] Therefore, when the sub-gasket devices 13b, 13c or 13d are assembled, the first bearing surface 26 of one of the sub-gaskets 12b, 12c or 12d is placed on the second bearing surface 24 of the main gasket 12a.

[0091] When using auxiliary shim devices 13b, 13c or 13d, the second bearing surface 27 of the auxiliary shims 12b, 12c or 12d used is the surface that abuts against the end 8 of the cylinder 4 when the shock absorber 2 is compressed to its maximum extent.

[0092] The main gasket 12a also includes a first retaining device arranged to position and retain the secondary gaskets 12b, 12c or 12d on the second bearing surface 24.

[0093] Similarly, each of the secondary gaskets 12b, 12c, 12d includes a second retaining device arranged to engage with a first retaining device to position and retain the secondary gasket 12b, 12c, or 12d on the second bearing surface 24 of the primary gasket 12a.

[0094] The first retaining device includes a hole, and the second retaining device includes a pin, and vice versa, the pin intended to be positioned in the hole.

[0095] In this configuration, the first fixing device for the main washer 12a includes two holes 28 positioned along the length of the upper surface of the central portion 22a of the main washer 12a (forming a portion of the second bearing surface 24); the second fixing device for each secondary washer includes two pins 29 positioned along the length of the central portion of the first bearing surface 26 of the secondary washer. Of course, the number of pins and holes can vary.

[0096] For a given oil temperature, the maintenance operator selects a gasket assembly 13 whose associated temperature range includes the given temperature, and assembles the gasket assembly 13 by positioning the appropriate auxiliary gaskets 12b, 12c, 12d on the main gasket 12a—unless the oil temperature is in the lowest range, in which case the main gasket assembly 13a is used directly without any other gaskets.

[0097] For example, gasket 12 is made of steel, such as 35NCD16-THR type steel. Gasket 12 can be made of any other suitable material, as long as it has the same properties according to the intended application.

[0098] The main gasket assembly 13a also includes a first protective element 30, which is arranged as abutment against the rod 5 and positioned between the rod 5 and the main gasket 12a when the main gasket assembly 13a is mounted on the shock absorber 2. This prevents the steel gasket 12 from damaging the coatings of the various components of the landing gear 3 (especially the chrome-plated components).

[0099] In this case, the first protective element 30 is made of plastic, such as polyoxymethylene (POM). The advantage of this material is that it does not expand or deform under humid and high-temperature conditions, such as in Asian climates. It is possible to use other materials with these properties. For example, nylon does not possess these properties and will expand in humid environments.

[0100] The first protective element 30 includes a recessed surface 31 that complements the cylindrical shape of the rod 5 and is intended to abut against the rod 5 while the main gasket assembly 13a is installed.

[0101] The main gasket assembly 13a also includes a strip 32 and a fastener 33 through which the strip 32 passes. The strip 32 holds the main gasket assembly 13a in place (as well as all the secondary gasket assemblies 13b, 13c, 13d constituting the main gasket assembly 13a). The strip 32 wraps around the rod 5, and the fastener 33 makes it possible to tighten the strip 32 around the rod 5, thereby securing the gasket assembly 13 to the rod 5.

[0102] The main gasket assembly 13a includes a second protective element 34, which is arranged to abut against the rod 5 and positioned between the rod 5 and the fastener 32 when the gasket assembly 13a is mounted onto the shock absorber 1. The second protective element 34 makes it possible to prevent the fastener from damaging the coating of the rod 5, and is, for example, also made of polyoxymethylene (but not required).

[0103] The second protective element 34 includes a recessed surface 35 that complements the cylindrical shape of the rod 5 and is intended to abut against the rod 5 while the main gasket assembly 13a is installed.

[0104] It should be noted that maintenance system 1 is very simple to use and can be easily transported by hand (possibly in a suitcase).

[0105] As described above, each gasket 12 includes an indicator that allows identification of the temperature range associated with the gasket assembly 13 including the gasket 12. To further facilitate operator selection, the entire surface of the gasket 12 is painted, except for functional surfaces (particularly bearing surfaces).

[0106] The higher the temperature range, the warmer the paint color. Therefore, the main gasket 12a is painted, for example, dark blue, while the secondary gasket 12d is painted, for example, red.

[0107] A “Remove Before Flight” sign (not shown) is attached to the front surface of the main pad 12a, ensuring that the operator does not forget the tools on the aircraft after performing maintenance on the shock absorber 2.

[0108] The first embodiment of the maintenance method for the pneumatic hydraulic shock absorber 2 will now be described.

[0109] An airplane is on the ground, on its wheels. An airplane can also be on its supports.

[0110] The method first includes the following preliminary steps.

[0111] The operator opens the filling valve 11 and connects the hose to the filling valve. The operator places the jack under the lever 5 and uses the jack to move the lever 5 upward to fully compress the shock absorber 2, thereby emptying all the oil contained in the chamber 10 of the shock absorber 2.

[0112] The operator then completely fills chamber 10 of shock absorber 2 with new oil. To do this, the operator connects a hose to the oil supply source. The operator then releases the jack, which acts as a release lever 5, causing it to fall back under gravity. Oil is drawn into shock absorber 2 in the same manner as a syringe. Chamber 10 is then completely filled with oil.

[0113] Once the outriggers are fully released, the operator measures the oil temperature. For example, the operator may use an infrared thermometer.

[0114] The operator then selects the gasket assembly 13 associated with a temperature range that includes the oil temperature and assembles the gasket assembly 13 (if it is a secondary gasket assembly 13b, 13c, or 13d).

[0115] Therefore, the operator selects the appropriate gasket set 12 corresponding to the recorded temperature. For example, if the operator reads an oil temperature of 35°C, he / she will select the third gasket set 13d, which covers the temperature range [+25°C; +40°C].

[0116] Then, the operator installs the gasket device 13 onto the shock absorber 2.

[0117] The operator places the main gasket 12a on the receiving surface 15 by correctly positioning the lateral stop 23 on either side of the radial protrusion 18, and wraps the strip 32 around the rod 5, then tightens the strip 32 with the aid of the fastener 33.

[0118] The operator then uses a jack to compress the shock absorber 2 until the end 8 of the cylinder 4 comes into contact with the gasket device 13. Then, the excess oil is discharged through the filling valve 11.

[0119] The operator removes the hose, closes the filling valve 11, and releases the jack. Rod 5 falls back under gravity.

[0120] The second embodiment of the maintenance method for pneumatic hydraulic shock absorbers will now be described.

[0121] An airplane is on the ground, on its wheels. An airplane can also be on its supports.

[0122] The operator measures the oil temperature. For example, the operator uses an infrared thermometer.

[0123] The operator then selects and assembles the gasket assembly 13 associated with the oil temperature range, which includes the oil temperature.

[0124] Then, the operator installs the gasket device 13 onto the shock absorber 2.

[0125] The operator places the main gasket 12a on the receiving surface 15 by correctly positioning the lateral stop 23 on either side of the radial protrusion 18, and wraps the strip 32 around the rod 5, then tightens the strip 32 with the aid of the fastener 33.

[0126] The operator places the jack under lever 5.

[0127] Then, the operator uses a jack to compress the shock absorber 2 to its maximum extent to purge it. All the oil is then discharged. Chamber 10 is emptied.

[0128] The jack slowly descends. Lever 5 also descends accordingly.

[0129] Shock absorber 2 sags. Therefore, cylinder 4 will press against shim device 13.

[0130] Then, the operator fills the chamber 10 of the shock absorber 2 with new oil. The operator ensures that the chamber 10 is completely filled with oil.

[0131] It should be noted that in the second embodiment of this maintenance method, the shim device 13 supports the mass of the aircraft and therefore must be very robust.

[0132] The gasket 13 is designed to maximize its contact area with the rod 5 and the cylinder 4.

[0133] In the illustrated example, each gasket assembly 13 can support a mass of 51 tons.

[0134] The surface area of ​​each flat surface 14a, 14b of the first bearing surface 14 is 729 mm. 2 .

[0135] The surface area of ​​the second bearing surface 24 of the main gasket 12a is 2772 mm². 2 , such that the applied load is equal to:

[0136] F / S = 510000 / 2772 = 183 MPa.

[0137] Of course, the present invention is not limited to the described embodiments, but includes any variations that fall within the scope of the invention as defined by the claims.

[0138] The maintenance system and the shim assembly used do not necessarily have to be mounted on the shock absorber rod; they can also be mounted on the cylinder. In this case, when the shock absorber is compressed to its maximum extent, the end of the rod abuts against the shim assembly.

[0139] When the gasket device is mounted on the rod, it is not necessarily positioned on the ear-shaped radial protrusion through which the connecting shaft of the compass connector moves; it can be positioned on different elements of the rod, especially on radial protrusions of different shapes.

[0140] As described above, the main gasket assembly includes a single gasket (the main gasket), and each secondary gasket assembly includes a single secondary gasket (in addition to the main gasket). This configuration is not mandatory.

[0141] For example, one or more secondary gasket assemblies can be provided to include a main gasket assembly and a plurality of secondary gaskets. In this case, at least one secondary gasket includes a third retaining device arranged to position and retain another secondary gasket on the secondary gasket. For example, the third retaining device may be a hole into which a pin of the other secondary gasket can be inserted (or vice versa).

[0142] The maintenance system can be implemented in any type of pneumatic or hydraulic shock absorber: main or auxiliary landing gear shock absorbers, shock absorbers integrated into or separate from the landing gear bay, shock absorbers mounted on aircraft other than airplanes, shock absorbers for other vehicles, etc.

Claims

1. A maintenance system (1) for a pneumatic hydraulic shock absorber (2), comprising a cylinder (4) and a rod (5) sliding within the cylinder, the cylinder (4) further comprising an oil-containing chamber (10), the maintenance system comprising a plurality of gaskets (12) arranged to be assembled to form a plurality of gasket devices (13) of different heights and each associated with a different temperature range, each gasket device being arranged to be mounted to the shock absorber by being positioned between an end (8) of the cylinder through which the rod passes and an end (9) of the rod located outside the cylinder to be inserted, such that when the shock absorber (2) is compressed such that the end of the cylinder or the end of the rod abuts against the gasket device (13), when the chamber (10) is filled to its maximum capacity, the amount of oil in the chamber (10) is equal to an amount optimized for the oil temperature within the temperature range associated with the gasket device (13).

2. The maintenance system according to claim 1, characterized in that, The gasket assembly (13) includes a main gasket assembly (13a) and at least one secondary gasket assembly (13b, 13c, 13d). The main gasket assembly is associated with a minimum temperature range and includes a separate main gasket (12a). Each secondary gasket assembly includes the main gasket assembly and at least one secondary gasket (12b, 12c, 12d) stacked on the main gasket.

3. The maintenance system according to claim 2, characterized in that, Each of the said secondary gasket devices (13b, 13c, 13d) includes the main gasket device (13a) and individual secondary gaskets (12b, 12c, 12d).

4. The maintenance system according to claim 2 or 3, characterized in that, The main gasket (12a) includes a first bearing surface (14) and a second bearing surface (24). The first bearing surface is arranged to be applied to the receiving surface (15) of the shock absorber (2). The receiving surface is close to the end (8) of the cylinder (4) or the end (9) of the rod (5). The second bearing surface is capable of holding the secondary gaskets (12b, 12c, 12d). The main gasket also includes a first retaining device (28) arranged to position and hold the secondary gaskets on the second bearing surface.

5. The maintenance system according to claim 4, characterized in that, The secondary gasket includes a second retaining device (29) arranged to engage with the first retaining device (28) to position and hold the secondary gasket on the second bearing surface of the primary gasket.

6. The maintenance system according to claim 5, characterized in that, The first retaining device includes a hole (28), and the second retaining device includes a pin (29), or the first retaining device includes a pin (29), and the second retaining device includes a hole (28), the pin being intended to be positioned in the hole.

7. The maintenance system according to claim 5 or 6, characterized in that, At least one of the sub-gaskets (12b, 12c, 12d) includes a third retaining device arranged to position and retain another sub-gasket on the sub-gasket.

8. The maintenance system according to claim 4, characterized in that, The cylinder (4) is the landing gear bay of the aircraft, and the rod (5) carries at least one wheel (7) of the landing gear, the main gasket device (13a) is arranged to be fixed to the rod, and the receiving surface (15) is the upper surface of the radial protrusion (18) of the rod.

9. The maintenance system according to claim 8, characterized in that, The radial protrusion (18) has a through hole (19) through which a connecting shaft (20) passes. The landing gear includes a compass joint, the lower branch (21) of which is pivotally mounted relative to the rod (5) via the connecting shaft.

10. The maintenance system according to claim 8 or 9, characterized in that, The main gasket assembly (13a) includes two lateral stops (23) arranged such that, when the main gasket assembly is installed, the radial protrusion (18) is positioned between the two lateral stops.

11. A method for maintaining a pneumatic hydraulic shock absorber (2) using a maintenance system (1) according to any one of the preceding claims, the method comprising the steps of: -Measure oil temperature; - Select the gasket device (13) associated with a temperature range including the oil temperature, and install the gasket device on the shock absorber; - Compress the shock absorber so that the end of the cylinder or the end of the rod abuts against the gasket device; - Ensure the shock absorber is filled with as much oil as possible.

12. The maintenance method according to claim 11, characterized in that, The procedure also includes the following steps: fully compressing the shock absorber (2) and emptying all the oil contained in the chamber (10) of the shock absorber, then fully filling the chamber with new oil, and subsequently expanding the shock absorber.

13. The maintenance method according to claim 12, characterized in that, When the end of the cylinder or the end of the rod abuts against the gasket device, excess oil is discharged, ensuring that the shock absorber is filled with oil to the maximum extent.

14. The maintenance method according to any one of claims 11 to 13, characterized in that, The pneumatic hydraulic shock absorber (2) is a shock absorber for the landing gear of an aircraft.

15. A landing gear assembly comprising an aircraft landing gear and a maintenance system (1) according to any one of claims 1 to 10, wherein the maintenance system is used to perform the maintenance method according to claim 14 in the landing gear.

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