Shock absorbing strut

Abstract

Shock struts are provided that include a first energy absorbing stage or first load limiter and a second energy absorbing stage or second load limiter. The second energy absorbing stage or second load limiter can include one or more disc springs (205). The shock struts can be used in both fixed and retractable landing gear while providing design tunability for obtaining a load-deflection curve that accommodates a range of descent or impact velocities.

Description

Background Technology

[0001] Most aircraft are equipped with landing gear that enables them to land safely on the ground. In some types of landing gear, shock-absorbing struts are used to cushion the landing impact, suppress repetitive oscillations, and reduce the aircraft's tendency to bounce or "rebound".

[0002] A type of vibration-absorbing strut suitable for use in landing gear that achieves these advantages is called a hydropneumatic strut (“hydraulic” strut), which provides elastic spring characteristics by converting kinetic energy into potential energy using pressurized gas. This energy conversion, resulting in damping and a reduction in “rebound,” is achieved through oil or the like, typically forced through damping orifices. In some constructions of vibration-absorbing struts, in addition to the compression and expansion of the gas, the damping force of the oil through the orifices also contributes to the reaction force of the hydraulic strut.

[0003] A prior art hydraulic strut is disclosed in U.S. Patent 9,914,532 and is shown in Figure 1A. Referring to Figure 1A, a conventional single-stage hydraulic strut is generally designated 10. The strut 10 includes an inner housing portion 12 slidably coupled to an outer housing portion 14. The inner housing portion 12 and the outer housing portion 14 together define a cavity 16 containing a fluid 18 consisting of oil 20 contained in its lower portion and gas 22 contained in its upper portion. The strut 10 also includes an orifice support tube 28 defining a conventional damping orifice 30 at its axial end. To improve the efficiency of the strut 10, an optional metering pin 32 may be provided for interaction with the damping orifice 30.

[0004] Figure 1B illustrates another hydraulic strut known in the prior art. Referring now to Figure 1B, a conventional two-stage hydropneumatic damping strut is generally designated 10′. The two-stage strut 10′ includes an inner shell portion 12′ slidably coupled within an outer shell portion 14′. A floating piston 40′ is slidably disposed within the inner shell portion 12′, defining a chamber 42′ between the floating piston 40′ and the closed lower end of the inner shell portion 12′. A seal, ring, or other suitable sealing device, typically designated 44′, is provided to form a sealed chamber for containing gas 46′ under high pressure. To improve the efficiency of the strut 10′, an optional metering pin (similar to that in Figure 1A but not shown) may also be provided for interaction with the damping orifice 30′.

[0005] Opposite to the high-pressure gas chamber 42′ (e.g., above the floating piston), the inner shell portion 12′ and the outer shell portion 14′ together define an inner cavity 16′ containing a fluid 18′ consisting of oil 20′ contained in its lower portion and low-pressure gas 22′ contained in its upper portion. An orifice support tube 28′ is provided in the outer shell portion 14′, which defines a conventional damping orifice 30′ at its axial end. The two-stage strut 10′ also includes an orifice plate 48′ fixedly mounted within the lower portion of the inner shell portion 12′ and above the floating piston 40′.

[0006] In some landing gear configurations, such as the nose landing gear, a type of hydropneumatic strut called a "jump strut" can be used to increase nose rotation during takeoff, in addition to reducing its impact capability. A jump strut typically consists of a hydraulic strut and a pneumatic system controlled by an electronic control system. The pneumatic system supplies high-pressure gas to the gas chambers of the hydraulic strut based on control signals received from the electronic control system. Applying high-pressure gas to the upper gas chambers causes the strut to extend rapidly, and the subsequent reaction force from the ground causes the aircraft's nose to rise. Summary of the Invention

[0007] The present invention provides a selection of concepts to introduce a simplified form, which are further described in the detailed description below. This invention is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0008] According to one aspect of this disclosure, an energy absorption device for an aircraft is provided. In one embodiment, the device includes a first load limiter comprising a fusible damping strut configured to absorb impact energy and a second load limiter integrally formed within the fusible damping strut. In one embodiment, the second load limiter includes one or more disc springs.

[0009] In one embodiment, the first load limiter is configured to absorb shock energy associated with normal operating conditions, while the second load limiter is configured to absorb additional shock energy beyond the shock energy associated with normal operating conditions of the aircraft.

[0010] In one embodiment, the hydropneumatic shock absorber strut includes an inner cavity and a piston. The inner cavity contains a strut fluid composed of gas and hydraulic fluid. The piston is capable of moving a predetermined distance within the inner cavity and compressing the gas. One or more disc springs are located within the inner cavity to absorb impact energy after the piston has moved the predetermined distance.

[0011] In one embodiment, one or more springs include a first set of disc springs located in the inner cavity and a second set of disc springs located in the inner cavity at a distance from the first set of disc springs.

[0012] In one embodiment, the oil-gas damping strut further includes a metering pin located in the piston and an orifice support tube arranged to slidably receive the metering pin through a damping orifice.

[0013] In one embodiment, the oil-gas damping strut further includes a plate located on an orifice support tube or metering pin to hold one or more disc springs.

[0014] In one embodiment, the piston strikes the plate when the piston moves a predetermined distance, or the orifice support tube strikes the plate when the piston moves a predetermined distance.

[0015] In one embodiment, the hydropneumatic shock absorber strut includes an inner shell portion slidably coupled within an outer shell portion, an inner cavity formed by the inner shell portion and the outer shell portion, a first chamber disposed in the inner cavity and containing pressurized gas, a floating piston located in the inner cavity to define a sealed second chamber on a first side of the floating piston, and hydraulic fluid disposed in the inner cavity between the first chamber and the floating piston. In one embodiment, one or more disc springs of the second load limiter are located in the second chamber.

[0016] According to another aspect of this disclosure, the retractable landing gear includes any embodiment of the aforementioned device.

[0017] According to another aspect of this disclosure, a vibration-absorbing strut for a vehicle is provided. In one embodiment, the strut includes: an inner shell portion slidably coupled within an outer shell portion; an inner cavity formed by the inner shell portion and the outer shell portion, the inner cavity defining a sealed fluid volume for receiving strut fluid (including hydraulic fluid and gas); a piston capable of moving a predetermined distance within the inner cavity to compress gas and absorb energy acting on the strut; a damping orifice in fluid communication with the hydraulic fluid; and one or more disc springs located within the strut to absorb additional energy acting on the strut after the piston has moved a predetermined distance.

[0018] In one embodiment, the piston and the inner shell portion are integrally formed.

[0019] In one embodiment, one or more disc springs are located at the end of the housing portion, and the piston acts on one or more disc springs when the piston moves a predetermined distance.

[0020] In one embodiment, the strut further includes an orifice support tube located within the housing portion and defining a damping orifice. In one embodiment, one or more disc springs are located around the orifice support tube.

[0021] In one embodiment, the strut further includes an orifice support tube located in the outer casing portion and a metering pin located in the piston. In one embodiment, the orifice support tube is configured to slidably receive the metering pin through a damping orifice. In another embodiment, the piston is integrally formed with the inner casing portion.

[0022] In one embodiment, the strut further includes an orifice support tube located within the housing portion and defining a damping orifice. One or more disc springs are located at the end of the inner housing portion in one embodiment, and the orifice support tube acts on the one or more disc springs when the piston moves a predetermined distance.

[0023] In one embodiment, one or more disc springs include a first set of disc springs located within an inner cavity and spaced apart from a second set of disc springs. In another embodiment, the first or second set of disc springs includes a plurality of disc springs arranged in parallel, in series, or in combination thereof.

[0024] In one embodiment, the strut further includes a pressurized gas source selectively connected in fluid communication with the cavity.

[0025] In one embodiment, the strut further includes a control valve in fluid communication with a pressurized gas source, wherein the control valve selectively supplies pressurized gas from the pressurized gas source into the cavity to cause the strut to extend rapidly.

[0026] According to another aspect of this disclosure, the retractable landing gear includes any embodiment of the aforementioned strut.

[0027] According to another aspect of this disclosure, a two-stage aircraft vibration-absorbing strut is provided. The two-stage strut includes: an inner shell portion slidably coupled within an outer shell portion; an inner cavity formed by the inner shell portion and the outer shell portion; a first chamber disposed in the inner cavity and containing pressurized gas; a floating piston located in the inner cavity to define a sealed second chamber on a first side of a floating piston; a hydraulic fluid disposed in the inner cavity between the first chamber containing pressurized gas and the floating piston; a damping orifice in fluid communication with the hydraulic fluid; and one or more disc springs located in the second chamber to absorb energy acting on the strut after the floating piston has moved a predetermined distance. Attached Figure Description

[0028] The foregoing aspects and numerous accompanying advantages of this disclosure will become more readily understood when viewed in conjunction with the accompanying drawings, as will be made even clearer by reference to the following detailed description, in which:

[0029] Figure 1A is a cross-sectional view of a conventional oil-gas damping strut;

[0030] Figure 1B is a cross-sectional view of a conventional two-stage oil-gas damping strut;

[0031] Figure 2 This is a perspective view of a representative embodiment of a vibration-absorbing strut according to the present disclosure;

[0032] Figure 3 yes Figure 2 An exploded view of the vibration-absorbing support shown;

[0033] Figures 4A to 4B It is along Figure 2 The cross-sectional view of the vibration-absorbing support column taken from line 4-4 in the figure;

[0034] Figure 5 This is a cross-sectional view of another embodiment of the vibration-absorbing support column according to the present disclosure;

[0035] Figure 6 This is a cross-sectional view of yet another embodiment of the vibration-absorbing strut according to the present disclosure;

[0036] Figure 7 This is a cross-sectional view of yet another embodiment of the vibration-absorbing support column according to the present disclosure;

[0037] Figure 8 This is a cross-sectional view of an embodiment of the two-stage vibration-absorbing column according to the present disclosure;

[0038] Figure 9 This is a cross-sectional view of an embodiment of the jumping support according to the present disclosure; and

[0039] Figures 10A to 10E Several representative arrangements of one or more springs are depicted. Detailed Implementation

[0040] The following detailed description is taken in conjunction with the accompanying drawings, wherein like reference numerals denote like elements. This detailed description is intended as a description of various embodiments of the disclosed subject matter and not as representation of only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as being more preferred or advantageous than other embodiments. The illustrative examples provided herein are not intended to exhaustively cover the claimed subject matter or to limit the claimed subject matter to the precise forms disclosed.

[0041] The following description provides several examples of techniques and methods for storing or absorbing energy in aircraft (e.g., airplanes, helicopters, etc.). Some techniques and methods also provide energy / vibration damping to vehicles. Examples of one or both of these techniques and methods can be implemented in shock absorbers, struts, load limiters, or other vibration / force absorption devices, as described in more detail below.

[0042] Several examples of these shock / force absorbing devices are particularly well-suited for use in the landing gear of fixed-wing or rotary-wing aircraft and are often referred to as shock absorber struts. In some embodiments, shock absorber struts can serve as the main struts of the landing gear. In some embodiments, shock absorber struts can be combined with retractable type landing gear.

[0043] Generally, shock absorber struts support the aircraft body during taxiing and takeoff, and absorb impact energy and / or dampen vibrations when the aircraft touches down after flight. In some embodiments, shock absorber struts can be specific to the operational requirements of a particular aircraft. For example, commercial airliners, with their heavy fuselages and payloads, require specific energy absorption and / or damping when performing conventional trajectory landings. Military aircraft performing vertical takeoff and landing have a different set of landing requirements, and the takeoff / landing requirements of aircraft carriers or other ship-based aircraft (e.g., vertical, catapult, intercept, etc.) can differ from those of land-based aircraft. For example, carrier-based aircraft using landing gear with bouncy struts can have a different set of operational (e.g., takeoff or landing) requirements. Helicopters performing emergency rapid landings have a different set of energy absorption and / or vibration absorption requirements. As will be described in more detail below, embodiments of shock absorber struts disclosed herein can be scaled to various design parameters by changing the size, number, or material of the strut itself or strut components.

[0044] In use, shock absorbers absorb and / or attenuate landing impact energy and are designed to prevent any “excessive” forces from landing from being transmitted to the aircraft body. In this regard, some embodiments of the shock absorbers disclosed herein include a first energy-absorbing stage or a first load limiter and a second energy-absorbing stage or a second load limiter to provide design flexibility, such as for accommodating descent speed ranges, aircraft weight, etc. In some of these embodiments, the first and second stages can be used in series or in parallel during takeoff and / or landing. In some embodiments, the second stage is capable of providing a variable spring rate to the strut, for example. In some embodiments, the strut and the second stage can be additionally or alternatively configured to meet various design / performance requirements (e.g., extreme temperatures, aircraft threshold height, flexibility to break loads at specific travel distances, etc.).

[0045] In the examples of struts disclosed herein, a first load limiter and a second load limiter can be used together during normal operating conditions of the aircraft. However, in some cases, landing generates abnormal or excessive forces on the aircraft, and conventional struts may be insufficient or ineffective when the landing forces exceed a pre-selected landing threshold. To address these operational challenges, in some embodiments, a first-stage or first-load limiter may be configured to absorb all normal impact forces occurring during normal landing conditions without the assistance of a second-stage or second-load limiter. However, during abnormal landing conditions where the landing forces exceed the normal operating cycle, the first-stage or first-load limiter and the second-stage or second-load limiter work together to absorb the abnormally high impact forces. In some embodiments of these examples, energy dissipation or attenuation may be additionally or alternatively performed in the first stage, the second stage, or both.

[0046] In some embodiments, the first stage or first load limiter is in the form of a hydropneumatic strut, while the second stage or second load limiter is in the form of one or more springs integrated with the hydropneumatic strut. In other embodiments, the first stage or first load limiter is the first stage of a two-stage hydraulic strut, such as the strut briefly described in FIG. 1B. In these embodiments, the second stage or second load limiter is in the form of one or more springs that can be used in place of the high-pressure gas chamber of the two-stage hydraulic strut. As will be described in more detail below, in some embodiments of these embodiments, one or more springs are disc springs, which have the advantage of allowing for the use of small damping struts, for example, in retractable landing gear.

[0047] While some embodiments of this disclosure will be described with reference to aircraft, those skilled in the art will understand that the disclosed embodiments are illustrative in nature and should therefore not be construed as limited to applications on aircraft. Thus, it is evident that the techniques and methods proposed by one or more representative embodiments of this disclosure have broad applications and can be used in any situation where energy absorption and / or attenuation is desired.

[0048] Now go to Figure 2 This illustrates a representative embodiment of a vibration-absorbing strut or shock-absorbing strut, typically designated 100. For example... Figure 2 As shown, the shock absorber strut 100 includes an inner shell portion 105 that is retractably engaged with the outer shell portion 110. Both the inner shell portion 105 and the outer shell portion 110 can be tubular bodies. As will be described in more detail below, the shock absorber strut 100 can be configured as a "hydraulic" type strut. In this respect, the shock absorber strut is configured to absorb and dissipate impact energy (e.g., during landing) by compressing a gas (e.g., nitrogen or dry air) contained in the shock absorber strut 100 and by dissipating a portion of the compression energy through the use of an incompressible fluid (e.g., hydraulic fluid) and damping orifices contained in the shock absorber strut 100.

[0049] Now for reference Figure 3 and Figures 4A to 4B This will be described in more detail. Figure 2 Each component of the shock-absorbing strut 100 shown. Figure 3 yes Figure 2 An exploded view of the support column 100 shown. Figure 4A and Figure 4B It is along Figure 2 Longitudinal cross-sectional view of strut 100 taken at centerline 4-4. The damping strut 100 has multiple static conditions or states (one in... Figure 4A (as shown in the image), and multiple compression conditions or states (one in...) Figure 4B (As shown in the figure). In this respect, the total length of the shock-absorbing strut 100 can change when the inner shell portion 105 translates relative to the outer shell portion 110. For example, when an external force F is applied to the first end of the inner shell portion 105, when the inner shell portion 105 transitions relative to the outer shell portion 110 from an uncompressed state (not shown) to one of the static states (e.g., ...). Figure 4A ) or from one of the static states (e.g., Figure 4A ) to one of the compressed states (e.g., Figure 4B When this is the case, the total length of the support column 100 defined along the longitudinal axis A can be shortened.

[0050] It should be understood that the static state of strut 100 is determined by, for example, sprung mass (e.g., the weight of the aircraft body) and the design of the strut. In some embodiments, the static length of strut 100 is within 5-10% (or less) of the static length of a conventional hydraulic strut used in retractable landing gear.

[0051] like Figure 4A As shown, the inner housing portion 105 is formed as a piston (“piston 105”), which is slidably coupled to the outer housing portion 110, hereinafter referred to as the outer cylinder 110, in a telescoping manner. The piston 105 and the outer cylinder 110 together define an inner cavity 130 containing propulsion fluid. The inner cavity 130 contains hydraulic fluid 135 in the piston 105 and gas 140 in the outer cylinder 110. The hydraulic fluid 135 and gas 140 together constitute a damping propulsion fluid. In some embodiments, the hydraulic fluid 135 includes, for example, oil, water, a water-oil emulsion, a salt solution, or combinations thereof, and the gas 140 includes air, nitrogen, or combinations thereof. Bearings (e.g., piston end flange 145 and lower bearing or cap 150) and seals (not shown) are provided between the piston 105 and the cylinder 110, which allow the piston 105 to slide within the outer cylinder 110 without leakage of propulsion fluid from the inner cavity 130. Therefore, the inner cavity 130 defines a chamber having a sealed fluid volume for containing the support fluid. In some embodiments, both the gas and the liquid can be compressible.

[0052] When applying such to the support 100 Figure 4B When a load such as force F is applied to the strut 100, the piston 105 slides into the outer cylinder 110, thereby switching the strut 100 to one of several compression states. This results in the compression of the gas 140 within the inner cavity 130, thereby absorbing energy. When a load such as force F is removed from the strut 100, the internal pressure of the strut fluid causes the piston 105 to slide out of the outer cylinder 110, causing the strut 100 to extend, thereby dissipating energy.

[0053] In some embodiments, the strut 100 is configured to suppress the movement of the piston relative to the outer cylinder, thereby dissipating at least some of the energy stored or consumed by the strut 100 and limiting the recoil of the strut 100 to reduce the chance of "bounce" upon landing. In this regard, a damper, a damping device, or other means for attenuation is provided.

[0054] In the illustrated embodiment, the damping device includes, for example, an optional metering pin 155 and an orifice support tube 160. In some embodiments, the orifice support tube 160 is located within the outer cylinder 110 and defines a damping orifice 165 at its axial end for receiving the metering pin 155. In some embodiments, the metering pin 155 may be located within the piston 105. The metering pin 155 may have an elongated body 170 that transitions to a base flange 175 at an attachment point or lower end of the piston 105. In some embodiments, the metering pin 155 may be arranged to be completely contained within the piston 105. In this or other embodiments, the metering pin 155 slidably engages the orifice support tube 160 through the damping orifice 165 as the piston 105 translates relative to the outer cylinder 110.

[0055] During operation, as the piston 105 translates relative to the outer cylinder 110, the orifice support tube 160 is received by the piston 105. Therefore, the cooperation between the metering pin 155 and the damping orifice 165 at least partially determines the damping characteristics of the strut 100. In some embodiments, the damping of the hydraulic fluid 135 through the damping orifice 165 contributes to the reaction force of the strut 100. Therefore, the absorption and / or attenuation of impact kinetic energy by the strut 100 is performed by a first impact reduction stage or a first load limiter.

[0056] It should be understood that the construction of the metering pin 155 can be varied in different embodiments to alter the performance characteristics of the strut 100 (e.g., spring rate, damping, etc.). In some embodiments, the elongated body 170 may be tapered or grooved (see...). Figure 3This allows for adjustment of the performance characteristics of the strut 100. For example, the cross-sectional area of ​​the elongated body 170 may gradually decrease from the base flange 175 toward the end 180 of the metering pin 155 or segmentally. Other shapes may also be used in embodiments of this disclosure. Of course, the metering pin 155 is optional and may be omitted in some embodiments. In embodiments where the metering pin 155 is omitted, the damping hole 165 provides damping for the strut 100.

[0057] In some embodiments, the orifice support tube 160 may further include a plurality of orifices 185 in the wall of the orifice support tube 160 to provide additional damping or forced stopping. Of course, the size, number and position of the orifices 185 may also be varied to affect the performance characteristics of the strut 100 (e.g., spring rate, damping, etc.).

[0058] The strut 100 also includes a second impact reduction stage or a second load limiter integrally formed within the strut 100. Figure 3 and Figures 4A to 4B An example of a second impact reduction stage or second load limiter that can be implemented through embodiments of this disclosure is shown. Figure 3 and Figures 4A to 4B As shown, the second stage includes one or more springs 205 (shown as three pairs of springs arranged in series) disposed in the attachment or upper end of the outer cylinder 110 and a sliding plate 210 exposed to the gas 140 and disposed near the one or more springs 205.

[0059] In the illustrated embodiment, each of the one or more springs 205 is a disc spring or a conical washer, sometimes referred to as a dish washer. In some embodiments, the one or more springs 205 are stacked around and supported by the base of the orifice support tube 160 and held in place by a plate 210. At this point, translational movement of the plate 210 in the opposite direction to the one or more springs can be limited by the shoulder 220 of the orifice support tube 215. In some embodiments, the plate 210 provides a substantially flat surface for contact with the piston 105 and distributes the force F uniformly around the periphery of the one or more springs 205. This uniform distribution of the force F provides a stable and predictable spring constant.

[0060] Optionally, plate 210 may include a pressure relief orifice 225 passing through one side therethrough to regulate gas pressure on both sides of plate 210. Other configurations may be available to allow gas communication between spaces formed on either side of plate 210. In these embodiments, the space containing one or more springs is part of the inner cavity 130. In other embodiments, the pressure relief orifice 225 is omitted, and seals, rings, or other sealing devices are used at the interface between plate 210 and the outer cylinder 110 and the orifice support tube 160 to form a sealed chamber for receiving one or more springs 205.

[0061] One or more springs 205 may include a plurality of springs 205 arranged in series, such as Figure 4A and 10C As shown in both, multiple springs 205 arranged in parallel (see Figure 10B ), or a plurality of springs 205 arranged in series / parallel combinations thereof (see Figure 10D and 10E Of course, a single spring 205 can also be used (see...). Figure 10A It should be understood that the number and arrangement of one or more springs 205 will determine the spring constant and flexural capacity of one or more springs 205. For example, along the same direction (e.g., in parallel, see...). Figure 10B Stacking springs will result in a larger spring constant, but less deflection. In cases such as... Figure 4A and 10C Stacking in alternating directions (e.g., in series) will result in a larger spring deflection but a lower spring constant. In some embodiments, one or more springs 205 may be preloaded. Changing the number and / or arrangement of springs 205 (in...) Figures 10A to 10E (Several examples are shown in the figure) The energy absorption capability of the second impact reduction stage can be customized for its intended application. Therefore, strut 100 can be designed for a range of descent velocities or impact velocities and aircraft weights.

[0062] Additionally or alternatively, other design parameters of one or more springs can be manipulated to tailor the energy absorption capacity of the second impact reduction stage for its intended application. For example, the thickness of one or more springs, the material of one or more springs, and the spring profile (e.g., height, outer diameter, inner diameter, etc.) affect the spring constant and flexural capacity. In some embodiments, one or more springs are made of metal. In other embodiments, one or more springs are made of or comprise composite materials that are lighter than metal (e.g., carbon fiber, carbon fiber reinforced polymer).

[0063] In embodiments of this disclosure, each of the above and / or other parameters can be manipulated individually or in any combination to achieve a desired load deflection curve to accommodate a range of descent velocities and aircraft weights. Thus, in some embodiments, each of one or more springs 205 is identical, and in other embodiments, one or more springs differ due to at least one parameter. In some embodiments comprising a set of springs, one or more springs or a subgroup of springs may be differentiated by two or more parameters, by three or more parameters, by four or more parameters, etc. In some embodiments comprising a plurality of springs, the parameters of each spring may be selected such that one or more springs fail, thereby releasing the energy stored therein. Additionally or alternatively, other energy release devices may be implemented through embodiments of this disclosure, including, for example, safety pin arrangements, friction-increasing techniques, one or more pressure relief valves, etc.

[0064] In some embodiments, a cap (not shown) may be provided near the upper end of the outer cylinder 110 to allow for the maintainability of one or more disc springs 205. For example, the cap may be screwed into the upper end of the outer cylinder 110 or otherwise detachably attached to the upper end of the outer cylinder 110. This allows for inspection of one or more disc springs 205 during a forced landing and replacement if necessary.

[0065] The foregoing embodiments have been described, in which both the first and second load limiters work together to absorb and / or attenuate impact energy during, for example, normal aircraft operating conditions. For instance, in some applications, normal aircraft operating conditions may include descent rates up to 10 feet per second (3.408 meters per second), in other applications up to 15 feet per second (4.572 meters per second), in other applications up to 20 feet per second (6.096 meters per second), and still in other applications between 24 and 28 feet per second (7.315 to 8.534 meters per second) or higher. Of course, other descent rates may also be considered “normal” because the intended application of the landing gear and landing requirements differ considerably.

[0066] However, in some situations, the force F on strut 100 may require further absorption and / or attenuation to prevent damage from impacts to the fuselage. For example, in some cases, the aircraft may experience emergency landings, rapid landings, weather-related conditions, etc., which may cause the aircraft to impact or strike the ground with forces greater than those experienced during normal operating conditions. Therefore, in some embodiments, strut 100 may be configured to provide additional shock kinetic energy absorption and / or attenuation during these abnormal conditions. In some embodiments, this absorption and / or attenuation of additional shock kinetic energy may be achieved through a second shock reduction stage or a second load limiter.

[0067] Now for reference Figures 4A to 4B A method of using the strut 100 according to embodiments of the present disclosure will now be described in detail. In one embodiment, when an impact force is applied to the piston 105 during, for example, normal operating conditions, a first impact reduction stage or first load limiter is arranged to absorb all the impact force without the assistance of a second impact reduction stage. However, when an abnormal impact force (e.g., a force exceeding the maximum impact force during normal operating conditions) is applied to the piston 105, the first impact reduction stage may not be able to absorb all the energy generated by the abnormal impact force.

[0068] As a result, the first impact reduction stage absorbs and attenuates as much impact energy as possible according to its design, and any additional impact energy is subsequently absorbed by the second impact reduction stage or the second load limiter. In one example, the first impact reduction stage absorbs enough impact energy to cause the piston 105 to "bottom out" or impact plate 210 (see...). Figure 4B Subsequently, due to the magnitude of the force F, piston 105 may continue to press against plate 210 and compress one or more springs 205 to absorb and / or attenuate additional impact energy. In another example, when sufficient pressure (e.g., equilibrium pressure) is generated by the translation of piston 105 and the compression of gas 140, any additional translation of piston 105 due to the magnitude of force F will compress one or more springs 205 to absorb and / or attenuate additional impact energy. In some embodiments, the magnitude of the force may trigger one or more energy storage release devices briefly described above.

[0069] Therefore, when subjected to abnormal impact forces, both the first and second impact reduction stages operate to reduce the likelihood of aircraft damage. In some embodiments, the strut 100 is designed such that the full energy and / or attenuation capacity of the first impact reduction stage is depleted before engaging with the second impact reduction stage. In some embodiments, this can be achieved when the piston is in the aforementioned position. Figure 4B This occurs at the position shown. In other embodiments, the second impact reduction stage engages before the piston contacts plate 210.

[0070] In some embodiments, one or more springs 205 and plate 210 may be arranged at different locations within the shock absorber strut. For example, one or more springs 205 may be positioned toward the attachment or lower end of piston 105, such as... Figure 5As illustrated in the embodiment, engagement can occur, for example, when the orifice support tube 160 contacts the plate 210, to provide a second impact reduction stage for additional energy absorption and / or attenuation to the strut 300. In this embodiment, the plate includes one or more pressure relief orifices 225, which serve as damping orifices to allow the plate 210 to translate against and compress one or more springs 205. In other embodiments, the pressure relief orifice 225 is omitted, and seals, rings, or other sealing devices are used to form a sealed gas chamber (e.g., under low pressure, at atmospheric pressure, under vacuum, etc.) for receiving one or more springs 205.

[0071] exist Figure 6 In other embodiments shown, the support column 400 may incorporate multiple sets of springs at different locations along the column to provide additional or secondary energy absorption and / or attenuation. For example, as Figure 6 As shown, the strut 400 can be coupled with a first set of springs 405 205 (substantially similar to strut 100) at the top of the cylinder 110 and a second set of springs 410 205 (substantially similar to strut 300) at the bottom of the piston 105. The first set of springs 405 and the second set of springs 410 205 together form a second impact reduction stage. In some embodiments, the pressure relief port 225 is omitted, and a sealed gas chamber (e.g., under low pressure, at atmospheric pressure, under vacuum, etc.) is formed using seals, rings, or other sealing devices to accommodate the first set of springs 405 205 and the second set of springs 410 205.

[0072] Figure 7 This is a cross-sectional view of another embodiment of the support formed according to the present invention, typically denoted by 500. For example... Figure 7 As shown, the support column 500 includes an inner shell portion 505 slidably coupled to the outer shell portion 510. The inner shell portion 505 and the outer shell portion 510 together define a cavity 515 containing fluid, which consists of hydraulic fluid 520 contained in its upper portion and gas 525 contained in its lower portion. The inner shell portion 505 includes a through-hole 530 defining a damping orifice. An optional metering pin 535 may be provided.

[0073] exist Figure 7 In one embodiment, a floating piston 540 is disposed within the inner housing portion 505 and separates the hydraulic fluid 520 from the gas 525. These components together form an embodiment of a first impact reduction stage or a first load limiter. Figure 7As shown, the support column 500 also includes a second impact reduction stage or second load limiter integrally formed therewith. In this embodiment, the second stage or second load limiter includes one or more springs 205 and a plate 210 disposed at the attachment end of the inner housing portion 505. In some embodiments, the pressure relief port 225 is omitted, and seals, rings, or other sealing devices are used to form a sealed gas chamber (e.g., under low pressure, at atmospheric pressure, under vacuum, etc.) to accommodate one or more springs 205.

[0074] Figure 8 This is a cross-sectional view of an embodiment employing multiple springs 205 as a second stage or second load limiter, typically denoted by 600. (e.g.) Figure 8 As shown, the two-stage support 600 includes an inner shell portion 605 slidably coupled to a housing portion 610. A floating piston 615 is slidably disposed within the inner shell portion 605, defining a chamber 620 between the floating piston 615 and the closed lower end of the inner shell portion 605. A seal, ring, or other suitable sealing device, typically designated 625, is provided to form a sealed chamber below the floating piston 615. A plurality of springs 205 are disposed within the sealed chamber and positioned to abut against the ends of the floating piston 615 and the inner shell portion 605, thereby forming an embodiment of a second stage or second load limiter. Depending on the intended application of the support, the sealed chamber can be filled with gas under low pressure, atmospheric pressure, or vacuum pressure.

[0075] Opposite to the sealed chamber 620 (e.g., above the floating piston), the inner shell portion 605 and the outer shell portion 610 together define an inner cavity 630 containing fluid 635, which consists of hydraulic fluid 640 contained in its lower portion and low-pressure gas 645 contained in its upper portion. An orifice support tube 650 is disposed in the outer shell portion 610 and defines one or more damping orifices 655 at its axial end. The two-stage strut 600 also includes an orifice plate 660, which is fixedly mounted within the lower portion of the inner shell portion 605 and spaced above the floating piston 615. The orifice plate 660 includes one or more orifices 665.

[0076] During landings or other loads for non-aviation purposes, the shock absorber strut 600... Figure 8The fully extended position, as shown, compresses through a first compression stage (not shown) and then to a second compression stage (not shown). When an initial load is applied in the first stage, hydraulic fluid is propelled by the piston surface of the inner housing portion 605 through one orifice 655 and compresses gas 645. Once an equilibrium is reached between the compressed gas 645 and the spring force generated by one or more springs 205 against the floating piston 615, further translation of the inner housing portion 605 due to external loads causes the floating piston 615 to push against and compress one or more springs 205 during the second stage, thereby absorbing additional energy (e.g., impact energy, bumps during coasting, etc.).

[0077] Figure 9 This is a cross-sectional view of another embodiment of the strut, sometimes called a jumping strut, typically designated 700, suitable for use in the nose landing gear. For example... Figure 9 As shown, the support 700 includes an inner shell portion 705 slidably coupled to the outer shell portion 710. The inner shell portion 705 and the outer shell portion 710 together define a cavity 715 containing fluid, which consists of hydraulic fluid 720 contained in its upper portion and gas 725 contained in its lower portion. The inner shell portion 705 includes a through-hole 730 defining a damping orifice. An optional metering pin 735 may be provided.

[0078] exist Figure 9 In one embodiment, a floating piston 740 is disposed within the inner housing portion 705 and separates the hydraulic fluid 720 from the gas 725. These components together form an embodiment of a first impact reduction stage or a first load limiter. Figure 9 As shown, the strut 700 also includes a second impact reduction stage or second load limiter integrally formed therewith. In this embodiment, the second stage or second load limiter includes one or more springs 205, which are separated by gas 725 via a plate 210 disposed at the attachment end of the inner housing portion 705. In some embodiments, the pressure relief port 225 is omitted, and seals, rings, or other sealing devices are used to form a sealed gas chamber (e.g., under low pressure, at atmospheric pressure, under vacuum, etc.) to accommodate one or more springs 205.

[0079] The support 700 also includes a movable actuating piston 760 disposed in the upper portion of the inner cavity 715. In the illustrated embodiment, a metering pin 735 is mounted on the actuating piston 760. A channel 765 is formed in the wall of the upper housing portion 710 above the actuating piston 760. A pressurized gas source (e.g., a pneumatic reservoir 770) is connected to the inner cavity via the channel 765. Pressurized gas stored in the pneumatic reservoir 770 is selectively supplied to the channel 765 under the control of one or more control valves 775. The control of the one or more control valves 775 is performed by one or more circuits of an electrical control system (ECS) 780.

[0080] Pillar 700 Figure 9 The image shows the aircraft in its static position before takeoff. In this static position, a balance is achieved between the compressed gas 725 and the spring force of the abutment plate 750 generated by one or more springs 205. A control signal is sent from the electrical control system 780 to the control valve 775, rapidly supplying high-pressure gas into the internal cavity via the channel 765. The supply of high-pressure gas to the internal cavity above the jumping piston 760, along with the engagement of one or more springs 205, causes the strut to extend rapidly, and the subsequent reaction force from the ground causes the nose of the aircraft to rise. An exhaust valve, etc., may be included to return the jumping strut to its pre-extended state.

[0081] It should be understood that struts 100, 300, 400, 500, 600, and / or 700 can be configured such that the first load limiter and the second load limiter cooperatively absorb and / or attenuate impact energy under normal operating loads. It should also be understood that struts 100, 300, 400, 500, 600, and / or 700 can be configured such that the first load limiter and the second load limiter cooperatively absorb and / or attenuate impact energy under abnormal operating loads. In some embodiments of struts 100, 300, 400, 500, 600, and / or 700, the second load limiter may be designed to engage only during abnormal or overload conditions.

[0082] Compared to conventional strut designs, the above-described embodiments of the strut offer one or more advantages. For example, aircraft, helicopters, and the like typically have very limited space to accommodate deployable wheel systems and / or landing gear, and fitting deployable wheel systems to fit within the available space in an aircraft or other vehicle can be challenging. Therefore, the combination of the strut's housing and vibration-absorbing features can limit the amount of energy storage and / or energy decay the strut can handle before component failure or aircraft damage.

[0083] The embodiments disclosed herein (including an integrally formed first load limiter and a second load limiter) address one or more problems in the prior art. In this regard, by using, for example, disc springs integrally, the static length of the strut can be kept within 5-10% (or less) of that of a conventional hydraulic shock-absorbing strut. Therefore, the compact construction of the strut allows its use on both fixed and retractable landing gear, while providing design adjustability for obtaining load-deflection curves that adapt to a range of descent or impact velocities. Thus, the struts of some embodiments provide compact, lightweight load limiters that can be particularly suitable for retractable landing gear. Other benefits can also be achieved, such as improved strut maintainability compared to prior art gas-based struts that are prone to leakage and require more frequent maintenance, through the use of mechanical springs.

[0084] In the foregoing description, specific details have been set forth to provide a thorough understanding of representative embodiments of the present disclosure. However, it will be apparent to those skilled in the art that the embodiments disclosed herein can be practiced without showing all the specific details. In some cases, well-known process steps have not been described in detail to avoid unnecessarily obscuring various aspects of the disclosure. Furthermore, it will be appreciated that embodiments of the present disclosure may employ any combination of the features described herein.

[0085] It should be noted that, for the purposes of this disclosure, terms such as “upper,” “lower,” “vertical,” “horizontal,” “inward,” “outward,” “inner,” “outer,” “front,” and “back” should be interpreted as descriptive rather than limiting the scope of the claimed subject matter. Furthermore, the use of “including,” “comprising,” or “having,” and variations thereof, means to include the items listed below and their equivalents, as well as additional items. Unless otherwise limited, the terms “connected,” “linked,” and “installed,” and variations thereof, are used extensively herein and cover both direct and indirect connections, linkages, and installations.

[0086] This application may also refer to quantities and numbers. Unless otherwise specified, such quantities and numbers are not considered limiting, but rather examples of possible quantities or numbers associated with this application. Also in this respect, the term "multiple" may be used to refer to quantities or numbers. In this respect, the term "multiple" means any number greater than one, such as two, three, four, five, etc. The terms "approximately," "approximately," "close to," etc., indicate positive or negative 5% of a specified value. For the purposes of this disclosure, the phrase "at least one of A, B, and C" refers, for example, to (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all other possible permutations when listing more than three elements.

[0087] The principles, representative embodiments, and modes of operation of this disclosure have been described in the foregoing description. However, the aspects of this disclosure intended to be protected should not be construed as limited to the specific embodiments disclosed. Furthermore, the embodiments described herein are to be considered illustrative rather than restrictive. It should be understood that variations and modifications can be made by others and by equivalents without departing from the spirit of this disclosure. Therefore, it is expressly intended that all such variations, modifications, and equivalents fall within the spirit and scope of this disclosure as claimed.

Claims

1. An energy absorption device for an aircraft, the device comprising: A first load limiter includes a hydropneumatic shock absorber strut configured to absorb impact energy applied to a strut strut, wherein the hydropneumatic shock absorber strut includes an inner cavity, an orifice support tube, and a piston, the inner cavity containing strut fluid composed of gas and hydraulic fluid, the orifice support tube being located within the inner cavity and defining at least one damping orifice, and the piston being movable within the inner cavity to force the strut fluid through the at least one damping orifice. as well as A second load limiter is integrally formed within the oil-gas shock absorber strut, wherein the second load limiter includes one or more disc springs configured to absorb impact energy applied to the strut by compressing the one or more disc springs, wherein the one or more disc springs are located within the cavity.

2. The device according to claim 1, wherein, The first load limiter is configured to absorb impact energy associated with normal operating conditions, and the second load limiter is configured to absorb additional impact energy beyond the impact energy associated with the normal operating conditions of the aircraft.

3. The device according to claim 1, wherein, The one or more springs include a first set of disc springs located in the inner cavity and a second set of disc springs located in the inner cavity at a distance from the first set of disc springs.

4. The device according to claim 1, wherein, The oil-gas damping strut further includes a metering pin located in the piston, wherein the orifice support tube is arranged to slidably receive the metering pin through the damping orifice.

5. The device according to claim 4, wherein, The oil-gas damping strut also includes a plate located around the orifice support tube or the metering pin to hold and contact the one or more disc springs.

6. The device according to claim 5, wherein, When the piston moves a predetermined distance in the inner cavity, the piston strikes the plate, or when the piston moves a predetermined distance in the inner cavity, the orifice support tube strikes the plate.

7. A retractable landing gear, comprising the device according to claim 1.

8. A vibration-absorbing strut for a vehicle, comprising: The inner shell portion is slidably connected to the outer shell portion; An inner cavity formed by the inner shell portion and the outer shell portion, the inner cavity defining a sealed fluid volume for containing support fluid, the support fluid including hydraulic fluid and gas; An orifice support tube is located within the inner cavity and defines at least one damping orifice; A piston capable of moving a predetermined distance within the cavity to force the strut fluid through the at least one damping orifice; as well as One or more disc springs, located in the inner cavity and around the orifice support tube, absorb additional energy acting on the support after the piston has moved the predetermined distance.

9. The vibration-absorbing support column according to claim 8, wherein the piston is integrally formed with the inner shell portion.

10. The vibration-absorbing support column according to claim 8, wherein, The one or more disc springs are located at the ends of the housing portion, and the piston acts on the one or more disc springs when the piston moves the predetermined distance.

11. The vibration-absorbing support column according to claim 8, further comprising: A metering pin is located in the piston, and the orifice support tube is arranged to slidably receive the metering pin through the damping orifice; The piston is integrally formed with the inner shell portion.

12. The vibration-absorbing support column according to claim 8, wherein, The one or more disc springs include a first group of disc springs located in the inner cavity and spaced apart from a second group of disc springs, wherein the first group of disc springs or the second group of disc springs includes a plurality of disc springs arranged in parallel, in series, or in combination thereof.

13. The vibration-absorbing support column according to claim 8, further comprising: A pressurized gas source that is selectively connected in fluid communication with the cavity.

14. The vibration-absorbing support column according to claim 13, further comprising: A control valve in fluid communication with the pressurized gas source, wherein the control valve selectively supplies pressurized gas from the pressurized gas source to the cavity to cause the support to extend rapidly.

15. A retractable landing gear comprising the vibration-absorbing strut as claimed in claim 8.

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