Patent Application
20230303250
This application claims priority to, and the benefit of, India Patent Application No. 202241017961, filed Mar. 28, 2022, (DAS code 1E0B) and titled “LOAD ABSORBING TIE ROD FOR AIRCRAFT STRUCTURE INTEGRATION,” which is incorporated by reference herein in its entirety for all purposes.
The present disclosure relates to tie rods for aircraft, and, more specifically, to load absorbing tie rods for securing interior cabin monuments.
Tie rods are used to secure cabin interior monuments, such as galley structures, lavatory structures, overhead bins, etc., to the aircraft frame. For example, cabinetry within the cabin galley may be affixed to the floor within the cabin and also affixed to the structure of the aircraft with tie rods. A severe loading event such as a 9 g forward inertia event, which may occur during a rejected take off or a crash landing, or a rapid decompression (RD) event, wherein the decompression of the cabin occurs in a matter of seconds, can apply a load of up to 25.0 kilonewtons (kN) to the tie rod. Such loading could potentially result in failure of the tie rod and/or over stressing the joints, brackets, and/or panels of the monument.
A load absorbing tie rod is disclosed herein. In accordance with various embodiments, the load absorbing tie rod comprises an outer cylinder, a piston located at least partially within the outer cylinder, and a compressed gas located in a volume defined by the piston and the outer cylinder. The compressed gas is configured to allow translation of the piston toward a first end surface of the outer cylinder in response to a load greater than a first load threshold being applied to the piston and to prevent translation of the piston toward the first end surface of the piston in response to loads less than the first load threshold being applied to the piston.
In various embodiments, the first load threshold may be greater than or equal to 5.0 kilonewtons. In various embodiments, the piston may include a piston head and a piston shaft extending from the piston head. A first surface of the piston head is oriented toward the first end surface of the outer cylinder. The first surface of the piston head, the first end surface of the outer cylinder, and an internal surface of the outer cylinder define the volume.
In various embodiments, a stopper may be located between a second surface of the piston head and a second end surface of the outer cylinder. In various embodiments, the stopper may be integral to the outer cylinder.
In various embodiments, a pressure within the volume may be between about 9.9 megapascals and about 19.7 megapascals. In various embodiments, a pressure release valve may be fluidly connected to the volume. The pressure release valve is configured to open in response to a second load threshold. The second load threshold may be greater than or equal to 25.0 kilonewtons
An assembly is also disclosed herein. In accordance with various embodiments, the assembly may comprise an interior cabin monument, an aircraft structure, and a load absorbing the rod coupled to the interior cabin monument and the aircraft structure. The load absorbing tie rod may include an outer cylinder coupled to the aircraft structure, a piston located at least partially within the outer cylinder and coupled to the interior cabin monument, and a compressed gas located in a volume defined by the piston and the outer cylinder.
In various embodiments, the piston includes a piston head and a piston shaft extending from the piston head. A first surface of the piston head is oriented toward a first end surface of the outer cylinder. The first surface of the piston head, the first end surface of the outer cylinder, and an internal surface of the outer cylinder define the volume.
In various embodiments, a stopper may be located between a second surface of the piston head and a second end surface of the outer cylinder. In various embodiments, the stopper may be integrally formed with the outer cylinder.
In various embodiments, a monument connector may be coupled to the piston and a bracket of the interior cabin monument, and an aircraft connector may be coupled to the outer cylinder and the aircraft structure. In various embodiments, the monument connector may be coupled to the piston via a threaded engagement. In various embodiments, the monument connector may be integrally formed with to the piston.
In various embodiments, the load absorbing tie rod may include a pressure release valve fluidly coupled to the volume.
A method is also disclosed herein. In accordance with various embodiments, the method may comprise the steps of attaching a piston of a load absorbing tie rod to an interior cabin monument and attaching an outer cylinder of the load absorbing tie rod to an aircraft structure. A compressed gas contained in the outer cylinder may be configured to allow translation of the piston toward a first end surface of the outer cylinder in response to a load greater than or equal to a first load threshold being applied to the piston and to prevent translation of the piston toward the first end surface of the piston in response to loads less than the first load threshold.
In various embodiments, the method may further comprise injecting the compressed gas through a valve fluidly coupled to the outer cylinder. The valve may be configured to open in response to the load applied to the piston being greater than a second load threshold.
In various embodiments, the method may further comprise locating a stopper between a piston head of the piston and a second end surface of the outer cylinder. In various embodiments, the first load threshold may be between about 4.0 kilonewtons and about 7.0 kilonewtons, and the second load threshold may be greater than or equal to 25.0 kilonewtons.
In various embodiments, the method may further comprise coupling a monument connector to the piston and the interior cabin monument and coupling an aircraft connector to the outer cylinder the aircraft structure. The interior cabin monument may comprise at least one of a galley structure, a lavatory structure, or an overhead bin
The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting.
The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the following figures, wherein like reference numbers denote like elements.
The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation.
The scope of the disclosure is defined by the appended claims and their legal equivalents rather than by merely the examples described. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, coupled, or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact.
Surface shading lines and/or cross-hatching may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials. Throughout the present disclosure, like reference numbers denote like elements. Accordingly, elements with like element numbering may be shown in the figures, but may not necessarily be repeated herein for the sake of clarity. An X-Y-Z axis has been provided in various figures for ease of illustration. In the provided X-Y-Z axis, the X-axis is oriented in a forward to aft direction, the Z-axis is oriented in a vertical direction, perpendicular to the plane formed by the X-axis and the Y-axis and to the floor of an aircraft, and the Y-axis is oriented in a horizontal direction, perpendicular to the plane formed by the X-axis and the Z-axis and parallel the floor of an aircraft.
As used herein, “aft” refers to the direction associated with a tail (e.g., the back end) of an aircraft, or generally, to the direction of exhaust of a gas turbine engine. As used herein, “forward” refers to the direction associated with a nose (e.g., the front end) of the aircraft, or generally, to the direction of flight or motion.
With reference now to
Various aviation regulations define the loads aircraft structures must be designed to withstand. For example, federal aviation regulation 25.561 prescribes that items of mass in an aircraft shall be restrained under all loads up a 3.0 g upward load, a 9.0 g forward load, a 3.0 g sideward load, a 6.0 g downward load and a 1.5 g rearward load, and that seats and items of mass (and their supporting structure) must not deform under any loads up to the above specified load in any manner that would impede subsequent rapid evacuation of occupants. Federal aviation regulation 25.365 prescribes that any structure, component, or part, inside or outside a pressurized aircraft compartment, the failure of which could interfere with continued safe flight and landing, must be designed to withstand the effects of a sudden release of pressure through an opening in any compartment at any operating altitude.
Disclosed herein is a load absorbing tie rod that includes a pressurized gas cylinder configured to compress in response to a severe loading event (e.g., a 9 g forward inertia event, a rapid decompression event, a 3.0 g upward, 3.0 g sideward, a 6.0 g downward, 1.5 g rearward, etc.). As used herein, the unit “g” refers to g-force and is approximately equal to the acceleration due to gravity at the Earth's surface (e.g., 1.0 g equals 32.17 ft/s2 or 9.81 m/s2). In accordance with various embodiments, the load absorbing tie rod includes a piston and a cylinder housing a compressed gas. During a severe loading event, the load applied to piston by the monument causes the piston to translate toward the compressed gas, thereby causing the compressed gas to further compress and store the energy. In this regard, the tie rod absorbs the load while allowing the monument to displace, thereby tending to reduce the stress concentrations at the joints, brackets, and/or panels of the monument. In accordance with various embodiments, the compressed gas is pressurized such that normal inflight loads do not translate the piston (e.g., do not further compress the compressed gas). In accordance with various embodiments, load absorbing tie rods, as disclosed herein, tend to reduce the load transfer generated by a monument and thereby absorb and/or dampen the load. In this regard, the load absorbing tie rods decrease the amount of load transferred to the aircraft structure and stress concentrations in monument, which increases overall safety during a severe loading event. The load absorbing tie rods may reduce the structural strength requirements of the aircraft structures due to the reduced loads, which may allow for lighter weight materials, which may also decrease costs.
With reference to
Load absorbing tie rod 120 includes an outer cylinder 126 and a piston 128. As described in further detail below, piston 128 is located, at least, partially in outer cylinder 126. Load absorbing tie rod 120 is configured to allow piston 128 to translate relative to outer cylinder 126 (e.g., telescope relative to outer cylinder 126) in response to a severe loading event, while reducing, or preventing, translation of piston 128 relative outer cylinder 126 when normal inflight loads (e.g., loads less than or equal to 5.0 kN are applied to load absorbing tie rod 120. In various embodiments, load absorbing tie rod 120 is configured to prevent translation of piston 128 relative outer cylinder 126 when a load of less than or equal to 5.0 kN is applied to load absorbing tie rod 120. However, tie rod 120 may be designed to prevent translation of piston 128 at any desired load.
In accordance with various embodiments, load absorbing tie rod 120 includes a monument connector 130 and an aircraft connector 132. Monument connector 130 is connected to piston 128. Aircraft connector 132 is connected to outer cylinder 126. Monument connector 130 couples piston 128 to monument 122. For example, in various embodiments, monument connector 130 may be connected to a bracket 134 of monument 122. Aircraft connector 132 couples outer cylinder 126 to aircraft structure 124. For example, in various embodiments, aircraft connector 132 may be connected to a bracket 136 of aircraft structure 124.
With reference to
In various embodiments, a valve 160 may be fluidly connected to volume 150. Valve 160 may be a pressure release valve configured to open in response to the pressure within volume 150 exceeding a valve pressure threshold. Valve 160 may also be employed to inject compressed gas 152 into volume 150. In this regard, compressed gas 152 may be injected into volume 150 via valve 160. First surface 146 of piston head 140 is oriented toward first end surface 148 of outer cylinder 126. A second surface 162 of piston head 140 is oriented away from (e.g., is opposite) first surface 146. Second surface is oriented toward a second end surface 164 of outer cylinder 126. Internal surface 144 of outer cylinder 126 may extend from first end surface 148 to second end surface 164. In various embodiments, a stopper 170 is located within outer cylinder 126 and between piston head 140 and second end surface 164. Stopper 170 is configured to prevent, or otherwise block, translation of piston head 140 toward second end surface 164. In this regard, stopper 170 counters the pressure applied by compressed gas 152 against first surface 146. In various embodiments, stopper is a discrete component located in outer cylinder 126. In various embodiments, stopper 170 is integral with outer cylinder 126. For example, internal surface 144 may have a first diameter in a first portion of cylinder and a second, smaller diameter in a second portion of inner cylinder. The second diameter being configured to generate an interference with piston head 140 and thereby preventing or reducing translation of piston head 140 toward second end surface 164.
In various embodiments, piston 128 includes a mounting section 172. Piston rod 142 may extend between piston head 140 and mounting section 172. A diameter of mounting section 172 may be greater than a diameter of piston rod 142. Monument connector 130 may be attached to mounting section 172. In various embodiments, monument connector 130 may be coupled to mounting section 172 via threaded engagement between monument connector 130 and mounting section 172. In various embodiments, monument connector 130 may be integral to mounting section 172. In this regard, piston 128 and monument connector 130 may be a single, monolithic component.
Aircraft connector 132 may be attached to outer cylinder 126 proximate first end surface 148. In various embodiments, aircraft connector 132 may be coupled to outer cylinder via threaded engagement between aircraft connector 132 and outer cylinder 126. In various embodiments, aircraft connector 132 may be integral with outer cylinder 126. In this regard, outer cylinder 126 and aircraft connector 132 may be a single, monolithic component.
The pressure applied by compressed gas 152 against piston head 140 is configured to prevent translation of piston 128 in response to a load L that is less than a threshold load. For example, compressed gas 152 is configured to prevent translation of piston 128 in response to normal inflight loads. In various embodiments, the threshold load may be 5.0 kN. In response to a load L that exceeds the threshold load (e.g., exceeding the pressure applied by compressed gas 152) piston 128 will translate toward first end surface 148, thereby further compressing compressed gas 152. In this regard, a portion of load L is absorbed and/or dampened, thereby reducing the load transfer generated by translation of the monument attached to monument connector 130.
Valve 160 is configured to open and release pressure from volume 150 in response to the pressure within volume 150 exceeding the valve pressure threshold. Stated differently, piston 128 translates toward first end surface 148 in response to a load L greater than a first (or minimum) load threshold and valve 160 opens in response to load L being greater than a second (or maximum) load threshold. For example, tie rod 120 may be configured to have a minimum load threshold of 5.0 kN and a maximum load threshold of 25.0 kN. In this regard, piston 128 translates toward first end surface 148 in response to a load L greater than 5 kN and valve 160 opens in response to a load L greater 25 kN. It is contemplated and understood that the above first/minimum load threshold and second/maximum load threshold of 5.0 kN and 25.0 kN, respectively, are exemplary, and tie rod 120 may be configured to have any desired first/minimum load threshold and second/maximum load threshold. The pressure within volume 150 may be selected based on the desired first/minimum load threshold and second/maximum load threshold, using the formula:
Pressure=Force/Area
where Force is the desired load threshold and Area is the area of a cross-section of volume 150. For example, a pressure in volume 150 for a tie rod 120 with an outer cylinder 126 having a 1.0 inch (25.4 millimeters (mm)) inner diameter (the inner diameter being measured at internal surface 144) and a minimum load threshold of 5.0 kN may be approximately 9.9 megapascals (MPa) (1435.9 pounds per square inch (psi)). The pressure in volume 150 at which valve 160 may open for a tie rod 120 having a 1.0 inch (25.4 mm) inner diameter outer cylinder 126 and a maximum load threshold of 25.0 kN may be approximately 49.3 MPa (7150 psi).
In accordance with various embodiments, the compressed gas within volume 150 is selected based on its compressibility factor, and volume 150 and outer cylinder 126 are designed based on the compressibility factor of the selected gas and the desired minimum load threshold and maximum load threshold. For example, the wall thickness of outer cylinder 126 is designed to accommodate the pressure rage associated with the desired minimum and maximum load thresholds.
In various embodiments, in a neutral state (i.e., prior to a load being applied to piston 128), a pressure within volume 150 may be between about 7.9 MPa and about 49.3 MPa (between 1145.8 psi and 7150.4 psi), between about 8.9 MPa and about 39.5 MPa (between 1290.8 psi and 5729.0 psi), between about 9.9 MPa and about 39.5 (between 1435.9 psi and 5729.0 psi), between about 9.9 MPa and about 29.6 MPa (between 1435.9 psi and 4293.1 psi), between about 9.9 MPa and about 19.7 MPa (between 1435.9 psi and 2857.2 psi), between about 9.9 MPa and about 13.8 MPa (between 1435.9 psi and 2001.5 psi), and/or about 9.9 MPa (1435.9 psi). In the previous context only, the term “about” means±0.5 MPa (±72.5 psi).
In various embodiments, the minimum load threshold of tie rod 120 (i.e., the minimum load at which piston translates toward first end surface 148) may at least 4.0 kN, at least 5.0 kN, at 10 kN, or any other desired minimum load. In various embodiments, the minimum load threshold of tie rod 120 may be between about 4.0 kN and about 25.0 kN, between about 4.5 kN and about 20.0 kN, between about 5.0 kN and about 20.0 kN, between about 5.0 kN and about 15.0 kN, between about 5.0 kN and about 10.0 kN, between about 4.0 and about 7.0 kN, and/or about 5.0 kN. In the previous context only, the term “about” means±0.5 kN.
In various embodiments, the maximum load threshold of tie rod 120 (i.e., the load at which pressure valve 160 opens) may be at least 20.0 kN, at least 25.0 kN, or any other desired load threshold. For example, in various embodiments, the maximum load threshold of tie rod 120 may be between about 20.0 kN and about 40.0 kN, between about 22.0 kN and about 30.0 kN, between about 25.0 kN and about 30.0 kN, and/or between about 25.0 kN and about 28.0 kN. In the previous context only, the term “about” means±0.5 kN.
With reference to
In various embodiments, method 200 may further include injecting the compressed gas through a valve fluidly coupled to the outer cylinder. A volume of the compressed fluid may be selected such that a pressure within a volume of outer cylinder is between about 7.9 MPa and about 49.3 MPa (between 1145.8 psi and 7150.4 psi), between about 8.9 MPa and about 39.5 MPa (between 1290.8 psi and 5729.0 psi), between about 9.9 MPa and about 39.5 (between 1435.9 psi and 5729.0 psi), between about 9.9 MPa and about 29.6 MPa (between 1435.9 psi and 4293.1 psi), between about 9.9 MPa and about 19.7 MPa (between 1435.9 psi and 2857.2 psi), between about 9.9 MPa and about 13.8 MPa (between 1435.9 psi and 2001.5 psi), and/or about 9.9 MPa (1435.9 psi). In the previous context only, the term “about” means±0.5 MPa (±72.5 psi).
In various embodiments, method 200 may further include locating a stopper between a piston head of the piston and a second end surface of the outer cylinder In various embodiments, the interior cabin monument comprises at least one of a galley structure, a lavatory structure, or an overhead bin. In various embodiments, method 200 may further include coupling a monument connector to the piston and the interior cabin monument and coupling an aircraft connector to the outer cylinder the aircraft structure.
Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials
Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment”, “an embodiment”, “various embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.
Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element is intended to invoke 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202241017961 | Mar 2022 | IN | national |
