The present invention relates to energy absorbing elements designed to limit accelerations, and, more specifically, to energy absorbing mounting hardware.
Generally bolts, nuts, and spacers are designed as rigid elements with no ‘give’ or flexibility. These elements are constructed of solid metal or plastic materials with care taken to fix their yield strength, but generally without regard to the stress-strain curve of the element.
U.S. Pat. No. 6,274,211 discloses a deformable element for absorbing kinetic energy which is a plastic pipe section having interior surfaces at opposite ends thereof. The plastic pipe section initially deforms elastically under an applied axial force and, when a yield stress limit is exceeded by the applied axial force, the plastic pipe section deforms or collapses with an approximately equal deforming force over a work stroke until adopting a physically deformed shape in which the interior surfaces at the opposite ends contact each other. The device for absorbing kinetic energy is also described including several plastic pipe sections stacked in a column with an intermediate plate between each adjacent pair of pipe sections. The plastic pipe sections and engaged around a tubular round body for support and guidance. An inner screw bolt can also be provided for pre-tensioning the plastic pipe sections.
JP 2002 227898 discloses enhancement of deformability function in horizontal and vertical directions of a base isolating damper used in combination with a base isolating device for carrying out base isolating support of a structure such as a building and a bridge. A steel pipe is used in a damper body, and an intermediate part between base parts of both ends in an axial direction of the steel pipe is cut to be a spiral shape, with the base parts being left, whereby a spiral part connected to the base parts is formed in the intermediate part between the base parts.
JP 2001 289274 A discloses a spring made of a brittle material to be suitable for a part for a semiconductor manufacturing device incapable of using, for example, a metallic material, rationally and evenly manufacture through simple constitution, improve a yield, improve responsiveness to reduction of size and weight and a low load, and besides, remove a machined surface and the corner part of a spring body surface in a cracked state and a roughened surface state during machining and prevent the occurrence of breakage during application of a load or assembly, and provide a desired shape and size and to provide its manufacturing method. Non-metallic and heat resistant brittle materials are continuously disposed at given pitches in a direction extending coaxially with a load-applying direction and a spring body is provided to be expandable and contractible in the load applying direction. A cut groove in a spiral state is continuously formed in a cylinder pipe of the brittle material in the axial direction of a pipe. The cut groove 6 is caused to communicate with the internal part of the pipe to form a spring body.
WO/2010/041235 discloses a method and apparatus for minimizing accelerations during impacts such as those encountered in motor vehicle accidents, helicopter and airplane crashes, explosions, and the like. The preferred embodiment takes the form of a helical spring-like member, designed to experience plastic deformation over a desired deformation length, under a given impact load threshold. The spring-like member is preferably installed in a mechanical linkage that is flattened under impact, straining the spring-like member in a predictable fashion. The operating characteristics of this system [namely the stress-strain curve, and thus the deformation length, impact load threshold, and acceptable load range for the system to be protected] can be easily controlled by varying the device dimensions and installation configuration.
Equipment of combat vehicle can be protected from a rude shock (mine actuation, collision, shell hit). Equipment can be fixed to the vehicle by means of single-event energy absorbers. Hence, there is a long-felt and unmet need to provide energy absorbing mounting hardware of standard sizes (nuts, spacers, bolts) suitable to common practice without any special preparations or change in mounting methods.
In order to understand the invention and to see how it may be implemented in practice, a plurality of embodiments is adapted to now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which
a-2c is a conceptual view of the motor base mounted onto the carbody;
The invention discloses an energy absorbing spacer such as an internally-threaded nut. This device is largely cylindrical but is provided with a helical or spiral cut that changes the stress-strain characteristics of the device in a controllable and repeatable way. When subjected to strains such as vibrations, explosions, and the like, the device will compress or/and uncoil like a stretched spring, thereby transferring smaller forces between its connected elements.
Another provision of the invention relates to attachment systems for chairs in vehicles. First of all any bolts, nuts, spacers and the like can be formed from the spiral elements referred to above.
It is one object of the present invention to provide an energy absorbing element (EAE) useful for limiting forces transmitted to an object attached thereto, said element comprising a hollow extruded member provided with threads, having a helical cut through the wall of said member, said helical cut and the extrusion axis of said member being coaxial, said member being adapted to undergo deformation when under strain, whereby the force-displacement curve of said spacer when under strain is of a predetermined form and wherein said element may be stretched or compress by a length depending upon the pitch of said helical cut such that forces transmitted to said object are limited.
It is another object of the present invention to provide the EAE as defined above, wherein said element is selected from the group consisting of a spacer, a bolt, a nut and any combination thereof.
It is another object of the present invention to provide the EAE as defined above, wherein said extruded member comprises a cylinder.
It is another object of the present invention to provide the EAE as defined above, where the plastic regime length of said force-displacement curve to the elastic regime length is within the range of about 4-70.
It is another object of the present invention to provide the EAE as defined above, where the material of said member is chosen from a group consisting of metal, carbon fiber, composite material, plastic and elastomer.
It is another object of the present invention to provide the EAE as defined above, where the cross section of said member is selected from a group consisting of: rectangular, square, ellipsoidal, triangular, and circular.
It is another object of the present invention to provide the EAE as defined above, where said threads are located on the inner surface of said extruded member.
It is still an object of the present invention to provide the EAE as defined above, where said threads are located on the outer surface of said extruded member.
It is lastly an object of the present invention to provide the EAE as defined above, further provided with strain relief provision at the ends of said helical cut selected from a group consisting of: boring holes at the ends of said helical cut, and adding additional revolutions of increased stiffness at the ends of said helical cut.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Military vehicles are exposed to various threats. IED's (Improvised Explosive Devices), shaped charges and etc. are known to impose significant effects to the crew and equipment inside the vehicle. Armored vehicles may successfully survive a blast and remain intact, within certain boundaries defined by the magnitude of accelerations experienced and construction of the vehicle. An explosion transfers large amounts of kinetic energy transferred through the vehicle's body due to the impact. That energy may deform the vehicle's walls rapidly, projecting dangerous shockwaves through the wall and beyond.
Civilian vehicles are likewise exposed to dangerously high accelerations on impacts during collisions and other road accidents.
In either case, the vehicle's walls are commonly used for mounting seats, boxes, electricity components, and other equipment. The mounting and attachments systems often rely on common threaded nuts and corresponding bolts. Bolts often are screwed in to threads drilled directly into the walls, or into welded “spacers” (which are often elongated nuts with internal threads).
Impacts and other accelerations may cause any object mounted to the walls to detach from the fixtures (tearing the threads, the nut, the bolt, or other attachment device such as welds). Any objects attached by such means may then be thrown about the passenger compartment, endangering seat occupants, crew, and equipment integrity.
The solution provided in the present invention comprises a deformable mounting spacer instead of the common threaded spacer. In case of impact—the EA spacer can deform and absorb impact energy, rather than transferring the entire shock to the mounted mass.
The invention actually deals with the 3 most commonly used connection elements:
Spacers are designed for extension and compression and can be used for welding purposes and in add-on solutions. The welded spacers are preferably symmetric. The symmetric geometry provides more flexibility in the operation process. The proposed spacer is small and does not necessarily exceed the normal size of standard spacers. The welded spacers are designed for use in standard welding procedures and the add-on spacers can be configured into a hexagonal shape for use with standard tools (i.e. wrenches and etc.)
Each spacer can be designed with a specific force-deflection curve to best suit a specific thread and mass.
Nuts are designed for use in standard assembly methods. General look is very similar to a standard nut. The proposed nuts are suited to use in combination with standard bolts and of all known thread types.
Bolts are designed for use in standard assembly methods. The proposed bolts have standard sizes. The proposed bolts are suited to use in combination with standard nuts of all thread types. In addition, the energy absorbing bolt can be modified from standard bolts to ease production.
The situation during a side impact is shown in
Reference is now made to
The method can be especially effective when implemented in combination with large masses. Since the total energy of the crash is final, by absorbing the energy from the large masses we reduce the energy transferred to other parts in the vehicle compartment (i.e. crew compartment).
E=W=F·X=m·a·X,
where: E is energy of the collision, W is work, F is force, X is travel; m is mass and a—acceleration.
Thus, if we connect the large masses with the proposed method, the more travel will result in more energy absorbed and not transferred to other parts in the vehicle. Amount of absorbed energy can be controlled by change in a number of the revolutions and shape thereof,
In accordance with the current invention a peak load applied to the structure is reduced by means energy absorption by the proposed absorbing mounting hardware.
The solution can be combined with no change to the current connection method and can be in parallel to any vibration control elements and etc.
Reference is now made to
In
In
In
It is shown by experiments that there is no effect welding the spacer 200 to the wall 240 on energy absorbing properties thereof (see
The energy absorbing element 200a shown in
Certain addition embodiments can be achieved by the following means:
Design advantages of seating systems incorporating the current invention include:
Since the system is based on a single moving component, it is highly reliable and repeatable. Environmental conditions have no affect on the system behavior. Dust, mud, oil, etc. do not influence it. The system will always react as planned and as manufactured. Other shock absorbing systems that involve the interactions between two or more parts generally are affected by frictional or viscous forces and are thus inevitably affected by environmental conditions such as temperature and infiltration of mud, sand, oil, high temperature gas, etc. that may clog, heat, or otherwise change the system before or during an explosion or other impact.
The system of the current invention is based on one or more energy-absorbing spacers as described herein.
When installed in various mechanisms as described herein, the device prevents rebound that occurs naturally in some other systems, since after extending, the helix or spiral member of the current invention opposes not only tension but also compression forces, thus preventing the mechanism from bouncing back. Just as deforming the member from initial to fully-extended configuration absorbs energy and limits the transmitted acceleration, deforming the member on rebound will likewise absorb energy and limit the transmitted rebound accelerations. The spiral member of the invention can repeat this scenario numerous times.
It is within provision of the current invention to convert hazardous impact energy into a plastic deformation of a solid component, which is designed to react within a predefined impact load threshold.
It is within provision of the invention to provide a safe range of motion, to allow the objects attached by means of the energy absorbing spacer to experience accelerations independent of the vehicle frame accelerations.
It is within provision of one embodiment of the current invention to dampen horizontal or vertical accelerations, restricting accelerations transferred to the device secured by the energy absorbing spacer to within safe limits.
It is within provision of an embodiment of the current invention to provide an absorption component that can be installed for mainly vertical or horizontal impacts, such as those experienced in mine explosions or head-on collisions.
The proposed technical solution provides energy absorbing mounting hardware of standard sizes (nuts, spacers, bolts) suitable to common practice without any special preparations or change in mounting methods. The conventional mounting hardware can be replaced be energy absorbing mounting hardware without any special preparations or change of mounting methods.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IL2010/001079 | 12/23/2010 | WO | 00 | 9/11/2012 |
Number | Date | Country | |
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61290019 | Dec 2009 | US |