Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
  • F16F9/32—Details
  • F16F9/56—Means for adjusting the length of, or for locking, the spring or damper, e.g. at the end of the stroke
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
  • B64G1/00—Cosmonautic vehicles
  • B64G1/22—Parts of, or equipment specially adapted for fitting in or to, cosmonautic vehicles
  • B64G1/64—Systems for coupling or separating cosmonautic vehicles or parts thereof, e.g. docking arrangements
  • B64G1/641—Interstage or payload connectors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
  • B64G1/00—Cosmonautic vehicles
  • B64G1/22—Parts of, or equipment specially adapted for fitting in or to, cosmonautic vehicles
  • B64G1/64—Systems for coupling or separating cosmonautic vehicles or parts thereof, e.g. docking arrangements
  • B64G1/645—Separators
  • B64G1/6457—Springs; Shape memory actuators
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B2200/00—Constructional details of connections not covered for in other groups of this subclass
  • F16B2200/77—Use of a shape-memory material
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F2224/00—Materials; Material properties
  • F16F2224/02—Materials; Material properties solids
  • F16F2224/0258—Shape-memory metals, e.g. Ni-Ti alloys
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F2230/00—Purpose; Design features
  • F16F2230/0041—Locking; Fixing in position

Definitions

• the present invention generally relates to equipment support struts that can be locked and released manually or remotely, and more particularly, supports struts useable in connection with remotely deployable systems.
• an apparatus for locking and releasing ends of a support strut coupled between a mounting platform and a load.
• the strut comprises a damping section coupled between the ends and having a gap therein when the strut is unlocked, a locking section coupled between the ends for closing the gap by applying stress to a portion of the damper section through a force transmitting member, and a releasing section coupled in parallel with part of the force transmitting member, the releasing section including a Shape Memory Alloy (SMA) and heater therefore. Heating the SMA relieves the stress and opens the gap. Release from the locked condition occurs gradually and without fracture or sudden shock and the heater can be actuated remotely.
• SMA Shape Memory Alloy
• a method for locking and releasing ends of a support strut coupled between a mounting platform and a load and having the above-noted elements comprises applying a force to the damper section using the locking section to lock the strut and heating the shape memory alloy to relieve the force applied to the damper section, thereby releasing the strut.
• the force is applied using a worm drive turnbuckle arrangement. Heating can be remotely actuated.
• FIG. 1 is a simplified conceptual side view of a remotely releasable support strut according to the present invention
• FIG. 2 is a left end view of the support strut of FIG. 1 ;
• FIG. 3 is a right end view of the support strut of FIG. 1;
• FIG. 4 is a simplified side view of a remotely releasable support strut according to the present invention showing further details;
• FIG. 5 is a left end view of the support strut of FIG. 4;
• FIG. 6 is a right end view of the support strut of FIG. 4;
• FIG. 7 is a simplified partial cross-sectional view of the support strut of FIGS. 4-6 showing interior details with the strut in a locked condition;
• FIG. 8 is a simplified partial cross-sectional view similar to FIG. 7 but with the strut of FIGS. 4-6 in a released condition;
• FIG. 9 is a simplified side view of a remotely releasable support strut according to a farther embodiment of the present invention.
• FIG. 10 is a left end view of the support strut of FIG. 9;
• FIG. 11 is a right end view of the support strut of FIG. 9;
• FIG. 12 is a simplified partial cross-sectional view of the support strut of FIGS. 9-11 showing interior details with the strut in a released (free) condition;
• FIG. 13 is a simplified partial cross-sectional view of the support strut of FIG. 12, with the strut in a locked condition;
• FIG. 14 is a partial cross-sectional view of a portion of the strut of FIGS. 9-13.
• FIG. 1 is a simplified conceptual side view of remotely releasable support strut 10 according to the present invention.
• FIG. 2 is a left side end view of the support strut of FIG. 1.
• FIG. 3 is a right side end view of the support strut of FIG. 1.
• Support strut 10 has enclosure or body 12, first attachment means or portion 14 and second attachment means or portion 16, respectively at distal ends of body 12.
• Body 12 is shown in highly simplified form and, as will be further explained, one or both of attachment means 14, 16 are intended to couple to internal supports within body 12 and not merely externally to body 12.
• Attachment portion 14 conveniently has hole 15 therein and attachment portion 16 conveniently has hole 17 therein to permit coupling of strut 10 to an external support (not shown) at one end and to a load (not shown) at the other end.
• attachment portions 14, 16 are shown as made up of a stud or shackle with one or more connection holes therein for attachment to the external support and load, this is merely for convenience of explanation and not intended to be limiting.
• any type of connecting arrangement may be used and that the present invention is not limited by the type of connection used, the nature of the connecting portions being used or the support or load to which the strut is attached.
• strut 10 conveniently has at least three functions therein; damper function 20, release function 22 and locking function 24. While these functions are illustrated in FIG. 1 as being arranged in series, this is merely for convenience of explanation and is not essential. One or more of these functions may conveniently be integrated in whole or part with other function(s). What is important is that strut 10 provide at least these three functions 20, 22, 24.
• Strut 10 is intended to be coupled between a support (not shown) and a load (not shown) via coupling or attachment portions 14, 16. Its function is to support the load used under a variety of conditions. For example:
• strut 10 should act as a substantially rigid support while the load is being moved. This condition is referred to as being "locked.” Accordingly, as used herein the words “lock” and “locked” are intended to mean a strut has been placed in a condition in which it is substantially rigid as far as the forces it is intended to withstand are concerned. For example, when strut 10 is used with a spacecraft deployable load, it must resist the inertial forces generated during the launch phase and any subsequent positioning rocket burns. The forces encountered during such activities can be quite high, many times the earth weight of the payload. For example, it is not unusual to require a support strut to withstand a 25,000-pound inertial force during launch of a spacecraft deployable load.
• the locked condition of the strut must be robust and capable of supporting large inertial forces. While this aspect is particularly important for space deployed systems, the same considerations apply equally well for earth- bound or marine applications where large inertial forces can be generated whenever sensitive equipment is being moved.
• the purpose of locking function 24 is to place strut 10 in a locked condition.
• strut 10 should desirably act to some degree as a flexible coupling between support and load after the primary movement of the load has been completed, for example, after a spacecraft deployable load has been placed in orbit.
• damper function 22 As used herein the words “damp”, “damping”, “damper” or “damper function” are intended to refer generally to any arrangement for providing a flexible coupling between attachment portions 14, 16 so that some relative motion thereof is possible. It is desirable that damper function 22 also include some means of cushioning the relative motion to absorb and/or dissipate mechanical energy so that the amount transmitted to or from the load is reduced, that is, so that there is provided some mechanical isolation between support and load.
• strut 10 When strut 10 is in a condition where damper function 22 is operative, it is referred to as being "free.”
• strut 10 desirably contains remote release function 22.
• the purpose of remote release function 22 is to unlock the strut after primary movement has been completed so as to place it in a "free" condition where damper function 20 is operative.
• release function 22 is 'soft", that is, that it occurs gradually and is not accompanied by any sudden shock, explosions or breakage of internal supports.
• Electrical plug 30 is provided in body 12 of strut 10 so that remote release function 22 may be electrically activated.
• FIG. 4 is a side view
• FIG. 5 is a left end view
• FIG. 6 is a right end view of support structure or strut 100, similar to strut 10, showing further details.
• Strut 100 has body 102 analogous to body 12 of FIG. 1, and attachment portions 141, 161 with coupling holes 151, 171 analogous to 14, 16 and 15, 17, respectively, of FIG. 1.
• FIG. 7 is a simplified partial cross- sectional view of support strut 100 of FIGS. 4-6, showing interior details with the strut in a locked condition.
• FIG. 7 is a view substantially on plane 7-7 indicated in FIGS. 5-6.
• locking bolts 120 are shown whole rather than in cross-section in FIGS. 7-8.
• FIG. 8 is a view similar to FIG. 7 but showing strut 100 in the free condition.
• attachment portion 161 is part of or attached to body 102 and attachment portion 141 is part of or attached to internal damper strut ("D-strut") 104.
• D-strut internal damper strut
• surface 105 of D-strut 104 rests against surface 106 of body 102.
• surfaces 105, 106 are spaced apart by gap 109 and D-strut 104 is coupled to body 102 by resilient member 108.
• Resilient member 108 is usefully a spring or bellows or elastomeric cushioning material or a combination thereof. Such materials are well known in the art.
• resilient member 108 provides damper function 20.
• gap 109 separates D-strut 104 and housing 102, and gap 113 separates D-strut 104 and jack-pad 110.
• Spring 111 insures that gap 113 remains open until locking screws 120 are activated.
• Spring 111 is substantially weaker than the spring action of resilient member 108 so gap 109 also remains open in the free condition.
• D-strut 104 and housing 102 are coupled only by resilient member 108, thus allowing attachment portions 141 and 161 to move with respect to each other as indicated by arrows 122.
• the range of motion of damping function 20 in strut 100 is determined by the size of gaps 109, 113 and the geometry of the various parts, and may be varied by the designer to suit a particular need.
• locking function 24 is provided by the combination of D-strut 104, jack- pad 110, compression block 112, locking screws 120 and expansion material 114.
• gap 113 is closed and jack-pad 110 is forced against D-strut 104, which, in turn, is forced against body 102 as gap 109 is closed (see FIG. 7).
• Locking screws 120 screw into and out of compression block 112 via threads 116.
• the reaction force created by screws 120 pressing against jack-pad 110 is transmitted to body 102 via expansion material 114.
• Expansion material 114 is firmly coupled to body 102 by joint 118 and to compression block 112 by joint 124.
• Joints 118, 124 may be formed by any convenient means, as for example, but not limited to, mechanical threads or brazing or welding or other means having comparatively high shear strength. Any means can be used provided that it has sufficient shear strength to resist the forces generating during pre-loading and release.
• Locking screws 120 are advanced to place strut 100 in the locked condition (FIG. 7) and backed off to return strut 100 to the free condition (FIG. 8), as for example, for test purposes. While only two locking screws 120 are shown in FIGS. 6-8, this is merely for convenience of explanation and is not intended to be limiting. The more screws 120, the larger their diameter, the finer their threads and the more robust compression block 112, the greater the stress that strut 100 can withstand in the locked state. Thus, by varying the number and type of locking screws, the properties of strut 100 can be adapted to different loads and different stress conditions associated with launch or other movement.
• Remote release function 24 is provided by expansion material 114 and heater 126.
• Expansion material 114 conveniently has the shape of a hollow cylinder with its longitudinal axis substantially coincident with axis 190 of strut 100.
• Heater 126 is thermally coupled to expansion material 114, in this example, mounted in intimate contact with the inside wall of the expansion material cylinder. However, heater 126 can equally well be mounted in thermal contact with the outside wall of expansion material 114. Either arrangement is useful.
• Heater 126 is electrically coupled to external plug 128 (see FIGS. 5-6) whereby electrical current is supplied to energize heater 126.
• Heater 126 may be energized remotely, that is for example, after a spacecraft deployable system has been launched into orbit or other load placed in an inaccessible location.
• Expansion material 114 is conveniently formed of a Shape Memory Alloy (SMA), such as, for example, a TiNi alloy sold by TiNi Aerospace, San Leandro, CA under the trade name "Nitinol.”
• SMA Shape Memory Alloy
• TiNi alloy sold by TiNi Aerospace, San Leandro, CA under the trade name "Nitinol.”
• Shape Memory Alloys are well known in the art. They have the property, among other things, that when heated to a critical temperature Tc, they undergo a phase transition to another crystalline form with an accompanying large expansion and, for some materials, a large increase in elasticity. This phenomenon can cause the SMA to recover from a mechanically preset state (e.g., to elongate) and remain in that condition after the heat is removed.
• SMA expansion material 114 is stressed in tension.
• heater 126 is energized to raise the temperature of SMA 114 above its transition point, a large strain occurs at constant stress, that is, SMA 114 significantly elongates, thereby moving compression block 112 to the right in FIGS. 7- 8, reopening gaps 109, 113.
• This change in shape is retained after heater 126 is de-energized.
• strut 100 is returned to the free condition.
• the length of SMA 114 (parallel to axis 190) is selected to provide the amount of deformation desired in order to have gaps 109, 113 of an appropriate size for the particular application.
• the thickness of SMA 114 (perpendicular to axis 190) is selected to withstand the pre-loading force exerted by bolts 120 when strut 100 is placed in the locked condition.
• a pre-load force of ⁇ 25,000 pounds can be placed on strut 100 when locked. That means that strut 100 can withstand a reaction force of ⁇ 25,000 pounds during system movement, e.g., launch.
• SMA 114 of Nitinol having a length of about 7.7 com, an outer diameter of about 6.4 cm and a wall thickness of about 1.5 cm, can increase in length by about 2.3 mm when heated to its phase transition temperature by heater 126.
• Jack-pad 110 is conveniently formed of Nitronic 60, and compression block 112, D-strut 104 and housing 102 are conveniently of Ti, although other materials well known in the art can also be used.
• FIG. 9 is a side view
• FIG. 10 is a left end view
• FIG. 11 is a right end view of support structure or strut 200, similar to strut 10 but according to a further embodiment.
• Strut 200 has body 202 analogous to body 12 of FIG. 1, and attachment portions 241, 261 with coupling holes 251, 271 analogous to 14, 16 and 15, 17, respectively, of FIG. 1.
• FIGS. 12, 13 are simplified partial cross-sectional views of support strut 200, analogous to FIGS. 8, 7 respectively, and along plane 12-12 shown in FIGS. 9-11.
• FIG. 12 shows strut 200 in the free or released condition
• FIG. 13 shows strut 200 in the locked condition.
• FIG. 14 is a simplified partial cross-sectional view of a portion of support strut 200 of FIGS. 9-13 along plane 14-14 in FIGS. 9, 12-13, showing further details.
• Support strut 200 has damper function region 220 analogous to function 20, release function region 222 analogous to function 22 and locking mechanism region 224 analogous to function 24 of strut 10 of FIG. 1.
• Locking mechanism 224 comprises worm gear pre-loader 204 partially visible in FIGS. 12-14.
• Worm gear pre-loader 204 includes worm 206 engaging pinion worm gear 208.
• Pinion worm gear 208 is rotationally held between portions 228 and 230 of body 202.
• Body portions 228, 230 are conveniently joined to portion 272 of body 202 by bolts 229.
• Worm 206 has one or more end region(s) 210 to which a torque wrench can be applied. Turning worm 206 causes pinion gear 208 to rotate with a mechanical advantage determined by the number of teeth on pinion gear 208.
• sleeve 212 Located within and axially concentric with pinion gear 208 is sleeve 212 with spline 213 that rotates with pinion 208. Inner portions 216, 218 of splined sleeve 214 are threaded, portion 216 being a right-hand thread and portion 218 being a left-hand thread (or vice- versa). Threaded portion 216 of sleeve 212 engages matching threads on end plug 226 which is fixed to end region 230 of body 202 by attachment means 231. Located within end plug 226 is spring 227 that engages cylindrical plug 232. Cylindrical plug 232 is concentric with and slides over a portion of end plug 226 in a manner that prevents mutual rotation thereof.
• Spline or polygonal shape 225 is used in the intersecting region of plugs 226, 232 to permit axial sliding (i.e., parallel to axis 214) but prevent rotation of cylindrical plug 232 relative to end plug 226.
• Threaded portion 218 of sleeve 212 engages matching threads on cylindrical plug 232.
• Plug 232 has cap 234 fixed thereon by attachment means 233. Taken together, plug 232 and cap 234 are referred to collectively as jack-pad 236.
• pinion gear 208 rotates
• splined sleeve 212 rotates and moves along threads 216 in a direction parallel to axis 214 of strut 200.
• jack-pad 236 moves to the right on threads 218 but by twice the distance which sleeve 212 moves.
• jack- pad 236 and concentric yoke 238 are spaced apart by first gap 237 (see FIG. 12).
• jack-pad 236 moves to the right closing first gap 237 and engaging yoke 238.
• Yoke 238 is fixed on mandrel 240 by attachment means 239.
• Concentrically surrounding mandrel 240 is expansion material 242 with concentric heater 244, analogous to expansion material and heater 114, 126 of strut 100 in FIGS 7-8.
• Mandrel cap 246 is attached to mandrel 240 by bolt 248.
• the dimensions and arrangement of mandrel 240, expansion material 242, mandrel cap 246 and bolt 248 are chosen so that expansion material 242 is preferably under axially directed compression, but this is not essential. However, it is important that expansion material 242 at least fit snugly between mandrel 240 and mandrel cap 246 in the axial direction.
• Mandrel cap 246 is coupled to flex mount holder 250 by attachment means 247. Taken collectively, mandrel 240, mandrel cap 246 and flex mount holder 250 comprise D-strut 254. D- strut 254 is coupled to end plate 252 by bolts 253 or other suitable attachment means. Mounting portion 241 is coupled to or a part of end plate 252.
• Body 202 has interior portion 256 that is coupled to D-strut 254 by resilient members 258, 260. It is resilient members 258, 260, in conjunction with D-strut 254 and body portion 256, that comprise damping function region 220 for providing damping function 20 in strut 200.
• resilient members 258, 260 are annular, fluid-filled bellows springs that are compressible in the direction of axis 214. Such fluid filled bellows springs are desirably coupled by a narrow tube (not shown) to allow fluid to flow from the bellows being axially compressed (e.g., 258 in FIG. 13) into the bellows being axially stretched (e.g., 260 in FIG. 13), but this is not essential.
• various other arrangements may be used, including but not limited to, rubber and/or plastic materials, springs, or any other arrangement that provides both a spring action and, desirably, viscous action of some kind to dissipate vibrational energy.
• Body 202 has skirt portion 262 coupled by attachment means 263 to body portion 272. In the free state, gap 265 exists between end 266 of skirt 262 and mating surface 268 of end plate 252. End plate 252 is also coupled to body portion 272 by spring 270.
• Spring 270 conveniently has a rectangular cross-section and extends from end plate 252 to body portion 272. Spring 270 can be machined as a part of end plate 252 and attached to body portion 272 by joining means (not shown). Alternatively, spring 270 can be a separate part joined to end plate 252 and body portion 272 by, for example, welding, brazing, threaded joints, or a combination thereof. The exact method of attachment is not critical and is omitted from FIGS. 12-13 for simplicity.
• Locking mechanism 224 with worm gear pre-loader 204 provides great mechanical advantage and allows a large pre-load force to be placed on strut 200, as for example, more than 25,000 pounds by a single wrench on worm gear ends 210 and with much reduced wrench torque, for example, ⁇ 70 foot-pounds. By reversing the direction of worm drive 204, this strut pre-load force may be relieved for testing and then re-applied without damage to strut 200 and without having to change or replace any interior parts thereof.
• expansion material 242 is, in the preferred embodiment, placed in compression during assembly of D-strut 254.
• This initial compressive pre-load force on expansion material 242 may or may not be overcome by the tension strut pre-loading through locking mechanism 224.
• expansion material 242 undergoes a phase transformation thereby significantly increasing its length. It does this against the restraining resistance of mandrel portion 240 of D-strut 254.
• the material and dimensions of mandrel portion 240 and expansion material 242 should be chosen so that the expansion force of expansion material 242 plastically stretches mandrel portion 240.
• Strut 200 is released by heating expansion material 242 with heater 244 to plastically deform D-strut 254 without fracture. As with strut 100, this release is a gradual and quiet process, without the sudden snap or explosive detachment encountered in the prior art. The speed of the release step is determined generally by the heating time-constant of heater 244 and expansion material 242 mounted on D-strut 254. Electricity is supplied to heater 244 via plug 280.
• Joints 231, 233, 239, 247, 263 in strut 200 may be formed by any convenient means, as for example and not intended to be limiting, mechanical threads or the like, brazing and welding or the like, or other means well known in the art having sufficient shear strength for the application.
• FIGS. 1-14 are intended to illustrate the principles of the invention and not be shop drawings. Differently shaped components and more or fewer assembly joints may be desirable to facilitate struts embodying the present invention. Further it will be appreciated that the order of assembly of parts of the struts may be varied to suit particular manufacturing needs and applications. Persons of skill in the art will know how to do this based on the description herein and the accompanying drawings.

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• Engineering & Computer Science (AREA)
• Remote Sensing (AREA)
• Aviation & Aerospace Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Vibration Prevention Devices (AREA)
• Vibration Dampers (AREA)

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• 2003
  • 2003-03-24 US US10/396,024 patent/US6920966B2/en not_active Expired - Lifetime
• 2004
  • 2004-03-24 DE DE602004020877T patent/DE602004020877D1/de not_active Expired - Lifetime
  • 2004-03-24 EP EP04749423A patent/EP1606164B1/en not_active Expired - Lifetime
  • 2004-03-24 JP JP2006532336A patent/JP4607115B2/ja not_active Expired - Fee Related
  • 2004-03-24 WO PCT/US2004/008890 patent/WO2004108532A1/en not_active Ceased

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