Patent Publication Number: US-2023155522-A1

Title: Stored energy release triggered by piezoelectric element

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to a stored energy release triggered by a piezoelectric element, and more particularly to a stored energy release incorporated within a water activated release system (WARS). 
     BACKGROUND 
     Water activated release systems (WARS) are known in the art and are typically configured to trigger release of the WARS from a restraint, such as a harness, once the system is submersed in seawater. To that end, the WARS may include sensors which, when submersed in seawater, detect a change in resistance due to the salinity of the seawater. Upon sensing a threshold salinity/drop in resistance, a capacitor is charged via a battery pack so as to discharge a current to a pyrotechnic element and thereby cause the pyrotechnic element to ignite its chemical agents. Firing of the pyrotechnic chemical agents evolves a high pressure gas which actuates locking pins to withdraw into the WARS so as to release the locking pins from the restraint. Other wetting conditions, such as freshwater, fog, rain or humidity will not trigger firing of the pyrotechnic. While pyrotechnic WARS are presently in use, such pyrotechnic systems suffer from high production costs, complex assembly requirements and potential failure due to decomposition or fouling of the pyrotechnic chemical agents. 
     SUMMARY 
     The present invention addresses the above need by providing a WARS without need of a pyrotechnic chemical agent. In an embodiment, a stored energy release comprises an actuatable member slidably received within a housing. The actuatable member has an extended orientation wherein a portion of the actuatable member extends outwardly from the housing and a retracted orientation wherein the actuatable member resides within the housing. A biasing member is located between the actuatable member and the housing and biases the actuatable member to the retracted orientation. A shaft is within the housing with the actuatable member configured for sliding movement along the shaft. A retaining member is located between the actuatable member and the shaft and maintains the actuatable member in the extended orientation whereby potential energy is stored within the biasing member. A piezoelectric element selectively engages the retaining member to disable the retaining member and release the stored potential energy within the biasing member to place the actuatable member in the retracted orientation. 
     In a further aspect of the present invention, the actuatable member includes a pin puller coupled to a locking pin whereby the locking pin is configured to extend outwardly from the housing when the actuatable member is in the extended orientation. The shaft may also include a shoulder with the retaining member configured to engage the shoulder when the piezoelectric element is in a first state and wherein the retaining member disengages the shoulder when the piezoelectric element is in a second state such that the actuatable member is biased to the retracted orientation. The shaft may alternatively include tapered ends while the retaining member includes a ring configured to engage the tapered end when the piezoelectric element is in the first state and wherein the ring disengages the tapered end when the piezoelectric element is in a second state such that the actuatable member is biased to the retracted orientation. 
     In another aspect of the present invention, a water activated release system configured to automatically uncouple an occupant worn harness from a link when immersed in salt water comprises a body having a first end coupled to either the occupant worn harness of the link and a second end coupled to the other of the occupant worn harness of the link. The first end includes a power supply and at least one sensor in communication with an electronics package assembly (EPA) having an internal circuit with activated and deactivated states. The at least one sensor is configured to sense when the WARS is immersed in salt water and trigger the EPA to the activated state. The second end includes a stored energy release assembly comprising an actuatable member slidably received within a housing. The actuatable member has an extended orientation wherein a portion of the actuatable member extends outwardly from the housing to couple the WARS to the link and a retracted orientation wherein the actuatable member resides within the housing to uncouple the WARS from the link. A biasing member is located between a portion of the actuatable member and the housing. The biasing member is configured to bias the actuatable member to the retracted orientation. A shaft is within the housing with the actuatable member configured for sliding movement along the shaft. A retaining member is located between the actuatable member and the shaft. The retaining member is configured to maintain the actuatable member in the extended orientation whereby potential energy is stored within the biasing member. A piezoelectric assembly is configured to receive electrical power from the power supply when the EPA is triggered to the activated state. The piezoelectric assembly includes a piezoelectric element configured to selectively engage the retaining member to disengage the retaining member from the shaft and release the stored potential energy within the biasing member to bias the actuatable member to the retracted orientation whereby the occupant worn harness is uncoupled from the link. 
     In still another aspect of the present invention, the link is further coupled to a parachute riser or an overhead reel and the power supply is one or more batteries. Also, the at least one sensor is configured to detect a change in resistance due to the salinity of the salt water. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       For a more complete understanding and appreciation of this invention, and its many advantages, reference will be made to the following detailed description taken in conjunction with the accompanying drawings. 
         FIG.  1    is an environmental view of a harness system including a water activated release system in accordance with the present invention; 
         FIG.  2    is an isolated view of the water activated release system shown in  FIG.  1   ; 
         FIG.  3    is a cross section view of a prior art pyrotechnic water activated release system with the pyrotechnic in an unfired condition and locking pins extended; 
         FIG.  4    is a cross section view of the prior art pyrotechnic water activated release system shown in  FIG.  3    following firing of the pyrotechnic and retraction of the locking pins; 
         FIG.  5    is a cross section view of a piezoelectric water activated release system in accordance with an aspect of the present invention; 
         FIG.  6    is a cross section view of an isolated piezoelectric assembly within the piezoelectric water activated release system shown in  FIG.  5   ; 
         FIG.  6 A  is an expanded view of a pin holder and dowel within the piezoelectric assembly shown in  FIG.  6   ; 
         FIG.  7    is an isolated, front cross section view of the pin holder and piezoelectric element within the piezoelectric assembly shown in  FIG.  6   ; 
         FIG.  8    is a cross section view of the piezoelectric water activated release system shown in  FIG.  5    with the locking pins manually placed within the retracted orientation; 
         FIG.  9    is a cross section view of the piezoelectric water activated release system shown in  FIG.  5    following actuation of the piezoelectric element and retraction of the locking pins. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate currently preferred embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION 
       FIG.  1    shows an exemplary environmental view of a harness configuration  10  which may suitably include a water activated release system (WARS). Harness configuration  10  may include a first strap  12  fixedly secured to a first end  14  of a manual release mechanism  16 . First strap  12  may, for example, be secured to an occupant-worn harness system, such as but not limited to a parachute harness. The opposing second end  18  of manual release mechanism  16  may include a clasp  20  configured to receive a link  22 . Pivoting clasp  20  enables release of link  22  from manual release mechanism  16 . Link  22  may be coupled to a second strap  24 . Second strap  24  may be secured to a further structure, such as an overhead reel (not shown) or may be a parachute riser of a parachute. In one instance, link  22  may be directly coupled to second strap  24  via pin  26  whereby second strap  24  would be released from first strap  12  only upon actuation of clasp  20  of manual release mechanism  16 . 
     With additional reference to  FIG.  2   , to provide for increased safety, particularly in those applications anticipated to occur on, near or over seawater, WARS  28  may be interposed between strap  24  and link  22 . In this instance, pin  26  is fixedly secured within openings  30  defined within lobes  31  which extend outwardly from first end  32  of body  29  of WARS  28 . Second end  34  of WARS  28  may include opposing locking pins  36  configured to be releasably coupled to link  22 . In this manner, upon submersion in seawater, WARS  28  may be activated to retract locking pins  36  and thereby disengage locking pins  36  from link  22 . First strap  12  may then be decoupled from second strap  24  whereby the occupant is released from the overhead reel or parachute riser and canopy. 
     With attention to  FIGS.  3  and  4   , a prior art pyrotechnic WARS is generally indicated by reference number  28   a . As can be seen, pyrotechnic WARS  28   a  includes a body  29   a  having opposing locking pins  36   a  slidably received within a channel  38   a  defined within second end  34   a . Locking pins  36   a  are biased outwardly of second end  34   a , such as by way of spring  40   a  so as to engage link  22 . First end  32   a  of WARS  28   a  may be include sensors  42   a  configured to sense when WARS  28   a  is submersed within seawater, such as by a change in resistance between the sensors. Sensors  42   a  may communicate with an electronics package assembly (EPA)  44   a  whereby, when sensors  42   a  indicate seawater submersion, EPA  44   a  may close a circuit to charge capacitor  45   a . Electrical power may be provided to sensors  42   a , EPA  44   a  and capacitor  45   a  by one or more button cells  46   a . Upon charging of capacitor  45   a , a discharge current may then be directed to pyrotechnic element  48   a  so as to fire the pyrotechnic chemical agent contained therein and thereby generate a gas. The gas may then travel through gas path  50   a  and exert a force against head  37   a  of each locking pin  36   a . The force exerted by the gas is sufficient to overcome the biasing force of spring  40   a  whereby locking pins  36   a  are driven inwardly within channel  38   a . Channel  38   a  may further include a ramped surface  52   a  whereby, when driven by the evolved gas, heads  37   a  may be wedged against ramped surface  52   a  such that locking pins  36   a  may not be biased outwardly by spring  40   a  following a drop in gas pressure. In this manner, WARS  28   a  may then be freely removed from link  22  as shown in  FIG.  4   . 
     Turning now to  FIGS.  5 - 9   , an embodiment of a piezoelectric WARS  28   b  generally includes a body  29   b  having first and second ends  32   b ,  34   b , respectively. It should be noted that first end  32   b  has been omitted from  FIGS.  6 ,  8  and  9    for purposes of clarity. With reference to  FIG.  5   , first end  32   b  of WARS  28   b  may include sensors  42   b  configured to sense when WARS  28   b  is submersed within seawater. Sensors  42   b  may communicate with EPA  44   b , when sensors  42   b  indicate seawater submersion. EPA  44   b  may then close a circuit to provide electrical power to piezoelectric assembly  35   b , which will be discussed in greater detail below. Electrical power may be provided by one or more button cells  46   b . 
     Second end  34   b  may include a piezoelectric assembly  35   b  within channel  38   b  defined within the housing of second end  34   b . Piezoelectric assembly  35   b  may comprise opposing locking pins  36   b  each biased outwardly from second end  34   b , such as by way of a respective conical spring  40   b  acting against a respective retaining member, such as holder  54   b . Each holder  54   b  abuts a respective shoulder  56   b  defined by central shaft or dowel  58   b  ( FIGS.  6  and  6 A ). Piezoelectric assembly  35   b  may further include a respective pin puller  60   b  coupled to flanged end  62   b  of a respective locking pin  36   b  at a first end  64   b . Together, each locking pin  36   b  and associated pin puller  60   b  may be referred to as an actuatable member. Opposing second end  66   b  of pin puller  60   b  includes a flange  68   b . Inner surface  70   b  of flange  68   b  engages holder  54   b  while outer surface  72   b  is configured to engage a biasing member, such as wave spring  74   b . The opposing end of each wave spring  74   b  seats against wall  76   b  of second end  34   b  such that wave spring  74   b  imparts an inward biasing force against pin puller  60   b , and thus locking pins  36   b . Potential energy is stored within each wave spring  74   b  and inward travel of locking pins  36   b  is prevented by engagement of holder  54   b  with shoulder  56   b . 
       FIG.  7    is an isolated view of a holder  54   b . Holder  54   b  may include a generally C-shaped member  77   b  defining a narrow gap  78   b  and central opening  80   b . A piezoelectric element  82   b  may extend across gap  78   b . Piezoelectric element  82   b  may be initially configured to be in a compressed state while central opening  80   b  is proportioned such that its diameter D is substantially equal to the outer diameter of reduced portion  84   b  of central dowel  58   b  (see  FIG.  6 A ) but less than the outer diameter of unreduced portion  86   b  of central dowel  58   b . In this manner, piezoelectric element  82   b  may clamp holder  54   b  to reduced portion  84   b  of central dowel  58   b  and thereby prevent inward travel of holder  54   b  when under the biasing force of wave spring  74   b  as described above. However, following a sensed seawater submersion, discharge of capacitor  45   b  may cause expansion of piezoelectric element  82   b . As a result, C-shaped member  77   b  may be deformed radially outward such that diameter D of central opening  80   b  may be expanded to be at least equal to the outer diameter of unreduced portion  84   b  of central dowel  58   b . C-shaped member  77   b  may further include a hinge point, such as recess  88   b , configured to assist control of the radially outward expansion of C-shaped member  77   b . In this manner, and as shown in  FIG.  9   , holder  54   b  may translate linearly inward within channel  38   b  as the potential energy stored within wave springs  74   b  is released. As pin puller  60   b  is coupled to wave spring  74   b , and locking pin  36   b  is coupled to pin puller  60   b , locking pin  36   b  also translates inwardly within channel  38   b  such that locking pin  36   b  lies below plane P b  defined by the terminus of second end  34   b . As a result, WARS  28   b  may be decoupled from link  22  as described above. 
     With reference to  FIG.  8   , WARS  28   b  may be manually coupled to link  22  without the use of tools. As shown in  FIG.  8   , locking pins  36   b  may be manually directed into second end  34   b  upon compression of conical springs  40   b . Inward travel of holder  54   b  is prevented by engagement of C-shaped member  77   b  with shoulder  56   b  as described above. In this manner, WARS  28   b  may slide within link  22 . With WARS  28   b  properly in place, compression of conical springs  40   b  is removed such that stored potential energy within conical springs  40   b  drives locking pins  36   b  outwardly such that locking pins  36   b  may engage link  22  so as to releasably couple WARS  28   b  to first strap  12 . 
     It should be understood the steps of the method presented herein do not necessarily have to be in the order in which it is presented. It is also understood that when an element is referred to as being “on”, “connected to/with”, or “coupled to/with” another element, the element can be directly on, connected to/with or coupled to/with the other element or intervening elements may also be present. 
     While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements or components thereof to adapt to particular situations without departing from the scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope and spirit of the following claims.