Abstract:
The present invention is directed to providing a biased releasable connection system that is compact, lightweight, inexpensive and low-power. The system comprises a releasable object that is biased against a retaining mechanism until the connection is released. The system further comprises a small and lightweight shape memory alloy member to actuate the release of the connection. When the connection is released, the biasing mechanism propels the releasable object in a particular direction. The compact design of the system is partly attributable to the strategic utilization and positioning of the shape memory member within the system.

Description:
FIELD 
       [0001]    The present invention relates generally to a releasable connection system, and more particularly to a biased releasable connection system comprising a restraining mechanism for restraining a biased releasable object that is actuated by a shape memory alloy member. 
       BACKGROUND 
       [0002]    Releasable connection devices are used in many applications to releasably connect one object to another object. In some instances, the connection device comprises bias means to urge or propel one object away from the other object once the connection between the two objects is released. 
         [0003]    Biased releasable connection systems are known. For example, they can be found in projectile launchers, ejection systems, and electrical connectors to name a few. However, existing biased releasable connection systems are not well suited for applications in which either the size or the weight of the connection system must be minimized. For example, in some applications, the releasable connection system must be compact so as to be installable in a very small space. In other applications, it is the weight of the system that must be limited. Size and weight limitations are generally an issue in the design of, for example, flying objects, and in particular for remote controlled airplanes, helicopters and other flying bodies. 
         [0004]    One problem with existing releasable connection systems is that they generally employ a purely mechanical or an electromechanical actuation device to release the connection. In some systems, the release mechanism is activated when an external force is applied to a trigger, typically by a user. The force applied to the trigger is transferred to the release mechanism through one or more levers, cogs or other mechanical components. These components contribute to the overall size, weight and cost of the connection system. Furthermore, systems having a manually operated trigger are not well suited to be operated remotely. As an alternative to a trigger, the release mechanism can be activated by an electromechanical element, which converts an electrical force into a mechanical force. A common type of electromechanical actuator is a solenoid. However, solenoids have a number of drawbacks. They are relatively large and heavy due to their coil. They also have complicated constructions, making them expensive. Furthermore, solenoids generally have a minimum input voltage, and this voltage can be significant. Where the connection system is incorporated into a battery-operated application, the minimum input voltage of the solenoid may be significantly higher than the voltage required to power the rest of the application, thereby necessitating bigger or additional batteries. Therefore solenoids are often not suitable for use in systems that must be compact, lightweight, inexpensive, or low-power. 
         [0005]    More recently, shape memory alloy actuators have become an attractive alternative to conventional actuators in certain applications. Shape memory alloy actuators are known in the art. They are metal alloys that possess a number of special characteristics, including the ability to return to their original shape after deformation. This characteristic makes shape memory alloys particularly suitable for use as actuators. Furthermore, shape memory alloy actuators are relatively small and lightweight, and can be inexpensive. Although shape memory alloy actuators are known in the art, they have yet to be efficiently utilized in biased releasable connection systems to reduce the overall size, weight and cost of the systems. 
         [0006]    It is therefore desirable to develop a biased releasable connection system comprising a compact, lightweight, inexpensive and low-power actuator. 
         [0007]    Another problem with existing biased releasable connection systems is that they generally comprise a biased piston or shuttle to either directly or indirectly propel the releasable object. In some instances, the overall size and weight of the connection system can be reduced if a piston or shuttle is not used. It is therefore also desirable to develop a connection system not having a plunger or a shuttle. 
         [0008]    For the foregoing reasons, it can be appreciated that a need exists for an inexpensive, compact, lightweight and low-power biased releasable connection system. 
       SUMMARY 
       [0009]    The present disclosure provides a biased releasable connection system that addresses the problems described above. The present connection system is a compact, lightweight, inexpensive and low-power system. Such a system can be used in a variety of different applications, and is particularly well suited for use in toys and flying objects to propel or release releasable objects. 
         [0010]    While the described embodiment is in the form of a toy projectile launcher, the scope of the present disclosure is not intended to be limited to toy projectile launchers. The present biased releasable connection system can be used for other applications and in other fields, including but not limited to projectile launchers, ejection systems, release systems, electrical connectors, and mechanical connectors. 
         [0011]    In one aspect, the present disclosure is directed to a biased releasable connection system comprising a releasable object, a biasing mechanism for exerting a biasing force on the releasable object, a retaining mechanism for retaining the releasable object against the bias of the biasing mechanism, and a release mechanism for releasing the releasable object thereby allowing the biasing mechanism to propel the releasable object from the retaining mechanism, the release mechanism comprising at least one shape memory alloy member for actuating the release. 
         [0012]    Another aspect of the present disclosure is directed to a projectile launcher comprising the biased releasable connection system as described herein. In at least one embodiment, the projectile launcher is part of a flying toy. 
         [0013]    In a further aspect, the present disclosure is directed to a flying object comprising the biased releasable connection system as described herein. In at least one embodiment, the flying object is a flying toy. 
         [0014]    In addition, in at least one embodiment, the shape memory alloy member is strategically disposed in the connection system to provide a compact design. 
         [0015]    In at least one embodiment, the actuation force of shape memory alloy member is substantially parallel to the bias force exerted by the biasing mechanism. 
         [0016]    Furthermore, in at least one embodiment, the connection system comprises a lever, which cooperates with a shape memory alloy actuator to provide a compact design. 
         [0017]    In addition, in at least one embodiment, the connection system comprises a lever to increase the amount of force transferred from the shape memory alloy actuator to the restraining mechanism to release the releasable object. 
         [0018]    Furthermore, in at least one embodiment, the biasing mechanism of the connection system propels the releasable object directly without the use of a shuttle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The present disclosure will be better understood having regard to the drawings in which: 
           [0020]      FIG. 1  is a perspective view of one embodiment of the biased releasable connection system; 
           [0021]      FIG. 2  is a perspective front view of the embodiment shown in  FIG. 1 ; 
           [0022]      FIG. 3A  is a sectional perspective view of the embodiment shown in  FIG. 1  wherein the restraining mechanism is not engaged with the releasable object; 
           [0023]      FIG. 3B  is a sectional perspective view of the embodiment shown in  FIG. 1  wherein the restraining mechanism is engaged with the releasable object; 
           [0024]      FIG. 4  is a perspective back view of the support mechanism of the embodiment shown in  FIG. 1 ; and 
           [0025]      FIG. 5  is an exploded view of the embodiment shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    The present biased releasable connection system is described in one embodiment in the following description with reference to the Figures. While this invention is described in terms of one mode for achieving the objectives of the invention, it will be appreciated by those skilled in the art that variations may be accomplished in view of these teachings without deviating from the scope of the present invention. 
         [0027]    The various features and components of the present biased releasable connection system are now described with reference to the Figures. 
         [0028]      FIGS. 1 to 5  show one embodiment of the biased releasable connection system  10 , which comprises a retaining mechanism  20 , a biasing mechanism  140 , a release mechanism  160 , and a releasable object  200 . 
         [0029]    The retaining mechanism  20  retains the releasable object  200  in position and against the bias of the biasing mechanism  140 . The release mechanism  160  releases the releasable object, thereby allowing it to be propelled by the biasing mechanism  140 . 
       Retaining Mechanism 
       [0030]    As best shown in  FIG. 5 , in at least one embodiment, the retaining mechanism  20  comprises a support mechanism  40  for supporting the releasable object  200 , and a restraining mechanism  80  for restraining the releasable object  200  against the bias of the biasing mechanism  140 . 
       Support Mechanism 
       [0031]    The support mechanism  40  supports and retains the releasable object  200  in position when forces are exerted on the releasable object  200  by the biasing mechanism  140  and the restraining mechanism  80 . The support mechanism  40  can also serve as a launch guide to direct the releasable object  200  in a specific direction once released. 
         [0032]    As best illustrated in  FIG. 5 , in at least one embodiment, the support mechanism  40  comprises a tubular structure  42  having a passageway therethrough, a back end opening  44  and a front end opening  46 . The tubular structure  42  can be adapted to receive at least part of the releasable object  200 . Having regard to  FIG. 2 , the front end opening  46  can comprise a guide plate  48 , the guide plate  48  having a hole  52  through its centre to receive the releasable object  200 . The plate  48  can be formed integrally with the tubular structure  42 , or may be a separate piece connected to the tubular structure  42  in any suitable manner known in the art. The plate  48  can be used, for example, to align the releasable object  200  within the tubular structure  42 . 
       Base 
       [0033]    As illustrated in the Figures, in at least one embodiment, the connection system  10  can comprise a base  120 . The base  120  can be utilized for any number of functions, including supporting the release mechanism  160 , the restraining mechanism  80 , or the biasing mechanism  140 . The base  120  may also comprise or be cooperable with mounting means (not shown in the Figures) for mounting the system  10  onto another surface or to connect it to some other object. Mounting means can be of any type known in the art. In at least one embodiment, the base  120  is formed integrally with or connected to the support mechanism  40 . 
       Biasing Mechanism 
       [0034]    The connection system  10  further comprises a biasing mechanism  140  for biasing the releasable object  200 . In at least one embodiment, the biasing mechanism  140  comprises a resilient member to provide a biasing force. As best shown in  FIGS. 3A ,  3 B and  5 , in at least one embodiment, the resilient member is a coil spring  142 , which biases the releasable object  200  in the direction of arrow B (see  FIG. 3B ). However, this is not intended to be limiting and those skilled in the art will appreciate that one or more resilient members of varying types, shapes, lengths and strengths can be used depending on the requirements of the given application. The resilient member can be made of metal, natural or synthetic elastomer, or any other suitable material. 
         [0035]    As illustrated in  FIGS. 3A and 3B , coil spring  142  can be disposed within the tubular structure  42  of the support mechanism  40 . The diameter of the spring  142  is best chosen such that the spring  142  can accommodate the releasable object  200 , but can also expand and contract freely within the tubular structure  42 . The releasable object  200  is moved into a cocked position, or “loaded”, by inserting the back end  212  of the releasable object  200  into the front end opening  46  of the tubular structure  42 . As the releasable object  200  is slid toward the back end opening  44  of the tubular structure  42  in the direction of arrow A (see  FIG. 3A ), a first mating surface  206  of a spline  204  on the releasable object  200  contacts and engages the spring  142 . As the releasable object  200  is moved even further in the direction of the back end opening  44 , the spring  142  is compressed (see  FIG. 3B ). 
         [0036]    As shown in  FIGS. 3A and 3B , in at least one embodiment, the releasable object  200  directly contacts the biasing mechanism  140 . The first mating surface  206  of the releasable object  200  contacts and engages the spring  142 . In one or more other embodiments, the connection system  10  can further comprise a shuttle (not shown in the Figures) that is disposed between the resilient member and the releasable object  200 . The shuttle can be connected to or disposed proximate the resilient member such that the releasable object  200  contacts the shuttle rather than the resilient member as the releasable object  200  is loaded into position. The shuttle can be an annular shuttle, a piston, a plunger, or any other suitable type of shuttle. 
         [0037]    The back end opening  44  of the tubular structure  42  can be at least partially obstructed to prevent the spring  142  from being pushed out of the back end opening  44  when the releasable object  200  is moved into the cocked position. As best seen in  FIG. 3B , the back end opening  44  can be partially obstructed by the restraining mechanism  80 , and in particular by the effort arm  92  of the lever  82 . However, the spring  142  can also be connected to the tubular structure  42  in order to retain it substantially within the structure  42  by well known methods, including but not limited to entrapping or hooking the end of the spring  142  into a molded feature in structure  42 . Furthermore, the releasable object  200  can extend beyond the back end opening  44  of the tubular structure  42  (see  FIGS. 1 ,  3 A and  3 B). In at lease one embodiment, this is achieved by providing a passageway  96  in the effort arm  92  of the lever  82  to allow the releasable object  200  to extend therethrough. 
       Restraining Mechanism 
       [0038]    Connection system  10  also comprises a restraining mechanism  80  for restraining the releasable object  200  in the cocked position against the bias of the biasing mechanism  140 .  FIG. 3B  shows one embodiment of the connection system  10  in which the releasable object  200  is in the cocked position. 
         [0039]    In at least one embodiment, the restraining mechanism  80  comprises a movable mechanical obstruction to engage and thereby restrain the releasable object  200 . As best illustrated in  FIGS. 3A ,  3 B and  5 , the restraining mechanism  80  can comprise a pivoting lever  82 . The lever  82  can further comprise a latch arm  86  and an effort arm  92 , the latch arm  86  for engaging the releasable object  200  and the effort arm  92  for cooperating with the release mechanism  160 . In the embodiment shown in the Figures, the angle between the latch arm  86  and the effort arm  92  is approximately 90 degrees. However, it will be apparent to those skilled in the art that other angles may also be suitable depending on the particular application. 
         [0040]    As illustrated in  FIG. 5 , the lever  82  can also comprise a pin aperture  84  for receiving a pivot pin  64 , which cooperates with pin holes or indentations  62  in the latch arm housing  56 . Furthermore, the latch arm  86  can comprise a latch hook  88  for engaging the second mating surface  210  on the spline  204  of the releasable object  200 . The second mating surface  210  is defined by a recess  208  in the spline  204 .  FIG. 3B  shows the latch hook  88  engaged with second mating surface  210  on the releasable object  200 . 
         [0041]    In at least one embodiment, as the releasable object  200  is moved from an uncocked position ( FIG. 3A ) into the cocked position ( FIG. 3B ), the releasable object  200  contacts and applies a compression force on the spring  142 . Part of this force compresses the spring  142  and part of the force is transferred through the spring  142  to the effort arm  92  of the lever  82 , which causes the lever  82  to rotate about pin  64 . This rotation swivels the effort arm  92  away from the tubular structure  42  and the latch arm  86  towards the releasable object  200  causing the latch hook  88  to engage the second mating surface  210  on the releasable object  200 . The latch arm  86  and hook  88  then hold the releasable object  200  against the compressed spring  142  ( FIG. 3B ). Furthermore, as shown in  FIG. 2 , the front end opening  46  of the tubular structure  42  can comprise a keyway  54 . The spline  204  on the releasable object  200  can serve as a key to ensure proper alignment of the spline  204  and second mating surface  210  with the latch arm  86  and the latch hook  88 . 
         [0042]    As illustrated in  FIGS. 3A and 3B , the lever  82  can be pivotally connected to the housing  56 . The lever  82  can be connected to the housing  56  by a pin  64 , the pin  64  extending through the pin aperture  84  in the lever  82 . The latch arm  86  of the lever  82  can be protected by housing  56  and can be rotated from the housing  56  into the inner portion of the tubular structure  42  through the longitudinal opening  58  in the tubular structure  42  ( FIG. 4 ) to engage the releasable object  200 . 
         [0043]    The restraining mechanism  140  can be made of plastic or any suitable material known in the art. 
       Release Mechanism 
       [0044]    The connection system  10  further comprises a release mechanism  160  for releasing the releasable object  200  from the cocked position, thereby allowing it to be propelled by the biasing mechanism  140 . The release mechanism  160  comprises at least one shape memory alloy member  162 , which produces an actuation force when heated above its transitional temperature. This actuation force causes the restraining mechanism  80  to disengage the releasable object  200  thereby allowing the biasing mechanism  140  to propel the releasable object  200 . 
         [0045]    As shown in the Figures, in at least one embodiment, the shape memory alloy member  162  of the release mechanism  160  is a wire, which contracts along its length when heated above its transition temperature. The ends of the wire can be coupled to electrical leads  164  and  166 , which can serve both as electrical contact points and anchor points. In operation, when the releasable object  200  is to be released, the shape memory alloy member  162  is heated above its transition temperature by any suitable means. When the shape memory alloy member  162  reaches its transition temperature, it contracts along its length, thereby exerting a pull force on the effort arm  92  of lever  82 . This pull force causes the lever  82  to pivot, pulling the effort arm  92  towards the support mechanism  40  and pivoting the latch arm  86  away from the releasable object  200 . This causes the latch hook  88  to disengage the releasable object  200 , thereby allowing the biasing mechanism  140  to propel the releasable object  200 . 
         [0046]    As best illustrated in  FIGS. 1 and 2 , in at least one embodiment, the shape memory alloy member  162  is connected to the restraining mechanism  80  and is anchored to one or more anchor positions. More specifically, the shape memory alloy member  162  is connected to a first electrical lead  164 , to the hook  94  on the effort arm  92  of the lever  82 , and to a second electrical lead  166 . The shape memory alloy member  162  is wound around the hook  94  such that it resides in the throat  98  of the hook  94 . The alloy member  162  can be anchored to one or more parts of the retaining mechanism  20 , such as the support mechanism  40 , the housing  56 , or the base  120 . In at least one embodiment, shape memory alloy member  162  is anchored to the base  120  by the leads  164  and  166 . The leads  164  and  166  can be disposed on the base  120  behind an obstruction such as wall  122 , the wall  122  serving to oppose the contraction force of the alloy member  162 . The wall  122  can comprise slots  124  and  126  to allow the shape memory alloy  162  to pass therethrough. 
         [0047]    As previously described, in at least one embodiment, the shape memory alloy member  162  is in the form of a wire that contracts along its length. Shape memory alloy wires that contract along their lengths typically do so by a specific percentage of their length, which is generally no greater than 10 percent. Therefore the length of such a wire is generally several times greater than the length of its stroke (i.e. distance by which it contracts). Depending on the desired stroke length, this can necessitate a relatively long shape memory alloy wire. The compact design of the present connection system  10  is partly attributable to the strategic positioning of the shape memory alloy member  162  relative the other components of the connection system  10 . As can be seen in  FIG. 3B , in at least one embodiment, the shape memory alloy member  162  is disposed such that its actuation force is exerted in a direction (indicated by arrow C) that is substantially parallel to the force exerted by the biasing mechanism  140  (indicated by arrow B). Positioning the longitudinal axis of the alloy member  162  close to and substantially parallel with the longitudinal axis of the support mechanism  42  can allow for a more compact design than if the alloy member  162  was not positioned parallel to the direction of the biasing force. Furthermore, such positioning can permit for a relatively lengthy actuation stroke without increasing the overall size of the connection system  10 . 
         [0048]    Furthermore, the compact design of the present invention results from, in at least one embodiment, the use of the shape memory alloy member  162  in conjunction with a lever to release the releasable object  200 . In particular, the direction of the actuation force produced by the shape memory alloy member  162  can be changed using, for example, a simple component such as an angular lever. Therefore the direction of the force needed to disengage the restraining mechanism  80  from the releasable object  200  need not be the same as the direction of the force produced by the shape memory alloy actuator  162 . As best illustrated in  FIG. 3B , in at least one embodiment of the present invention, the lever  82  of the restraining mechanism  80  is an angular lever. The angular lever changes the direction of the force and motion produced by the shape memory alloy member  162  (arrow C) to a direction that can be used to disengage the latch hook  88  from the releasable object  200  (arrow D). 
         [0049]    In addition to changing the direction of a force or motion, a lever can also be used to obtain a mechanical advantage. This can be useful in producing a sufficient amount of force to overcome the static friction between the latch hook  88  and the second mating surface  210  of the releasable object  200 . It will be apparent to a person skilled in the art how to change the mechanical advantage of the lever by changing the lengths of the latch arm  86  and effort arm  92 . 
         [0050]    Shape memory alloys are known in the art and are readily available. A defining characteristic of a shape memory alloy is that it changes shape when heated above its transition temperature. Without being bound by theory, this change in shape is the result of a molecular realignment, the energy for which comes from the heat applied to the alloy. The transition temperature of a shape memory alloy is the temperature at which the alloy changes from the Martensite phase to the Austenite phase. To start, an alloy is heated into its Austenite phase and then formed into a given shape (the “original” shape). The alloy is then cooled and allowed to change into its Martensite phase. At this point, the shape memory alloy can be deformed by, for example, being stretched or bent by some external force. When heated again above its transition temperature, the alloy changes into its Austenite phase, which returns it to its original shape. 
         [0051]    In at least one embodiment, the shape memory alloy member  162  is deformed by being stretched along its length. This stretching occurs when the releasable object  200  is moved into the cocked position. As previously described, when the releasable object  200  is loaded into the cocked position, some of the force transferred to the spring  142  from the releasable object  200  is transferred to the effort arm  92  of the lever  82 , thereby causing the effort arm  92  and thus the hook  94  to rotate away from the tubular structure  42 . This stretches the shape memory alloy member  162  along its length. Then, when the shape memory alloy member  162  is heated above its transition temperature, the alloy member  162  contracts to its original length from its stretched length. The force generated by this contraction pulls the effort arm  92  towards the tubular structure  42 , which causes the latch arm  86  and latch hook  88  to rotate away from the releasable object  200  thereby disengaging the releasable object  200 , which is then propelled by the biasing force of the biasing mechanism  140 . 
         [0052]    The shape memory alloy member  162  is heated by any suitable means known in the art. In at least one embodiment, a power source, which is not shown in the Figures, can be electrically coupled to the alloy member  162  through leads  164  and  166 . The power source can be any suitable power source that is capable of providing sufficient power to the shape memory alloy member  162  to heat it above its transition temperature. Some shape memory alloy actuators can be activated with less power than comparable solenoids. In addition to the power source, suitable means can be utilized to control the type, amount and timing of the power supplied to the shape memory alloy member  162 . Furthermore, the supply of power to the alloy member  162  can be activated by any suitable means, including but not limited to a user-initiated signal transmitted through a wired or wireless transmission medium. 
         [0053]    In addition, in at least one embodiment, the shape memory alloy member  162  is disposed externally to the exterior surface of the biased releasable connection system  10 . This permits the alloy member  162  to be cooled by surrounding air, and thus may eliminate the need for a heat sink. 
         [0054]    Those skilled in the art will recognize that the shape memory alloy member  162  can have any suitable shape, including but not limited to that of a strip, ribbon, coil, tube, or sheet. Furthermore, the release mechanism  160  of the present connection system  10  is not limited to a single shape memory alloy member; it can comprise a plurality of shape memory alloy members, which can be arranged in any suitable configuration. 
         [0055]    The shape memory alloy member  162  can be made of any suitable shape memory alloy known in the art. These include but are not limited to shape memory alloys made of nickel-titanium (NiTi), iron-manganese-silicon (FeMnSi), copper-aluminum-nickel (CuAlNi), and copper-zinc-aluminum (CuZnAl). 
         [0056]    The previous detailed description is provided to enable any person skilled in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention described herein. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article “a” or “an” is not intended to mean “one and only one” unless specifically so stated, but rather “one or more”. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.