Abstract:
A pin pulling device moves a member such as a pin or shaft by a non-pyrotechnic actuation force, such as a spring(s). The actuation member or spring(s) is (are) held in the compressed and loaded position by a release mechanism, such as an explosive bolt coupled to the member through a retainer. When activated by a signal, the release mechanism is severed from the retainer and the member is actuated by the force of the actuation member or compressed springs as the springs expand.

Description:
This invention was made with Government support under contract no. F08626-95-C-0106 awarded by the U.S. Department of Defense. The Government has certain rights to this invention. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to an actuation device. More particularly, the present invention is related to an explosive activated spring actuated device. 
     2. State of the Art 
     In the discussion of the state of the art that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods: do not qualify as prior art against the present invention. 
     Certain actuation devices in use today, such as pin pullers, use a piston housed in a cylinder which is pressurized by a pyrotechnic charge. The pyrotechnic charge is detonated by an electrical current or other means. The resulting gas pressure forces the piston and an integral pin or shaft associated with it to move over a predetermined distance. The piston and pin or shaft are unique to the particular device application. 
     Conventional devices having the above-mentioned construction, and their associated methods, pose certain problems and disadvantages. 
     First, devices of the above-described construction are one-time use or “one-shot”devices. 
     Second, the use of the pyrotechnic force for activation and actuation of the device presents certain difficulties. 
     Use of the pyrotechnic charge for actuation results in ballistic shock impact forces that must be taken into account in the design of the device. For instance, the housing and the pin of such devices must be designed with sufficient strength to withstand the forces created upon detonation of the pyrotechnic charge. 
     Also, since the explosive gas pressure created by the pyrotechnic charge dissipates immediately after actuation, a means of preventing “bounce-back” of the actuated pin is required. Typically, such devices are provided with a mechanism for locking the pin in its actuated position. The requirement of providing such mechanisms further complicates the design. 
     Moreover, choosing the proper size of the pyrotechnic charge is not a simple task. Generally, the charge must be large enough to effectively actuate the piston and its integral pin or shaft, but cannot be so large that it causes problems such as excessive “bounce-back”, or fracture, of the pin. 
     The design of such devices is even more difficult when the pin or shaft to be actuated is relatively heavy. In attempting to design such a device for actuation of a relatively heavy pin it has been found that conventional practices for sizing the pyrotechnic charge and dealing with the ballistics of the device are inadequate to lock the pin, and thereby prevent bounce back. 
     Thus, there is a need for an improved actuation device, and associated method, which are both reliable and economical. 
     SUMMARY OF THE INVENTION 
     According to the present invention, device and method are provided which overcome the disadvantages set forth above, and others. 
     According to one aspect, the present invention provides a pin puller device comprising: a housing; a non-pyrotechnic actuation mechanism disposed within the housing; a release mechanism constructed to initiate the release of the actuation mechanism in response to an activation signal; and a pin or shaft member operatively associated with the actuation mechanism. 
     According to a further aspect, the present invention provides a method of actuating a pin or shaft, the method comprising: providing a housing; providing a non-pyrotechnic actuation device within the housing; providing a release mechanism; providing a pin or shaft operatively associated with the actuation mechanism; transmitting an activation signal to the release mechanism; releasing the actuation mechanism; and actuating the pin or shaft. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     The objects and advantages of the invention will become apparent from the following detailed description of preferred embodiments thereof in connection with the accompanying drawings in which like numerals designate like elements and in which: 
     FIG. 1 is a perspective view of an embodiment of an actuation device according to the present invention; and 
     FIG. 2 is a longitudinal cross-sectional view of the device of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     According to the present invention, a device, and its associated method are provided in which a member to be actuated which is operatively associated with the device is actuated through separate release and actuation mechanisms. Preferably, the actuation mechanism is a non-pyrotechnic mechanism. By providing separate and distinct release and actuation mechanisms, the forces required for the release and actuation functions are separated, and thus become more manageable thereby facilitating design of the overall device. The terms “release or activation” and “actuation” should be clear to those of ordinary skill in the art, particularly when taken in light of the description which follows. 
     Numerous configurations or devices, and their associated methods, are comprehended by the concepts of the present invention. Specific embodiments of the present invention are described below, aided by reference to FIGS. 1 and 2. 
     FIGS. 1 and 2 illustrate a device  10  which is constructed consistent with the principles of the present invention. The device  10  preferably includes a housing  15 . The housing  15  can have any suitable construction. It is contemplated that the specific configuration of the housing  15  can vary greatly, depending on the particular device and its intended use or application. In the embodiment illustrated in FIGS. 1 and 2, the housing  15  includes a base  20  having one or more through holes  22  disposed therein, and a cooperating cover  25 . A gasket member  30  may be provided between the base and cover for the purpose of providing an appropriate seal. The material(s) from which the housing  15  and its components are constructed depends upon the intended application or use of the device. For example, the housing  15  and its components can be constructed of a stainless steel, which provides mechanical strength and corrosion resistance. The gasket  30  can be constructed of any suitable material, such as silicone rubber. 
     The device  10  further includes an actuation mechanism  35 . Preferably, the actuation mechanism is non-pyrotechnic. Numerous mechanisms are envisioned. One particularly suitable mechanism is a spring. The use of springs for the actuation mechanism  35  are beneficial in that the forces generated by such springs are easily determined and/or modified thereby facilitating design of the device  10 . In the illustrated embodiment, actuation mechanism  35  is shown in the form of an arrangement of belleville springs or washers  37 . The belleville springs  37  are beneficial in that they are particularly compact thereby reducing the space necessary for incorporating the actuation mechanism into the device  10 . 
     A separate release or activation mechanism  40  is also provided in the illustrated device  10 . In certain embodiments, the release or activation mechanism  40  is provided with a construction that it is responsive to an actuation signal. It is within the scope of the present invention that the release or activation mechanism  40  be constructed in a manner which is responsive to one or more of any number of different types of signals. In certain embodiments, the release or activation mechanism  40  is constructed to be responsive to an electrical signal. In the illustrated embodiment, the release or activation mechanism  40  is shown as an explosive bolt  42 . The explosive bolt  42  is provided with electrical connectors in the form of wires  45  for the purposes of transmitting an activation signal. The explosive bolt  42  is further provided with a scribe mark  47  which creates a weakness in the bolt which fractures upon activation of the explosive bolt  42 . 
     A member to be actuated  50  is further operatively associated with the overall device  10 , as well as the actuation mechanism  35 . The particular type of member to be actuated can vary considerably depending upon the intended use or application of the device  10 . For example, the member  50  can be constructed for reciprocating and/or rotating actuating movements, cutting, and/or the fracturing of frangible materials. In the illustrated embodiment, member  50  is in the form of a pin or shaft  52 . 
     The above described components can be operatively arranged in any suitable fashion. In the illustrated embodiment, the pin or shaft  52  and the explosive bolt  42  are received within a respective through-hole  22  formed in the base  20 . One end of both the pin or shaft  52  and the explosive bolt  42  are connected to a retainer member  55 . The connection can be made by any suitable means. For example, the end of explosive bolt  42  may be threaded into a cooperating threaded blind hole formed in retainer  55 , while the pin or shaft  52  is attached to retainer  55  via a threaded fastener or screw  60 . A suitable number of belleville springs  37  are received between the base  20  and the retainer  55 . The particular number of belleville springs  37  utilized will depend primarily upon the force necessary to actuate the pin or shaft  52 , as well as the space limitations imposed on the device  10 . In the illustrated embodiment, thirty-two such belleville springs  37  are utilized. The cover  25  is then mounted to the base  20  with an intervening gasket  30 . 
     The device of the present invention has a variety of applications in both commercial and military mechanical systems. One specific example is the incorporation of the device  10  of the present invention into the tail housing of an ordinance, with the pin or shaft  52  protruding into a locking mechanism in the control surface gearing (not shown). The wires  45  of the explosive bolt  42  are connected to the control circuitry of the ordinance. The device  10  is mounted to the tail housing of the ordinance by mounting screws (not shown) which are received within the mounting holes  65 . 
     An illustrative mode of operation is described as follows. An activation signal, such as an electrical current, is carried through wires  45  and into the explosive bolt  42 . The explosive bolt  42  detonates and breaks in two, preferably along the scribe mark  47 , thereby releasing the compressed belleville springs  37  causing the retainer  55  and the attached pin or shaft  52  to travel backwards within the housing  15  within the space defined between the retainer  55  and the cover  25 . In the context of the specific control surface gearing application discussed above, the pin or shaft  52  would be withdrawn from the locking mechanism of the gearing, thereby enabling activation of the control surface mechanism of the ordinance. 
     Among the advantages, of the present invention, particularly over a purely pyrotechnic design, is that the forces required to activate or release the member and the force required to actuate the member are independent and thus more manageable. A spring can be sized for the required load to pull the pin out of a control mechanism, and the explosive bolt charge can be sized for breaking of the bolt. No locking device at the end-of-stroke is necessary because residual spring force sufficiently holds the pin in its actuated position, and little or no bounce-back occurs. Ballistic shock impact is eliminated with a resulting reduction in required strength of the pin and the housing. Also, fewer part types are used and the final production cost for this unit is significantly less than conventional designs. 
     Although the present invention has been described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without department from the spirit and scope of the invention as defined in the appended claims.