Abstract:
An initiator assembly that includes a header body, an insulating spacer that is coupled to the header body, an initiator, a plurality of terminals that extend through the header body, a plurality of contacts, an input charge, an output charge and a cover that includes an axially threaded portion into which the output charge is housed. The initiator includes a plurality of electric interfaces and is disposed on a side of the insulating spacer opposite the header body. The contacts electrically couple the electric interfaces to the terminals. The input charge is formed of a secondary explosive and is disposed proximate the initiator so as to be capable of detonating to release energy upon activation of the initiator. The cover is coupled to the header body and cooperates with the header body to house the insulating spacer, the initiator chip, the contacts, the input charge and the output charge.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/424,463 filed Dec. 17, 2010, the disclosure of which is incorporated by reference as if set forth herein in its entirety. 
     FIELD 
     The present disclosure relates to devices for initiating combustion, deflagration and/or detonation events. 
     Modern initiators, such as detonators, commonly employ materials including ceramics and stainless steels in their construction. These materials are typically selected to provide the initiator with a degree of robustness that permits the initiator to withstand extreme changes in temperature and humidity, as well as to resist oxidization. While modern initiator configurations are generally satisfactory for their intended purposes, they are nonetheless susceptible to improvement. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     In one form the present teachings provide an initiator assembly that includes a header body, an insulating spacer that is coupled to the header body, an initiator, a plurality of terminals that extend through the header body, a plurality of contacts, an input charge, an output charge and a cover. The initiator forms at least a portion of an exploding foil initiator and includes a plurality of electric interfaces. The initiator is disposed on a side of the insulating spacer opposite the header body. The contacts electrically couple the electric interfaces to the terminals. The input charge is formed of a secondary explosive and is disposed proximate the initiator so as to be capable of detonating to release energy upon activation of the initiator. The output charge is formed of an energetic material and is configured to at least one of detonate, deflagrate and combust in response to receipt of energy released from detonation of the input charge. The cover is coupled to the header body and cooperates with the header body to house the insulating spacer, the initiator chip, the contacts, the input charge and the output charge. The cover includes an axially threaded portion into which the output charge is housed. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a rear perspective view of an initiator assembly constructed in accordance with the teachings of the present disclosure; 
         FIG. 2  is a front perspective view of the initiator assembly of  FIG. 1 ; 
         FIG. 3  is a longitudinal section view of the initiator assembly of  FIG. 1 ; 
         FIG. 4  is a rear elevation view of the initiator assembly of  FIG. 1 ; and 
         FIG. 5  is an elevation view of a portion of the initiator assembly of  FIG. 1 , illustrating an initiator, contacts and a frame member of a header body in more detail. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     With reference to  FIGS. 1 through 3  of the drawings, the initiator assembly  10  can include a header assembly  12 , a cover or housing assembly  14 , an input pellet assembly  16 , a barrier system  18  and an output charge  20 . The header assembly  12  can include a header  30 , an insulating spacer  32 , a frame member  34 , an initiator  36  and a plurality of contacts  38  ( FIG. 5 ). The header  30  can include a header body  40 , a plurality of terminals  42  and a plurality of seal members  44 . 
     The header body  40  can be formed of an appropriate material, such as KOVAR®, and can be shaped in a desired manner. In the particular example provided, the header body  40  includes a body portion  50  and a shroud member  52 . The body portion  50  can define a first axial end face  54 , a second (opposite) axial end face  56 , a shoulder  58 , a nose  60  and a plurality of seal apertures  62  that can extend through and between the first and second axial end faces  54  and  56 . The shoulder  58  can have a radially outer surface  66  and an abutting face  68  that can be generally perpendicular to the radially outer surface  66 . The radially outer surface  66  can have any desired shape, but in the particular example provided is generally cylindrical. The nose  60  can extend between the shoulder  58  and the first axial end face  54  and can be sized somewhat smaller in diameter than the radially outer surface  66  to thereby form the abutting face therebetween. The shroud member  52  can be fixedly coupled to (e.g., integrally formed with) the body portion  50  and can encircle the terminals  42  to at least partially shroud the terminals  42  and/or to provide a datum surface  70  that is adapted for use in guiding terminals (not shown) in a mating connector (not shown) into engagement with the terminals  42 . 
     The terminals  42  can be received through respective ones of the seal apertures  62  and can have a first portion  42 - 1  and a second portion  42 - 2 . The first portion  42 - 1  can be formed of a first diameter, while the second portion  42 - 2  can have second, smaller diameter that is configured to encourage buckling of the terminal  42  should an axial load be applied to the terminal  42 . The seal members  44  can be formed of a suitable material, such as glass conforming to 2304 Natural or another dielectric material, and can be received into the seal apertures  62  coaxially about the terminals  42 . The seal members  44  can sealingly engage the body portion  50  as well as the first portion  42 - 1  of the terminals  42  so as to form a relatively strong seal, such as a seal that will leak at a rate less than about 1×10 −5  or 1×10 −6  cc/min when one side of the header body  40  is exposed to helium gas at a gauge pressure of about one atmosphere while the other side of the header body  40  is exposed to atmospheric pressure (i.e., a gauge pressure of zero). 
     The insulating spacer  32  can be formed of a suitable dielectric material, such as polycarbonate, synthetic resin bonded paper, or epoxy resin bonded glass fabric, and can have a plurality of clearance apertures C that are sized to receive the terminals therethrough. At least one pocket can be formed in the insulating spacer  32  to provide space for one or more of the terminals  42  to buckle when an axially-directed force is applied to an end of the second portion  42 - 2  of the terminals  42  that is opposite the first portion  42 - 1 . In the particular example provided, each of the clearance apertures P has an enlarged portion EP that is positioned on a side adjacent the first axial face  54  of the header body  40  and which provides space for the second portion  42 - 2  of a corresponding one of the terminals  42  to buckle. The insulating spacer  32  can be formed in a manner that is described in U.S. Pat. No. 7,430,963, the disclosure of which is hereby incorporated by reference as if fully set forth in detail herein. The insulating spacer  32  can be abutted against the first axial face  54  of the header body  40 . 
     With reference to  FIGS. 3 and 5 , the frame member  34  can include a body  76  and a plurality of electrical conductors  78 . The body  76  can be formed of an appropriate dielectric material, such as synthetic resin bonded paper or epoxy resin bonded glass fabric. The conductors  78  can be arranged about the body  76  in a predetermined manner and can comprise one or more conductive layers of material, such as gold, silver, copper, nickel and alloys thereof. The conductors  78  can be formed onto the body  76  in any desired manner, such as through metallization of the entire surface of the body  76  and acid-etch removal of portions of the metallization that are not desired. The frame member  34  can be sized and shaped to closely conform to a pocket  80  in the size and shape of the insulating spacer  32  and can include a plurality of terminal apertures  82  and an interior aperture  84  that is sized to receive the initiator  36 . The terminal apertures  82  can be sized to receive a corresponding one of the terminals  42  therein. 
     The initiator  36  can be constructed in a manner that is disclosed in U.S. patent application Ser. Nos. 11/431,111 and 11/430,944 entitled “Full Function Initiator With Integrated Planar Switch” the disclosures of which are hereby incorporated by reference as if fully set forth in detail herein. For example, the initiator  36  can include at least a portion of an exploding foil initiator  90 , such as first and second bridge contacts  92  and  94 , respectively, a bridge  96 , a flyer  98  and a barrel layer  100 . In the particular example shown, the first and second bridge contacts  92  and  94 , the bridge  96 , the flyer  98  and the barrel layer  100  are fixedly mounted on a substrate  104  that is received in the interior aperture  84  formed in the frame member  34  and fixedly coupled to the frame member  34 , but it will be appreciated that the first and second bridge contacts  92  and  94 , the bridge  96 , the flyer  98  and the barrel layer  100  can be mounted directly to the frame member  34  in the alternative. The flyer  98  can be received between the bridge  96  and the barrel layer  100  and can be formed of a suitable material, such as polyamide. The barrel layer  100  can be formed of a suitable electrically insulating material, such as polyamide. The barrel layer  100  can cover the frame member  34  and the contacts  38  to electrically isolate these elements from the input pellet assembly  16 . Additionally, the barrel layer  100  can define a barrel aperture (not specifically shown) through which the flyer  98  may be expelled when the initiator  36  is activated. In this regard, it will be appreciated that the barrel aperture, the flyer  98  and the bridge  96  are disposed in-line with one another. 
     If desired, an adhesive, such as SCOTCH-WELD™ EC-2216 Grey epoxy marketed by Minnesota Mining and Manufacturing Company of St. Paul, Minn., can be employed to bond the frame member  34  and the initiator  36  to the insulating spacer  32  as well as to bond the insulating spacer  32  to the first axial face  54  of the header body  40  so that a front surface of the initiator  36  will be substantially parallel and co-planar with a front surface of the frame member  34 . 
     The contacts  38  can be formed of a suitable electrically conductive material, such as KOVAR® having a thickness of about 0.003 inch, and can include a terminal aperture  120  that can receive an associated one of the terminals  42  and a plurality of solder apertures  122 . The contacts  38  can be shaped to engage an associated electric interface (e.g., the first bridge contact  92 , the second bridge contact  94 ). In the particular example provided, the contacts  38  are soldered to an associated one of the terminals  42  and an associated one of the electric interfaces with an appropriate solder, such as a F540SN62-86D4 solder paste marketed by Heraeus Inc., Circuit Materials Division of Scottsville, Ariz. The solder apertures  122  permit solder to flow through the contacts  38  in predetermined areas, such as locations in-line with the associated electric interfaces and in-line with the conductors  78  of the frame member  34 . Accordingly, it is possible to visually-inspect the solder joints associated with each contact  389  through the solder apertures  122  and the terminal aperture  120 . 
     It will be appreciated that the thicknesses of the barrel layer  100 , the contacts  38  and the solder that couples the contacts  38  to the terminals  42  and the first and second bridge contacts  92  and  94  is selected to space the bridge  96  apart from the input pellet assembly  16  by a predetermined spacing, such as about 0.004 inch to about 0.008 inch. It will be also appreciated that it can be important in some situations that the contacts  38  be relatively flat so as not to affect the spacing between the bridge  96  and the input pellet assembly  16 . 
     The input pellet assembly  16  can comprise an input sleeve  130  and an input charge  132 . The input sleeve  130  can be configured to support the input charge  132  and direct energy from the input charge  132  in a desired direction. In the particular example provided, the input sleeve  130  is formed of a suitable steel and defines a cavity  134  that can be located in-line with the bridge  96 . The input sleeve  130  can be sized relatively smaller than the size of the nose  60  and the insulating spacer  32  so as to permit the input sleeve  130  to be packaged in the housing assembly  14  as will be described in more detail, below. The input charge  132  can be formed of a suitable energetic material, such as RSI-007, which is available from Reynolds Systems, Inc. of Middletown, Calif. The input charge  132  can be received in the cavity  134  in the input sleeve  130  and compacted to a desired density. It will be appreciated that in some applications, the input charge  132  may fill the entire volume of the cavity  134 . It will also be appreciated that in some applications the input sleeve  130  may be deleted. 
     With reference to  FIGS. 1 through 4 , the housing assembly  14  can include a housing  140  and a closure member  142 . The housing  140  can be formed of a suitable material, such as KOVAR®, and can comprise a first housing portion  150 , a second housing portion  152 , a first internal bore  154  and a second internal bore  156 . 
     The first housing portion  150  can define an outer surface  160  that can have a desired shape, such as a non-circular shape, that permits a tool to be engaged to the first housing portion  150  to install the initiator  36  to a device. In the example provided, the outer surface  160  has a generally hexagonal shape that defines a plurality of wrench flats that permit the housing  140  to be engaged by a wrench or socket to install the initiator assembly  10 . 
     The second housing portion  152  can be integrally formed with and can extend forwardly from the first housing portion  150 . The second housing portion  152  can define a plurality of external threads  170  and an undercut  172  that is disposed axially between the first housing portion  150  and the external threads  170  and which can be sized at or smaller than the minor diameter of the threads  170 . The threads  170  can be sized in a desired manner, and may have a major diameter that is less than or equal to ½ (0.50) inch, such as less than or equal to ⅜ (0.38) inch. 
     The first internal bore  154  can include first and second counterbores  180  and  182 , respectively, and a rear bore portion  186 , while the second internal bore  156  can comprise a forward bore portion  190  and an end counterbore  192 . The first counterbore  180  can be sized to receive the shoulder  58  of the body portion  50  of the header body  40 , the second counterbore  182  can be sized to receive the nose  60  of the body portion  50  of the header body  40  and the rear bore portion  186  can be sized to receive the insulating spacer  32 , the initiator  36  and the input pellet assembly  16 . The first internal bore  154  can be sized to provide clearance in an axial direction between the housing  140  and the first axial end face  54  of the header body  40  and between the housing  140  and the barrel layer  100 . Radial clearance may also be provided between the nose  60  and the housing  140 . The radially outer surface  66  of the shoulder  58  can be configured to engage the housing  140  via an interference fit to aid in aligning the header assembly  12  to the housing  140 . A weld  200  may be employed at the joint where the radially outer surface  66  of the shoulder  58  is engaged to the housing  140  to fixedly couple and hermetically seal the header assembly  12  to the housing  140 . It will be appreciated that the weld  200  can be positioned on an end of the initiator  36  that is not critical to the operation of the initiator assembly  10 . 
     The second internal bore  156  can be coaxial with the first internal bore  154 . In the example provided, the second internal bore  156  is contiguous with the first internal bore  154  such that the same machining or forming tool may be employed to form all or portions of both (e.g., portions of the rear and forward bore portions  186  and  190  that intersect one another). It should be appreciated, however, that a portion of the housing  140  may be disposed between the first and second internal bores  154  and  156  such that an internal wall (not shown) divides or separates the first internal bore  154  from the second internal bore  156 . In this alternate configuration the internal wall could be employed as a portion of the barrier system. The end counterbore  192  can be sized to receive the closure member  142 . 
     The barrier system  18  can be employed to separate the input charge  132  from the output charge  20 . In the particular example provided, the barrier system  18  includes a first barrier member  210 , a second barrier member  212  and a barrier cup  214 . The first barrier member  210 , which can be abutted against the input sleeve  130 , can be a formed of a reactive material, which may be a metal, such as titanium, or another suitably reactive material that is inert under normal circumstances. The second barrier member  212 , which can be abutted against the first barrier member  210 , can be formed of an oxidizable material, such as polytetrafluoroethylene. The positions of the first and second barrier members  210  and  212  can be reversed and/or additional pieces of the first barrier member  210  and/or the second barrier member  212  may be employed. The barrier cup  214  can define a cup-like structure that can be received within the forward bore portion  190  (e.g., engaged to the second housing portion  152  via an interference fit) and axially abutted against the first and second barrier members  210  and  212  on a side opposite the input pellet assembly  16 . The barrier cup  214  can include an interior aperture  220 , which can receive the output charge  20  as will be discussed in more detail, below, that can be bounded on its rear side by an end wall  222 . The end wall  222  can have a thickness that can be tailored in a desired manner. In the particular example provided, a central portion of the end wall  222  is relatively thinner than a remaining portion of the material that forms the barrier cup  214 . 
     The output charge  20  can be formed of any suitable energetic material, such as boron potassium nitrate (BKNO 3 ) or titanium hydride potassium perchlorate (THPP) and can be received into the interior aperture  220  in the barrier cup  214 . In some situations, the output charge  20  can be pre-compacted into a pellet and assembled as one or more discrete pellet components into the interior aperture  220  in the barrier cup  214 . Alternatively, the material that forms the output charge  20  can be compacted directly in the interior aperture  220  in the barrier cup  214 . Also alternatively, the barrier cup  214  could be omitted altogether and the output charge  20  can be inserted directly into the forward bore portion  190  in the housing  140 . 
     One or more resilient elements can be employed to dampen vibration transmitted axially through the output charge  20 . In the particular example provided, a first resilient element  230  is disposed between the output charge  20  and the end wall  222  and a second resilient element  232  is disposed between the output charge  20  and the closure member  142 . The first and second resilient elements  230  and  232  can be formed of a suitable material, such as silicone rubber, and can have a desired shape with or without one or more apertures to attenuate energy from released into or out from the barrier cup  214 . In the example provided, each of the first and second resilient elements  230  and  232  has an annular shape. 
     The closure member  142  can include a cover body  240 , which can be formed of a suitable material, such as KOVAR®, and a rim  242 . The cover body  240  can be a disk-like structure that can received in the forward bore portion  190  and abutted against a distal end of the barrier cup  214  and against the second resilient element  232 . The rim  242  can be received into the end counterbore  192  and abutted against the cover body  240 . The rim  242  can be welded to the second housing portion  152  in an appropriate manner (e.g., laser welded) to fixedly and sealingly couple the closure member  142  to the housing  140 . It will be appreciated that a preload force can be applied to the closure member  142  to seat the cover body  240  to the housing  140  and as such, various components of the initiator assembly  10 , such as the output charge  30 , the barrier system  18 , the frame member  34  and the initiator  36  can be maintained in a state of compression. 
     It will be appreciated from the foregoing discussion and appended drawings that the output charge  20  can be packaged into the initiator assembly  10  in a relatively compact manner, such as in an axially forward portion of the housing  140  of the initiator assembly  10  within a volume that is smaller on its radially outer surface than the minor diameter of a portion of the housing  140  that is threaded into another component (e.g., bulkhead). 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.