The present disclosure relates to an initiator assembly with an exploding foil initiator and a detonation detection switch.
This section provides background information related to the present disclosure which is not necessarily prior art.
In modern military munitions that employ an initiator assembly having an exploding foil initiator that is configured to initiate detonation of an input charge that is formed of a high explosive material, it can be desirable to have high-speed feedback in the form of an electronic signal that confirms that the exploding foil initiator had successfully initiated detonation of the input charge. This feedback may be employed, for example, to control the operation of other devices, including other exploding foil initiators. These other devices could be employed to selectively operate a redundant actuator and/or to perform functions such as shaping a detonation wavefront as it travels through a primary charge of high explosive in the munition.
U.S. Pat. No. 8,485,097 discloses an initiator assembly having an exploding foil initiator and a normally open grounding switch. The grounding switch employs energy from a detonating input charge to close the grounding switch, which operates to connect a terminal of the exploding foil initiator to an electrical ground to dissipate excess energy that was applied to the exploding foil initiator. While the grounding switch of the '097 patent works satisfactorily for its intended purpose, it is not capable of closing after the onset of detonation in the input charge as quickly as is desired. Accordingly, there remains a need in the art for an initiator assembly having an exploding foil initiator and a detonation detection switch that is more responsive to the initiation of detonation in an input charge.
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 disclosure provides an initiator assembly that includes an exploding foil initiator, a detonation detection switch and an input charge. The exploding foil initiator has a base, a pair of bridge lands, a bridge element, and a plurality of non-metallic material layers. The bridge lands are coupled to the base. The bridge element is disposed between the bridge lands. The non-metallic material layers form a flyer layer and a barrel. The flyer layer is disposed over the bridge element. The barrel defines a barrel aperture and is disposed over the flyer layer such that the barrel aperture is disposed in-line with the bridge element. The detonation detection switch is coupled to the base of the exploding foil initiator and includes first and second switch lands and a switch shunt. The first and second switch lands are coupled to the base and are spaced apart from one another so as not to be in electrical contact with one another. The switch shunt being fixedly coupled to one of the non-metallic material layers on a side of the one of the non-metallic material layers that faces away from the first and second switch lands so that the one of the non-metallic layers is disposed between the switch shunt and at least one of the first and second switch lands. The switch shunt overlies at least a portion of each of the first and second switch lands. The input charge is formed of a secondary explosive, the input charge being disposed in-line with the barrel aperture. The one of the non-metallic material layers is a dielectric material at standard conditions for temperature and pressure. The one of the non-metallic material layers is also a conductor when subjected to at least one of a shock wave and a compressive stress generated by the input charge when the input charge detonates.
In a further form, the present disclosure provides an initiator assembly that includes an exploding foil initiator, an input charge and a detonation detection switch. The exploding foil initiator has a base, a pair of bridge lands, a bridge element, and a plurality of non-metallic material layers. The bridge lands are coupled to the base. The bridge element is disposed between the bridge lands. The non-metallic material layers form a flyer layer and a barrel. The flyer layer is disposed over the bridge element. The barrel defines a barrel aperture and is disposed over the flyer layer such that the barrel aperture is disposed in-line with the bridge element. The input charge is formed of a secondary explosive, the input charge being disposed in-line with the barrel aperture. The detonation detection switch is mounted to the exploding foil initiator within an area defined by an outer perimeter of the base.
In still another form, the present disclosure provides a method for operating an initiator assembly. The method includes: providing an exploding foil initiator, an input charge and a detonation detection switch, the exploding foil initiator having a base, a pair of bridge lands, a bridge element, and a plurality of non-metallic material layers, the bridge lands being coupled to the base, the bridge element being disposed between the bridge lands, the plurality of non-metallic material layers forming a flyer layer and a barrel, the flyer layer being disposed over the bridge element, the barrel defining a barrel aperture, the barrel being disposed over the flyer layer and positioned such that the barrel aperture is disposed in-line with the bridge element, the input charge being formed of a secondary explosive and disposed in-line with the barrel aperture, the detonation detection switch being mounted to the exploding foil initiator within an area defined by an outer perimeter of the base; operating the exploding foil initiator to detonate the input charge; and changing a state of the detonating detecting switch with energy released from the detonating input charge.
In another form, the present disclosure provides an initiator assembly that includes first and second housing components, an exploding foil initiator, an input charge and a detonation detection switch. The first housing component defines an interior surface. The second housing is component fixedly coupled to the first housing component. The first and second housing components define a cavity. The exploding foil initiator is received in the cavity proximate the interior surface and has a pair of bridge lands, a bridge element, and a plurality of non-metallic material layers. The bridge lands are coupled to the first housing component. The bridge element is disposed between the bridge lands. The plurality of non-metallic material layers form a flyer layer, which is disposed over the bridge element, and a barrel that defines a barrel aperture. The barrel is disposed over the flyer layer and positioned such that the barrel aperture is disposed in-line with the bridge element. The input charge is formed of a secondary explosive and is disposed in the cavity in-line with the barrel aperture. The input charge has an axial end that faces the interior surface. The detonation detection switch is coupled to the first housing component and is disposed in the cavity between the interior surface the axial end of the input charge.
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.
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.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
With reference to
Briefly, the initiator assembly 10 can include a housing assembly 12, an input charge 14, an input sleeve 16, an output charge 18, and an optional grounding switch 20. In the particular example provided, the housing assembly 12 includes a header assembly 30 and a cover 32.
With reference to
Returning to
With reference to
The seal members 54 can be formed of a suitable material, such as glass conforming to 2304 Natural or another dielectric material, and can be received into an associated one of the terminal apertures 66. The seal members 54 can sealingly engage the header body 51 as well as an associated one of the terminals 52.
With reference to
The frame member 44 can include a body 44a and a plurality of electrical conductors 44b. The body 44a can be formed of an appropriate dielectric material, such as synthetic resin bonded paper (SRBP) or epoxy resin bonded glass fabric (ERBGF). The conductors 44b can be arranged about the body 44a 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 44b can be formed onto the body 44a in any desired manner, such as through metallization of the entire surface of the body 44a and acid-etch removal of portions of the metallization that are not desired. The frame member 44 can be sized and shaped to closely conform to the size and shape of the insulating spacer 42 and can include a plurality of terminal apertures 90 and an interior aperture 92 that is sized to receive the exploding foil initiator 46. The terminal apertures 90 can be sized to receive a corresponding one of the terminals 52 (e.g., terminals 52a through 52c in
With reference to
The flyer 110 can be formed of a suitable non-metal material layer, while the barrel 112 can be formed of another non-metal material layer that can be deposited or overlaid onto the non-metal material layer that forms the flyer 110. The non-metal material layer that forms the flyer 110 can be deposited over the bridge 108 on a side of the bridge 108 that faces away from the base 102. The barrel 112 can define a barrel aperture 114 that can be located in-line with the flyer 110 and the bridge 108.
The non-metal material layer that forms the flyer 110 (hereinafter “the first non-metal material layer”) and the non-metal material layer that forms the barrel 112 (hereinafter “the second non-metal material layer”) can be formed of an appropriate material that is electrically insulating prior to detonation of the input charge 14. At least one of the first and second non-metal material layers can have varying electrical properties. Specifically, the at least one of the first and second non-metal material layers that has varying electrical properties (hereinafter “the non-metal material layer with varying electrical properties”) can be a dielectric at standard pressure and temperature (i.e., an absolute pressure of 1 atmosphere and a temperature of 0° C.), but can become conductive in response to a shockwave and/or compressive stress generated when the input charge 14 detonates. One exemplary material having these characteristics is polyimide.
The detonation detection switch 48 can include a first switch land 120, a second switch land 122 and a switch shunt 124. The first and second switch lands 120 and 122 can be coupled to the base 102 and can be formed similar to the first and second bridge lands 104 and 106. In the particular example provided, the first and second switch lands 120 and 122 are directly mounted to the base 102, but it will be appreciated that if desired, one or both of the first and second switch lands 120 and 122 can be mounted fully or partly on another layer of the exploding foil initiator 46 (e.g., on a non-metal material layer that forms the flyer 110 or the barrel 112). The first and second switch lands 120 and 122 can be spaced apart from one another (via a gap 128) so that they are not electrically connected to one another. At least one non-metal material layer with varying electrical properties can be disposed over a portion of the second switch land 122. The at least one non-metal material layer with varying electrical properties can be formed of polyamide or poly 4,4′-oxydiphenylene-pyromellitimide (e.g., KAPTON®), for example, and can be deposited over the second switch land via spin-coating. It will be appreciated that the thickness of the at least one non-metal material layer with varying electrical properties can be relatively thin, such as 4 to 8 microns in thickness.
With reference to
With reference to
With reference to
It will be appreciated that the thicknesses of the barrel 112, the contacts 50 and the solder that couples the contacts 50 to the terminals 52 and the lands 104, 106, 120, 122 can be selected to space the bridge 108 apart from the input charge 14 (
With reference to
The first switch member 138 can be fixedly and electrically coupled to the first grounding contact 132. It will be appreciated that the first grounding contact 132 and the first switch member 138 can be integrally formed from a suitable conductive material. The first switch member 138 can comprise a first conductive target 138a that can be configured to extend away from the insulating spacer 42 (
The second switch member 140 can be fixedly and electrically coupled to the second grounding contact 134. It will be appreciated that the second grounding contact 134 and the second switch member 140 can be integrally formed from a suitable conductive material. The second switch member 140 can comprise a second conductive target 140a that can be offset from the first conductive target 138a and can be configured to extend away from the insulating spacer 42 (
The first insulating member 142 can be received between the first and second conductive targets 138a and 140a and can electrically insulate the first switch member 138 from the second switch member 140. In the particular example provided the first insulating member 142 is sized larger than the first and second conductive targets 138a and 140a and extends outwardly from the first and second conductive targets 138a and 140a in vertical and horizontal directions. For example, the first insulating member 142 can be formed of a Kapton film and can have a suitable thickness, such as a thickness of 0.001 inch. It will be appreciated that other types of insulating materials can be employed including air, an inert gas or a vacuum, or that a combination of insulating materials could be employed. The first insulating member 142 can be coupled to the one or both of the first and second switch members 138 and 140 in any desired manner, such as with a suitable adhesive.
The second insulating member 144 can be formed of an electrically insulating material that can be coated, deposited or fitted onto the first and second switch members 138 and 140 to thereby form a barrier that electrically insulates the first and second switch members 138 and 140 from the housing assembly 12 (
While the first and second switch members 138 and 140 have been shown and described in a particular order (i.e., with the second switch member 140 being radially inward of the first switch member 138), it will be appreciated that the positioning of the first and second switch members 138 and 140 could be reversed (i.e., so that the first switch member 138 is radially inward of the second switch member 140).
With reference to
The input charge 14 can be formed of a suitable energetic material, such as RSI-007, which is a secondary explosive that is available from Reynolds Systems, Inc. of Middletown, Calif. It will be appreciated however that various types of secondary explosives, such as HNS-I, HNS-IV, PETN, NONA, CCLS-20 FPS, and combinations thereof, could be employed for all or a portion of the input charge 14. The input charge 14 can be received in the cavity 180 in the input sleeve 16 and compacted to a desired density. It will be appreciated that in some applications, the input charge 14 may fill the entire volume of the cavity 180.
Returning to
The cover 32 can be formed of a suitable material, such as KOVAR®, and can include a cover body 240 and a rim 242. The cover body 240 can be a cup-line structure that can receive annular shoulder wall 72 of the header body 51, as well as the insulating spacer 42, the frame member 44, the exploding foil initiator 46, the detonation detection switch 48, the input sleeve 16, the input charge 14, and if included, the grounding switch 20 and the output charge 18 therein. The rim 242 can extend radially outwardly from the cover body 240 and can matingly engage the shoulder 64 on the header body 51. The rim 242 and the shoulder 64 can be welded in an appropriate manner (e.g., laser welded) to fixedly and sealingly couple the cover 32 to the header body 51.
With renewed reference to
Energy released by the detonation of the input charge 14 can be employed to fragment a portion of the input sleeve 16, such as at a portion of the input sleeve 16 proximate the weakened zone 190, and propel the fragmented portion of the input sleeve 16 through the second insulating member 144 and against the first and second switch members 138 and 140 (
As another example, energy released during the detonation event could be employed to close the grounding switch 20. In this regard, a compressive force, which can be applied to the grounding switch 20 as a result of the detonation event, can cause the second switch member 140 to puncture or travel through the first insulating member 142 (
Those of skill in the art will appreciate that residual energy remaining on the terminal 52a after vaporization of the bridge 108 can be directed to an electrical ground via a predetermined electrical path by closing the grounding switch 20.
Energy released by the input charge 14 as the input charge 14 starts to detonate, which can take the form of a shock wave or a compressive stress that is applied or transmitted through the non-metal material layer with varying electrical properties 130, can cause the non-metal material layer with varying electrical properties 130 to change from an insulator, which inhibits the transmission of electrical power between the first switch land 120 and the second switch land 122, to a conductor that permits the transmission of electrical power between the first switch land 120 and the second switch land 122. The non-metal material layer with varying electrical properties 130 should be very responsive to the shock wave and/or compressive stress generated by the detonating input charge 14 and as such, the change in the non-metal material layer with varying electrical properties 130 from an electric insulator to an electric conductor should occur within 500 nano-seconds of the initiation of detonation in the input charge 14, preferably within 250 nano-seconds of the initiation of detonation in the input charge 14, and still more preferably within 150 nano-seconds of the initiation of detonation in the input charge 14. Accordingly, a relatively low voltage signal input to the detonation detection switch 48, for example via terminal 52c and an associated one of the contacts 50, can be transmitted from the first switch land 120 through the switch shunt 124 and the non-metal layer with varying electrical properties 130, to the second switch land 122 and onto the terminal 52d (via another one of the contacts 50). Because of the in-line positioning of the detonation detection switch 48 with the input charge 14, and the fact that energy (from the detonating input charge 14) alone is employed to change the state of the detonation detection switch 48 (i.e., from a normally open state to a closed state in the example provided), the detonation detection switch 48 can change states very rapidly and much more rapidly than the grounding switch 20 is able to close. In this regard, the positioning of the first and second conductive targets 138a and 140a at locations that are radially offset from both the input charge 14 and the input sleeve 16, the need for portions of the input sleeve 16 to fragment, accelerate and travel to a radially outward location (where the grounding switch 20 is located), as well as the fact that the fragments of the input sleeve 16 travel at approximately one-third the velocity of the velocity with which the detonation wavefront travels through the input charge 14 significantly extends the length of time that is needed to change in the state of the grounding switch 20 (from the normally open state to a closed state) as compared to the length of time that is needed to change the state of the detonation detection switch 48. The delay associated with the change of the switch state in the grounding switch 20 is satisfactory when the function of the switch is to provide a conductive path to dissipate excess energy not used to vaporize the bridge 108, but it is entirely unsatisfactory when the change in the state of the switch were to be used for other functions, such as coordinating the operation of several exploding foil initiators to shape a detonation wavefront through an energetic material (not shown) in a desired manner.
It will be appreciated that the detonation detection switch 48 is a normally open switch that closes in response to energy released by the detonation of the input charge 14. It will also be appreciated that the energy released by the detonation of the input charge 14 will ultimately dissipate and would cause the destruction of both the base 102 of the exploding foil initiator 46 and the detonation detection switch 48. As such, it will be appreciated that during operation of the initiator assembly 10, the detonation detection switch 48 will close briefly or “momentarily” and that any associated controller (not shown) to which the detonation detection switch 48 is coupled would understand the closure of the detonation detection switch 48 as an indication that the input charge 14 had in fact started to detonate.
It will further be appreciated that the function of the grounding switch 20 cannot be directly performed by the detonation detection switch 48 due to the momentary operation of the detonation detection switch 48. In this regard, the detonation detection switch 48 will not be in a closed state for a long enough duration that would permit excess energy on the terminal 52a and bridge land 104 to travel to ground.
While the detonation detection switch 48 has been illustrated and described as having a switch shunt that is permanently coupled to one of the switch lands, it will be appreciated that the detonation detection switch could be constructed somewhat differently. With reference to
Moreover while the detonation detection switch has been illustrated and described as a normally open switch, it will be appreciated that the detonation detection switch 48″ could be configured as a normally closed switch as depicted in
It will also be appreciated that the switch land 120 could be coupled to (or shared with) the bridge land 104. In this arrangement, excess residual electrical energy on the bridge land 104 after the bridge 108 has been converted into a plasma is employed as an electrical input to the detonation detection switch.
It will further be appreciated that the detonation detection switch could be positioned between the second end face 62 of the header body 51 and the base 102 of the exploding foil initiator 46. More specifically, the detonation detection switch could be formed onto the second end face 62 of the header body 51, the insulating spacer 42, or a side of the base 102 opposite the side on which the bridge 108 is formed.
From the foregoing, it will be appreciated that an initiator assembly constructed in accordance with the present teachings may be equipped with a relatively inexpensive and compact detonation detection switch. The detonation detection switch can be disposed in a volume in a housing assembly between an interior surface of a first component of the housing assembly, such as the first end face 60 (
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.
This application claims the benefit of U.S. Provisional Patent Application No. 62/486,538 filed Apr. 18, 2017, the disclosure of which is incorporated by reference as if fully set forth in detail herein.
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