Patent Description:
Energetic time delay systems and methods may have various manufacturing issues. Additionally, energetic time delay systems may include trial and error tests during verification and validation of a design and each production lot in order to determine the correct timing. Due to the inefficient process of design and manufacture of energetic time delay systems and methods, energetic time delay devices may be relatively expensive. Since the delay is created with energetics, there may be obsolescence issues. Additionally, energetic time delays may be a life limited part, resulting in additional cost of replacing the energetic time delay over the life of an asset, such as an aircraft or the like. <CIT> discloses a trigger mechanism for a firing pin for an explosive device.

An inert time delay device is provided according to claim <NUM>. A method of manufacturing an inert time delay device according to claim <NUM> is provided by claim <NUM>. The inert time delay device comprises a damper system comprising:.

In various embodiments, the damper system may further comprise a release arm assembly configured to retain the firing pin axially for a predetermined period of time during translation of the moveable housing toward the firing pin. The release arm assembly may comprise a release mechanism, the firing pin configured to release from the release arm assembly in response to the moveable housing engaging the release mechanism. The release mechanism may be a guide ramp. The chamber may be a hydraulic chamber configured to receive a working fluid. The moveable housing is configured to translate axially relative to the fixed piston. The first spring and the second spring are configured to compress in response to the moveable housing translating axially relative to the fixed piston. The firing pin may be configured to translate axially in response to the firing pin being released after, and in response to, the moveable housing translating a predetermined distance.

An inert time delay device is disclosed herein. The inert time delay comprises: a housing having a first axial end and a second axial end and defining a chamber extending from the first axial end to the second axial end; an ignition disposed at the first axial end; a primer disposed at the second axial end; and a damper system disposed in the housing, the damper system comprising: a firing pin spaced apart axially from the primer; a moveable housing disposed within the chamber and spaced apart axially from the ignition; a fixed piston comprising a piston head disposed in the moveable housing and a first rod extending from the piston head axially, and outward from, the moveable housing in the direction of the second axial end of the housing to a second rod, the second rod extending radially through the chamber and being fixedly coupled to the housing, so that the piston is fixedly coupled to the housing; and a first spring and a second spring each being disposed axially between the moveable housing and the firing pin, the damper system configured to initiate an inert time delay from the ignition receiving a pyrotechnic input to the primer sending a pyrotechnic output.

In various embodiments, the damper system further comprises a release arm assembly configured to retain the firing pin in an axial position until the release arm assembly is released from the firing pin. The release arm assembly may release the firing pin in response to the moveable housing engaging a release mechanism of the release arm assembly. The release arm assembly may release the firing pin in response to the moveable housing travelling a first axial distance. The first and second spring may compress in response to the moveable housing traveling the first axial distance. The first and second spring may expand, causing the firing pin to travel a second axial distance and engage the primer in response to the release arm assembly releasing the firing pin. The moveable housing may define a hydraulic chamber configured to receive a working fluid. The inert time delay device may further comprise the working fluid disposed in the hydraulic chamber.

A method of manufacturing an inert time delay device as described above is disclosed herein. The method may comprise: coupling a release arm assembly to a first portion of a housing; disposing a damper system in the first portion of the housing, the damper system comprising a moveable housing, a fixed piston, a first spring, a second spring, and a firing pin, the firing pin engaging the release arm assembly; coupling a second portion of the housing to the first portion of the housing; and coupling a primer to the second portion of the housing.

The first spring and the second spring extend axially from the moveable housing to the firing pin. The moveable housing may comprise a hydraulic chamber disposed therein, the hydraulic chamber including a working fluid. In various embodiments, coupling the release arm assembly to the first portion may further comprise disposing a release arm spring radially through the housing to engage a release arm of the release arm assembly and coupling the release arm spring to the first portion of the housing.

The forgoing features and elements as well as the operation of the disclosed embodiments will become more apparent in light of the following description and accompanying drawings.

Time delay devices for use with mines, demolition charges, ejection seats, or the like currently consist of cord type safety fuses, electric, electronic, and mechanical clocks, and chemical acting devices utilizing the corrosive effect of an acid on wire. Chemical type devices usually consist of a glass vial containing an acid mounted adjacent a spring loaded wire restraining a firing pin, such that when the vial is broken the acid spills over the wire and after the time delay taken for the wire to corrode through under the action of the acid the firing pin is released. Energetic time delays often involve an explosive column that burns at a specific rate. However, these devices are extremely sensitive to temperature and for the same device the time delay may vary between several hours to many days under varying conditions. Also, there is no indication how quickly the wire will break under the corrosive action, and should the glass vial be subjected to internal damage the possibility that the wire will break almost immediately can lead to serious accidents in relation to personnel handling the devices.

Disclosed herein are time delay systems and methods utilizing a spring damper system. In various embodiments, the time delay system utilizes a mechanical delay facilitated by a spring damper system instead of energetics. In various embodiments, a time delay device with the time delay system disclosed herein would be more efficient to manufacture and/or cost less relative to an energetic time delay device, in accordance with various embodiments.

Referring now to <FIG> and <FIG>, a cross-sectional schematic view (<FIG>) and a cross-sectional detailed view (<FIG>) of a portion of a pyrotechnic system <NUM> with an inert time delay device <NUM> having a damper system <NUM> is illustrated, in accordance with various embodiments. The inert time delay device <NUM> is inert (i.e., chemically inactive), in accordance with various embodiments. In this regard, a life of the time delay system may be extended relative to typical time delay systems with pyrotechnic inputs and outputs.

In various embodiments, having the inert time delay device <NUM> is configured to couple to an input explosive transfer line ("ETL") <NUM> and an output ETL <NUM>. In this regard, the inert time delay device <NUM> is configured to generate a time delay from receiving an input signal from the input ETL <NUM> to outputting a signal to the output ETL <NUM>. In various embodiments, the inert time delay device <NUM> is adaptable for any pyrotechnic system <NUM> configured for a predetermined time delay between an ETL being imitated and a firing device being initiated, such as demolition, fireworks, launch vehicle payload deployment systems, explosives in mining, or the like.

In various embodiments, the inert time delay device <NUM> comprises a housing <NUM> having a first end <NUM> and a second end <NUM>, a low energy ("LE") ignition <NUM>, a primer <NUM>, and the damper system <NUM>. "Low energy ignition" or "gas generator ignition" ("GG") as defined herein is a term of art referring to an ignition configured to generate a pressure front event at an output energy between <NUM> and <NUM> Joules, or between <NUM> and <NUM> Joules, or approximately <NUM> Joules, in accordance with various embodiments.

In various embodiments, the LE or GG ignition <NUM> is disposed at the first end <NUM> of the housing <NUM> and the primer <NUM> is disposed at the second end <NUM> of the housing <NUM>. The second end <NUM> is disposed opposite the first end <NUM>. In various embodiments, the housing <NUM> may be cylindrical, cuboidal, or the like. The damper system <NUM> is disposed within the housing <NUM> and configured to generate a predetermined time delay from receiving an ignition at LE or GG ignition <NUM> at first end <NUM> and releasing a firing pin <NUM> into the primer <NUM> at second end <NUM>.

In various embodiments, the damper system <NUM> comprises a first spring <NUM>, a second spring <NUM>, the firing pin <NUM>, a moveable housing <NUM>, a hydraulic chamber <NUM>, and a fixed piston <NUM>, and a release arm assembly <NUM>. The housing <NUM> defines a chamber <NUM> extending from the first end <NUM> to the second end <NUM> of the housing <NUM>. In various embodiments, the moveable housing <NUM> is disposed within the chamber <NUM> and spaced apart axially from the LE or GG ignition <NUM>. The hydraulic chamber <NUM> is disposed within the moveable housing <NUM>.

In various embodiments, in response to LE or GG ignition <NUM> being ignited, the LE or GG ignition <NUM> may generate a flame and pressure between the LE or GG ignition <NUM> and the moveable housing <NUM> in the chamber <NUM>. In various embodiments, as described further herein, the pressure generated from the LE or GG ignition <NUM> results in a force being applied on the moveable housing <NUM> towards the second end <NUM> of the housing <NUM>, which results in the moveable housing <NUM> translating axially towards the second end <NUM> of the housing <NUM> and compressing the springs <NUM>, <NUM> until the firing pin <NUM> is released, causing the firing pin to translate towards the primer <NUM>.

With combined reference to <FIG>, <FIG>, and <FIG>, the fixed piston <NUM> comprises a piston head <NUM>, a first rod <NUM> and a second rod <NUM>. The first rod <NUM> extends axially away from the piston head <NUM> toward the second end <NUM> of the housing <NUM> to the second rod <NUM>. The second rod <NUM> extends radially through the chamber <NUM>. In various embodiments, the piston head <NUM> is disposed in the hydraulic chamber <NUM>. In this regard, the piston head <NUM> may further comprise apertures disposed therethrough to allow fluid communication between sides from one side of the piston head <NUM> to the other side of the piston head <NUM> during operation of the inert time delay device <NUM> as described further herein. The second rod <NUM> is coupled to the housing <NUM>. In this regard, the second rod <NUM> fixes the fixed piston <NUM> during operation of the inert time delay device <NUM>. The springs <NUM>, <NUM> are disposed radially outward from the first rod <NUM> and disposed axially between the moveable housing <NUM> and the firing pin <NUM>. Due to the second rod <NUM> being coupled to the housing <NUM> at least two springs <NUM>, <NUM> may be utilized for balancing a spring force during operation of the inert time delay device <NUM>.

In various embodiments, the hydraulic chamber <NUM> may be sealed from the chamber <NUM> by any method known in the art, such as an elastomeric seal, a gasket, or the like. In this regard, a working fluid <NUM> disposed in the hydraulic chamber <NUM> is configured is fluidly isolated from the chamber <NUM> during operation of the damper system <NUM>. The working fluid <NUM> may be any working fluid, such as water, oil, air, or any other liquid or gas, etc. In various embodiments, the working fluid <NUM> may be chosen based on a desired viscosity and/or a desired predetermined time delay. In this regard, the structure of the inert time delay device <NUM> may be maintained and only a working fluid <NUM> may be changed to change a delay time from a first delay time to a second delay time, in accordance with various embodiments.

In various embodiments, the firing pin <NUM> comprises the head <NUM> disposed proximate (i.e., spaced apart from) the primer <NUM>. The firing pin <NUM> is coupled to the moveable housing <NUM> via springs <NUM>, <NUM>. The first spring <NUM> and the second spring <NUM> each extend axially from the moveable housing <NUM> to the firing pin <NUM>. The springs <NUM>, <NUM> are compression springs. The springs <NUM>, <NUM> are installed in a neutral state (i.e., with no stored energy) or in a compressed state. The present disclosure is not limited in this regard.

In various embodiments, the release arm assembly <NUM> comprises a release arm <NUM> that is disposed radially outward from the first rod <NUM> of the fixed piston <NUM>. The release arm assembly <NUM> is pivotably coupled to the housing <NUM> (e.g., via a pin or the like). The release arm assembly <NUM> comprises a release mechanism <NUM> configured to release the release arm <NUM> from engagement with the firing pin <NUM>. For example, the release arm <NUM> comprises an engagement end <NUM> configured to engage the firing pin <NUM>. In response to engaging the firing pin <NUM>, the release arm <NUM> may prevent the firing pin <NUM> from extending past an axial position in the chamber <NUM> during compression of the springs <NUM>, <NUM>, allowing the springs <NUM>, <NUM> to store energy that is released upon releasing of the release arm <NUM>, allowing the firing pin <NUM> to translate towards, and make contact with, the primer <NUM> as described further herein. In various embodiments, the release mechanism <NUM> comprises a guide ramp <NUM> sloping radially inward into the chamber <NUM>. As described further herein, the moveable housing <NUM> is configured to contact the guide ramp <NUM> and cause the release arm <NUM> to pivot about a pivot <NUM> radially outward to release the firing pin <NUM> from the release arm <NUM>.

In various embodiments, the release arm assembly <NUM> further comprises a spring <NUM> disposed radially outward from a centerline of the housing <NUM> and radially between the housing <NUM> and the release arm <NUM>. In various embodiments, the spring <NUM> is a compression spring. In an installed position, the spring <NUM> may bias the release arm towards the firing pin <NUM> to engage the firing pin <NUM>. In this regard, the firing pin <NUM> may be retained axially until release of the release arm <NUM> as described further herein.

The inert time delay device <NUM> may comprise a plurality of the release arm assembly <NUM> disposed circumferentially about the housing <NUM>. Any number of release arm assemblies may be disposed circumferentially about the housing <NUM>. For example, the inert time delay device <NUM> may comprise between <NUM> and <NUM> release arm assemblies <NUM>, or between <NUM> and <NUM> release arm assemblies <NUM>, or approximately <NUM> release arm assemblies <NUM>, in accordance with various embodiments.

With reference now to <FIG>, the housing <NUM> may be split into a first portion <NUM> and a second portion <NUM> to facilitate assembly. For example, the damper system <NUM> may be installed within the first portion <NUM> through an opening proximate the second end <NUM> of the housing <NUM>. Then, after installation of the damper system <NUM>, the second portion <NUM> of the housing <NUM> may be coupled to the first portion <NUM> by any method known in the art (e.g., threaded connection press fit, or the like). Then, the primer <NUM> may be coupled to the second portion <NUM>. In various embodiments, the primer <NUM> may be coupled to the second portion <NUM> prior to coupling the second portion <NUM> to the first portion <NUM>.

In various embodiments, spring <NUM> of a respective release arm assembly <NUM> may be a final component installed in the release arm assembly <NUM>. For example, the spring <NUM> may be disposed through an aperture in the first portion <NUM> of the housing <NUM> and coupled to the housing <NUM> via welding or the like. In this regard, the spring <NUM> may include a fixed portion (i.e., a non-spring portion) configured to be coupled to the housing <NUM>.

Referring now to <FIG> and <FIG>, a cross-sectional view of an initial sequence of the inert time delay device <NUM> is illustrated, in accordance with various embodiments. As shown in <FIG>, a time delay sequence is initiated in response to the LE or GG ignition <NUM> receiving a pyrotechnic input supplied via input ETL <NUM> axially between the LE or GG ignition <NUM> and the moveable housing <NUM>. In response to the LE or GG ignition <NUM> receiving the pyrotechnic input, the LE or GG ignition <NUM> may generate a low energy spark within the chamber <NUM>. In this regard, the pressure from the low energy spark generated by the LE or GG ignition <NUM> creates an axial force on the moveable housing <NUM>, causing the moveable housing <NUM> to translate axially towards the second end <NUM> of the housing <NUM>, compressing the springs <NUM>, <NUM> between the moveable housing <NUM> and the firing pin <NUM>.

The moveable housing <NUM> translates relative to the fixed piston <NUM>. In this regard, the hydraulic chamber <NUM> moves axially relative to the piston head <NUM> of the fixed piston <NUM> damping the axial motion a predetermined amount. For example, a viscosity of the working fluid <NUM> disposed in the hydraulic chamber <NUM> may be various based on a desired time delay for the inert time delay device <NUM>.

In various embodiments, the springs <NUM>, <NUM> begin being compressed in response to the moveable housing <NUM> moving axially towards the firing pin <NUM> and the firing pin <NUM> being retained axially by the release arm assembly <NUM>.

With reference now to <FIG>, in response to translating axially within the housing <NUM> towards the second end <NUM>, the moveable housing <NUM> engages the guide ramp <NUM> of the release mechanism <NUM>. In this regard, engagement of the moveable housing <NUM> with the guide ramp <NUM> causes the release arm <NUM> of the release arm assembly <NUM> to pivot about the pivot <NUM> in a radially outward direction. Once the moveable housing <NUM> has fully engaged the guide ramp <NUM> (as shown in <FIG>), the engagement end <NUM> of the release arm <NUM> disengages from the firing pin <NUM>. Immediately after release of the release arm <NUM> from engagement with the firing pin <NUM>, the springs <NUM>, <NUM> are compressed to a predetermined length. Thus, the springs <NUM>, <NUM> have a predetermined amount of stored energy which, when released, causes translation of the firing pin <NUM> toward the primer <NUM> (as shown in <FIG>).

Referring now to <FIG>, the springs <NUM>, <NUM> cause the firing pin <NUM> to translate axially towards the second end <NUM> of the housing <NUM> causing the head <NUM> of the firing pin <NUM> to contact the primer <NUM> igniting a respective propellent in the primer <NUM>, which in turn ignites an output ETL <NUM> and to complete a respective time delay.

Claim 1:
An inert time delay device, comprising:
a housing (<NUM>) having a first axial end (<NUM>) and a second axial end (<NUM>) and defining a chamber (<NUM>) extending from the first axial end (<NUM>) to the second axial end (<NUM>);
an ignition (<NUM>) configured to generate a pressure front event disposed at the first axial end (<NUM>);
a primer (<NUM>) disposed at the second axial end (<NUM>); and
a damper system (<NUM>) disposed in the housing, the damper system comprising:
a firing pin (<NUM>) spaced apart axially from the primer (<NUM>);
a moveable housing (<NUM>) disposed within the chamber (<NUM>) and spaced apart axially from the ignition (<NUM>);
a fixed piston (<NUM>) comprising a piston head (<NUM>) disposed in the moveable housing (<NUM>) and a first rod (<NUM>) extending from the piston head axially, and outward from, the moveable housing (<NUM>), in the direction of the second axial end (<NUM>) of the housing (<NUM>) to a second rod (<NUM>), the second rod (<NUM>) extending radially through the chamber (<NUM>) and being fixedly coupled to the housing (<NUM>), so that the piston (<NUM>) is fixedly coupled to the housing (<NUM>);
a first spring (<NUM>) and a second spring (<NUM>) each being disposed axially between the moveable housing (<NUM>) and the firing pin (<NUM>), the damper system configured to initiate an inert time delay from the ignition (<NUM>) receiving a pyrotechnic input to the primer (<NUM>) sending a pyrotechnic output.