Firing devices are used to initiate a detonation in one end of a shock tube. The detonation travels through the shock tube and allows for the detonation of explosives at the other end of the shock tube.
Illustrative embodiments of the preferred embodiment are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
In this specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of this disclosure, the devices, members, apparatuses, etc. described herein may be positioned in any desired orientation. Thus, the use of terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the device described herein may be oriented in any desired direction.
There is a need for an improved firing device having multiple primer-ignition devices, such as a strikers or firing pins, for initiating detonations in shock tubes. In the preferred embodiment, at least one primer-ignition device is able to be actuated when one or more of the other primer-ignition devices are inoperable. The design includes a sear carrier that allows the primer-ignition devices to be actuated by a translatable trigger, a rotary trigger, or a lever. The design also allows for immediate restrike capability.
Two parallel bores 23 are formed in a forward portion of housing 13 and allow for shock-tube inserts (shown in
Trigger assembly 15 comprises a forward actuation portion 25 and a rearward carrier portion 27. In the embodiment shown, actuation portion 25 and carrier portion 27 are formed as a unitary component, though portions 25, 27 may alternatively be formed as separate components. Actuation portion 25 has a forward surface 29 shaped for receiving a finger of a user, surface 29 being oriented to allow the user to move trigger assembly 15 rearward within housing 13 by applying rearward force in a pulling motion. As visible in the figures and especially in
Each sear 33 is a rigid body, and each pin 35 is located in a central portion of the corresponding sear 33. On the rearward portion of each sear 33, a pair of upper and lower curved cam surfaces 45 are separated by a central sear face 47. The rear portion of sear 33 is biased outward by a spring 48 that exerts force between spring recess 49 in an inner portion of sear pocket 31 and spring recess 51 in sear 33. Trigger assembly 15 is biased by trigger spring assembly 53 toward the forward, neutral position shown in
A pair of strikers 57 are located within housing 13 on each side of device 11, and each striker 57 is biased forward by a striker spring 58 toward a forward neutral position, as shown in
When striker 57 is moved rearward to compress striker spring 58 and then released, striker 57 moves forward enough so that tip 63 extends forward out of guide 73 and into bore 23 for striking and igniting a primer in the corresponding shock-tube insert installed in bore 23. After striking the primer, rebound spring 72 causes striker 57 to rebound a slight distance to the neutral position, wherein striker tip 63 is recessed from bore 23.
To prevent tip 63 from entering bore 23 in an unintended movement and thereby causing an unwanted ignition of a primer, a striker block 74 engages block engagement portion 61. Block 74 is capable of vertical movement relative to striker 57 and is biased downward by a spring (not shown) to a safe position, in which striker is prevented from moving forward from the neutral position enough to extend tip 63 into bore 23. Block 74 is moved upward to a firing position as striker block actuator arms 41 are moved rearward. An inclined cam surface 75 is located on a forward portion of each arm 41, and surface 75 forces block 74 upward as surface 75 passes under block 74. This moves block 74 to the firing position, wherein striker 57 is unlocked and allowed to move forward from the neutral position an amount sufficient to extend tip 63 into bore 23.
As trigger assembly 15 is moved rearward, each sear 33 engages lug 59 of the corresponding striker 57 for causing striker 57 to move rearward and compress striker spring 58. Sear face 47 contacts a lug face 77 for causing striker 57 to move rearward with trigger assembly 15. To release striker 57 during this rearward motion after striker spring 58 is sufficiently compressed, a longitudinal cam profile 79 is formed on upper and lower portions of each side of housing 13 for acting on cam surfaces 45 on the corresponding sear 33. As shown in
After strikers 57 have moved forward, the user releases trigger assembly 15, and sears 33 move forward, lug 59 causing the rear of sears 33 to rotate inward as they pass lugs 59. Sears 33 then reset in front of lugs 59, and this allows the user to pull trigger assembly 15 rearward again for immediate restrike capability in case of a failure to fire one or more primers. The independent configuration of sears 33 and strikers 57 allows operation of at least one striker 57 when other strikers 57 are inoperable.
To prevent unintended rearward movement of trigger assembly 15, an external manual safety 87 is shown installed on trigger assembly 15. Safety 87 comprises an upper slider 89 and a lower slider 91, sliders 89, 91 connected to each other by post 93 extending through transverse slot 95. Upper slider 89 has a tab 97 extending laterally and sized for engaging a notch 99 formed in aperture 21 of housing 13. Safety 87 is selectively movable relative to trigger assembly 15 between a “safe” position (as shown in
As mentioned above, the internal volume of the enclosure of device 11 is preferably waterproof or at least resistant to water or dust entering the volume. To increase the likelihood of continued operation of device 11 if dust or water has entered the volume, cover plate 17 is shown with optional dust grooves 101 formed thereon, providing a space for sand, dust, dirt, debris, or water to collect away from the operating parts of device 11. Likewise, one or more voids 103 are preferably formed in trigger assembly 15 to provide additional space for dust or water to collect. Voids 103 also reduce the mass of trigger assembly 15, allowing trigger to return forward more quickly when released after firing.
The configuration of device 11 enables a user to easily disassemble device 11 for maintenance or repair. In the embodiment shown, a user can remove rear plate 19, allowing removal of the internal components from the rear of device 11, as shown in
Referring to
For example,
Additionally, two devices 11 may be assembled together using optional features on cover plate 17, such as male/female dovetails, and both devices 11 can optionally be fired simultaneously with use of a transfer bar (not shown) or similar component connecting trigger assemblies 15 of devices 11. Also, a shock-tube cutter may be installed or formed on device 11.
Inserts 115 are provided with a primer (not shown) installed in primer pocket 123, and insert 115 is installed by threading collar 119 into bore 23 until the rear end of insert 115 contacts the forward end of tip guide 73. This places the rear of primer pocket 123 adjacent guide 73 and in a position to allow striker tip 63 to strike and ignite a primer when striker 57 is released from a rearward position and is propelled forward by striker spring 58. The ignition products of the ignited primer travel forward through bore 121 for initiating detonation within shock tube 117.
Sears 131 are pivotally carried by trigger 139, each sear pivoting on a vertical pin 141. As trigger assembly 145 is moved rearward, each sear 131 engages lug 147 of the corresponding striker. Sear face 149 contacts lug face 151 for causing the striker to move rearward with trigger assembly 145. To release the striker during this rearward motion after the striker spring is sufficiently compressed, an S-shaped slot 153 is formed on upper plate 135 for guiding lower posts 133 and causing rotation of sears 131. Each slot 153 comprises an enlarged forward section 155, an angled central section 157, and a rear section 159 offset from forward sections 155. A spring 161 biases the rear portion of each sear 131 toward the corresponding striker. Though shown with slots 153 formed in upper plate 135 of housing 137, slots may alternatively be formed in a cover plate (not shown) that cooperates with housing 137 to form an enclosure.
As trigger assembly 145 moves rearward, sear face 149 presses against lug face 151, forcing the striker rearward. Spring 161 forces lower post 133 against the outer edge of enlarged section 155 of slot 153, and posts 133 pass from section 155 to angled section 157. Posts 133 are captured within angled section 157, which causes sear 131 to rotate about pin 141 as section 157 forces posts 133 inward. This rotation of sear 131 begins to move sear face 149 inward, and as posts 133 move from angled section 157 to straight section 159, sear 131 has rotated enough so that sear face 149 disengages from lug face 151. This rotated position of sear 131 allows the striker to move forward at a high velocity due to the force of the compressed striker spring.
After the strikers have moved forward, the user releases trigger assembly 145. As sears 131 move forward, angled section 157 guides posts 133 outward, causing sear 131 to rotate back to the original position. Enlarged section 155 allows room for posts 133 to move inward as lug 147 causes sear 131 to rotate as it passes lug 147. Sears 131 then reset in front of lugs 147, and this allows the user to pull trigger assembly 145 rearward again for immediate restrike capability in case of a failure to fire one or more primers. One aspect to this embodiment is that posts 133 are captured by section 157 of each slot 153, which completely controls rotation of each sear 131. As with device 11 above, the independent configuration of sears 131 and the strikers allows operation of at least one striker, even when the other striker is inoperable.
Device 163 comprises a housing 165 and a trigger assembly 167 carried within and longitudinally movable relative to housing 165. Trigger assembly 167 comprises trigger 169, which is generally configured similarly to trigger 25 of device 11, and assembly 167 is biased forward toward a neutral position shown in the figure. Assembly 167 comprises an actuation portion 170, and elongated sears 171 are pivotally connected to a carrier portion 172 of trigger 169 by vertical pins 173. Unlike devices 11 and 129, in which strikers are moved rearward to compress a striker spring, in device 163 each sear 171 is used to rotate a corresponding hammer 174 for hitting a firing pin 175, propelling it forward so that the tip of pin 175 extends into primer pocket 123 of installed shock-tube insert 115. Each pin 175 is preferably a rigid, one-piece component comprising a rear end 177, a flange 179, a central section 181, a block engagement section 182, and a tip 183. Each pin 175 is carried within a bore 185 formed in housing 165, and the forward tip 183 of each pin 175 is located in a cylindrical tip guide 187. A pin spring 189 biases the corresponding pin 175 rearward and extends between a forward end of bore 185 and flange 179.
When hammer 174 is rotated away from firing pin 175, spring 189 causes pin 175 to move rearward until flange 179 contacts a rear cap 191 of bore 185. Rear end 177 of pin 175 then extends past the rear surface of cap 191. When hammer 174 falls and hits rear end 177 of pin 175, pin 175 is propelled forward with enough momentum to overcome the rearward biasing force of spring 189. Pin 175 continues forward far enough that tip 183 extends into primer pocket 123 for striking and igniting a primer contained therein, and then spring 189 returns firing pin 175 to the original position, wherein tip 183 is recessed from primer pocket 123. As in device 11, firing pin blocks 164 cooperate with engagement portion 182 of each pin 175 to prevent forward movement of pin 175 until blocks 164 have been moved upward by actuators (not shown) on trigger assembly 167.
Each hammer 174 is pivotally connected to housing 165 by a pin 193, allowing hammers 174 to rotate about pin 193 relative to housing 165. Each hammer 174 comprises a plate 195 and an integral shaft 197 with a notch 199 for engaging the corresponding sear 171. Each sear 171 comprises an arm 201 terminating in a hand 203 configured to engage notch 199 of hammer 174. A hammer mainspring 205 biases hammer 174 toward the forward rotational position shown in
To fire device 163, trigger assembly 167 is moved rearward, which causes hand 203 of each sear 171 to press against notch 199 for the corresponding hammer 174. This causes hammers 174 to rotate rearward relative to housing 165 about pins 193, and this allows firing pins 175 to move rearward, such that rear end 177 protrudes from cap 191. Hammer mainspring 205 is compressed as hammer 174 is rotated rearward, increasing the biasing force. The angle of notch 199 relative to hand 203 changes as hammer 174 rotates, and hand 203 will slip from notch 199, allowing hammer 174 to be forcefully rotated forward by compressed mainspring 205. Plate 195 hits rear end 177 of pin 175, propelling pin 175 forward, with tip 183 entering primer pocket 123 to ignite a primer. As hammer 174 rotates forward, the rear portion of sear 171 moves outward of shaft 197. As the user allows trigger assembly 167 to return to the neutral position, hand 203 of sear 171 slides against shaft 197 and then resets when hand 203 is realigned with notch 199, allowing for trigger assembly 167 to again rotate hammers 174 when assembly 167 is moved rearward. This configuration allows for immediate restrike capability in case one or more primers do not ignite.
Though not shown, in an alternative version of device 163 each hammer 174 includes a post on at least one side of hammer 174 that serves the same function as that of notch 199. Hand 203 of each sear 171 is configured to engage the post, allowing sear 171 to rotate the associated hammer 174 rearward as trigger assembly 167 is moved rearward.
As trigger assembly 209 is moved rearward, sear face 221 of each sear 215 engages lug face 223 of the corresponding striker 227 and forces striker 227 rearward, compressing spring 58. Sear 215 moves rearward as part of trigger assembly 209, and cam lug 229 slides rearward along inner surface 231 of cover plate 218. A ramp 233 is formed on or affixed to surface 231 at a rearward central position, and each cam lug 229 rides up and over ramp 233, forcing the rear of each sear 215 upward enough to move sear face 221 from engagement with lug face 223. This motion releases strikers 227 to move forward due to the force of compressed springs 58. When the user allows trigger assembly 209 to move forward after release of strikers 227, a reset face 235 on sear 215 slides up and over an angled face 237 on lug 225 of corresponding striker 227, thereby resetting sears 215 forward of lugs 225. Though shown with ramp 233 being located on cover plate 218 for forcing sears 215 away from plate 218, trigger assembly 209 may alternatively be configured with sears 215 inverted and configured to engage a ramp located on the housing (not shown).
As trigger assembly 241 is moved rearward, sear face 255 of each sear 247 engages lug face 257 of the corresponding striker 261 for forcing striker 261 rearward and compressing the striker spring. Sears 247 move rearward as part of trigger assembly 241, and an outer edge of each sear 247 slides along an associated vertical inner surface 267. A ramp 269 is formed on or affixed to surface 267 at a rearward position, and each sear 247 rides up and over ramp 269, forcing the rear of each sear 247 inward enough to move sear face 255 from engagement with lug face 257. This motion releases strikers 261 to move forward due to the force of the compressed striker springs. When the user allows trigger assembly 241 to move forward after release of strikers 261, a reset face 271 on sear 247 slides up and over an angled face 273 on lug 259 of the corresponding striker 261, thereby resetting sears 247 forward of lugs 259.
While shown as having a translatable trigger for moving the carrier portion rearward, it should be noted that other types of actuation portions may be used for other embodiments of the firing device, such as, for example, rotary triggers or pivoting triggers. To allow for a compact firing device, it is preferred that any trigger be located within the volume defined by the outer surfaces of the device enclosure, as shown in the embodiments herein, and not protrude during operation.
The firing device of this disclosure provides several significant advantages, including having independently operated strikers, immediate restrike capability, safety, reliability, durability, modularity, ease of use, ease of field maintenance, fixed headspacing, and excellent resistance to penetration of dirt and water from the outside environment.
This disclosure includes illustrative embodiments having a limited number of forms, which are amenable to various changes and modifications without departing from the spirit thereof.
This disclosure claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 62/160,040, filed on May 12, 2015, and titled FIRING DEVICE HAVING DUAL STRIKERS, the entire content of which is hereby expressly incorporated by reference. Not applicable.
Number | Date | Country | |
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62160040 | May 2015 | US |