English:
[0002] Electric and electronic delay detonators are known in the art, including detonators which have electronic timing circuits therein. This enables setting electronic time delays between the receipt of an initiation signal and firing of the detonator. Such electric and electronic delay detonators are often provided with a test circuit and, for safety's sake, the energy used for testing is normally set at a level which is insufficient to initiate the igniter. This is usually accomplished by including a ballast resistor in series with the igniter so that the voltage drop across the resistor is great enough to insure that the voltage used to test the igniter is insufficient to activate the igniter. The resistor consumes as waste heat a substantial amount of the energy supplied to the detonator. Such detonators must therefore have an energy supply capable of both satisfying the voltage drop over the resistor and carrying out the testing. When the detonator is to be initiated, sufficient energy must be available both to run the timing circuit and, ultimately, to fire the igniter. This increased energy demand for testing and firing results in smaller shot sizes and a reduction in available delay times. This is because, obviously, larger shot sizes require more energy and longer delay times require the delay circuits to run longer, thereby consuming more energy.
[0003] In seismic applications, boreholes are typically primed well in advance of shooting the holes. An unattended primed borehole with a typical seismic blasting detonator may result in initiation of the blast by stray currents or by tampering. Even the energy available from a common flashlight battery connected across the exposed leg wires may initiate the detonator. The art has employed various methods to increase the voltage required to initiate a detonator in order to reduce the sensitivity to stray currents and tampering. However, such prior art methods also increase the energy required to initiate the detonators. Accordingly, there is a need in the art for a detonator ignition protection circuit that overcomes these drawbacks.
[0004] An embodiment of the invention includes an ignition circuit for a detonator, having an igniter, a transient voltage suppressor (TVS), an energy source and a switch, all electrically connected in series with each other. Current flow through the igniter sufficient to ignite the igniter is prevented until an ignition voltage is applied across the TVS that is equal to or greater than the breakdown voltage of the TVS.
[0005] Referring now to the drawings, which are meant to be exemplary and not limiting, and wherein like elements are numbered alike in the accompanying Figures:
[0006] Figure 1 depicts in cross-sectional schematic view a detonator shell for use in accordance with an embodiment of the invention;
[0007] Figure 2 depicts a schematic of an exemplary firing circuit in accordance with an embodiment of the invention; and
[0008] Figure 3 depicts an alternate igniter to that depicted in Figure 2 for use in accordance with an embodiment of the invention.
[0009] An embodiment of the invention, as shown and described by the various figures and accompanying text, provides a detonator ignition protection circuit that provides for a greater firing voltage to fire an electric or electronic igniter without substantially increasing the energy requirements of the igniter. A transient voltage suppressor (TVS), or TVS diode, is placed in series with the igniter, a firing switch and an energy storage device. Alternative to a TVS diode, a metal oxide varistor (MOV) may be employed if size and speed of switching to a conductive state is not a major concern. Both a TVS diode and MOV function in a manner similar to a zener diode. That is, no current will flow through these devices until their respective design threshold voltages are reached or exceeded. Once the threshold or breakdown voltage of such a device is reached or exceeded, the devices exhibit a non-ohmic resistance change and will conduct current. Despite the high breakdown voltage imposed by the TVS in series with the igniter, a substantial increase in energy is not required to fire the electric or electronic igniter due to the non-ohmic resistance change once the breakdown voltage of the TVS is reached or exceeded. In an embodiment, the TVS has a breakdown voltage of 20-volts. In another embodiment, the TVS has a breakdown voltage rating of 200-volts.
[0010] Referring to Figure 1, an exemplary detonator 100 is depicted in cross-sectional schematic view having a detonator shell 105 that houses an input connector 110 having input pins 115 and output pins 120, a protection circuit 125 (to be discussed in more detail below with reference to Figure 2), an output connector 130 having input pins 135 and output pins 140, an ignition region 145, a first stage detonator charge 150, a second stage detonator charge 155, and a third stage detonator charge 160. Receipt of a planned ignition voltage at input pins 115 is transferred to protection circuit 125 via output pins 120, which properly passes through protection circuit 125 in a manner to be discussed in more detail below to cause a chain reaction starting with ignition of an igniter 210 (discussed below with reference to Figure 2) disposed within ignition region 145, which in succession causes firing of the first stage detonator charge 150, the second stage detonator charge 155, and then the third stage detonator charge 160. In an embodiment, the detonator shell 105 is standard commercial detonator shell having a 0.25 inch (6.5 mm) nominal diameter opening, the first stage detonator charge 150 is diazo (diazo dinitro phenol, usually referred to as DDNP), the second stage detonator charge 155 is loose PETN (pentae- rythritol tetranitrate, also known as penthrite), and the third stage detonator charge 160 is pressed PETN.
[0011] Referring now to Figure 2, an exemplary ignition circuit 200 is depicted having protection circuit 205, an igniter 210 having first 211 and second 212 terminals, a source of electrical energy 215, and a switch 220. In an embodiment, protection circuit 205 includes a TVS 225 having first 226 and second 227 terminals, and an optional resistor 235. As illustrated, TVS 225 is electrically connected in series with igniter 210 at first terminal 211, and energy source 215 is electrically connected in series with igniter 210 at the opposing second terminal 212. As also illustrated, energy source 215 and switch 220 are electrically connected in series with each other, and electrically connected across first terminal 226 of TVS 225 and second terminal 212 of igniter 210, which places all components of ignition circuit 200 in series with each other in the absence of optional resistor 235.
[0012] In relating Figure 2 to Figure 1, contact points 240, 245 in Figure 2 are electrically synonymous with input pins 115 in Figure 1, contact points 250, 255 in Figure 2 are electrically synonymous with output pins 120 in Figure 1, contact points 260, 265 in Figure 2 are electrically synonymous with input pins 135 in Figure 1, and terminals 211, 212 in Figure 2 are electrically synonymous with output pins 140 in Figure 1. While not specifically depicted in Figure 1, it will be appreciated by the description and illustration disclosed herein that the energy source 215 and switch 220 illustrated in Figure 2 are connected to pins 115 of detonator 100 in Figure 1 (synonymous with contact points 240, 245 of Figure 2), thereby providing the necessary energy, switching means and ignition voltage to fire igniter 210 disposed in ignition region 145. In an embodiment, energy source 215 is a battery, a charged capacitor, or any other energy source suitable for the purposes disclosed herein, and switch 220 is an electronic switching device, or any other switching device suitable for the purposes disclosed herein, where switch 220 is a separate component or integrated within a time delay module.
[0013] As mentioned above, resistor 235 may be optionally disposed in electrical connection across first terminal 226 of TVS 225 and second terminal 212 of igniter 210, and in parallel with the series-connected energy source 215 and switch 220. When present, resistor 235 provides an electrical path in front of TVS 225 and igniter 210 for pre-testing the integrity of electrical connections from the firing station (not illustrated) up to the protection circuit 205 and igniter 210, and for protecting the circuit 205 against stray static voltages.
[0014] In accordance with an embodiment of the invention, current flow through igniter 210 sufficient to ignite igniter 210 is prevented until an ignition voltage is applied across the terminals 250, 255 of protection circuit 205 that is equal to or greater than the breakdown voltage of TVS 225.
[0016] In an embodiment, TVS 225 and optional resistor 235 are surface mounted on a circuit board, generally depicted by reference numeral 205 and the associated dashed-line graphical box depicted in Figure 2. The combination of circuit board 205 with surface-mounted TVS 225 and resistor 235 (collectively referred to as surface-mounted components) is so dimensioned as to be insertable through the space defined by the opening of detonator shell 105, which in an embodiment is a standard commercial detonator shell having a 0.25 inch (6.5 mm) nominal diameter opening. When the circuit board with surface-mounted components is positioned within the detonator shell, the dielectric breakdown voltage between any of the surface-mounted components and the interior wall of the detonator shell is greater than the breakdown voltage of TVS 225, and preferably the through-air dielectric breakdown voltage between any of the surface-mounted components and the interior wall of the detonator shell is greater than the breakdown voltage of TVS 225. In an embodiment, the through-air dielectric breakdown voltage is greater than 500 volts, which results in an unobstructed through-air distance of about 0.017 inches (0.43 mm) at a through-air breakdown voltage of 30,000 volts/inch (1,181 volts/mm).
[0017] Upon closure of the switch 220 (planned ignition), not only does the energy source 215 have sufficient energy to generate a voltage at terminals 250, 255 in excess of the breakdown voltage of TVS 225 to generate sufficient current flow to ignite the igniter 210, but also the energy source 215 further has sufficient energy to permanently damage TVS 225. Since the detonator 100 is an intended self-destructive device, there is no need for TVS 225 to be designed for passing a non-leakage current without damage thereto. As such, a TVS 225 having a conductive current rating far below the actual current passed are fully sufficient for the purposes disclosed herein, thereby permitting a small TVS to be used in a compact design for the protection circuit 205.
[0018] In an embodiment and in the event of the switch 220 being closed, the energy source 215 has sufficient energy to generate an ignition voltage to ignite the igniter 210 that is equal to or greater than 1.1 times the breakdown voltage of TVS 225. And, in the event of the switch 220 being open, TVS 225 has a breakdown voltage sufficient to prevent the igniter 210 from firing upon the occurrence of a stray voltage at terminals 250, 255 less than the breakdown voltage of TVS 225.
[0019] It is contemplated that in an embodiment where TVS 225 has a breakdown voltage of 200 Volts, sufficient protection of igniter 210 will be provided against a standard 120 VAC-rms voltage at input pins 115 having a peak voltage of about 170 Volts. By employing a TVS having a 200 Volt breakdown voltage and a very small current rating, a relatively large energy pulse from a sufficiently charged capacitor discharge firing system will result in a one-time use of TVS 225, which will fail in conduction mode. Since TVS 225 needs to work only once, such an occurrence of failure in the conduction mode is perfectly acceptable for the purposes disclosed herein.
[0020] While embodiments of the invention have been described herein employing a circuit board 205 with TVS 225 and resistor 235 surface-mounted thereon, it will be appreciated that other packaging arrangements can be employed for the purposes disclosed herein, such as integrally molding TVS 225 and resistor 235 into a plug, again generally depicted by reference numeral 205 and the associated dashed-line graphical box depicted in Figure 2, where the plug 205 with the integrally-molded TVS 225 and resistor 235 is so dimensioned as to be insertable through the space defined by the opening of a standard size 0.25 inch (6.5 mm) diameter detonator shell 105.
[0021] Devices other than the TVS 225 device may act in a similar fashion as the aforementioned TVS device, where after the breakdown voltage is reached the voltage across the device drops to very close to zero voltage, thereby allowing full firing power to pass through circuit 205 to igniter 210. For example, an MOV device may be substituted for the TVS 225 in circuit 205, with the other components remaining the same. However, TVS devices are preferred over an MOV because the leakage currents from a TVS are generally an order of magnitude lower than those from an MOV. And, as discussed above, the TVS device or the MOV may be readily molded inline with the lead-in wire or internal plug of the detonator.
[0023] While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best or only mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and de- scriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

中文:
[0002]电气和电子延时引爆器在本领域中是已知的,其包括在其中具有电子定时电路的引爆器。这使得能够设置收到起动信号和引爆器点火之间的电子时间延时。这样的电气和电子引爆器通常提供有测试电路,并且为了安全起见,用于测试的能量通常被设置在不足以起动引爆器的水平。这通常通过包括与点火器相串联的镇流电阻器来完成,以使得电阻器上的电压降大到足以确保用于测试点火器的电压不足以激活引爆器。电阻器消耗提供给引爆器的相当多的能量作为废热。因此这样的引爆器必须具有既能够满足电阻器上的电压降又能够执行测试的能量供应。当要起动引爆器时,必须可获得足够的能量来既运行定时电路又最终点燃点火器。这种用于测试和点火的增加的能量要求导致了较小的射程(shot size)以及可获得的延时时间的减少。显然,这是因为较大的射程需要更多能量,较长的延时时间需要延时电路运行更长久,因而消耗更多能量。
[0003]在地震应用中,典型地在炸孔之前给炮孔预先装好药。带有典型的地震爆炸引爆器的无人值守的装药的炮孔可能由于杂散电流或者干扰(tampering)导致爆炸起动。甚至从连接在暴露的脚线上的常用的手电筒电池获得的能量都可能起动引爆器。现有技术已经采用了各种方法增加起动引爆器所要求的电压,以降低对杂散电流和干扰的敏感性。然而,这种现有技术也增加了起动引爆器所需要的能量。因而,在现有技术中存在对克服这些缺点的引爆器点火保护电路的需要。
[0004]本发明的实施例包括引爆器点火电路,该引爆器点火电路具有点火器、瞬时电压抑制器(TVS)、能量源和开关,彼此全部串联电连接。阻止足以点燃点火器电流流过点火器,直到大于等于TVS的击穿电压的点火电压跨TVS而被施加。
[0005]现在参考附图,附图旨在为示例性的而不是限定性的,其中,在附图中类似的元素被类似地编号:
[0006]图1示出了用于根据本发明的实施例使用的引爆器外壳的横截面示意图;
[0007]图2示出了根据本发明的实施例的示例性的点火电路的示意图;以及
[0008]图3示出了用于根据本发明的实施例使用的、对于图2中描述的点火器的替代性的点火器。
[0009]如各图和所附文字所示及说明的本发明的实施例提供了引爆器点火保护电路,其能够提供更大的点火电压来点燃电气或电子点火器,而不会相当大地增加点火器的能量要求。瞬时电压抑制器(TVS)或TVS二极管被布置成与点火器、点火开关以及能量储存装置相串联。作为对TVS二极管的替代,如果尺寸和向导通状态的切换速度不是主要的关心对象,则可以使用金属氧化物变阻器(MOV)。TVS二极管和MOV都以与齐纳二极管相类似的方式起作用。也就是说,将没有电流流过这些器件,直到达到或超过这些器件相应的设计阈值电压。一旦达到或者超过这种器件的阈值或者击穿电压,则器件显示非欧姆电阻变化并将传导电流。不管与点火器相串联的TVS所施加的高击穿电压,一旦达到或者超过TVS的击穿电压,则由于非欧姆电阻变化而不需要相当大的能量增加来点燃电气或电子引爆器。在实施例中,TVS具有20伏特的击穿电压。在另一实施例中,TVS具有200伏特的额定击穿电压。
[0010]参考图1,在横截面示意图中示出了具有引爆器外壳105的示例性引爆器100,该引爆器外壳105容纳有具有输入引脚115和输出引脚120的输入连接器110、保护电路125(下面将参考图2更详细讨论)、具有输入引脚135和输出引脚140的输出连接器130、点火区域145、第一级引爆器装药150,第二级引爆器装药155以及第三级引爆器装药160。在输入引脚115处对计划的点火电压的接收被经由输出引脚120传输到保护电路125,并被以下面将更详细描述的方式适当地传递经过保护电路125,以引起从被布置在引爆区域145中的点火器210(下面参考图2讨论)被点燃开始的连锁反应,这将连续引起第一级引爆器装药150的起爆、第二级引爆器装药155的起爆、然后是第三级引爆器装药160的起爆。在实施例中,引爆器外壳105是标准的商业引爆器外壳,其具有0.25英寸(6.5mm)的标称直径开口,第一级引爆器装药150是重氮基(重氮基二硝基氨基苯,通常称为DDNP),第二级引爆器装药155是松散的PETN(季戊四醇四硝酸酯,也称为季戊炸药),第三级引爆器装药160是加压的PETN。
[0011]以下参考图2,示出了示例性的点火电路200,其具有保护电路205、具有第一端子211和第二端子212的点火器210、电能源215以及开关220。实施例中,保护电路205包括具有第一端子226和第二端子227的TVS 225以及可选电阻器235。如所示出的,TVS 225在第一端子211处与点火器210串联电连接,能量源215在相对的第二端子212处与点火器210串联电连接。仍如所示出的,能量源215和开关220彼此串联电连接,并且跨TVS 225的第一端子226和点火器的第二端子212而电连接,这使得在没有可选电阻器235的情况下将点火电路200的所有元件彼此串联地布置。
[0012]将图2和图1关联起来,图2中的接触点240、245与图1中的输入引脚115是电学等效的,图2中的接触点250、255与图1中的输出引脚120是电学等效的,图2中的接触点260、265与图1中的输入引脚135是电学等效的,并且图2中的端子211、212与图1中的输出引脚140是电学等效的。尽管在图1中没有具体地示出,但是通过这里公开的说明和图示应当理解,图2所示的能量源215和开关220在图1中被连接到引爆器100的引脚115(与图2中的接触点240、245等效),因而提供了必要的能量、开关装置以及点火电压以用于点燃布置在引爆区域145中的点火器210。在实施例中,能量源215是电池、充电电容器、或者任何其它的适用于在此公开的目的的能量源,开关220是电子开关装置,或者任何其它的适用于在此公开的目的的开关装置,其中开关220是独立的元件或者被集成在时间延迟模块里。
[0013]如上所述,电阻器235可以被可选地布置成跨TVS 225的第一端子226和点火器210的第二端子212而电连接且与串联连接的能量源215和开关220相并联。当存在电阻器235时,电阻器235在TVS 225和点火器210前面提供了电气通路,用于预测试从点火位置(未示出)直到保护电路205和点火器210的电连接的完整性,以及用于保护电路205以防止杂散静电电压。
[0014]根据本发明的实施例,阻止足以点燃点火器210的电流流过点火器210,直到跨保护电路205的端子250和255而施加大于等于TVS 225的击穿电压的点火电压。
[0016]在实施例中,一般地在图2中如附图标记205所示和相关联的虚线图框所示,TVS 225和可选电阻器235都被表面安装在电路板上。电路板205和表面安装的TVS 225以及电阻器235的组合(统称为表面安装元件)的尺寸使得可插入穿过由引爆器外壳105的开口所限定的空间中,在实施例中该引爆器外壳105是具有0.25英寸(6.5mm)的标称直径开口的标准商业引爆器外壳。当具有表面安装元件的电路板被定位在引爆器外壳内时,在任何表面安装元件和引爆器外壳的内壁之间的介质击穿电压大于TVS 225的击穿电压,并且优选地,在任何表面安装元件和引爆器外壳的内壁之间的穿过空气的(through-air)介质击穿电压大于TVS 225的击穿电压。在实施例中,穿过空气的介质击穿电压超过500伏特,这导致了在穿过空气的击穿电压为30000伏特/英寸(1.181伏特/mm)时无阻塞的穿过空气的距离大约为0.017英寸(0.43mm)。
[0017]在开关220闭合(计划的点火)后,能量源215不仅具有足够的能量以产生跨端子250和255的超过TVS 225的击穿电压的电压,以产生充足的电流来点燃点火器210,而且能量源215还具有足够的能量以永久性地损坏TVS 225。由于引爆器100是旨在自毁型装置,因此TVS 225不需要被设计用于不破坏非泄漏电流地使非泄漏电流通过。这样,具有远低于实际经过的电流的额定导通电流TVS 225对于在此公开的目的而言是完全足够的,从而在用于保护电路205的紧凑设计中允许使用小的TVS。
[0018]在实施例中,在开关220闭合的情况下,能量源215具有有足够的能量以产生用于点燃点火器210的点火电压,该点火电压大于等于TVS 225的击穿电压的1.1倍。并且,如果开关220断开,则TVS 225具有足够用于在比TVS 225的击穿电压低的杂散电压出现在端子250和255处时阻止点火器210点燃的击穿电压。
[0019]设想在实施例中TVS 225具有200伏特的击穿电压,将为点火器210提供足够的保护以防止在输入引脚115处的具有约170伏特的峰值电压的、标准的120VAC-rms电压。通过使用具有200伏特的击穿电压和很小的额定电流的TVS,来自充分充电的电容器放电点火系统的相对大的能量脉冲将导致TVS 225的一次性使用,这在导通模式下将失败。既然TVS225只需要工作一次,这种在导通模式下的失败的出现对于在此公开的目的而言是完全可以接受的。
[0020]尽管在此使用在其上表面安装有TVS 225和电阻器235的电路板205对本发明的实施例进行了说明,但是应当理解,为了在此公开的目的,可以使用其它的封装布置,例如将TVS 225和电阻器235集成模制到插头中,一般地,仍如图2中的附图标记205所示和相关的虚线图框所示,其中具有集成模制的TVS 225和电阻器235的插头205的尺寸使得可插入穿过由标准尺寸0.25英寸(6.5mm)的标称直径的引爆器外壳105的开口所限定的空间中。
[0021]除了TVS 225器件之外的器件可以以与上述的TVS器件相类似的方式动作,其中在达到击穿电压之后跨该器件的电压下降到非常接近于零电压,因而允许全部的点火能量传递通过电路205到达点火器210。例如,MOV器件可以代替电路205中的TVS 225,并且其它元件保持相同。不过,相对于MOV而言,TVS器件是优选的,这是因为来自TVS的泄漏电流一般比来自MOV的泄漏电流的数量级更低。并且,如上文所讨论的,TVS器件或者MOV可以被容易地模制内嵌到引爆器的引入线或者内部插头中。
[0023]尽管参考示例性实施例对本发明进行了说明,但是本领域的技术人员将理解,可以对本发明进行各种变化,以及可以将本发明的元件替换为等价物,而不脱离本发明的范围。此外,可以进行许多变型以调整特定的状况或者材料以适应于本发明的教导,而不脱离本发明的基本范围。因此,本发明旨在并不限定于被公开作为最佳模式或只是所设想的用于实施本发明的模式的特定实施例,而是本发明包括所有落入所附的权利要求的范围内的实施方式。此外,在附图和说明书中,已公开了本发明的示例性实施例,尽管可能使用了具体术语,但是该具体术语只是使用除非必要否则如何的方式来陈述的一般性和描述性的语气,并不是为了限定的目的。因而本发明的范围并不由此受到限制。而且,词汇第一、第二等的使用并不表示任何顺序或重要性,而是词汇第一、第二等被用于区分一个元件和另一个元件。此外,词汇“一(a,an)”等的使用并不表示对数量的限制,而是表示存在至少一个所称的项。