US 3885223 A
An explosive switch includes a thin metallic tube having a collapsed portion encircled by an electrically conductive band. The collapsed portion has an oblong transverse cross section and diametrically opposed ridges extending in the direction of the axis of the tube. An explosive material is located in the tube to pressurize the interior of the tube and cause the tube to assume an inflated cylindrical shape. A first pair of contacts respectively engage the band adjacent the ridges when the tube is in its normal uninflated condition. A second pair of contacts, which are normally spaced from the band, are adapted to respectively engage the lateral sides of the band upon inflation of the tube by the explosive material. Inflation of the tube produces a radially inward movement of the band to electrically disconnect the first pair of contacts. When the tube is in the inflated condition, the band functions to electrically interconnect the second pair of contacts.
Claims available in
Description (OCR text may contain errors)
United States Patent 1 Green EXPLOSIVELY OPERATED MULTI-CIRCUIT BAND SWITCH INCLUDING FLEXIABLE DIAPHRAGM BAG 11] 3,885,223 1 May 20, 1975 3,698,323 10/1972 Apstein et a1 200/83 R X 3,793,501 2/1974 Stonestrom ZOO/61.08
Primary Examinerlames R. Scott CONTACT Attorney, Agent, or FirmR. W. Luther; Richard A.  Inventor: Alan N. Green, Cochranville, Pa. Domon  Assignee: Colt Industries Operating C0rp.,
Hartford, Conn.  ABSTRACT I An explosive switch includes a thin metallic tube hav-  1974 ing a collapsed portion encircled by an electrically  Appl. No.: 460,016 conductive band. The collapsed portion has an oblong transverse cross section and diametrically opposed 'd t d' th d' t' fth fth 52 U.S. Cl 337/406; 92/92; 102/702 R; n ges ex m e dre-c o o e 4 tube. An explosive material 15 located in the tube to 200/6108 200/83 200/83 200/275 pressurize the interior of the tube and cause the tube [5 Clto assume an i fl yli i Shape. A fi p of  held of Search Q 83 83 contacts respectively engage the band adjacent the 200/83 C, 83 N, 83 T, 275, 102/702 ridges when the tube is in its normal uninflated condi 702 28 92/50 337/40l 4l2 tion. A second pair of contacts, which are normally spaced from the band, are adapted to respectively en-  References Cited gage the lateral sides of the band upon inflation of the UNITED STATES PATENTS tube by the explosive material. Inflation of the tube 2,917,597 12/1959 Pope 200/83 B produces a radially inward movement of the band to 293L874 4/1960 Leaman 200/6108 X electrically disconnect the first pair of contacts. When 9 3/1962 jg 200/83 N the tube is in the inflated condition, the band func- 37121-157 2/l964 Benedlk 200/83 N X tions to electrically interconnect the second pair of 3,247,341 4/1966 Kizilos 200/83 B contacts 3,304,386 2/1967 Shlesinger, .lr 200/83 N 3,541,484 11/1970 De Lucia 200/275 X 4 Claims, 8 Drawing Figures U/V VPED M G/7 j. a ,1 J6 lea re 32 Ji 1 I 25a [5 48 L55". 2' 50 a Z6 A a 4% 2a if 4m EXPLOSIVELY OPERATED MULTI-CIRCUIT BAND SWITCH INCLUDING FLEXIABLE DIAPHRAGM BAG CONTACT BACKGROUND OF THE INVENTION This invention relates to switches and more particularly to explosively operated switches. This invention also relates to switches for bomb fusing systems.
A known form of an explosively operated switch which has found wide application in bomb fusing systems is disclosed in U.S. Pat. No. 3,698,323. The switch of this patent incorporates a shaft adapted to move axially from a first position to a second position upon deformation of a concave diaphragm by an explosive charge. The axial movement of the shaft functions to disconnect a pair of initially connected contacts and to electrically interconnect another pair of contacts which were initially disconnected. The disconnection and interconnection of the contacts is achieved by means of a flanged contact cup carried by the end of the shaft, the cup being deformed upon actuation of the switch. Since the shaft and the cup must be propelled and guided, the structure of the switch is relatively complex.
Such a switch construction necessitates strict adherence to specified manufacturing tolerances and techniques if reliability is not to be impaired. In this respect, manufacturing specifications are not easily complied with. To briefly explain, the flared cup and the guide therefore must be extremely clean for proper functioning of the switch. In addition, while the cup wall must be thin, it must not be so thin as to permit penetration by the shaft upon switch actuation. Furthermore, the predetermined geometry of the ends of the electrical contact members must be precisely duplicated for a firm electrical connection. Perhaps the most difficult component to accurately manufacture is the diaphragm which should be devoid of thin spots in the convoluted area. A rupture of this diaphragm could possibly short circuit all four electrical contact members.
SUMMARY OF THE INVENTION The invention provides a switch which is simple in construction and relatively inexpensive to manufacture. A switch of the invention need not include sliding components which would inherently detract from reliability.
A switch according to the invention has an inflatable metallic tube with a collapsed portion encircled by an electrically conductive band which engages a first pair of electrical contact members. A second pair of electrical contact members is situated in spaced relationship to the band such that they are adapted to be contacted thereby when the tube is inflated by a pressure generating device associated therewith. Inflation of the tube produces a deformation of the band which causes it to withdraw from engagement with the first pair of electrical contact members and thereby assume a spaced relationship with respect thereto. Succinctly stated, inflation of the tube occasions a disconnection between the band and the first pair of contacts, thereby electrically disconnecting the first pair of contacts and essentially simultaneously causing an engagement between the band and the second pair of contacts which electrically connects the second pair of contacts.
The invention also embraces a switch which includes only one pair of contact members. For example, the
first pair of contact members could be omitted to thereby form a normally open switch; conversely, the second pair of contact members could be omitted to define a normally closed switch.
It will be appreciated that a switch according to the invention may have no moving parts save for the distensible tube and band. Therefore, a device according to the invention is exceedingly simple and relatively inexpensive to manufacture. Moreover. a switch of the invention is highly reliable since the only action attendant to its functioning is the inflation or distention of a tube.
Accordingly, it is a primary object of the invention to provide a switching device for either connecting or disconnecting a pair of contact members.
It is another object to provide a switching device for disconnecting a first pair of contact members and connecting a second pair of contact members.
Yet another object is to provide a simple and inexpensive explosive-type switching device which exhibits a high degree of reliability.
A further object is to provide a switching device incorporating an inflatable flattened tube, encircled by an electrically conductive band.
Other objects, aspects, uses and advantages of the invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional, side elevational view of a first preferred explosive switch of the invention in its unfired condition.
FIG. 2 is a sectional view of the switch of FIG. I, taken along the line 2-2 of FIG. 1.
FIG. 3 is a view similar to that of FIG. 1, showing the switch in the fired condition.
FIG. 4 is the sectional view of the switch of FIG. 3, taken along the line 4-4 of FIG. 3.
FIG. 5 is a schematic representation of the switch of FIGS. 1 through 4, illustrating its function.
FIG. 6 is a front elevational view of a second preferred explosive switch of the invention in its unfired condition.
FIG. 7 is sectional, side elevational view of the switch of FIG. 6, taken along the line 7-7 of FIG. 6.
FIG. 8 is a sectional, upper plan view of the switch of FIG. 6, taken along the line 88 of FIG. 7.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Turning now to FIG. I, there is shown a first embodiment of a switch according to the invention in its unfired condition prior to actuation. The switch comprises a housing, generally shown at 10, which is constituted by a casing 12 and first and second spaced blocks of insulating material 14 and I6, respectively. The casing 12 comprises flanges at the axial ends thereof to contain the first and second blocks of insulating material 14 and 16, respectively, therein. The block 14 has a recess 18 which confronts the recess 20 in the block 16. The recesses I8 and 20 and the space between the blocks 14 and I6 define a cavity in the housing. The blocks 14 and 16 are spaced :1 distance sufficient to allow for insertion of electrical contact members 22, 24, 26 and 28 therebetween. The electrical contact members 22, 24, 26 and 28 are identical in construe tion and resemble a hook in form. For example, contact member 28 has a long leg 28a, a short leg 28b parallel to the long leg 28a and a base 28c interconnecting the long and short legs. Each of the contact members has its legs imbedded in the block 16 and its base disposed between the blocks 14 and 16 such that the base extends a small distance radially inwardly from the walls of the recesses 18 and 20. As depicted in FIG. 2, the contact members 22 and 24 define parallel planes and the contact members 26 and 28 define parallel planes such that the planes of contact members 26 and 28 are perpendicular to the planes of contact members 22 and 24 as is explained hereinafter. Contact members 22 and 24 are normally electrically connected; that is, they are electrically connected until the switch is actuated. The contact members 26 and 28 are normally electrically disconnected; that is, they are disconnected until the switch is actuated.
Within the cavity in the housing is positioned an actuator, generally designated 30, which functions to irreversibly electrically disconnect contact members 22 and 24 and to subsequently, but essentially simultaneously, connect contact members 26 and 28. The actuator 30 comprises an inflatable, thin-walled tube, mounted in the housing I0, 32 made of a ductile metal and having a cylindrical mass of pyrotechnic material inserted therein. The pyrotechnic material in the tube 32 comprises an ignition charge 34 and a main charge 36 mounted within a charge retainer 38. A resistance element (not shown) is embedded in the ignition charge 34 and connected to a pair of leg wires 40 and 42 which extend through a molded plug 44 mounted in an opening in the rear of the tube 32 to hermetically seal the interior volume of the tube. The leg wires are adapted to be connected to a source of electrical potential to heat the resistance element and thereby ignite the ignition charge 34. Preferably, the tube 32 is made of a soft metal such as stainless steel 304, 321, or 302, copper, or gilding metal, although the selection of a particular material is not critical. An intermediate portion of the tube 32 is collapsed or flattened by a sleeve comprising an outer band 46 of electrically conductive material such as silver, copper, or gold plated copper and an inner band 48 of insulating material, such as Mylar, the band 48 being contiguous with both the outer band 46 and the tube 32. It will be noted that the collapsed portion of the tube has an oblong transverse cross section and diametrically opposed ridges 32a and 32b extending in the direction of the tubes axis.
As may best be appreciated from FIG. 2, the band 46 encircles the tube 32 transverse to the tubes axis such that the lateral sides of the band are separated by a dis tance less than that between the portions of the band 46 adjacent the ridges 32a and 32b. It will be noted that while the recesses 18 and are generally cylindrical, they include opposing narrow channels to receive the upper and lower portions of the sleeve to prevent twisting of the tube 32, these channels being designated 16a, 16b. and 18a and 18b. As FIG. 2 shows, the base of contact member 22 protrudes into the channel 16a and engages the top of band 46. Similarly, the base of contact member 24 protrudes into the channel 16b to engage the bottom of the band 46. Hence, in the unfired condition of the switch, the contact members 22 and 24 are electrically connected by the band 46. It will also be noted from FIG. 2 that the bases of contact members 26 and 28 protrude into the cavity a distance sufficient to engage the lateral sides of the band upon inflation of the tube 32. FIGS. 2 and 4 show that the contact members 22 and 24 are diametrically opposed and the contact members 26 are similarly diametrically opposed. It will be noted that the portions of the contact members which protrude into the cavity generally define the points of a rhombus in the cavity when viewed along the axis of the tube.
When the pyrotechnic mass is ignited, the tube 32 is thereby pressurized and subsequently inflates to the shape shown in FIGS. 3 and 4. If it were not for the constraint provided by the contact members 26 and 28, the tube 32 would assume a cylindrical shape upon inflation; but instead, the lateral sides of the band flatten as they are contacted by the respective electrical contact members. Hence, the portions of the band 46 adjacent the ridges 32a and 32b are withdrawn radially inwardly by inflation of the tube 32, thereby disconnecting contact members 22 and 24. Contact members 26 and 28 are subsequently electrically connected when the sides of the band 46 make respective contact therewith, this action occurring essentially simultaneously with disconnection of contact members 22 and 24 since the tube inflates within a millisecond.
As depicted schematically in FIG. 5, the electrical contact members 22 and 24 are normally closed; that is, they are electrically interconnected by the band 46 prior to actuation or firing of the switch. In addition, prior to actuation of the switch, the contact members 26 and 28 are normally open; that is, they are not electrically interconnected. When the switch is actuated lateral contact members 26 and 28 become irreversibly connected.
A second embodiment of a switch of the invention is depicted in FIGS. 6-8. In this embodiment of the invention, the actuator is identical to the actuator 30 of the previously described embodiment and comprises a band 46, an inner band 48', a tube 32 and leg wires and 42'. The salient differences between the two embodiments concern the housings and the contact members.
Referring to FIGS. 6-8, a housing 50 has a cavity 52 defined therein in which is positioned the actuator 30'. Also retained in the cavity 52 is a contact support 54 and an insulating spacer disk 56, a space being defined between the disk and the contact support. The disk 56 includes four spaced apertures adapted to respectively receive electrical contact members 58, 60, 62 and 64. The contact members are generally flat and are characterized by rectangular cross sections, as best shown in FIG. 6. As may be seen from FIGS. 7 and 8, each of the contact members is provided with two right angle bends such that the section lying therebetween is located in the space separating the Contact support 54 and the disk 56 and such that the contact support engages the inboard surfaces of the contact members. It should be noted that the segment of each contact member which extends to the left of contact support acts as a leaf spring to ensure that the inboard surface adjacent the left end firmly engages the band 46' either prior to or subsequent to switch actuation. Sealant masses 66 and 68 are situated at the left and right ends of the cavity 52 to respectively secure the actuator 30' and the disk 56 in the cavity 52.
The operation of the switch of FIGS. 6-8 is the same as that of the previously described embodiment. Upon actuation of the switch, initially connected contact members 58 and 60 are disconnected and initially disconnected contact members 62 and 64 are subsequently connected.
Obviously, many variations and modifications are possible in light of the above teachings with respect to the disclosed embodiments. For example, the band 46 need not be continuous but may be split as long as an electrical path is provided in the unfired and fired conditions of the switch. The band could also take the form of a helical wire. Furthermore, if desired, a switch of the invention may incorporate a plurality of axially spaced bands. Of course, for each band, at least a pair of contact members must be provided. In such an arrangement, the contact members associated with each band may either be connected or disconnected upon switch actuation.
It will also be appreciated that the contact members may engage the band at locations other than the top, bottom, and sides although in both the fired and unfired conditions, the illustrated arrangements furnish the greatest separation between the contact members of each pair and between the disconnected contact member and the band. By way of illustration, the contact members of each pair could be closely adjacent. Also, as previously noted, the invention may be practiced with a single pair of contact members.
it will be understood that the tube could be inflated by means other than a pyrotechnic charge. For example, a source of compressed gas or hydraulic pressure may be employed to inflate the tube. Indeed, the pressure generating device, whatever its nature, could be located remote from the tube. Also, it is within the scope of the invention to increase the pressure on the interior of the tube by a mechanical device which forcibly distends the tube.
1. A switch comprising:
a housing having a cavity therein;
a tube mounted in the housing so as to be positioned within the cavity, the tube having a collapsed portion in the cavity with an oblong transverse cross section and diametrically opposed ridges extending in the direction of the tubes axis;
at least one band, made of an electrically conductive material, at least partially encircling the collapsed portion of the tube transverse to the tubes axis;
a pair of diametrically opposed electrical contact members mounted in the housing so as to protrude into the cavity in respective contact with the band adjacent the ridges; and
means to inflate the tube for causing the collapsed portion to assume a cylindrical shape, whereby the band will radially withdraw from and disconnect the contact members.
2. The switch of claim 1, further including:
another pair of diametrically opposed electrical contact members mounted in the housing so as to protrude into the cavity in spaced relationship to the band such that the pairs of contact members generally define the points of a rhombus in the cavity when viewed along the axis of the tube, the spacing between the first mentioned pair of contact members being greater than the spacing between the second mentioned pair of contact members such that inflation of the tube causes the band to engage and connect the second mentioned pair of contact members.
3. The switch of claim 2, wherein the inflating means comprises:
a pyrotechnic charge mounted in the tube.
4. The switch of claim 3, wherein each electrical contact member comprises: