US2775941A - Magnetic inertia controlled fuze - Google Patents

Description

Jan 1, 1957 H. J. PLUMLEY MAGNETIC INRTIA CONTROLLED FUZE 2 Sheets-Sheet l Fued Dec. 25, 1946 'llllllfIl/lll.

.N @NBN lIan. 1, 1957 H PLUMLEY 2,775,941

MAGNETIC INERTIA C'ONTROLLED FUZE Filed Dec. 25, 1946 2 Sheets-Sheet 2 E@ 3. Eagan.

.Q7 Il@ H J Plain/ley United States Patent() MAGNETIC INERTIA CGNTROLLED FUZE Harold Jfllumley,l Washington, D. C;

Application December 23, 1946,..Serial No. 718,098

21 Claims. (Cl. 102-7 022) (Granted under Il`itle 3,5, U. S. Code (1952),.sec; 266) This inventionV relates to aninertia voltage generator suitable for use in a magnetically controlled inertia fuze for detonating an explosive charge, and more particularly to improvements in theinertia generator disclosed in my copending application for Magnetic Inertia Controlled Fuze` Serial No. 535,799., led May 1,6, 1944, iny which the suddenV movement of a magnetic-element jin response to inertia forces applied thereto causes a change in the ux of a magnetic circuit thereby to generate a current in a coil disposed adjacent the magnetic `circuit suicient to iire a low energy detonating device.

As. was fully pointed out in the aforesaid copending application, prior art inertia controlled devices have been of limited value for a variety of reasons. Spring` means were sometimes employed to retain the inertia element yieldably in its initial position, and` such arrangements were subject to the inuence of frictionwhich sometimes prevented satisfactory operation of the device when the projectile struck the target a glancing blow.' Furthermore, such prior art devices were `relatively insensitive, so that when used in a projectile Awhich struck a target comprising a relatively thinplate, the set forward force generatedl was insucient to cause the dislodgingor movement of the inertia element.

The inertia voltage generator of the presentinventionI is suitable for use in projectiles havingall ranges of velocities, and is adapted for use inprojectiles which do not spin, such 'as rockets, guided lmissiles, and depth'charges. As will subsequently be explainedythe generator is characterized by high sensitivity, makinguit suitable for use with projectiles to which the target .offersI very little resistance, for example, a target such as the wing` of an aircraft. When a high velocity projectile. strikes land passeslthrough the Wing of an aircraft,.lvery little retardation forcel is generated upon impact. The subject inertia generatorhas suicient sensitivity to render `it useable insuch an application.

The inertia generator of the subject invention is suitable also for use with projectiles which are normally subjected to small random inertia forces due to movement, suchas those which would be received in a torpedo due to broaching or yawing. By the use of a spring suspension, an arrangement is provided .in which inertia forces of short duration caused by the aforementioned*randomA movements are insufficient toV generate a voltage, `Whereas small forces of somewhat Vlonger duration received from stri-king `a target are sutiicient to cause the operation of the device.

In the subject invention, the increased sensitivity mentioned before-is achieved in Apart by providing a `magnetic bridge arrangement. T lie inertia element described in my prior application identified hereinbefore, is in the subject apparatus replaced by an inertia Vassemblage comprising a magnetic casing having disposed ltherein a magnetic element adapted togenerte a flux. When the casing and element are 'in their initial positions, the magnetic iiux follows one magnetic circuit; when the assemblage has 2 been dislodged by inertia forces acting thereon, at second magnetic1 circuit' is established;

Whereas the inertia voltage generator described herein is particularly well adaptedfor useV in= projectiles, it: may be employed in a number of other` applications, for ex ample, a crashcontrolfsystem for aircraft.

The increased sensitivity of the generator of the present invention is alsol obtained by the use of a spring suspension for the generator which transforms inertia forces of long duration-andi small magnitude intoinertia forces of large magnitude whereby the generator-is adapted to be actuated by forces of long durationv and small magnitude andi is preventeda from beingactuated by countermine shock. InV oneembodiment off the invention, the sensitivity is further increased by usingV spring biasing means adapted?. to exert .aforce on-the inertia assemblage which adds to any inertia force received, and` reduces the strengthv of inertial forces required to actuate the device.

rlhe subject invention'A alsoprovides means adapted to control the forces acting on the inertiaassemblage, thereby topredetermine the character of an inertial force adapted tomovethe-keeperor inertia assemblage, where character means magnitude and! or duration.

In generali, t-wo means of'accomplishing this areused; A magnetic bridge circuit is provided for rapidly removing the force ofi magnetic .attraction on the inertia assemblage 4by providing ani alternate path for the lines of flux. The effect of the presencefof this alternate path is tocinsure that' inertia 'forces of relatively short duration, when applied directly to the inertia.` assemblage, are suflicient to dislodge it-from the bodyfof the generator. Spring means is also employed, loperatively connected to thev inertiaassemblage, and, adaptedI to addi, algebraically, tothe total of' forces acting thereon. Several arrangements of the spring are provided, -inV which the spring may oppose the torce of magnetic` attraction, oppose the inertia force, or modifyf theduration and -magnitude of the inertia force.

One of the objects of the present invention is toprovide aA new andfimprove'd inertia voltage generator having` sucient sensitivity for .use in` the fuze of a projectile which receives llow inertia forces upon impact with ythe target'.

Another object `is to: provide an inertia generator in which movement yof an inertia; element or assemblage a predetermined distance resultsin substantial modiiication of the magnetic circuit soithat no magneticrestoring force is thereafter applied tothe assemblage.

Another object is toprovid'e a new and improved inertia voltage generator of increased sensitivity and which is responsive to` inertiaforces 4applied thereto in or from substantially any direction.

Stilly another object is to provide anI inertia voltage generator of increased sensitivity in which a magnetic retaining force on the inertia element or assemblage is, only slightly greater than a spring removing force on the inertia assemblage, whereby very small inertia removing forces are sutiicient to dislodge the assemblage and generate a voltage.

A further object is to provide an inertia voltage generator in which means ist provided to predetermine the character of an inertia ,force adapted to move the keeper or inertia assemblage.

A further object is toprovide an inertia generator having'force transforming means `for changing inertia forces of relatively long duration and small magnitude into forces of relatively short duration and large magnitude..

Still a further object is to provide an inertia voltage generator particularly adapted for use in torpedoesand resistant to countermining operations.

Still. other objects, advantages and improvementsv will become apparent from aconsideration of the Vfollowing description taken in connection with the accompanying drawings, of which:

Fig. 1 is a View partly in elevation and partly in section of a bomb employing the device of the present invention;

Fig. 2 is an enlarged detailed view in section of the fuze of Fig. l;

Fig. 3 is a schematic circuit diagram of the electrical tiring circuit of Fig. 2;

Fig. 4 is an enlarged sectional view of a slightly modied inertia voltage generator from that of Fig. 2, showing spring restoring means for the inertia assemblage;

Fig. 5 is a detailed sectional View showing another embodiment of the invention; and

Fig. 6 is a detailed sectional View showing a third embodiment of the invention.

Referring now to the drawings in which like numerals are used throughout to designate like parts, and more particularly to Fig. 1 thereof, there is shown a bomb having the general `designation 1 and having tail tins 2, a portion of the walls 3 being cut away near the nose of the bomb to reveal the fuze having the general designation 5, the fuze being inserted in threaded fuze aperture 8 in the nose of the bomb, the fuze having propellers or vanes 9 for arming the mechanism thereof in a manner to be more fully explained subsequently, the fuze being surrounded by the explosive charge 4 which may be inserted into the body of the bomb through aperture 6 having closure plate 7.

Reference is made now to Fig. 2, which shows an enlarged cross sectional view of the fuze 5 of Fig. l, as it appears when in an armed condition. The mechanism of the fuze is contained largely within a main housing 195 having a somewhat enlarged threaded portion 208 near one end thereof forming a shoulder 207, the threads being adapted to engage the threads in the aforementioned fuze bore 8, Fig. l, in the nose of the bomb, thereby to secure the fuze to the body of the bomb. The housing 195 has a reduced end 196 threaded both internally and externally, a shoulder 197 being formed for receiving the end of a casing extension 187 in threaded engagement with the housing 195.

Disposed within the housing 195 is the inertia generator, comprising an outer supporting casing 31 composed of non-magnetic material and preferablyhaving the inside wall slightly tapered as shown, and having an outwardly extending flange 32 at one end thereof for purposes to be subsequently apparent, the diameter of the flange being such that it may -be moved or slide within the central opening of the housing 195, when the fuze is in an unarmed position, as will be more fully described later. The casing 31 has an extended end section 60 of insulating material, which is separated from the main portion by an insulating ring 50, with a small space 40 between insulating members 50 and 6) for receiving a clamping lip 59 of metallic cap or contact member 153, thereby to securely x the cap to the body of the inertia generator, the cap or contact member being provided for purposes to be explained subsequently, and being insulated from the main body 31 of the casing. Disposed within -the casing 31 is a cylindrical sleeve or casing 37 composed `of magnetic material. The term magnetic material as used herein is defined as material capable of being magnetized but not necessarily possessing any residual or permanent magnetization. Disposed within the magnetic casing 37 is a coil frame 45 having raised flanges 46 for securely supporting and positioning a coil 44 which is adapted to have a voltage induced therein in a manner to lbe presently more fully described, and which may be composed of a large number of turns, the size of the wire and the resistance thereof being chosen to permit optimum energy to be delivered to the load, in the application shown the explosive squib 156. Disposed within the coil is a core 42 of any suitable magnetic material, having an enlarged head portion 43 adapted to abut against' the casing 37. The inner end of core 42 may be approximately in alignment with the inner end of casing 37, as shown, for reasons to be subsequently apparent.

Disposed within casing 31 also is an inertia assemblage comprising a relatively long sleeve or casing 51 composed of magnetic material and having a closed end portion 57 having a bore 58 therein in which is fixed an element 64 yof magnetic material having disposed adjacent thereto va permanently magnetized element 43 having positioned at one end thereof an adjacent magnetic element of somewhat larger diameter 52. Disposed between the members 48 and 51 is a suitable non-magnetic ller material 63, for example lead, for purposes to be hereafter explained. The ends of elements 51 and 52 abut on the adjacent ends of casing 37 and core 42 respectively, being normally maintained in abutting relation by the force of magnetic attraction.

ln the operation ofthe inertia generator, when the elements are in the position shown, the lux generated by permanently magnetized element 43 foilows a magnetic circuit including elements 48 and 52, core 42, head 43, casing 37, casing 51, end portion 57, and member 64. Upon the dislodging -of the inertia assemblage comprising elements 51, 64, 43, and 52 in response to inertial forces applied thereto, gaps of high reluctance arc introduced between core 42 and element 52, and between casing 37 and casing 51 respectively. When the elements of the assemblage have moved a suicient distance whereby the combined reluctances of the gaps exceed the reluctance -of the path through non-magnetic material 63 between elements 52 and 51, a new magnetic circuitincluding elements 52, 48, 64, and 51 is established. The lines of force linking coil 44 collapse, inducing a substantial voltage therein.

Whereas the element 48 is shown and described as generating a flux for energizing the magnetic circuit, and may be of any suitable material, it is understood that any one, or several of the elements of the inertia assemblage could be flux generating elements if desired.

The casing 18,17 has in the end thereof, as shown, an annular recess 177 and an inwardly extending lip 178 for receiving and holding the end -or closure plate 176. Disposed within the casing 187 is the block or retaining member 186 having a longitudinal bore 174 of substantial diameter in the end thereof for receiving a booster charge 168. Near longitudinal bore 174 is a transverse bore 159 having a much smaller bore extension or bearing hole 160 at one end thereof, and a considerably enlarged portion at the other end thereof, the bore 159 having disposed therein a detonator rotor 162 having bearing studs 161 and 184 on the ends thereof, stud 161 being adapted to rotate in bore 160 and stud 184 being adapted to rotate in a bore 183 in a cover or keeper 182 for the enlarged portion 135 of bore 159.

The longitudinal bore 174 has a small bore 173 connecting it with Itransverse bore 159, bore 173 having disposed therein a lead-in charge 172. The rotor 162 has provided therein a transverse bore 166 having a flaring yend 167 and containing a housing 165 having therein detonator charge 164, `the bore 166 being located in rotor 162 whereby bore 166 and bore 173 in block 186 will register when the rotor is mounted in the position shown'. The rotor also has another transverse bore 163 for receiving the end of plunger or rod 151 when the fuze is in an unarmed condition, as will be hereafter explained, bore 163 and bore 166 being at right angles to each other as shown.

Within the block 186 at .the opposite end thereof from bore 174, is a longitudinal bore 157 having a smaller bore 169 connecting it with transverse bore159, the bore 157 having disposed therein an explosive squib 156 for exploding the bomb in a manner to be hereafter more fully explained, the bore 169 registering with 'bore 167 in rotor 162 when the rotor is turned to the position shown and the fuze is armed. Disposed somewhat beadriaan neatl1 l-`ig.` 2, -bore157 is a. longitudinal bore 158 for wreceivingplunger and .permitting movement thereof ina manner to ybe more 'fully explained subsequently. 1

,"Di'sp'osed: within the casing '195 is a sleeve of non-con 'ductive or insulating. material 19'8'having. an inwardly extending hflange orl lip 170 on one end tl'iere'if,l for purposes to 4be hereafter apparent, and having therein a pair of roppositely disposed .grooves 1.",71 inA which are 'positioned a pair of metal strips 1-5'5Hhaving inwardly .afring end portions l1'54 at one end thereof to form an elec- 'tr'ical contact with the aforementioned metallic member or contact piece 153 fixed yto the cap or hea-d 2050i? the inertia generator for purposes to be hereafter explained. The metal strips 155 are securelydhel'd in. their respective .grooves byan annular sleeve or casing-199 of non-met-allic and-non-conductive material, the casing having a rib "209v therein with 'abore 200 therethrough for passage of the rod or plunger`1d51. The sleeve 199 has at one end thereof an enlarged vextendedpot-'tion forming shoulder 189 against which. the end of sleeve 198' abuts, Athe shoulder ,portion 139 having therein a bore 193` for receiving dowel .pin192 securely 'fixed in block 186, thereby to prevent relative rotary movement between the two parts.` In the cutalway portion 421=o1fsleeve 199 is disposed the termina-l'. portion 211 of one of the metal strips 155. To

this terminal is4 attached a lead wire 201 connecting the stri-p 155 with `squib 1 56. The other lead from the squib runswto a binding posh-202 mounted on block 186, the binding Vpost having fixed thereto a contact member 203 `adapted to maintain any unbroken electrical connection to metallic rod 1151 while allowing movement-of the rod .with .respect to the contact member 203.

. 4The right handend, Fig. -2, of -rod 151 passes through a boief2tl6' iii-cap 295, and a reduced portion. 1152 of yrod 151 isl secu-rely fixed in a bore 65 in the `core 42 of the inertia generator, whereby axial movement 'of the generator withi-n the casing 195- i-nf response 'to the action `of coiled springA 219 exerting tension between the shoulder formed by .flange A170 and ange -32 causes vplunger V4or rod. 151 to m-ove` within .the bore 158', .thereby to' "cause Vthe "rotor 162 to bev 'freed t'o rota-te, as will be later A'ex- .plainedA y `Fixed en' rod 151 is ah electrical termin-al `or connec; tion'- 204,. .from whence -a lead connection goes to coil 44, the other lead to coil 44 being connected at terminal 1.75 to metallic contact member which is adapted, `when the fuze is in armed condition, to`- make contact `with. member 154, thereby completing an elec- -trical circuit betweencoil'dt and squib i156, the `cir'ciuit being traced as follows: coil 44y through terminal 175 to lcontitctfsleeve 153 `to upper contact 154 to strip 1'55 `to terminal A2.11 through lead 201 to squib 1556 to post 202 .to contact 203 to rod `151 to connection 2021 through the associated lead wire' to coil 44.

Whereas the view of Figi.l 2 shows the fuZe lin armed condition with the electrical circuit complete, the unarmed condition the whole inertia generator i's moved `back to left, Fig. 2, and maintained in that 'position by the actionof member 220 pressinga'g'ainst the 'adjacent end `of the inertia generator, before action .of the propellers '9, -a's the b'omb moves through the air, has u'nscrewed th'e screw 220 to the position shown, as will be hereafter explained. when the inertia generator is moved .to 'the left, and. when 'the rufze lis in an unarmed condition, the rotor 162 is rotated l9'() degrees from 1the position shown, yandrod 1-51 is then inserted in `bore 163 and maintains 'the rotor in that position until `v/i'thtlr'aw'n duetto movement of the generator t'o the right in response to action of spring 219. When vthe 'rod 1'51i`s withdrawn from bore 163, a spring actuated plunger, not shown, of conventional design causes rotor 162 to turn 90 degrees, the spring being shown in dashed outline at 1'46 within bore 1'47.

1n. the unarmed condition, when the inertia generator is moved somewhat to the left from the position shown in Fig. 2, the spring contacts .154 make contact with the metallic casing 31, instead of theA metallic contact cap V153 as shown, thereby electrically grounding one end of the squib lead connection 201.. The electrical circuit when the vfuze is in unarmedI conditionis shownv in Fig. 3, the circuit or position of switch contact 1-54- when the fuze is in armed condition being indicated vby the. dotted line.

Assume now by way of explanation that the bomb is about to be launched from. the aircraft or other carrier. rThe fuze is in unarmed condition. The rotor H'162'. is turned degrees from the position shown in. Fig.2, so that bores 1'63fand 158 are in alignment, and rod 151 4is inserted in bore l1763. The inertia generator is maintained by the action of screw 220 in a 'positionI considerably to the left of that shown in Fig. 2, the coil spring 219 being considerably compressed and exerting considcrable pressure on shoulder and ange 32..

After the bomb is' launched, the vanes 9 cause-screw l220 to turn in a direction which withdraws the screw to the right, Fig. 2.k .Spring 21.9 exerting pressure on flange 3'2 and shoulder 170 causes the inertia generator to move to the right., maintaining the head or end 64 of the inertia element in contact with thescrew. As the generator moves, rod 151, which is attached to core 42, moves to the right, being slowly withdrawn from bore 163. When the bomb has descended an amount sulficient A-to withdraw screw 220 a predetermined distance, rod 1-51 is completely withdrawn from ybore 163:, `and the action of the aforementioned spring actuated plunger causes the rotor 162` to turn' to the position shown. When the vanes have withdrawn screw 224i s-ufllcient to permit rc-tor 162 to turn, vthe inertia generator has. `also moved substantially to the position shown, where arms 154 malte rcontact with member 153,. electrically connecting coil `44 tovsqzui'b 156;. i

The movement of the -i-n'ertia generator -to thel right is limited by flange 32 abutting against the shoulders `of reta-iningmember 2.16, the position shown in. Fig. 2. The screw 220 lis adapted to be withdrawn somewhat `beyond the position which allows full movement of the 'casing 31, thereby to: free the inertia assemblage for movement i-nresponse to inertial lforces applied thereto.

Assume 'now by way of description that the h'omb strikes its target. A considerable set forward force applied 'to the inertia assemblage 'comprising ` rrierrihersl 511, 64, 48, and 52 causes them to be dislodged from rthe position shown, where they Vwere held by vmagnetic attraction after the withdrawal of screw 220 had `freextlzl them.. Upon the movement of the aforementioned "assemblage of magnetic elements, the magnetic held .about coil 44 collapses, inducing a voltage in the coil. The voltage is applied through .leads 20`1'to'explosiive sq-ui'b 156, which Ais designed to explode upon the 'energy received. Explosion 'of squib 156 'i'gnites detonator charge 164 which fires lead-in charge 1-72 and booster charge `168, the explosion of which explodesy the main ibomb charge'4.

' For arming the fuze, the aforementioned arming screw 220, vanes 9, rand associated apparatus are provided. The arming screw is threaded for movement in threaded bore 218 in the fuz'e head 216. The vhead also has' a 'core 217 for receiving and permitting movement of -re- 'taining rod 222, for purposes to be hereafter apparent. The screw 220 has an extended `shank or hub portion to which is fixed a gear 232, having adjacent thereto a -gear'231 free to rotate on the shaft but fixed 'against rotary movement with respect 'to the fu'ze by pin '235: in bore 234, the pin being connected to rod 222. -Both gears mesh with gear 233 Vrotatably mounted on pi'n 221,1 which is xed to 'the supporting arm 'of'on'e of 'the vanesl, the vanesrotating upo'n the bearing `provided by 'shaft 236. Counter-weight 2-37 is provided for 4proper balancing ofthe apparatus. Rotation of the vanes, then, 'as the bomb descends, causes screw 220 to turn, and the end of the screw to be withdrawn away from the inertia generator, releasing the generator to be moved by action of spring 219 to the armed position,

'Reference is made now to Fig. 4 which shows la cross sectional view of lan inertia voltage generator similar to that of Fig. '2, Ibut hav-ing spring restoring means for the inertia assemblage. A'n outer casing 31' which may be substantially cylindrical, has an end 35 with threads -disposed internally thereof, and may have the other end slightly tapered fas sh-own, with .an annular recess 3'3 .around the periphery thereof for receiving end plate 39 .and may have an :annular overhanging lip 32 -as shown. In threaded engagement 'with the inside :of the threaded end of casing 31 is an inner casing lor ring support 37' having threads 36, and having `an extended or flaring head portion 38. The casing '31 should preferably be of non-magnetic material, Whereas the casing 37 should be of magnetic material. The head 38 has a bore 41 substantially centnally disposed thereof -for receiving a core 42 of magnetic material, the core having head 43. The end of the lcore `42 may be in .substantial alignment with the :adjacent end -of casing 37. IDisposed around the core 42 .is a coil support 45 having flanges '46 extending there- :from defining a coil compartment in whi-ch coil 44' is disposed, lead 'wi-res 47 connecting the coil with the load circuit. The coil 44 may be composed of a predetermined number of turns of wire of predetermined size and resistance, whereby optimum energy is delivered to the load. Disposed within the other end of the outer casing 31 is a relatively heavy .sleeve 51 of magneti-c material Fand having a `solid end portion '57 having Ia recess 458' therein for receiving iixedly the end '61 of 'a member 48' of permanently magnetized material, `the member having an adjacent enlarged magnetic element '52'. The inner wall of vthe casing has a recessed portion 62 to provide a space between the casing 5l and the members -48 and 52 to receive a -ller of non-magnetic material 63.

Whereas the member 48 is described as being of-permanently magnetized material, it is understood that 'at least f one of the casing 5K1' or elements 4S or S2' must be of iiux generating material whereby, when the member 52' abuts with the `core I42 and lcasing 37 :abuts with .casing or Isleeve yS1', an energized magnetic circuit including 4the four elements is established. Once established, the magnetic attraction in the circuittends to maintain the elements of the inertia lassembly in the abutting relation shown. The spring 3'4, disposed between the end 57 of the sleeve `a-nd .the plate `39, provides .a restoring [force for returning the member 48 and ysleeve 51' of the inertia assembly into their normal posi-tions, when they have been moved therefrom in response to inertial for-ces a-pplied thereto. Whereas the magnetic attnaction between Ielements is sometimes alone suicient to restore the inertia assemblage, when the generator is designed for maximum sensitivity, the addition of the spring may be necessary.

Assume now 'by Way of description that the leads `d'7 are connected to an explosive squib of suitable design, and that theinertia generator of Fig. 4 is utilized in the fuze of ya bomb which strikes its target so that a substantial inertial or set forward force is applied to the inertia -assemblfage substantially along the longitudinal axis thereof. Just prior to the .application of the for-ce, the magnetic lines of `force extend centrally through the core 42 .and members 52 and '48', thence looping back through sleeve '51' :and casing 37' to complete the circuit. The inertial force, when of sucient magnitude, causes the inertia assemblage including member 48 and sleeve 51 to be dislodged, so that `a gap exists between these and core 4'2 `and casing 37 respectively. The reluctance of the magnetic circuit is sharply increased, cau-sing .at least some of the lines of force linking coil 44 to collapse, inducing a voltagentherein. When the member 52 and sleeve lSil have moved a suicient distance 'from core 42' and .casing '37 respectively that the combined distances are slightly greater than the distance through the non-mag' netic tller 63' between member 52' :and the adjacent portion of sleeve '51', .the magnetic uX is shunted through the path through the filler or non-magnetic material, and substantially .all the lines cutting coil 414' collapse, generating the maximum Ivoltage therein, and iirin-g the explosive squib.

Assume now that .in handl-ing .the inerti-a generator, `shocks cause the inertia assemblage including members *52' and 48', iand sleeve 5'1' to be prematurely dislodged from the remainder .of the device, the tension of spring 34 restores it to its abutting position, `where it is normally maintained by magnetic attraction.

Reference is made now to Fig. 5, which shows another embodiment of the invention, one particularly well adapted for use :on projectiles of very low velocity, such as a homing torpedo, and adapted to tire a fuse when the projectile strikes the target :at any angle.

These two features are accomplished by spring mounting the housing for the inert-ia generator within sa tubular casing or outer housing, whereby slow decelerations of the device bearing the inertia generator result in compression of :the spring unitl the housing for the generator receives a sharp impact :against the ends or Wall of the outer housing whereupon the inertia element or inertia assemblage is dislodged and the volt-age generated. The springs mount lthe generator housing for free movement i-n substantially 'any direct-ion in response to inertial forces lapplied thereto. yin Fig. 5, an outer cylindrical casing 7d of non-magnetic material may be lsuitably mounted in the projectile, and has threaded ends to receive end pieces 72 and 73, end 72 having ya bore 74 therein through which lead-wires 93 pass to lthe coil :of the inertia generator. Disposed within the chamber 'formed by casing 71 and ends 72 Iand 73 is 4an inertia generator having a non-magnetic :casing or housing 77 to which :are attached near the `ends thereof, =as by welding or sweating, two ` annular rings 75 and 76. Disposed laround the ends of the casing 77 are two frusto-conical ycoiled springs `67 4and A68, the inner ends of the springs `abutting against the rings 75 l.and 76 respectively, the outer ends of the springs abutting against the end pieces 72 and 73 respectively, tensions of the two springs maintaining the casing 77 :and contents thereof normally in suspension within the outer casing 7'1.

The casing 77 has the ends thereof threaded to receive end pieces 8d land '82, end Ipiece "81 having a bore -89 therein for passage of lead wires 93, the end pieces having iixed thereon or integral therewith studs `83 wand S4 respectively, these being adapted to strike laga-inst 'the chamber ends 72. `and 73 respectively selectively as the springs `67 .and 68 are compressed in response to axial or orthogonal inertial or lset .forward forces :applied to the inertia generator, and zto thereby impart a sharp shock to the generator sufficient to dislodge the inertia elements or assemblage .and cause the generation of a voltage therein.

The rings 75 and 76 are also adapted to abut against the inside wall of the cylinder 7-1 selectively in :accordance with transverse :or orthogonal inertial forces applied to the generator which cause the springs to yield'ably permit movement of the generator lwithin .the casing. When .the rings come in contact with 4the wall, va sharp .shock is imparted t-o the generator suicient to dislodge the inertia assemblage and generate a vol-tage in the coil.

The generator casing 77 may contain an inertia generator somewhat similar to that of Fig. 4. A casing 95 of magnetic material is disposed within one end of sleeve or casing 77, which should he of non-magnetic material. Inside theycasing 95 is a chamber in which is disposed a coil 94, and within the coil a core 96 of magnetic material having a head 97 thereon, the head having a bore therein for the passage of thelead wires 93. The coil '94 is supported within its chamber by frame l9S having retaining anges 99 on the ends thereof. The inner end of magnetic material having one end thereof open and enclosing said coil, a core of magnetic material disposed within said coil and 'having one end in abutting relation with the closed end of said casing, the other end of said core being in substantial alignment with the open end of said casing, a second casing of magnetic material having one end open and having a diameter corresponding roughly to the diameter of said rst casing and adapted to be normally positioned whereby the open ends of said casings are in abutting relationship, a member of magnetic material mounted within said second casing substantially axially thereof and having the end thereof in substantial alignment with the open end of the second casing, said member bein-g of substantially smaller cross-section than said second casing whereby a gap exists between the end of said member and the open end of said second casing, at least one of said second casing and said member being of substantially permanently magnetized material whereby an energized magnetic circuit including said rst and second casings and said core and said member is established, said iirst and second casings being normally maintained with their open ends in abutting relation by magnetic attraction, said second casing and member being adapted to be moved away from said rst casing and core respectively in response to inertial 'forces applied thereto whereby a gap is introduced between the casings of higher reluctance than said first mentioned gap thereby to cause said magnetic circuit to be altered to include substantially only said second casing and said member, the change'in said magnetic circuit causing a voltage to be generated in said coil as the lines of force cutting said coil collapse.

2. Apparatus according to claim 1 including in addition spring means for restoring said casings to abutting yrelation when the inertial force is no longer applied.

3. In an inertia generator, a coil; means for setting up a normally closed magnetic circuit including a pair of casings of magnetic material, permanently magnetized clement disposed centrally of one of said casings, and a magnetic core disposed centrally of the other of said casings; said casings being normally in abutting relationship to each other, and said core and element being normally in abutting relationship; said coil being disposed around said core whereby a change in the reluctance of said circuit causes a voltage to be induced in said coil; said casings, and said core and element, being adapted to be moved away from each other respectively in response to inertial forces applied to said element and one of said casings whereby said magnetic circuit is opened and the reluctance thereof is changed.

4. In an inertia generator, a coil, means for setting up a magnetic circuit including a core of magnetic material for said coil, said core having an enlarged head portion, atirst casing of magnetic material disposed around said core and coil, a second casing having a closed end portion, at least one magnetic element disposed Within said second casing and adapted to generate a flux, said casings and said core and element being normally disposed and maintained in abutting positions respectively by the force of magnetic attraction therebetween and adapted to form a closed magnetic circuit, said second casing and element being adapted to be dislodged from their initial positions in response to inertial forces applied thereto whereby at least one gap of high reluctance is introduced in said circuit and a voltage is generated in said coil as the lines of flux in the core associated with said coil collapse.

5. An inertia generator comprising a cylindrical hous ing of non-magnetic material, one end of said housing having an annular recess around the inside thereof and an inwardly extending ange adjacent thereto, a cover plate mounted in said recess and engaged by the ange for sealing the end of said housing, the other end of said housing having fixed on the inside thereof a cylindrical casing of magnetic material, said casing having a closed outer end and being of shorter length than said housing, a coil disposed within said casing, a core of magnetic material disposed inside said coil and in abutting relation with the outer end oif said casing, a second casing of magnetic material disposed within said housing and having a closed end and an open end normally abutting on the open end of said rst named casing, a magnetic element fixed within said second casing and normally abutting against the closed end thereof and against said core, at least one of said second casing and said element being of permanently magnetized material whereby an energized magnetic circuit is established, said second casing and said element being adapted to be moved from their initial positions in response to inertial forces applied thereto, and a spring disposed between said cover plate and the end of said second casing and adapted by the tension thereof to restore said second casing and element to their initial positions when the inertial forces are removed therefrom.

f 6. An inertia generator comprising a first cylindrical housing of non-magnetic material, a second cylindrical housing of non-magnetic material and of substantially smaller dimensions than the corresponding dimensions of said rst housing, said second housing being disposed within said first housing, a plurality of springs disposed within said first housing and engaging said second housing for yieldably maintaining said second housing in suspension therein, said second housing having disposed therein means including a plurality of magnetic elements for setting up an energized magnetic circuit, a coil disposed in predetermined position with respect to one of said elements and adapted to have a voltage induced therein when the amount of flux in said magnetic circuit changes, at least one of said elements being adapted to be moved from an initial position in response to an inertial force or' predetermined character applied thereto thereby to aiter the iiux in said magnetic circuit and generate a voltage in said coil, said second housing being adapted to be moved against the tension of said springs in response to inertial forces of different character applied to said second housing until the second housing abuts against the inner walls of said rst housing, contact between said two housings applying said inertial force of predetermined character to said movable magnetic element thereby to move said element from its initial position.

7. An inertia generator comprising a coil, means including a plurality of magnetic elements for setting up and energizing a magnetic circuit, said coil being disposed in predetermined position with respect to at least one of said magnetic elements whereby a change of ilux in said circuit induces a voltage in said coil, at least one of said magnetic elements being adapted to be moved from aninitial position in response to inertial forces applied thereto whereby the flux in said circuit is changed and a voltage is generated in said coil, said last named magnetic element being normally maintained in its initial position by magnetic attraction, and initially tensioned spring actuated means engaging said last named element and adapted to yieldably oppose the force of magnetic attraction and to add to said inertial force thereby to reduce the magnitude of the inertial force required to move said last named element from its initial position.

8., In an inertia device of the character disclosed, voltage generator means including a coil and at least a pair of magnetic elements disposed in predetermined relation to said coil, one of said elements being adapted to generate a flux, said pair of magnetic elements being movable relative to each other whereby the ux linking said coil is altered and a voltage is generated in the coil when relative movement occurs between said elements, said elements beingmaintained in initial relative positions by the force of magnetic attraction therebetween, and initially tensioned spring means engaging one of said elements and adapted to yieldably oppose the force of magnetic attraction thereon, said last named element being adapted to be moved from its initial position upon the application of an inertia force Vof predetermined character applied thereto,

13 the .character :of said force rbeing determined in `part by the tension. `of saidspr'ingand .said .force off 1magnetic attraction.

9. `In-an inertia fgenerator of thefcharacter disclosed, a magnetic circuit-,including anuinertia assemblage of magnetic elements, oneof said elements bein-g adapted to set up a llux within said circuit, a coil normally positioned with `respect to `said vcircuit whereby the lines of force link saidicoil, Vsaid inertiaassemblage occupying aninitial position .in said circuit :and being :normally maintained insaidinitiabpositionhy the force .of'magnetic attraction, and initially tensionedspringfactuated rneansengaging said inertia assemblage and adapted ,to yieldably oppose the force of magnetic attraction thereon, -said inertia assemblage being adapted to fbemoved from said initial positionin response `to antinertia force of `predetermined character applied theretotherebyptoalter the reluctance of said magnetic circuit and- Ki'nduceavoltage in said coil, the character `of said inertia force fbeing determined at least in part'by the `ten-sion'ofsaidspring means and the force of magnetic attraction.

10. .An inertia `generator comprisingan-external housing composed of non-magnetic material; spring suspension means; an internal housing composed of non-magneticmaterial yieldably `mounted by said fspring suspension means within sai'dlexternal housing; and generator means disposed within said internal housing and-includinga coil, flux generating means, and atleast apairofmagn'etic elements, one of said elements being disposed in predetermined position relative to said coil; said elements being movable relative to each other for vgenerating a voltage in said'coil when relative motion occurs -between said elements; said elements being adapted to be maintained in their initial positions bythe'force of magnetic attraction; said spring `suspension means-providing a force transformer whereby small forces of relatively long duration resulting from `movement .of .-said external lhousing are changed into :inertia forces of lrelatively short duration and large magnitude sucient todislodge 'said last named element from its initial positionassaid internal housing moves into engagement Withw-s/aid externalhousing.

1l. In,anlinertiaigeneratonithecombinationof a coil, means for setting up .am'agnetic .field within the coil, an inertia element of magnetic material within said ield and adaptedfto-be movedinlresponseftoinertia-forces applied l thereto thereby to ,generate a voltage in said coil, and spring actuated means engaging said inertia element and adapteditoexert a force thereonp supplementing said inertia forces whereby-themagnitudeiof an .inertia force yadapted to move the element is reduced to a predetermined value. l2. In a fuze for a projectile, a coil; means for setting up a normally closed magnetic circuit including a pair of casings of magnetic material, a permanently magnetized element disposed centrally of one of said casings, and a magnetic core disposed centrally of the other of said casings; said casings being normally in abutting relationship to each other, and said core and element being normally in abutting relationship; said coil being disposed around said core whereby a change in the reluctance of said circuit causes a voltage to be induced in said coil; said casings, and said core and element, being adapted to be moved away from each other respectively in response to inertial forces applied -to said element and one of said casings whereby said magnetic circuit is opened and the reluctance thereof is changed; and electroresponsive detonating means operated by the voltage generated in said coil.

13. In a fuze of the character described, means for establishing a normally closed magnetic circuit including a pair of substantially coaxial casings of magnetic material initially maintained in end engagement with one another, a core disposed centrally within one of said casings, a coil carried by said core, a plurality of magnetic elements, at least one of said elements being of permanently magnetized material and disposed centrally of the other of said casings whereby magnetic ilux is generated, at

least one of said velements being disposed in ,predetermined position with respect to said coil wherebya change in theux insaid `lastnamed element induces a voltage in said coil, said =plurality of magnetic elements being initially disposed inpredetermined lpositions whereby a first magnetic circuit is. established in which a substantial number of magnetic .lines of .forcelink said coil, a group comprising some of said `magnetic elements beingadapted to be moved from their initial positions to second positions in response to inertial forces applied thereto whereby a second magnetic circuit is established in which the uX includes substanti-ally only said group `of elements and the number of magnetic lines of force in the element associated with saidzcoil is substantially zero, the change in the lines of force resulting in -a voltage generated in said coil, 'and electroresponsive detonating means operated by the Voltage generated in said coil,

14. In a fuze of the character disclosed; a plurality of abutting Vcoaxial casings of magnetic material, a plurality of `relatively movable vmagnetic elements disposed within said casings wherebya magnetic field comprising rst and second `paths of relatively low and high reluctance respectively is effected; said magnetic elements normally o'ccupying positions whereby the ux lines of said magnetic field follow said rst path of low reluctance; said plurality of elements being `adapted `to be moved relative to each other `to second positions `in response to inertial forces applied thereto, substantially all the'lines of force of said magnetic field taking said second path when said elements are in said second positions thereof; a coil disposed within one ofthe casingsfand inpredetermined position with respect to atleast Voneoi said 'elements and adapted to have a .voltage induced therein lwhen the lines of ux shift from said first to said second'paths; and electroresponsive 'detonating means operated by the voltage .generated in said coil.

l5. ln a fuze of the character disclosed, an external housing composedof non-magnetic material; spring suspension means; `an internal housing composed of nonmagnetic material yieldably mounted by said spring sus pension means within said external housing; generator means disposed within said internal housing and including a coil, llux vgenerating means, and at least a pair of magnetic elements, one of said elements being disposed in `predetermined position relative to said coil; said elements being movable relative to each other for generating a voltagefm/said coil when relative motion occurs between 'said elements; said elements being adapted to be maintained in their initial positions bythe force of magrnetic attraction; said spring suspension means providing a force transformer whereby small forces of relatively long duration resulting from movement of said external housing are changed into inertia forces of relatively short duration and large magnitude suicient to dislodge said last named element from its initial position as said internal housing moves into engagement with said external hous` ing; and electroresponsive detonating means operated by the voltage generated in said coil.

16. ln a fuze of the character disclosed, a coil, means including a plurality of magnetic elements for setting up and energizing a magnetic circuit, said coil being disposed in predetermined position with respect to at least one of said magnetic elements whereby a change ot linx in said circuit induces a voltage in said coil, at least one or said magnetic elements being adapted to be moved from an initial position in response to inertial forces applied thereto whereby the flux in said circuit is changed and a voltage is generated in said coil, said last named magnetic element being normally maintained in its initial position by magnetic attraction, and initially tensioned spring actuated means engaging said last named element and adapted to yieldably oppose the force of magnetic attraction and to add to said inertial force thereby to reduce the magnitude of the inertial force required to move said last named element from its initial position, and electroresponsive detonating means operated by `the voltage generated in said coil. t

17. In a uze of the character disclosed, generator means including a coil and at least a pair of magnetic elements, one of said elements being disposed in predetermined relation to said coil, one of said elements being adapted to generate a flux, said pair of magnetic elements being movable relative to each other whereby the ux linking said coil is altered and a voltage is generated in said coil when relative movementoccurs between said elements, said elements being maintained in initial relative positions by the force ofl magnetic attraction, and initially tensioned spring actuated means engaging one of said elements and adapted to oppose the force of mag# netic attraction, said last named element being adapted to be moved from its initial position in response to an inertia force applied thereto, said spring means and said magnetic torce determining at least in part the character of the inertia force adapted to move said last named element, and electroresponsive detonating means operated by the voltage generated in said coil.

18. In a fuze for a projectile, in combination, an explosive charge arranged within the projectile, electroresponsive detonating means for detona'ting said charge,

and a voltage generator within the fuze and adapted to generate suti'icient voltage to operate said detonating means as the projectile strikes a target, said voltage generator comprising a coil, a plurality of magnetic elements arranged to form a magnetic circuit, energizing means for said circuit, at least one of said elements being disposed in predetermined position with respect to said coil, at least two of said magnetic elements being maintained in their initial positions by the force of magnetic attraction, said last named elements being adapted to be moved from their initial positions in response to inertial forces applied thereto whereby the reluctance of said circuit is altered and a voltage generated in said coil, and spring means operatively connected to said last named elements and adapted to yieldably oppose the force of magnetic attraction thereby to predetermine the character of the inertia force adapted to move said elements.

19. in a fuze of the character disclosed, in combination, a iirst casing of magnetic material, structure disposed within said iirst casing comprising a core element and a coil carried by said core element, a second casing of magnetic material in substantially coaxial and abutting relationship with the iirst casing, a structure Within said second casing comprising a plurality of elements composed of magnetic material and including a permanently magnetized element, said elements being in-abutting relationship with one another, and a sleeve of non-magnetic filler material positioned between the second casing and said elements whereby one of said casings together with the structure contained therein is magnetically urged into engagement with the other casing and the structure contained therein.

2,0. An inertia device of the character disclosed for mounting on a moving body, comprising in combination, generator means including a coil and at least a pair of magnetic elements movable relative to each other, said elements being adapted to generate a flux and induce a voltage in the coil when one of said elements is moving relative to the other one of said elements, one of said elements being adapted to be dislodged from its initial position in response to aninertial force of predetermined duration and magnitude applied thereto, and force transforming means comprising at least one spring for yieldably supportingsaid generator means from the body, whereby the generator means is moved gradually in response to inertial forces applied to said body.

2l. An inertia generator comprising a coil, a plurality of magnetic elements, at least three of said elements being movable as a unit with respect to the other elements, said magnetic elements comprising a magnetic bridge circuit including a path of relatively high reluctance and a path of relatively low reluctance, at least one of said three elements being adapted to set up a magnetic tield within said circuit whereby said plurality of elements is maintained in initial positions by the force of said iield following said iirst and second paths selectively in accordance with the position of said movable elements with respect to the other elements, said movable elements being adapted to be moved from said initial positions thereof in response to a predetermined inertial force applied thereto, said coil being disposed in predetermined positionwith respect to at least one of said other of the elements and adapted to have a voltage induced therein when the lines of force shift between said two paths, and spring actuated means engaging said movable unit of elements and adapted to exert a force opposing the force of magnetic attraction thereon thereby to reduce the magnitude of said predetermined inertia force.

References Cited in the tile of this patent FOREIGN PATENTS

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