US2376080A - Mechanical time fuse for ordnance equipment - Google Patents

Description

May l5, 1945 T. M. PERRY Erm. 2,376,080

MECHANICAL TIME FUSE FOR ORDNANCE EQUIPMENT Filed July 1, 1945 2 Sheets-Sheet l May 15 1945- T. M. PERRY ETAL 2,376,080

MECHANICAL TIME FUSE FOR ORDNANCE EQUIPMENT Filed July l, 1945 2 Sheets-Sheet 2 Patented May l5, 1945 vMECiEiItHfJAib TIME SE FOR ORDNANCE EQUIPMENT Thomas M. Perry, West Hartford, and `Frederick H. Hunter, Wethersfield, Conn., assignors to M. H. Rhodes Incorporated, Hartford, Conn., a y.corporation kof Connecticut Applicationiluly l, 1,943, Serial No. 493,114

(Si. IGZ-84) 6 Claims.

This .invention relates generally to mechanical time fuses for ordnance equipment. In thepresent illustrative disclosure, our improvements are shown .for illustrative purposes as embodied in a mechanism having a firing device, time-operation of which is controlled by a timing device which is released or 4armed by ypulling out a length of strand or cord. A mechanism constructed in accordance with the present invention has various applications but, .as an instance of a use to which it maybe applied, reference may be had to the ring .of parachute flares and the like.

An Object of the invention is to provide an improved .time-controlled firing mechanism which is safe to handle and transport.

A further aim of the invention is to provide an improved time-controlled ring mechanism lwith arming means which are so constructed and arranged that accidental arming or release ofthe timing device isr guarded against during handling and, in operation, it is necessary to draw outl a relatively vlong length of .strand or cord so as vto insure 'that arming of the mechanism will .not take place accidentally.

A still further aim of the invention is to provide an improved arrangement of this sort with disposable safety means which positively locks the timing device, the firing pin, and the arming means against operation until such time as .it is desired to employ the mechanism for the purpose for which itis designed.

A further aim of the invention is to provide a 4mechanism of this sort which is characterized by its simplicity in construction, its economy in manufacture, and its eiectiveness in operation.

.Other objects Will be in part -obvious and in part pointed out more in detail hereinafter..

The invention .accordingly consists rin Ythe features of construction, combination of .elements and arrangement of parts which will be exemplied in the construction hereinafter set forth and the scope .of the .application of which will be .indicated'in'the appended claims.

Referring to the drawings, wherein is's'hown, for illustrative purposes, one of the embodiments which Vthe present invention may take:

Figure l is a top plan view of our improved time-controlled iiring mechanism; Y

Fig. '2 is a longitudinal sectional View therethrough, the same .being taken lon line 2-2 .of Fig. 1 looking in the direction ofthe arrows;

Fig. 3 is a view similar to Fig. Y1 lbut with the top plate and the parts thereabove removed;

Fig. 4 is a detailed view through the firing .device v.and the :disposable .safety lock, this view vbeing taken substantially on line li-li of Fig. l looking in the direction lof .the arrows; and

Fig. 5 is a sectional view taken .substantially online-5 5 of Fig. 3.

Referring to the drawings in detail, the mechanism yhas a frame which comprises two .spaced plates til and Il secured together by suitable pil'. lars l2. Carried by these `plates is a tim-ing `clevice which, for purposes of .exemplication is shown in the drawings -as comprising a clock mechanism provided with an arbor i3 journaled in vlzvearings provided in the plates it and I i. The timing device has a coiled driving spring it, the inner end of which is `anchored to the `arbor I3 as at I5, and the outer end of which is suitably connected to the .bottomgplate il, the connection not being shown. Fixed tothe arbor is a gear t6 which drives, throughs. pinion and gear train il, an Vescapement wheel i8. Cooperating with this 4escapement Wheel is a pallet Wheel iB which, inthe present instance, is shown .as being of the well-known type having a disk provided with two pins. ,Driven onto the Aknurled portion 20 of the arbor, and located above the upper plate L0, is a-.collar `25 having on vits lower end a radially extending circular iiange 25, Positioned on this 'flange is a safety disk 2l having a depending lug 2B engaged in a notch in the flange 25B whereby this safety disk is xed against rotation relative `to the arbor i3. This safety disk has a radially extending lobe', the outer edge of which Vvis of .like radius to, and concentric with, the periphery of a timing disk t5 positioned upon thesafety disk. This timing disk '35 is angularly adjustable relative vto the collar 25 "in order to .set the time interval between the arming of the device and the release of the firing pin 5 ,"but it is rotatable with the varbor and collar L25 when the arbor is driven by the spring Hi after arming. To these-ends, .the timing disk is urged into Vfrictional engagement with the safety disk by a crowned resilient spring'SB surrounding `the collar vr25. On the upper threaded end oi the arbor i3 is a .nut '3l vbetween which and the spring 'is interposed a washer 38. By adjusting the nut, the .pressure with which the spring urges the timing disk againstthe safety disk may be varied as desired. Struck up Vfrom .the timing disk are two ears 39 by means of which the timing disk on the setting of the timing disk, has elapsed. A purpose of the safety disk 21 is to prevent the trigger l5 from operating before the arbo-r has rotated through a sufficient angle to insure that the fuse cannot set E the flare before the parachute, for example, has time to fall a safe distance from the airplane. A further purpose of the safety disk is that, should other safety means fail in case of accident or damage to the device,

the interlock between the safety piece i and i the safety disk would prevent operation of the ring mechanism.

Referring now to the firing device, the same includes a firing pin Fl, the lower end of which slidably extends through an opening 5I in the bottom plate i l. The upper end of the firing pin extends through a bushing 52 and a cap 53 screwed over the top of the bushing. Encircling the firing pin and interposed between a shoulder 54 thereon and the cap 53 is a coiled spring 55 which, when the firing pin is released from its cocked position shown in Fig. 4, will drive the ring pin downwardly against a primer which is not shown as the construction thereof is immaterial. The firing pin is held in the cocked position shown in Fig. 4 by a sear or detent 56 which is in the form of a bar of rectangular cross section, as shown most clearly in Fig. 5. The bar has at its opposite ends trunnions 5l which are journaled in notches 58 on the upper edges of two parallel lugs 59 struck up from lthe bottom plate. This Sear has, fixed adjacent one end thereof, an upstanding arm t0 the upper end of which extends through a slot 6l in the upper plate I9.

The upper end of this arm cooperates with the trigger in such manner that the trigger will hold the arm in the upright position and the Sear in the firing pin holding position shown in the drawings until the slot di) of the timing plate registers with the free end of the trigger. The trigger is pivoted to the top plate, as at 65, and at its free end has an upstanding lug 66 adapted to bear against the perimeter of the timing disk and to move into the slot 4l] when the slot comes into registry with the lug.

Referring now to the arming means, l0 designates a detent in the form of a leaf spring, the free end of which is adapted to engage the teeth ofthe escapement wheel i8 of the timing device so as to hold the gear train Il stationary. The spring, adjacent its other end, bears against one of the pillars l2, and connected to the spring between its ends is a safety plate 'Il pivoted on top of the bottom plate Ii as at '12. This plate has at one corner an upstanding ear 13, the curved upper edge of which lies below, and in the path of movement of, the shoulder 54 of the ring pin. Due to the resiliency of the detent 'l and 'the manner in which it is mounted, the free end of the detent is normally urged into engagement with the escapement wheel i8, and the safety plate is urged into the safety position shown in the drawings. The safety plate is for the purpose of preventing the ring pin from moving to fired position in the event that the sear 56 should be accidentally released or broken as might be the case if the mechanism were inadvertently dropped. The detent 'it is moved away from the escapement wheel i3 to arm the timing device, and the safety plate is moved out of safety position by means of a strand or cord 'M which acts through a suitable connection which, in the present instance, is shown by way of exemplication as comprising a Maltese or Geneva gearing. The cord is wound about a drum or housing 75 journaled between the plates l0 and Il on an arbor 16. This drum has a groove 'Il for accommodating the convolutions of the cord. The inner end .of the cord is connected to the drum in such manner that when the cord is entirely pulled out, the cord will come loose from the drum. To this end, the drum has a vertical bore 18 which intersects the groove 11, and on the inner end of the cord is a knot 'I9 adapted to engage in this bore. The cord passes from the drum up through a tubular guide 8| secured to the top plate lll. The upper end of the opening through this guide is enlarged or counterbored as at 82 so as to provide a seat for a cylindrical sleeve or stop 83 fixed to`a cord adjacent the free end thereof. This sleeve may be of lead or similar material and may be compressed about the cord so as to anchor it; thereto.

rI'he drum or housing 15 is normally urged in a direction to wind the cord thereon by a coiled spring 84 located within the drum. The inner end of this spring is anchored to the arbor 16 as at 85, and the outer convolution of the spring is in frictional engagement with the internal periphery of the drum. To Wind up the spring, the arbor 16 is turned (clockwise with reference to Fig. 3) While the drum is held stationary. Retrograde rotation of the arbor is prevented by a ratchet wheel 86 xed to the arbor 16 and a spring pressed pawl 87 pivoted to the top plate l0.

The spring is wound up at the factory until it slips with respect to the drum. In operation, when the apparatus is dropped from an airplane, for example, the upper end of the cord being connected to the airplane, the cord will be unwound from the drum causing the drum to rotate. Rotation of the drum causes actuation of the operative connection between the drum and the detent 10 to release the latter from the escapement wheel I8 and thus arm the mechanism. As stated, this connection, in the present instance, is shown as being in the form of a Maltese or Geneva gearing acting through the safety plate ll. The driving gear 90 of this gearing is fixed to the Ybottom of the housing 15 by driving the gear onto a hub l5 on the lower end thereof. The driving gear has a single tooth 9| with a notch 92 at each side thereof. The driven gear 93 is journaled on a stud 93 fixed to the bottom plate II. The driven gear has three lobes 94 with rectangular slots 95 therebetween. The outer edges of the lobes 94 are concentric to the periphery of the gear 9D, and the slots 95 are adapted to receive the tooth 9L The driven gear 93 has a nger 96 lying in the plane of the safety plate 1| and adapted to engage the opposing edge thereof to throw the safety plate out of safety position and the detent ll) out of engagement with the escapement wheel I8 when the cord has been substantially completely unwound from the drum. In the present instance, during the operation of unwinding the cord from the drum, the drum will make substantially three revolutions during which time the driven gear will be rotated substantially one-half of a revolution. When the cord 'i4 has been pulled free of the drum l5, the finger 96 on the driven gear 93 is engaged with the tooth provided on the safety plate 'H and, therefore, the spring 84 cannot rotate the gear 93 in a direction which would permit the plate 'll to again disarm the device. Further, an examination of Fig, 3 will show that once the device is armed, a clockwise rotation of the driving gear would not result in a counterclockwise rotation of the driven gear as the driving gear would merely jam against the driven gear sincev there are no mating surfaces enabling the driving gear to drive the driven gear counterclockwise.,

In order to render the mechanism safe duringhandling and transportation, the firing pin is` positively locked or secured in cocked position bya disposable nut, and the timing disk and safety disk are positively secured in safety position and the cord or strand is positively prevented from being pulled out by a disposable lock or member which, in the present instance, is secured in place by the disposable nut. As. will be seen most clearly from Figs. aand 5, the upper end of the firing pin extends. through the cap 53 and is threaded sow as4 to. receive a disposable nut H10. This nutv is adapted to bottom against the top of the cap 53, and when in place positively secures. the ring pin against escape from its cocked position. Thus, it. prevents accidental firing of the fuse in the; event that the sear should become displaced and the safety plate 'il should be jarred from safety position, which happenings might take place in the event that the `mechanisms were accidentally dropped, for example. The safety lock for the timing device and cord .comprises a plate lill adapted to be clamped against the top. of the cap 5S by the disposable nut lilik. From Fig. 4, it will be seen that the nut has a. boss m2 adapted to be received by an opening lilv in the body portion of the plate lill. This plate has a laterally extending arm |04 projecting over the timing disk 35, and the free end of this arm is turned down as at |85 and has a lug IUS adapted to extend through the slot l0 of the. timing disk 3d and into an aperture lill in the lobe of the safety disk 2l. The plate, at its other end, overlies the top of the cord guide 8| and the anchor member or sleeve B3, and it is slotted as at |88 so as to accommodate the protruding end of the cord. This end of the plate is bent downwardly and then backwardly so as to provide a hook m9 the free end of which takes into the circumferential groove Il!) adjacent the top of the guide 8l.

It will be seen from the foregoing description, taken in connection with the accompanying drawings, that when the disposable nut 100 and the lock plate itil are secured in place, the various instrumentalities or devices of the mechanism are secured against operation. In no event can the firing pin be released; the lug IBS positively locks the timing device against operation with the two disks thereof in safety position, and the plate Il prevents the cord from being pulled out since it locks the sleeve 83 in the counterbore in the upper end of the guide 8l. Thus the mechanism is rendered safe in handling and transportation. When it is desired to put the mechanism into use at the eld of operation, it is necessary to unscrew the nut |00 and lift oi the safety plate IUI and dispose of them, and these operations may be very rapidly carried out. After the safety nut and lock plate have been removed and disposed of, the mechanism is still relatively safe to handle. The detent 'l0 prevents operation of the timing device, and the safety disk prevents operation of the trigger even after the timing disk has been adjusted in accordance with the desired time interval between the dropping of the device and the release of the iiring pin. Furthermore, if, in handling, the cord should be only partially pulled out, the mechanism will not be armed. It will be observed that, due to` the length of the cord Wound upon the drum and the extent to which the drum must be rotated before the mechanism is armed, a substantial portion of the cord may be pulled out with safety. During the drawing out of the cord,A the drum 'I5 will slip with respect to the wound up spring 8&5,V and if the cord is then released, the spring will grip the drum and turn it in a direction, to again wind the, cord thereon. In operation, after the safety nut and lock plate. have been removed and disposed of, the timing plate 35 is adjusted by means of the wings or lugs 3B in accordance with the predetermined time interval which it is desired to have elapse between the arming of the mechanism and the release of the firing pin. In the event that the mechanism is used for controlling the ringof a parachute flare dropped from an airplane,A the free end of the cord 'I4 may be secured to the under side of the plane. Then, when the parachute flare and the timing mechanism are dropped, the weight thereof will cause the cord to unwind from the drum, and when the cord has been completely unwound, the knot T9' at the end thereof will be pulled out of the bore or opening '18, thus freeing the cord from the drum. During such unwinding of the cord froml the drum, the drum will make substantially three revolutions so as to operate the driven gear 94 in a series of stepsand thus bring the nnger 96'of this driven gear against the edge of the s afety plate li,4 whereupon the safety plate 1l is moved out of safety position and the detent 'lil is released from the escapement wheel. It will be observed that, with this arrangement, the cord lli is of substantial length and, therefore, the timing device is not armed until the mechanism has. dropped a substantial distance away from the plane. When the detent is withdrawn from the escapement wheel iS, the timing device is free to Operate causing rotation of the arbor i3 and, withdrawal.

of the lobe ofy the safety disk from the path` of movement of the free end of the trigger 115. When the timing disk 35 has been rotated by the spring I4 to a position where the slot 40 therein registers with the free end of the trigger, the trigger is free to pivot (counterclockwise, in Fig. 1) and thus release the sear 56. When the sear is released, the firing pin spring 55 will move the ring pin downwardly with a sharp movement resulting in ring of the primer of the nare (not shown).

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the following claims is intended to cover all of the generic and speciiic features of the invention herein described and all statements of the scope of the invention which, as a mattei' of language, might be said to fall therebetween.

We claim as our invention:

l. In a time-controlled firing mechanism, a firing device having a firing pin; a spring operated timing device for controlling the release of said iiring pin; means for arming said timing device comprising a member normally holding the same against operation, a drum, an operative for releasing the member from the timing device to arm the latter when the drum has been rotated to a predetermined extent, and a cord detachably connected to and wound about said drum and adapted to rotate the same when the cord is pulled out; and disposable safety means for locking said ring pin against operation and for preventing said cord from being pulled out.

2. In a time-controlled firing mechanism, a ring device having a spring operated firing pin; a timing device for controlling the release of said pin; arming means for the timing device ccmprising an operating cord adapted to be pulled out and a member secured to the cord adjacent its free end; a disposable safety nut screwed onto said pin for positively locking the same in cocked position, and a Vdisposable safety plate secured in position by said nut and cooperating with said member for preventing operation of the cord.

3. In a time-controlled firing mechanism, a ring device having a firing pin; a timing device for controlling the release of said ring pin and having a safety disk with an aperture and an adjustable timing disk provided with a slot; arming means for the timing device having a detent engageable therewith, a rotatable drum, an operative connection between the drum and detent, a cord wound about the drum, a guide through which the cord passes, and a member secured to the cord and adapted to seat within said guide,

said guide having adjacent said seat a circumferential groove; a disposable safety nut screwed onto said firing pin for positively locking the `same in cocked position, and a disposable lock ing said timing device and including a detent engageable therewith, a drum, an operative connection between said drum and detent for disengaging the detent from the timing device after the drum has been rotated a plurality of revolutions, a pull cord of substantial length Wound about said drum for rotating the same when the cord is pulled out, and a coiled spring within said drum tending to rotate the same in a direction to Wind the cord thereon, said spring being anchored at its inner end and having its outer convolution in frictional engagement with said drum.

5. In a time-controlled ring mechanism, a firing device; a timing device for controlling the release of said firing device; and means for arming said timing device including a detent engageable therewith, a rotatable drum, an operative connection between said drum and detent and including a Maltese gearing having a one-toothed driving gear Xed to the drum and a driven gear, a pull cord of substantial length wound about said drum, and a spring associated with said drum normally tending to rotate the same in a direction to wind the cord thereon.

G. In a time-controlled ring mechanism, a ring device having a spring pressed ring pin provided with a shoulder, a timing device for controlling the release of said firing pin, a, pivoted safety plate having a portion normally lying in the path of movement of said shoulder, a spring detent connected to said plate and adapted to engage said timing device, a rotatable drum, a Maltese gearing having a driving gear xed to said drum and a driven gear provided with a nger adapted to engage the edge of said safety plate to move said plate out of safety position and release said detent from said timing device, a pull cord wound about said drum, and a spring normally tending to rotate said drum in a direction to wind up the cord thereon.

THOMAS M, PERRY, FREDERICK H. HUNTER.

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