US3421442A

US3421442A - Environmental fuze device for air-dropped flares and the like

Info

Publication number: US3421442A
Application number: US666906A
Authority: US
Inventors: Donald R St Clair
Original assignee: General Time Corp
Current assignee: Electrodynamics Inc
Priority date: 1967-09-11
Filing date: 1967-09-11
Publication date: 1969-01-14
Anticipated expiration: 1986-01-14

Description

Jan. 14, 969 D, R, 5T, CLAN-Q 3,421,442

ENVI'RONMENTAL FUZE DEVICE FOR AIR-DROPPED FLARES AND THE LIKE Filed Sept. ll, 1967 Sheet of 5 INVENTOR aNALo R.ST.C`LA|R 1 :w I ,ma/7am y 0% Arrvs,

Jan. 14, 1969 D, R, $11 CLAlFQ l 3,421,442

ENVIRONMENTAL FUZE DEVICE FOR AIR-DROPPED FLARES AND THE LIKE Filed Sept. ll, 1967 Sheet 2 of 3 m Aw RS'LCLAIE 1,3.' www MMM, V51# @Am A'rTYs.

Jan. M, E969 D. R. sT. CLAlR 3,4%,442

ENVIRONMENTAL FUZE DEVICE FOR AIR-DROPPED FLARES AND THE LIKE Filed sept. 11, 1967 sheet 3 of :s

5o fr@ NvENron @www RS'LCLAIR United States Patent C 8 Claims Int. Cl. F42c 9/02; F42c 5/00; F42c 15/00 ABSTRACT F THE DISCLOSURE An improved environmental fuze device for use with air-dropped dares and the like. The fuze includes a timed firing mechanism for ring the launched ilare or other article a preselected time interval after launching. The fuze includes several safety features, one of which disables the tiring mechanism for a preselected time delay interval after launching, so that the flare or other article cannot be fired until it has dropped a safe distance below the launching aircraft, Another safety feature is a pressure responsive device which measures a preselected pressure change as the fuze descends through the atmosphere after launching. This pressure responsive device is operatively connected to the tiring mechanism for blocking the tiring of the launched article until the preselected pressure change has been measured. In the illustrated embodiment, the pressure responsive device is in the form of a bellows which is enclosed within the fuze until it has been launched. After launching, the fuze opens to expose the interior of the bellows to the ambient atmosphere, and then the bellows is closed to initiate measurement of the preselected pressure change.

The present invention relates generally to environmental fuze devices and, more particularly, to an improved environmental fuze device for air-dropped flares and the like.

It is a primary object of the present invention to provide an improved environmental fuze device for air-dropped flares and the like which eliminates the possibility of accidental functioning of the flares aboard or near the aircraft from which they are dropped. A related object is to provide such a fuze device which improves both the safety and mission reliability of chemical flares, or other air-dropped articles, under all delivery conditions.

Another object of this invention is to provide an improved environmental fuze device of the foregoing type which includes safety features which are operative in all environments of the flares controlled thereby, including storage and handling, normal delivery, and abort delivery.

It is a further object of the invention to provide an improved environmental fuze device of the type described above which is extremely accurate and insensitive to vibration.

Still another object of the invention is to provide such an improved fuze device which is easy to set. In this connection, a particular object of the invention is to provide such a fuze which can readily be set in conditions of darkness or poor visibility.

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

FIGURE l is a top-plan view of an environmental fuze device embodying the present invention;

FIG. 2 is a side elevation of the device of FIGURE 1;

FIG. 3 is a top view of the device of FIGURE 1 with the cover removed;

FIG. 4 is a vertical section taken along line 4 4 in FIGURE 1;

3,421,442 Patented Jan. 14, 1969 rice FIG. 5 is a fragmentary section showing the timing mechanism in the fuze device of FIGURE l;

FIG. 6 is a fragmentary elevation of the bellows assembly in the fuze device of FIGUREv l; and

FIG. 7 is a schematic diagram of the various safety features associated with the tiring mechanism in the fuze device of FIGURE l.

While the invention will be described in connection with certain preferred embodiments, it will be understood that it is not intended to limit the invention to these particular embodiments. On the contrary, it is intended to cover all alternatives, modications, and equivalent arrangements as may be included within the spirit and scope of the invention as dened by the appended claims.

Turning now to the drawings, the illustrative fuze assembly embodying the present invention includes a cover 10 mounted on an adapter 11 designed to mount the fuze assembly on a projectile such as a chemical are or the like. The adapter 11 forms a central chamber `12 for receiving the charge to be tired by the fuze mechanism, and carries a mounting assembly including a base member 13 secured to the adapter 11 by a plurality of set screws 14, a plurality of integral pillars -15, and a top mounting plate 16 secured to the pillars 15 by means of screws 17. To secure the fuze cover 10' to the adapter 11, a plurality of separation pins 18 are secured at their upper ends to the cover 10 by set screws 19, and project downwardly from the cover into complementally formed holes in the adapter 11 and base member 13 (FIG. 4). The lower portion of each pin 18 is provided with a beveled shoulder 20 for engaging an arm of a spider 21 which is biased against the pins 18 to hold the cover 10` against the adapter 11.

For the purpose of sealing the interior cavity formed by the cover 1t] and the adapter 11 from the ambient atmosphere, an O-ring 22 is placed therebetween. As the cover 10 and the adapter '11 are drawn together, the O-ring 22 is slightly compressed, as illustrated in FIG. 4, to insure good sealing engagement with the mating surfaces of the two units.

Before the fuze is launched, it is set to tire the charge in chamber 12 after a selected time interval measured from the time of launch. To permit the selection of different time intervals, the illustrative fuze includes a time set knob 23 keyed to a shaft 24 in a recess 25 formed in the top of the cover 10. Inside the cover 10, the shaft 24 is connected to a `gear wheel 26 engaging a one-way pawl 27 to provide a detent action so that the operator feels repetitive clicks as the time set knob .23 is turned. This feature is especially helpful when the time setting must be made in the dark or poor lighting conditions. The gear wheel 26 also engages a time set gear 28 which carried a depending lug 29 (FIG. 5). As the gear 28 is turned in response to manual movement of the outside knob 23, the depending lug 29 engages a cooperating upwardly projecting lug 29a on a timing disc 46, thereby setting the disc 46 to a selected angular position. corresponding to the setting of the knob 23. Thus, as will be apparent from the ensuing description, the angular position of the lug 29, as set by the gear 26 and knob 23, actually determines the time interval measured by the fuze between launching and firing. To maintain a seal between the interior of the fuze and the ambient atmosphere, an O-ring 30 is preferably placed between the gear 26 yand the top of the cover 10.

In order to arm the illustrative fuze, it is necessary to withdraw both a safety pin 31 and an arming pin 32 from a transverse hole 33 through the cover 10, thereby releasing a bore-riding pin 34 slidably mounted within the hole 33 (FIG. 4). The safety pin 31 is 'withdrawn manually before the fuze-carrying projectile is placed in the launching chute, and the arming pin 32 is withdrawn automatically as the fuze passes through the launching chute. Thus, when the fuze clears the launching chute, both

pins

31 and 32 have already been withdrawn, and the pin 34 is ejected from the fuze under the urging of a biasing spring 35. In order to seal the interior of the fuze from the ambient atmosphere before the pin 34 is ejected, an O-ring 34a is seated in a circumferential groove in the pin, in sealing engagement with the wall of the hole 33.

As long as the bore-riding pin 34 is in its retracted position, it serves as a stop for an upright lever 36 formed as an integral part of the separation spider 21. As soon as the pin 34 clears the inside wall of the cover 10, the separation spider 21 is released, and itis immediately cammed in a counterclockwiseY direction. The camming action is effected by a plurality of separation springs 37 which urge the cover and thus the separation pins 18, away from the adapter 11 on which the spider 21 is mounted. As long as the spider 21 is held in locking engagement with the shoulders of the pins 18 -due to the blocking action of the bore-riding pin 34, the cover 10 and the adapter 11 are held rmly together. When the pin 34 is ejected, however, the beveled shoulder 20 immediately cams the spider 21 away from the pins 18 under the urging of the separation springs 37, thereby separating the cover 10 from the adapter 11 and exposing the interior of `the fuze to the ambient atmosphere. This separating movement is limited by a second shoulder 38 on the lower portion of each pin 18 abutting an opposed shoulder 39 on the base member 13. Consequently, the cover 10 and the adapter 11 are separated only by a distance equal to the original distance between the two opposed

shoulders

38 and 39, and are then held in such separated positions by the biasing action of the springs 37. In the particular embodiment illustrated, the separation springs 37 are mounted on a plurality of pins 40 formed as integral parts of the base member 13, but it will be apparent that a number of different mounting arrangements might be used.

The limited separation of the fuze cover 10 from the adapter 11 in response to launching of the fuze serves to initiate several different functions in the fuze. First of all, the separation actuates the timing mechanism of the fuze to initiate the measurement of the particular time interval selected by the setting of the outside knob 23. Thus, as the fuze cover 10 is separated from the adapter 11, a laterally projecting set screw 41 on the inside wall of the cover is disengaged from a pallet 42 in the escapement mechanism of a timer assembly 43 (FIG. 5) so as to start the timer. The timer 43 rotates an output shaft 44, which in turn rotates a safety disc 45 and a timing disc 46. As the timing disc 46 is rotated, a cut-out or notch 47 formed in the periphery thereof is eventually brought into register with a sensor element 48 to actuate the tiring mechanism, as will be described in more detail below. It can be seen that the time interval between actuation of the timer 43 and registration of the notch 47 and sensor 48 depends on the initial setting of the timing disc 46 'via the time set knob 23. Thus, the time interval measured by the timing mechanism between launching and firing is accurately and reliably controlled by the angular setting of the timing disc 46. To prevent any movement of the safety disc 45 during the manual setting of the timing disc 46, a slip clutch preferably connects the two discs so that the initial setting movement of the disc 46 does not affect the position of the disc 45.

In accordance with the present invention, the fuze device is provided with a pressure responsive safety means for measuring a preselected pressure change following launching of the fuze, as it descends through the atmosphere, with the safety means being operatively connected to the firing mechanism for blocking the firing of the launched charge until the preselected pressure change has been measured. Thus in the illustrative fuze, a pressure sensing bellows 50 has its interior cavity connected to the interior of the fuze assembly through a control valve 51 and interconnecting tubing 51a. The opening and closing of the valve 51 is controlled by a spring loaded stem 52 which is normally held in its open position by means of a conventional release sear 53 operated by a springbiased release shaft 54, carrying the sensor 48. Thus, the valve 51 is open at the time of separation of the fuze cover 10 from the adapter 11 so as to expose the interior of the bellows 50 to the ambient atmosphere at the time of separation, i.e., the interior of the bellows is at the same pressure as the ambient atmosphere at the launching altitude. After the fuze has been launched, the bellows is automatically closed, as described in more detail below, to initiate measurement of the preselected pressure change.

As a further feature of 'this' invention, a time delay means is operatively associated with the pressure responsive safety means and the fuze timer for delaying the initiation of the measurement of the selected pressure change, and at the same time blocking actuation of the firing mechanism, for a predetermined delay time interval after launching, and then automatically closing the bellows to initiate the pressure measurement. Thus, in the illustrative embodiment, a depending lug 60 on the sensor 48 rides on the edge of the safety disc 45 so as to hold the sensor in its original blocked position for a predetermined time interval atter the separation has been effected. This time interval is determined by the length of the engaging edge of the safety disc 45, and the velocity at which it is driven by the timer 43.

At the end of the delay interval, the sensor 48 drops off the safety disc 45 onto the timing disc 46 under the urging of a biasing spring 57. This limited angular movement of the sensor 48 turns the release shaft 54 sufficiently to upset the sear 53, thereby releasing the valve stem 52 for movement to the closed position under the urging of its biasing spring. As the sensor 48 engages the timing disc 46, it also engages a blocking pin 58 mounted on the top of the bellows 50 so that the sensor is blocked by the dual action of the timing disc 46 and the bellows pin 58. Thus, the sensor cannot advance any further until 1) the bellows 50 has contracted suiciently to retract the blocking pin 58 below the sensor 48 and (2) the timing disc 46 has rotated sufficiently to bring the notch 47 therein into register with the end of the sensor 48.

Since the bellows 50 is closed in response to the dropping of the sensor from the safety disc 45 onto the timing disc 46, as described above, it begins to contract as the ambient atmospheric pressure increases during descent of the fuze-carrying article. 'I'hat is, the pressure on the inside of the bellows 50 remains constant at the pressure existing in the ambient atmosphere when the [bellows w'as closed, while the pressure outside the bellows continuously increases as the fuze descends to lower altitudes, thereby contracting the bellows and withdrawing the pin 58 from the sensor arm 56. When the bellows 50 has contracted sufficiently to clear the sensor 48, i.e., when the fuze has dropped through the pnessure lchiange wihich the bellows is designed to measure, the sensor is free to drop into the timing disc notch 47 when it comes into register with the depending lug 60 on the enfd of the sensor. On the other hand, if the timing disc notch 47 reaches its position of registration with the sensor lug 60 before the bellows pin 58 clears the sensor 48, the timing disc 46 continues to rotate so as to advance the notch 47 past its point of registration with lug `60. This provides a safety feature so that if the bellows does contract to clear the sensor 48 at a later time, the fuze will dud. This is an important feature that allows the fuze to fire only if the designed pressure change occurs within the time interval selected by the original setting of the time set knob 23. Consequently, a hung up flare or other fuzerd article can be safety retained in the launching aircraft with no danger of a delayed firing during an altitude change later in the flight.

If the bellows pin 58 clears the sensor 48 Within the selected time interval, the ldepending lug 60 on the sensor drops into the timing disc notch 47 when it comes into register therewith, thereby turning the release shaft 54 suiciently to upset a second release sear 65. The upsetting of the sear 65 releases a ring pin 66 for axial movement under the urging of a biasing spring 67. The advancement of the firing pin 66 ignites the charge contained in the chamber 12 in the usual manner.

In order to counterbalance any acceleration or vibnation that might be acting on the mass of the bellows system, a conventional counterweight 61 is preferably connected to the movable end of the bellows via a lever 62 halving a fixed pivot point 63, as shown in FIGURE 6. This counterweight prevents the upper end of the bellows 50 from moving sideways or downwards, for example, when the fuze is placed in a spin condition. To permit adjustment of the bellows assembly an adjustable spring 64 is connected to the counter-weight side of the lever 62` so las to provide a variable biasing means.

In laccordance with another aspect of this invention, a further safety means is provided in the form of @a blocking pin S5 which projects longitudinally inwardly from Ithe fuze cover for cooperation with a laterally projecting arm 56 on the sensor element 48. This safety blocking pin 55 prevents the sensor 48 from being pivoted sufficiently to upset the release sear 53y as long as the fuze cover remains closed, thereby providing a safety block in the event of a stripping of the gear train of the timer, or a closing of the bellows due to extreme shock or crushing, for example. The blocking pin 55 is retracted to clear the sensor arm 56 only when the cover 10 separates from the adapter 11, thereby releasing the sensor 48 for angular movement as 'described previously.

`It will be appreciated from the foregoing description that the interior of the bellows 50 is exposed to the ambient atmosphere at the time of launching or separation, or a preselected delay time interval thereafter. Consequently, the interior of the bellows assumes the pressure existing Iat the launching altitude, and is then closed to measure the preselected pressure change during the ensuing ldescent. As a result, the blocking pin SS on the top of the bellows 50 is always in the same fixed position at the time of separation, regardless of the particular altitude at which the fuze is launched, so that the bellows 50 does not respond to pressure uctuations due to altitude changes until after the fuze has been launched, and the sepan-ation effected. This open bellows system has the advantage of eliminating any need for temperature compensation, such as that required when a closed bellows system is used. It will be understood that fuze devices of this type must operate over a wide range of temperatures that normally require a rather expensive temperature compensating system.

The delay time interval provided by the safety disc 45 also has a number of advantages. For example, it insures that the bellows will not be closed until the fuze has dropped below any pressure fluctuations caused by the launching aircraft, thereby insuring that exactly the desired pressure ohange will be measured, and contributing to the overall reliability of the fuze device. Moreover, the Idelay interval provides a safety feature to prevent an aibortve tiring in the immediate space surrounding the launching aircraft, .e., it blocks the firing mechanism until the fuze has dropped a safe distance below the aircraft. In addition, the delay interval insures that the bellows will remain open for a sutiicient interval following separation to achieve equilibrium with the ambient atmosphere. Consequently, even in the event of a failure, both the pressure responsive safety means and the timer control, tihe launching aircraft and the personnel therein are still protected.

As can be seen from the foregoing detailed description, this invention provides an improved environmental fuze device which eliminates the possibility of accidental functioning of the fuzed article aboard or near the aircraft from which it is dropped. The fuze device provided by this invention includes safety features which are independently responsive to both pressure land time so as to improve both the safety and mission reliability of the fuzed flare or other article under all delivery conditions. Since the pressure responsive safety device is rendered operative only in response to launching of the fuze, the flare on which the fuze is used is completely inoperative until it has been launched, regardless of the type of environment to which it is subjected during storage and handling prior to the launched time. Moreover, the internal structure of the fuze is such that both the time and pressure measurements made thereby are extremely accunate and insensitive to vibration.

I claim as my invention:

1. An improved fuze device for air-launched articles such as flares and the like, said fuze device comprising the combination of a timed firing mechanism for ring the launched article at a preselected time after launching, pressure-responsive safety means for measuring a preselected pressure change as the fuze descends through the atmosphere after launching, said safety means being operatively connected to said timed firing mechanism for blocking the firing of the launched article until said preselected pressure change has been measured, and time responsive safety means operatively associated with said timed firing mechanism and said pressure responsive safety means for blocking the actuation of said firing mechanism after said preselected tiring time so that said article cannot be tired if said preselected pressure change is measured subsequent to said preselected tiring time.

2. An improved fuze device as defined in claim 1 which includes means for automatically exposing said pressureresponsive safety means to the ambient atmosphere in response to the launching of said fuze.

3. An improved fuze device for air-launched articles such as flares and the like, said fuze device comprising the combination of a timed firing mechanism for firing the launched article a preselected time interval after launching, and pressure-responsive safety means for measuring a preselected pressure change as the fuze descends through the atmosphere after launching, said pressure-responsive safety means including a bellows and associated v-alve means for opening the bellows to the ambient atmosphere at launching and then closing the bellows after launching to render the bellows responsive to changes in the atmospheric pressure during descent of the fuze, said bellows being operatively connected to said timed firing mechanism for blocking the firing of the launched article until said preselected pressure change has been measured.

4. An improved fuze device as defined in claim 3 which includes time-delay means operatively associated with said pressure-responsive safety means for delaying the initiation of the measurement of said preselected pressure change for a preselected delay time interval after said launching.

5. An improved fuze device for air-launched articles such as flares and the like, said fuze device comprising the combination of timing mechanism responsive to the launching of said article for measuring a preselected time interval after said launching, tiring mechanism operatively connected to said timing mechanism and said article for firing said article at a preselected tiring time determined by the preselected time interval measured by said timing mechanism, pressure-responsive safety means operatively connected to said timing mechanism and said firing mechanism for measuring a preselected pressure change following the launching of said article and preventing the ring of said article until the measurement of said pressure change is completed, and sensing means responsive to both said timing mechanism and said pressure responsive safety means for actuating said firing mechanism at said preselected firing time only if said preselected pressure change is measured prior to said preselected firing time and blocking the actuation of said firing mechanism after said preselected firing time -whereby the actuation of said firing mechanism is prevented if said preselected pressure change is not measured until after said preselected ring time.

6. An improved fuze device for air-launched articles such as flares `and the like, said fuze device comprising the combination of timing mechanism responsive to the launching of said article for measuring a preselected time interval after said launching, tiring mechanism operatively connected to said timing mechanism and said yarticle for firing said article in response to completion of the measurement of the preselected time interval by said timing mechanism, pressure responsive safety means operatively connected to said timing mechanism and said firing mechanism for measuring -a preselected pressure change following the launching of said article and blocking said tiring mechanism until the measurement of said pressure change is completed, and time delay means operatively connected to said timing mechanism and said pressure responsive safety means for blocking said firing mechanism and delaying the measurement of said pressure change for a predetermined time interval following launching.

7. An improved fuze device for air-launched articles such as ares and the like, said fuze device comprising the combination of a timed firing mechanism for ring the launched article at a preselected time after launching, pressure responsive safety means for measuring a preselected pressure change as the fuze descends through the atmosphere after launching, said safety means being operatively connected to said timed ring mechanism for blocking the firing of the launched article until said preselected pressure change has been measured, control means operatively connected to said pressure responsive safety means for enabling said safety means in response to launching of the fuze device so that said safety means is unaffected by environmental changes prior to launching, and time responsive safety means operatively associated with said timed ring mechanism and said pressure yresponsive safety means for blocking actuation of said ring mechanism after said preselected firing time so that said article cannot be fired if said preselected pressure change is measured subsequent to said preselected tiring time.

8. An improved fuze device as defined in claim 7 in which said pressure responsive safety means is a bellows which is normally open, and said control means is a valve mechanism for automatically closing said bellows in response to launching of the fuze device.

References Cited UNITED STATES PATENTS 2,513,185 6/1950 Lauritsen 102-81 2,940,392 6/1960 Loren et al. 102-70 2,988,992 6/1961 Elmer 102-16 SAMUEL FEINBERG, Primary Examiner. GERALD H. GLANZMAN, Assistant Examiner.

U.S. Cl. X.R. 102-81