US2415362A - Fuze and setting mechanism therefor - Google Patents

Description

Feb. 4, 1947; A. H. MIDGLEY 2,415,362

/ FUSE AND SE TTING MECHANISM THEREFOR Filed March 19, 1942 3 Sheets-Sheet l I I I I [Fig.1

MICROPHONE.

Feb; 4', 11947. A. H. MIDGLEY 2,415,362

FUSE AND SETTING MECHANISM THEREFOR Filed Marh 19, 1942 3 Sheets- Sheet 2 Feh4, 1947. A. H. MIDGLEY FUSE AND SETTING MECHANISM THEREFOR Filed March 19, 1942 3 Sheets-Sheet 3 Fig. W

In venT' KS ff B Jeri/7V 6'- X WU) flfl'orntys Patented Feb. 4, 1947 (OFFICE FUZE AND SETTING MECHANISM THEREFOR Albert Henry Midgley, Northwood, and Donald John Grey, Swanley, England Application March 19, 1942, Serial No. 435,352 In Great Britain October 28, 1940 Claims. (01. 's9 1) 1 This invention relates to time fuzes for projectiles with more particular reference to the mechanical time fuzes such as are now largely employed in connection with the projectiles for antiaircraft guns.

In order to obtain the correct settin of the fuze to ensure that the shell will burst at the moment when it reaches the target, use is made of an observing and calculating instrument called a predictor, which gives the time of flight of the shell, that is, the interval between the firing of the shell and the moment at which it should reach the target. This is the time to which the fuze should theoretically be set for accurate results but under the system at present adopted allowance has to be made for what is known as the dead time, that is, the time occupied by the gun crew in setting the fuze and inserting the round in the gun. Such allowance is made by assuming a dead time and adding this to the calculated time but inasmuch as this assumes that the targets course, speed, and height remain the same during this period and since the actual amount of dead time varies with different gun crews, it is obvious that such a method makes it very difficult to secure an accurate setting.

The object of the present invention is to eliminate the dead time and ensure that the time adjustment of the time fuze at the moment that it is fired from a un is as desired at that moment, and the invention consists in means for setting the time fuze after the shell has been loaded in the gun and atthe instant of firing.

'I'heinvention also consists in the provision of means whereby the setting of the fuze and the operation of firing the gun are under the control of a predictor or observing and calculating instrument.

The invention also consists in a time fuze incorporating a setting clockwork mechanism brought into operation at the moment when the shell is loaded into the gun and means whereby such clockwork mechanism may be accurately synchronised with a contact-making device in the firing circuit of the gun co-operating with a contact under the control of the predictor,

The invention also consists in a fuze according to the preceding paragraph in which the setting clockwork is slidable in the fuze so that on firing the gun the clockwork sets back due to inertia and locks-the setting of the fuze by suitable means.

Further features ofthe invention will be apparent from the description given hereafter.

; The accompanying drawings illustrate one con- 2 V venient form of apparatus in accordance with the invention.

Figure 1 is a diagrammatic view showing the fuze, predictor and intervening circuit and mechanism.

Figure 2 is a sectional elevation on a larger scale of one form of fuze in accordance with the invention.

Figure 3 illustrates a detail.

Figure 4 is an inverted plan of a part of Figure 2.

Figure 5 is a view showing one method of bringing the setting clockwork into operation, and

Figure 6 is a plan of Figure 5.

In carrying our invention into efiect in one convenient manner as, for example, in its application to an anti-aircraft shell, the shell is provided with a known clockwork time fuze aof thetype provided with a hand I) spring-loaded against a slotted race 0 so that when the handf' coin,- cides with the slot d (Figure 4) in the race at the end of the time set itis movable therethrough for the purpose or detonating the fuze and bursting the shell. This form of clockwork time fuze is Well known and it is therefore believed that a detailed description of it herein is unnecessary. However, for further details reference may be had to the specification of British Patent No. 146,487 of October 16, 1916, which describes an example of this type of fuze, the manner in which the clockwork is normally maintained inactive,

. and the means by which it is set in motion at the time of firing the gun. The said specification also describes how the hand is maintained out of contact with the race prior to firing and then released for engagement therewith.

According to this invention, however, the fuze is provided with an additional clockwork mechanism e for setting the race, the hand being moved by the ordinary timing clockwork a and for the purpose of clarity the two mechanisms will be distinguished as setting and timing mechanisms respectively. The setting clockwork on the spindle of which the race is mounted, is slidable in the body of the fuze and co-operates with three nails f (Figure 2) or other means by which the race may be locked in position as hereafter explained. Q

- The setting clockwork is arranged to revolve the race at the rate of, say, one revolution per second for a period of ten seconds, and it is provided with a governor preferably of the fan type and is adapted to be set into operation by a clutch which may be released by magnetic operation of a steel rod, or mechanically as hereafter de scribed. The setting clockwork is also provided with a high pitch reed g which is struck by a small pin h on the race once in every revolution at zero setting, the reed and pin being shown diagrammatically in Figure 1, and in detail in Figures 2 and 3. The sound emitted by the reed is pickedupfrom the gun barrel or mounting by a microphone 2' or pick-up such as is used for engine-testing for example. The signal from the microphone or pick-up is taken to an amplifier i which may be at some distance away from the gun (provided with filter circuits for all frequencies other than those of thereed) and the amplified and rectified signal is taken to the grid of a gas-filled relay i the circuit of which is arranged to give a pulse of current of about a quarter second duration.

The sound given off by the reed is, as explained. used for the purpose of synchronising the setting of the race with a contact in the firing circuit under the control of the predictor, and for the purpose of such synchronisation we provide a constant speed motor (not shown) revolving at 60 revolutions per minute for which purpose a good' class gramophone motor provided with means for slight adjustment of speed is suitable. The motor is provided with a small fly-wheel k in place of the gramophone turntable and on the spindle of the motor are frictionally held two cams k, 76 fixed together (or a double cam) cooperating respectively with pins 1', 1 upon a spring-controlled slidable bar Z associated with the cams and adapted also to be controlled by an electro-magnet m in the circuit of the gasfilled relay above referred to, the bar I being mounted for sliding movement in ny suitable form of guide (not shown). When the motor is set in motion the cams will be held stationary against the friction of the driving spindle by the pin Z on'the bar I co-operating with the cam it but when the first synchronising impulse arrives the bar will be moved to release the cams for rotation. If the speed of the cams is exactly the same as that of the setting clockwork in the nose of the fuze they will continue to revolve since each impulse of synchronising current will move thepin away from its cam at the correct moment. If, however, the speed of the motor is high then the cams will be held a fraction of a second by the pin 1' engaging the cam 70' in order to bring the speeds into exact synchronism. On the other hand, if the speed of the motor is low then the other pin 1 engaging the cam R will force the cams forward the correct amount to secure synchronisation.

The cams carry a contact n which is atzero position when the slot in the race isat zero and it will be seen therefore that the position of the contact will always give an external indication of the position of the race in the fuze. The contact is arranged in the firing circuit for the gun, which also embodies a firing switch 0, and there is a second contact in the circuit under the control of the predictor; for example, such contact maybe carried by a pointer revolving in a circular path round the cams, this pointer being operated by the predictor and following at all times the setting given by the predictor.

Theoperation is as follows:

The synchronising motor is running and the predictor pointer is moving round the cams but the latterare stationary. With the arrangement of fuze shewn in Figure 1, the end of the fuze is placed in the end of an electro or permanent magnet which, by its attractive force on the steel rod 1' moves the latter (within the limits imposed by a stop r projecting into a slot in the rod 1) and disengages the clutch r of the setting clockwork e so that the latter is set in motion at the moment when the shell is loaded into the gun. The first sound of the reed picked up by the microphone starts the cams rotating while further impulses will keep the contact on the cams in synchronism with the setting of the race in the fuze. When now the firing switch 0 is closed the gun will fire immediately the predictor contact on the arm p makes with the cam contact 72 and on the firing of the gun the setting clockwork sets or moves back so that the nails J are pushed forward, by engagement of their rear ends on the abutment f entering into the slot or opening f in the clockwork body, which is smaller than the nails but facilitates the entry of the nails, and thus due to inertia the race is locked at the exact setting required by the nails entering and enlarging at the point of entry the space B. At the same time the timing clockwork a of the fuze is set in motion in the normal manner as described for example in the before-mentioned British specification and thus the exact timing of the fuze Without any allowance. for dead-time is obtained.

Figures 2 and 5 show a mechanical arrangement for setting in motion the setting clockwork at the moment the shell is loaded into the gun. In this construction the rod 1' in the nose of the fuze is surrounded by two wire circlets r fitting tightly in grooves in the rod. When the rod is mechanically pushed inward the upper circlet r expands into the recess surrounding it allowing the rod to pass through. This inward movement of the rod causes it to engage the spring s on the rocker s so as to pivot the latter and raise the catch s which releases the setting clockwork.

The setting clockwork is normally retained by a shear pin t which is sheared when the clockwork sets back on the firing of the gun, and the clockwork is guided in its sliding movement by the pin t engaging the slot t in the clockwork casing.

As explained above the timing fuze is also started automatically on the firing of the gun and the hand b is urged by its spring into engagement with the race which has been locked in position by the nails J. The rotation of the "hand continues until it register with the slot in the race when it is then urged into the slot and this further movement of the hand releases the firin pin or other detonating element.

As soon as the race has been locked in position the cams will be held stationary in their zero position thus indicating that the gun requires reloading or, if desired, any suitable alarm circuit may be provided for the purpose.

Since the cams always become stationary in the zero position it is preferable to arrange the predictor contact so that it cannot make with the cam contact at zero, or, say, one second, in which case it will be impossible to fire the gun with the-fuze set' at zero or onesecond.

In practice the predictor and cam contacts would preferably not carry thefiring current but would operate a relay in the firing circuit.

It will be understood that the invention is not limited to the particular construction of time-mechanical fuze hereinbefore given byway of'example, nor do we wish to limit ourselves to the particular constructionsgiven, since the invention extends broadly to any arrangement'adapted to give a setting of the fuze after 'the shell has been loaded into the gun. As examples of some such modifications we may instance the use of a mechanical interference gear in place of the electric contacts above referred to and in the case of guns fired by ether than electrical means the firing gear can be altered to electric, or it may be adapted either electrically or mechanically to fire by the joint action of the trigger and the external mechanism in accordance with the invention.

We claim:

1. Means for controlling the setting of the time fuze of a projectile comprising in combination a predictor for giving the time of flight, an electrical firing circuit for the gun, and a self-contained fuze within the projectile comprising a clockwork timing mechanism adapted to be set in motion at the moment of firing, a second clockwork mechanism for setting the timing mechanism and means operable to bring said second mechanism into operation at the moment of loading the projectile into the gun, a, contact-making device in the firing circuit of the gun co-operating with a contact under the control of the predictor and means whereby the setting clockwork mechanism may be accurately synchronized with said contact-making device.

2. The combination of a time fuze including a timing clockwork mechanism, a setting clockwork mechanism, means for bringing said last named mechanism into operation at the moment When the shell is loaded into the gun, said setting clockwork mechanism being slidable in the fuze, and means to lock the setting of said clockwork when on firing the gun said clockwork moves back due to inertia, a firing circuit including a contact making device, and means for synchronizing said setting clockwork mechanism with said contact making device.

3. A combination according to claim 2 including a reed in the fuze, a pin carried by said setting clockwork mechanism for striking said reed to emit sound impulses, and electrical means actuated by said sound impulses for controlling the synchronizing means.

4. The combination of a gun firing mechanism, and a time fuze for a projectile comprising a timing clockwork embodying a hand and a race having a slot through which the hand may pass when the two are in register to cause detonation of the fuze, a second clockwork for setting the race to an angular position determining the time of fiight of the projectile before detonation of the fuze, means for starting the setting clockwork in motion at the moment the projectile is loaded into the gun, and means for stopping the operation of said setting clockwork at the moment the gun is fired and thereby fixing the setting of said fuze for a desired time interval, said firing mechanism including means movable in correspondence with the slot in said race, and means to actuate the firing mechanism to fire the gun when the slot in the race occupies a position corresponding to the desired time interval.

5. A combination according to claim 4 wherein said fuze includes a catch for restrainin the setting clockwork and a rod in the nose of the fuze movable to release said catch for the purpose of starting the setting clockwork.

6. A combination according to claim 4 including a movable contact device forming part of said firing mechanism which is at zero position when the slot in the race is at zero, a reed in the fuze, a pin carried by the race for striking said reed to emit sound impulses, and electrical synchronizing means actuated by said sound impulses for synchronizing the movements of said race and said contact device whereby the position of the latter Will at all times correspond with the position of the slot in the race within the fuze.

7. A combination according to claim 4 wherein said gun firing mechanism comprises an electrical firing circuit and a movable contact for closing said circuit and determining the instant of firing, and which includes means for synchroiiizing the movements of said race and said conact.

8. A combination according to claim 4 wherein said gun firing mechanism comprises an electrical firing circuit, and which includes a predictor for determining the time of flight, a contact in the firing circuit under the control of the predictor, a movable contact in the firing circuit cooperating With the predictor-controlled contact to complete said firing circuit, and means for synchronizing the movements of said race and said movable contact.

9. The combination of a gun firing mechanism, and a time fuze for a projectile having a pair of relatively movable members the positions of which with respect to one another at the instant of firing the gun determine the time of flight of the projectile before detonation of the fuze, a clockwork setting mechanism for moving one of said members relatively to the other to set the fuze, means operable to put said clockwork mechanism into operation at the time the projectile is loaded into the gun, and means for stopping the operation of said clockwork mechanism at the moment the gun is fired and thereby fixing the setting of said fuze for a desired time interval, said firing mechanism including a member movable in correspondence with the member of said fuze which is moved by said clockwork setting mechanism, and means to actuate the firing mechanism to fire the gun when said last named member occupies a position corresponding to the desired time interval.

10. A combination according to claim 9 wherein said gun firing mechanism includes an electrical firing circuit, a contact carried by the movable member of said firing mechanism, a cooperating contact movable under the control of a predictor or observing and calculating instrument, and means for synchronizing the movements of the-movable member of said firing mechanism and the fuze member moved by said setting clockwork mechanism.

ALBERT HENRY MIDGLEY. DONALD JOHN GREY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,635,365 Karnes July 12, 1927 FOREIGN PATENTS Number Country Date 58,603 Swedish Jan. '7, 1924

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