US2596171A

US2596171A - Pressure switch for fuses

Info

Publication number: US2596171A
Application number: US108382A
Authority: US
Inventors: Rabinow Jacob
Original assignee: US Department of Army
Current assignee: US Department of Army
Priority date: 1949-08-03
Filing date: 1949-08-03
Publication date: 1952-05-13
Anticipated expiration: 1969-05-13

Description

y 3, 1952 J. RABINOW PRESSURE SWITCH FOR FUSES 2 SHEETSSHEET 1 Filed Aug. 5, 1949 gwuon'fo'b Jucub Hnbinuw zw wwmg g May 13, 1952 J. RABINOW PRESSURE SWITCH FOR FUSES Filed Aug. 3,- 1949 2 SHEETS-SHEET 2 gwwcmfom a 22 wJnED b Huhinuw Patented May 13, 1952 UNITED 'iATS PATENT FFIE PRESSURE SWITCH FOR FUSES (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

My invention relates to arming devices for electrically operated fuses for ordnance projectiles, such as bombs or artillery shells. By an electrically operated fuse, I mean a fuse in which the final firing is accomplished by or requires the closing of, an electric circuit in the fuse.

In ordnance fuses it is essential to provide the utmost degree of safety against abnormal conditions such as shocks which might occur in handling or transportation, and to make the fuse responsive only tothose conditions which occur uniquely when the projectile bearing the fuse has been launched against a target in actual use, so that only when the fuse is subject to these conditions can it be armed. One condition common to both bombs and shells is velocity relative to the ambient atmosphere, since the projectile is extremely unlikely to encounter velocities of the order of magnitude which occur when it is in flight after launching, except when it actually has been launched or fired.

It is an object of my invention to provide a fuse which is uniquely actuated by high velocity motion relative to its ambient atmosphere and which is' unaffected by shocks or high acceleration or deceleration such as might occur from dropping onto a hard surface or being struck by another projectile. It is also an object to provide this feature in a simple, inexpensive, foolproof and relatively tamper-proof device which is positive and definite in operation.

The specific nature of the invention as well as other objects and advantages will clearly appear from a description from a preferred embodiment in the accompanying drawings in which:

Figure 1 is a longitudinal axial sectional view of a fuse embodying my invention showing the principle of operation.

Figure 2 is a sectional view taken on line 2-2 of Figure 1.

Figure 3 is a view similar to Figure 1 showing a bimetallic switch element instead of a simple pressure responsive element.

Figure 4 is a view partly in section of a fused projectile responsive to temperature rise only.

In the drawings I is the nose of a fuse adapted to be threaded at 2 into a projectile such as a bomb or a shell 3 and provided with a threaded portion 4 adapted to receive a threaded base element 5 which can also be screwed into the body portion of an electric fuse 6 which may be of any Jacob Rabinow, Washington, D. 0., assignor t0 the United States of America as represented by desired or known type requiring the closing of an electric circuit for arming the fuse. This electric circuit is represented by leads '5, connected to terminals 8 which are adapted to be bridged by a circular dished snap disc 9 to close the circuit to arm the fuse.

Snap disc 9 has two positions as shown in the dotted and solid lines respectively. In the unarmed position the switch will of course be in the center raised position shown by the solid lines. The snap diaphragm 9 is supported concentrically between two resilient rings I! and i2 which may be of rubber or of similar resilient material under compression by screwing down the threaded member 5.

The diaphragm 9 is clamped between rings H and [2 at a radius approximately two thirds the total radius of the diaphragm so that the mass of that part of the diaphragm radially beyond the clamping means is approximately equal to the mass of the part within the clamping rings; ther fore ordinary shocks will not close the ring as they act on a balanced member which is also resiliently supported by the rings. Shock forces thus tend to balance out around the rings as a pivot. Opening [0 which is preferably located in the nose of the fuse may have a needle valve l3 for controlling the effective size of aperture Hi. This aperture leads to pressure chamber iii. A time delay is thus provided by requiring a longer or shorter time to build up a critical pressure in chamber it according to the setting of valve Hi When the projectile is in flight.

The operation of the device should be self evident from the above description. When the projectile is in flight, due to the increased atmospheric pressure on the nose thereof air flows down the passage l9 past needle valve I3 and into chamber I6. As the resilient rings H and I2 form a tight seal, the pressure in chamber l6 acts only upon the central portion of the diaphragm 9 and when this pressure reaches a predetermined amount, the diaphragm is snapped down into circuit closing relationship, with the contacts 8. This action is positive and certain and since the contacts are in a closed chamber, they will remain clean and in good condition until ready for use.

In Figure 3 the diaphragm is dimensioned and mounted exactly as in Figure 1 but in this case it is constructed as a bimetallic snap disc 9. This type of construction is old and well known for use as a thermostatic switch element per se, but in the device shown it is made use of in a switch responsive to both pressure and temperature. The temperature in this case would result from the relatively rapid compression of gas in chamber [6, and this can be pre-set so that only when the pressure rises at a rate corresponding to what will occur when the projectile is correctly launched and properly in flight will the correct combination of pressure and temperature be present which will snap the diaphragm to close the switch.

Figure 4 shows a rocket having a warhead 2| and a combustion chamber 22 wherein the rocket propellant is contained to propel the missile. Between the warhead and combustion chamber is a switch chamber 23 containing a balanced bimetallic snap switch element 24 in all respects similar to switch 9 of Figure 3, except that it is not arranged to be affected by air pressure, but by temperature change only. When the rocket is launched, the heat of combustion in chamber 23 will eventually reach the point for which the bimetallic element 24 is set and it will snap over to bridge terminals 25 to arm the fuse generally indicated at 26. 7

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction within the scope of my invention as defined in the appended claims.

I claim:

1. In an electric fuse for projectiles, a safety arming switch having contact means, an actuating member for engaging said contact means to close the switch, said actuating member comprising a dished flexible snap disc capable of being flexed into either of two dish-shaped forms, supporting means engaging said disc circumferentially at points on a perimeter defining within it substantially one-half of the mass of the disc, whereby the disc is balanced against inertia forces acting directly thereon, said disc being arranged, when flexed into one dished position to close the switch and when flexed into the alternate dished position to open said contact means.

2. In an electric fuse for projectiles a safety arming switch having contact means, an actuating member for bridging said contact means to close said switch, said actuating member comprising a dished flexible snap disc capable of be ing flexed into either of two stable dish shaped forms, supporting means engaging said disc circumferentially at points at a radius substantially two thirds the total radius of the snap disc whereby the disc is balanced against inertia forces, said disc being initially flexed to open circuit position on said supporting means, a chamber having a portion of said disc as part of the wall thereof, said portion comprising a central area of said disc with respect to said supporting means, and an aperture leading from said chamber to the ambient atmosphere, said disc being arranged when flexed to its alternative dished position to bridge said contact means to close said safety arming switch.

3. The invention recited in claim 2, wherein said flexible snap member comprises a bimetallic temperature responsive element constructed and arranged to flex into the switch closing position only upon the attainment of a predetermined combination of temperature and pressure rise in said chamber.

4. In a projectile having a nose portion a safety arming switch having contact means, an actuating member for engaging said contact means to close the switch, said actuating member comprising a snap disc capable of being flexed into either of two dish-shaped forms, a chamber in said nose portion having a portion of the said disc as part of the wall thereof and.,

an elongated aperture leading from said chamber to the ambient atmosphere.

5. The invention as set forth in claim 4 wherein said snap disc comprises a bimetallic temperature responsive member located to flex into switch closing position upon the attainment of a predetermined combination of temperature and pressure rise.

6. The invention as set forth in claim 5 wherein said contact means comprises a pair of contact members and wherein said snap disc directly bridges said contact members to close a fuse circuit.

'7. The invention as set forth in claim 4 wherein said snap disc is located to flex into switch closing position upon the attainment of a predetermined pressure rise.

8. In a rocket or the like a combustion chamber, a switch chamber in the said rocket adjacent thereto, a safety arming switch in said switch chamber and having contact means, an actuating member for engaging said contact means to close the switch, said actuating member comprising a bimetallic temperature responsive snap disc capable of being flexed into either of two dish-shaped forms and forming a part of the wall of the said switch chamber, whereby the said snap disc flexes into switch closing position upon attainment of a predetermined temperature after a predetermined period of fuel combustion in said combustion chamber.

JACOB RABINGW.

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

UNITED STATES PATENTS 578,154 Great Britain June 18, 194.6