US3286057A - Centrifugal switch - Google Patents

Description

Nov. 15, 1966 P. KRUPEN 3,286,057

CENTRIFUGAL SWITCH Filed May 6, 1964 F IG. 4

INVENTOR. PHILIP KRUPEN BY-' I fi M p -411? .4 TTOR NE Y5.

United States Patent Ofifice 3,286,057 CENTRIFUGAL SWITCH Philip Krupen, Silver Spring, Md., assignor to the United States of America as represented by the Secretary of the Army Filed May 6, 1964, Ser. No. 365,540 2 Claims. (Cl. ZOO-80) The invention described herein may be manufactured and used for or by the Government of the United States of America for governmental purposes without the payment to me of any royalty thereon.

This invention relates to an improved centrifugal switch and more particularly to an improved safety switch for arming rotating artillery shells.

Centrifugal switches are well known and are used in many types of rotating equipment and machinery. However, they are perhaps best known for their use as arming switches in rotation projectiles and especially in artillery shells. The switches are used in conjunction with impact, proximity, and other types of fuzes to keep the projectile disarmed or disabled until such a time as the projectile is subject to substantial radial or centrifugal forces during inflight rotation. When used in this manner, the centrifugal switches are safety devices preventing premature detonation of the projectile and very often are used to maintain a short across the squib or detonating mechanism of the projectile until such time as the projectile is fired. In other arrangements, the switch is in series with the detonating mechanism of the projectile and presents an open circuit until the projectile is launched.

Both series and shunt type centrifugal switches have been provided utilizing an inertial mass sometimes in the form of a plunger or piston biased by a spring inwardly of the switch and adapted to move outwardly through a suitable cylinder or chamber to either open or close a circuit as the case may be. The inward bias force of the spring is conventionally overcome only by the substantial forces to which the switch is subjected when the projectile, i.e. an artillery shell, is fired.

Both the known series and shunt type centrifugal switches suffer from the serious disadvantage that breakage which may be caused by dropping the switch during handling, or other serious malfunction of the unit, may render the switch either completely incapable of disarming the projectile or subsequently properly arming it. For example, in switches incorporating a frangible element, if the switch is dropped and the frangible element broken prior to firing the projectile, even the slightest mis-alignment or malfuuction may render the switch completely incapable of preventing premature detonation of the projectile charge.

The present invention avoids the abovementioned difficulties by providing a very simple, inexpensive centrifugal switch incorporating a double safety feature which very significantly reduces the possibility of switch malfunction. The switch of the present invention presents, in effect, two separate and completely independent switches in series, both of which must be closed to arm a projectile. This added safety feature is obtained while at the same time maintaining the overall simplicity, small-size, and reliability of operation so necessary to a satisfactory artillery shell switch.

It is therefore one object of the present invention to provide a novel centrifugal switch.

Another object of the present invention is to provide an improved safety switch.

Another object of the present invention is to provide an improved arming device for rotary projectiles.

Another object of the present invention is to provide 3 ,286,057 Patented Nov. 15, 1966 an improved series type centrifugal switch having a double switch closure safety feature.

Another object of the present invention is to provide an improved detonating circuit for rotary type projectiles.

These and further objects and advantages of the invention will be more apparent upon reference to the following specification, claims and appended drawings wherein:

FIGURE 1 is a perspective view showing the simplified centrifugal switch of the present invention.

FIGURE 2 is a cross section through the switch of FIGURE 1 in the rest or open circuit position.

FIGURE 3 is a cross section similar to FIGURE 2, showing the switch elements moved to the closed position under the influence of centrifugal forces; and

FIGURE 4 shows a projectile fuze incorporating the switch of the present invention.

Referring to the drawings, the novel centrifugal switch of this invention generally indicated at 10 comprises a cylindrical casing 12 preferably of circular cross sectional configuration and formed of electrically conductive material such as brass. As illustrated in FIGURE 1, the switch 10 is adapted to be rotated in an artillery shell or other rotating device about a vertical axis 14 passing through the center of the switch and perpendicular to its longitudinal axis in a direction indicated by the arrow 16.

Cylindrical casing 12 as illustrated in FIGURE 2 and 3 is provided at each end with a circular cylindrical chamber 18 and 20 extending from each end of the casing almost to the center line or rotational axis 1-4. The inner ends of the chambers 18 and 20 are separated by a solid central portion 22 defining inner ends 24 and 26 for the chambers while the outer ends of the chambers are provided with flanges 27 and 29 closed off by annular in sulating discs or plugs 28 or 30. Imbedded within and received through the plugs 28 and 30 are a pair of electrical leads or contacts in the form of conductive metal rods 32 and 34.

Slidably received within the chambers 18 and 20 are a pair of inertial masses in the form of electrically conductive slugs or pistons 36 and 38 biased radially inwardly of the device by a pair of coil springs 40 and 42. The radially outer ends of the pistons 36 and 38 are provided with reduced diameter portions or bosses 44 and 46 over which the inner ends of the coil springs are received so that the inner ends of the springs bear against the pistons while the outer ends of the springs bear against the flanges 27 and 29. The pistons may, if desired, be positioned against the inner ends 24 and 26 of the chambers by stops 48 and 50.

FIGURE 2 shows the normal or open circuit position of the switch with the pistons 36 and 38 biased against the inner ends of the chambers by the coil springs 40 and 42. When the switch is rotated so that the pistons 36 and 38 are subjected to centrifugal forces as illustrated by the arrows 52 and 54 in FIGURE 3 the pistons slide through the chambers 18 and 20, compressing the springs 40 and 42 until the bosses 44 and 46 engage the inwardly projecting ends of the electrical leads 32 and 34. At this time, a circuit is completed from lead 32 by way of piston 36, electrically conducting casing 12 and piston 38 to the other lead 34. If either of the pistons 36 or 38 does not engage its respective lead, then the circuit is not completed.

FIGURE 4 illustrates in dashed lines a. projectile 60 such as a rotary artillery shell incorporating the novel switch 10 of this invention. In FIGURE 4 the switch is shown as connecting a power supply represented by the battery 62 through a proximity or other detonating device 64 to the squib or firing element 66 of the projectile. As can be seen, the pistons 36 and 38 which are similarly numbered in FIGURE 4 provide two separate and completely independent switches in series, both of which must be closed to complete the circuit from the battery 62 through the fuze to the squib 66. If either one of these switches is not closed, actuation of the device 64 will not fire the squib.

As can be seen from the above, the present invention provides a novel switch and projectile firing circuit having improved safety features over prior constructions While at the same time maintaining the extremely small size and minimum of complexity particularly suited for incorporation in projectiles. The rotational speed at which switch closure occurs may be adjusted as desired, and is a function of the mass of the pistons 36 and 38, the stiltness of the springs 40 and 42, the distance of travel of the pistons, and other factors such as the frictional resistance between the pistons and the walls of the chambers. While it is normally not necessary, the ends of the springs 40 and 42 may be conductively secured to the walls of the chambers and to the pistons so as to insure continuous electrical contact between the pistons and the casing 12 through the springs. The circuit of FIGURE 4 cannot be completed even if the switch is dropped and one of the springs broken since both pistons must move completely through the chambers and engage the leads or contacts 32 and 34 to complete the circuit.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. A centrifugal switch comprising an electrically conductive casing having a pair of radial chambers on diametrically opposite sides of a rotational axis passing through the center of said casing, an insulating plug closing ofi the radial outer ends of each of said chambers, a conductive metal rod fixedly imbedded in and passing completely through each of said plugs, a conductive piston slidable in each of said chambers and electrically coupled to said casing, and coiled spring means biasing said pistons radially inward of said casing away from said metal rods.

2. A centrifugal switch according to claim 1 including a separate coiled spring in each of said chambers. each of said springs bearing at one end against one of said pistons and at the other end against said housing at the closed end of said chambers.

References Cited by the Examiner UNITED STATES PATENTS 1,896,798 2/1933 Leslie 200- 2,584,983 2/1952 Butterworth 20080 X 2,712,791 7/1955 Bleakney et a1 10279 X 2,900,909 8/1959 Jordan 102-702 3,035,521 5/1962 Hynard 102-79 X 3,181,466 5/1965 Czajkowski 102--70.2

BENJAMIN A. BORCHELT, Primary Examiner.

G. H. GLANZMAN, Assistant Examiner.

Claims (1)

1. A CENTRIFUGAL SWITCH COMPRISING AN ELECTRICALLY CONDUCTIVE CASING HAVING A PAIR OF RADIAL CHAMBERS ON DIAMETRICALLY OPPOSITE SIDES OF A ROTATIONAL AXIS PASSING THROUGH THE CENTER OF SAID CASING, AN INSULATING PLUG CLOSING OFF THE RADIAL OUTER ENDS OF EACH OF SAID CHAMBERS, A CONDUCTIVE METAL ROD FIXEDLY IMBEDDED IN AND PASSING COMPLETELY THROUGH EACH OF SAID PLUGS, CONDUCTIVE PISTON SLIDABLE IN EACH OF SAID CHAMBERS AND ELECTRICALLY COUPLED TO SAID CASING, AND COILED SPRING MEANS BIASING SAID PISTONS RADIALLY INWARD OF SAID CASING AWAY FROM SAID METAL RODS.

Images