US3891466A

US3891466A - Attachment device

Info

Publication number: US3891466A
Application number: US742975A
Authority: US
Inventors: Porter W Erickson; Alvin G Hellfritzsch
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1968-07-02
Filing date: 1968-07-02
Publication date: 1975-06-24
Anticipated expiration: 1992-06-24

Abstract

A thermoelectric magnet for interconnecting metallic elements utilizing a thermocouple having an insulated heat-producing chemical charge at the ''''hot'''' junction thereof which is activated on command and permanently magnetizes the core material.

Description

United States Patent 1 Erickson et a1.

ATTACHMENT DEVICE inventors: Porter W. Erickson; Alvin G.

l'lellfritmch, both of Silver Spring, Md.

The United States of America as represented by the Secretary of the Navy, Washington, DC.

Filed: July 2, 1968 Appl. No.: 742,975

Assignee:

US. Cl. 136/200; 136/205; 317/133.5 Int. Cl. H0lh 47/26 Field of Search 136/200, 205; 317/123,

References Cited UNITED STATES PATENTS 9/1945 Paille 317/123 1 June 24, 1975 2,400,384 5/1946 Betz 317/[23 2,720,614 10/1955 Cairns, Jr 317/123 2,767,355 10/1956 Wolff 317/123 Primary Examiner--Ver1in R. Pendegrass Attorney, Agent, or FirmR. S. Sciascia; .1. A. Cooke ABSTRACT A thermoelectric magnet for interconnecting metallic elements utilizing a thermocoup1e having an insulated heat-producing chemical charge at the hot" junction thereof which is activated on command and permanently magnetizes the core material.

10 Claims, 4 Drawing Figures ATTACHMENT DEVICE BACKGROUND OF THE INVENTION The invention generally relates to attaching devices and more particularly to a magnetic type attaching device for interconnecting metallic elements.

The present methods and apparatus used to clandestinely attach an ordnance device such as a mine or the like to the bottom area of a ship involves the use of permanent magnets which are formed as part of the mine. This apparatus which is termed a Limpet-type mine has been discovered to have severe limitations in the use thereof because the swimmer, whose function is to attach the device to the bottom area of the ship is required to navigate underwater by compass in view of the depth and darkness at which he is operating. Since the magnetic field surrounding the Limpet mine causes the compass needle to act erratically, the swimmer is unable rely on his compass to aid him in searching out his target. Therefore, the swimmer cannot hold the mine in his hand. Dragging the mine behind by a rope or the like would subject the mine to shock if it comes into contact with a solid surface and would increase the liklehood of snagging the mine on various impediments present under the water.

A further problem arises upon the application of the metallic magnet mine to the metallic surface of the ships hull. It was discovered that since the Limpet mine incorporated a strong permanent magnet, it was almost impossible to bring the mine in contact with the steel plate of a hull without creating a loud noise upon magnetic siezure. Such noise is subject to detection by acoustic sensors and indicates the presence of activity adjacent to the ship. This, in turn, may result in the swimmers being captured and the mine located.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved device for magnetically attaching ferromagnetic elements together.

Another object of this invention is the provision of a magnetic attaching device which is capable of activation immediately prior to use thereof.

Still another object of this invention is to provide a magnetic attaching device having high magnetic attraction characteristics and capable of interconnecting ferromagnetic elements without creating any noise upon the application of the attaching device to the elements.

A still further object of the present invention is to provide a magnetic attaching device which is normally in an inoperative mode and therefore may be carried with magnetically sensitive devices without affecting the operation of the same.

An additional object of the present invention is the provision of a magnetic attaching device which can be carried together with a magnetic compass used for guidance without affecting the operation of said compass.

According to the present invention, the foregoing and other objects are attained by a magnetic attaching device having an electromagnet activated by a thermocouple, the thermocouple being activated, in turn, by an insulated heat producing chemical charge adjacent to the hot junction of the thermocouple and activated on command. Upon activation of the thermocouple, the core material of the electromagnet becomes a permanent magnet.

DESCRIPTION OF THE DRAWING A more complete appreciation of the invention and many of the attendant advantages thereof will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is an elevation view of a preferred embodiment of the invention;

FIG. 2 is a section of the device taken along the lines 22 of FIG. 1;

FIG. 3 is a sectional view taken along lines 3-3 of FIG. 1', and

FIG. 4 is a cross-sectional view taken along the lines 44 of FIG. 2.

BRIEF DESCRIPTION OF PREFERRED EMBODIMENT Referring now to the drawings wherein like reference characters designate identical or corresponding parts throughout the several views, and more particularly to FIGS. 1 and 2 thereof, a magnetic attaching device generally indicated at 10 is illustrated as interconnecting an explosive mine shown generally at 12 to the hull of a ship generally indicated at 14 and floating in a water medium 15. The device 10 includes basically a thermoelectric magnet 16 actuated by a heat producing chemical charge assembly 18. Again referring to FIGS. 1 and 2 the thermoelectric magnet 16 is of the general type manufactured by the Central Scientific Company and generally shown by U.S. Pat. No. 1,893,748. This apparatus 16 comprises a pair of bars 20, only one of which will be described, constructed of heavy conductive material, such as copper or the like, of square crosssectional configuration bent into the form of a coil 22 and terminating in a thermocouple generally indicated at 23. Thermocouple 23, in turn, comprises a pair of

arms

24 and 25 extending from the coil 22 and across which is connected, as by brazing, welding, or the like, a rod 26 of a metallic material dissimilar to the material of the arms 24 and 2S, and may be a material such as constantan or the like. The connection of rod 26 at arm 24 forms the hot junction 27 of the thermocouple 23 while the connection of rod 26 at arm 25 forms the cold" junction 28 of the thermocouple 23.

The bars 20 are partially housed within a cylindrical block 30 constructed of any ferrous material capable of being permanently magnetized such as Cunico, 34% cobalt steel or the like. The block 30 has each end 32 thereof ground flat and polished, in which has been milled or otherwise formed a circular groove 34 for positioning the coil 22 of the bar 20.

As shown more clearly in FIG. 2, the

arms

24 and 25 are offset inwardly as at 36 in order to provide the device 10 with a pair of completely clear vertical surfaces for permitting the mine 12 and hull 14 to be coupled to the device and as shown in FIG. 4, to form a supporting surface 42 at the junction of arms 24 to which the assembly 18 is thermally connected.

Turning now to FIGS. 3 and 4, the heat-producing chemical charge assembly 18 is constructed of a barrel 40 flattened along a portion of the surface thereof at 42 and connected by a thermal connection as by brazing, welding or the like to the arms 24 adjacent the hot junction 27. The barrel 40 is externally threaded at 43 and has an internal bore at 44 and counterbore at 46 to receive a heat generating cartridge 50 of a thermitetype pyrotechnic mixture 52 which is explosively actuated by a percussion type primer charge 54. Such cartridges 50 are of the type known and used in the soldering iron art and is of the type manufactured by the Kemode Manufacturing Company under the tradename of Quilt-Shot. This cartridge contains ten thousand calories of heat energy supplied by the thermite mixture which is sealed in the steel shell. The temperature generated by the cartridge is in the order of magnitude of 800 to 900F and such temperature may be maintained for a period of 6 to 8 minutes. The generation of such high degree of heat over such long periods of time enables the hot" junction 27 to be heated to a sufficiently high temperature differential with respect to the cold junction 28 the latter of which is exposed to the surrounding water medium 15. This differential in temperature between the two junctions causes a current to flow through the bar and permanently magnetize the cylindrical block 30. It should be understood that although not shown, the arm 24 and barrel 40 can be further coated or surrounded with an insulating medium to minimize the dissipation of heat energy from the cartridge 50 to the surrounding water medium 15. It should further be understood that in order to insulate the heat producing cartridge 50 from the surrounding water medium 15, it is within the scope of the present invention to provide a ceramic or other lining between the cartridge 50 and the side of the barrel 40 which is remote from the hotjunction 27 of bar 20 to thereby insure that more of the heat produced by the actuation of cartridge 50 passes to the arm 24 to thereby attain a greater temperature differential between the arms 24 and and create a greater current through the coil 22 and provide a higher degree of efficiency in magnetizing the cylindrical block 30.

The primer charge 54 of the cartridge 50 is fired by a firing mechanism 60 now to be described. The barrel 40 at its externally threaded cylindrical portion 43 threadably receives a firing chamber 62 which is internally threaded at 64. Chamber 62 includes an annular O-ring seal 66 to maintain the assembly 18 in a water tight condition. A firing pin 68 is slideably retained in the chamber 62 and is moveably disposed between a safe and firing position. A compression spring 74 urges the firing pin 68 to the firing position. The pin 68 is withdrawable by knob 78 to the safe position and is held in such position by a safety pin 80 which is slideably and removably positioned within the chamber 62 and passes through the firing pin 68 to retain the same in the safe position.

It should be understood that firing mechanisms other than that shown herein may be utilized to actuate the cartridge 50 and that other thermite-type pyrotechnic devices may be used other than the cartridge 50 to generate the heat required to magnetize the cylindrical block 30.

In operation, the swimmer carries the magnetic attaching device 10 in the inoperative mode and the mine 12 to the hull of a ship 14. The swimmer locates a smooth and flattened surface of the hull l4 and positions one end 32 of the block against the metallic hull 14. At this time the pin 80 is removed from the chamber 62. The firing pin 68 is urged by spring 74 into engagement with the primer charge 54 which deflagrates the mixture 52 of cartridge 50. The heat produced by cartridge 50 is transferred to the copper bars 20 which in turn, due to the temperature differential between the hot" and cold"

junctions

27 and 28, respectively, causes a current to flow through the coil 22 and permanently magnetize the block 30. A magnetic coupling is then attained between the device 10 and the hull of the ship 14. Similarly, the other end 32 of block 30 has been transformed into a permanent magnet and the ferromagnetic mine 12 be brought into contact therewith to be coupled thereby to the hull 14 of the ship.

By reason of this mechanism and the actuation thereof the swimmer is not inhibited in his use of a magnetic compass to locate the hull of the ship since the magnetic attaching device is in an inoperative mode during the time the swimmer is using the magnetic compass and therefore the compass will be unaffected thereby. Additionally, the noise which would be created by applying a strong permanent magnet to the hull of the ship is avoided since the magnetic forces of attraction are not set up until the magnetic attaching device 10 is in contact and abutment with the hull 14.

it is to be further understood that although two magnetized surfaces are illustrated and disclosed above, only one such surface may be utilized without departing from the scope of the present invention. In lieu of the other magnetized surface to which the mine 12 is applied there may be placed a mechanical connection such as a hook or the like to which the mine may be suspended. This deviation may be required in the instance where the mine to be attached is not ferromagnetic.

Obviously, numerous other modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A magnetic device attachable to a ferromagnetic surface comprising:

a core;

coil means for said core;

thermocouple means energizing said core said thermocouple means having a hot" junction and a cold junction;

chemical charge means for producing heat energy and coupled to said hot junction;

said chemical charge means being selectively activated to produce sufficient heat at said hot junction to cause current to flow through said coil means and magnetize said core.

2. The device as defined in claim 1 wherein said core is constructed of material capable of being permanently magnetized and said charge means is capable of providing sufficient heat to permanently magnetize said core.

3. The device as defined in claim 2 wherein said thermocouple means includes:

a pair of arms extending from said coil means, said arms being constructed of similar conductive material;

a bar member formed of a material dissimilar to said arms and connected to one of said arms to form said *hot" junction and to the other of said arms to form said cold" junction.

4. The device as defined in claim 3 wherein said chemical charge means includes:

a cartridge;

said cartridge containing a high caloric, thermitetype mixture for producing sufficient heat energy to magnetize said core;

primer charge means adjacent said mixture for igniting said mixture upon receipt of an impacting force.

5. The device as defined in claim 4 further including:

a barrel member for receiving at least one of said cartridgcs;

said barrel member being in thermal communication with said hot junction;

firing means associated with said barrel member for selective impacting engagement with said primer charge means.

6. The device as defined in claim 5 wherein said firing means includes:

firing pin means for engaging said primer charge means and movable between an impacting position and a withdrawn position;

spring means urging said pin means to said impacting position;

trigger means releasably retaining said pin means in said withdrawn position against the urging of said spring means.

7. The device as defined in claim 6 wherein said coil means and said depending arms are constructed of copper and said bar member is formed of constantan.

8. The device as defined in claim 1 wherein said chemical charge means includes:

a cartridge;

9. The device as defined in claim 8 further including:

a barrel member for receiving at least one of said cartridges;

said barrel member being in thermal communication with said hot" junction;

10. The device as defined in claim 1 wherein a pair of coils surround said core and thermocouple means is connected to each of said coils.

Claims

1. A magnetic device attachable to a ferromagnetic surface comprising: a core; coil means for said core; thermocouple means energizing said core said thermocouple means having a ''''hot'''' junction and a ''''cold'''' junction; chemical charge means for producing heat energy and coupled to said ''''hot'''' junction; said chemical charge means being selectively activated to produce sufficient heat at said ''''hot'''' junction to cause current to flow through said coil means and magnetize said core.

3. The device as defined in claim 2 wherein said thermocouple means includes: a pair of arms extending from said coil means, said arms being constructed of similar conductive material; a bar member formed of a material dissimilar to said arms and connected to one of said arms to form said ''''hot'''' junction and to the other of said arms to form said ''''cold'''' junction.

4. The device as defined in claim 3 wherein said chemical charge means includes: a cartridge; said cartridge containing a high caloric, thermite-type mixture for producing sufficient heat energy to magnetize said core; primer charge means adjacent said mixture for igniting said mixture upon receipt of an impacting force.

5. The device as defined in claim 4 further including: a barrel member for receiving at least one of said cartridges; said barrel member being in thermal communication with said ''''hot'''' junction; firing means associated with said barrel member for selective impacting engagement with said primer charge means.

6. The device as defined in claim 5 wherein said firing means includes: firing pin means for engaging said primer charge means and movable between an impacting position and a withdrawn position; spring means urging said pin means to said impacting position; trigger means releasably retaining said pin means in said withdrawn position against the urging of said spring means.

8. The device as defined in claim 1 wherein said chemical charge means includes: a cartridge; said cartridge containing a high caloric, thermite-type mixture for producing sufficient heat energy to magnetize said core; primer charge means adjacent said mixture for igniting said mixture upon receipt of an impacting force.

9. The device as defined in claim 8 further including: a barrel member for receiving at least one of said cartridges; said barrel member being in thermal communication with said ''''hot'''' junction; firing means associated with said barrel member for selective impacting engagement with said primer charge means.