Magnetic separation device

['•1 3,582,017

<td colspan="3"> United States Patent</td>

<td> [72]</td><td> Inventor</td><td> Alphonse M. Zecca Dallas, Tex.</td>

<td> [21]</td><td> Appl. No</td><td> 759,580</td>

<td> [22]</td><td> Filed</td><td> Sept. 13,1968</td>

<td> [45]</td><td> Patented</td><td> June 1,1971</td>

<td> [73]</td><td> Assignee</td><td> LTV Aerospace Corporation Dallas, Tex.</td>

[54] MAGNETIC SEPARATION DEVICE

Claims, 2 Drawing Figs.

(52] U.S.C1........................................................ 244/1,

102/49.4,285/1,285/9,292/251.5,335/306

[51] Int.CI......................................................... B64g 1/00

[50] Field of Search............................................ 244/1 SS 1

E; 102/49.4; 285/1,9,9 M; 292/251.5;

335/306 Inquired;

337/30 Inquired

[56] References Cited

UNITED STATES PATENTS 3,262,654 7/1966 Kaempen.................244/l(SS(R&amp;D))

3,288,511 11/1966 Tavano......................... 292/251.5

3,420,470 1/1969 Meyer.......................... 244/liSS)

3,468,576 9/1969 Beyeretal................. 292/251.5

Primary Examiner—Milton Buehler

Assistant Examiner—Jeffrey L. Forman

Attorneys—Charles W. McHugh and H. C. Goldwire

ABSTRACT: An assembly comprising a plurality of separable sections releasable interconnected. A control device is provided for releasing the separable sections in response to a predetermined signal, and a magnetic separation means is operatively associated with the separable sections for exerting a separation force therebetween upon release of the sections.

14 •2

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30 8

34

CONTROL &gt; DEVICE

58

60

SOURCE OF

ELECTROMOTIVE

FORCE

PATENTED JUN 11971

3,582,017

14

CONTROL DEVICE ²²A&lt;

34. I ⁵⁶ ' cn ⁵⁸ θθ

SOURCE OF ELECTROMOTIVE

FORCE

FIG

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SOURCE OF ELECTROMOTIVE ~⁴⁸ ALPHONSE M. ZECCA

FORCE INVENTOR

AGENT

3,582,017

MAGNETIC SEPARATION DEVICE

This invention relates to a separable assembly, and more particularly to an assembly in which magnetic forces are utilized to effect a smooth, reliable separation of certain parts when connection between the parts is severed.

In the past, continuous and extensive efforts have been expended to develop a satisfactory and reliable means to separate smoothly a plurality of releasably interconnected sections. In many of these previous separating mechanisms, explosive energy has been utilized for simultaneously disconnecting and moving one section relative to another section. Explosive devices have not been without their problems, however, and several persistent difficulties associated with the use of explosive energy for moving separable sections apart have been noted. Other than because of a favorable speed of response, explosive releasing devices have usually been employed for either or both of two reasons. The first reason is that the strength requirements of the joint between separable sections is so high that only explosives have the capability of releasing the connecting means at the desired time. The second reason is that explosive devices are appropriately suited for remote actuation, and commands can be sent by radio signals or the like over appreciable distances. The use of explosive devices because of strength considerations, however, is probably the one use which is accompanied by the most deleterious side effects. Thus, if a connecting device must have high strength when intact, it naturally follows that a high concentration of explosive energy is required for rupturing or otherwise releasing such a device. Hence, even when the surface of a connecting structure is scored such that the parting line is fixed with some degree of certainty, the force of a large explosion often forms undesirably sharp, irregular, and deformed edges on the respective sections. When the aforementioned explosive separation is employed, for example, to effect a heat-shield or payload separation from a space vehicle, the undesirably sharp, deformed edges can extend outwardly from their respective severed sections into the adjacent air stream, thereby creating a turbulent flow condition adjacent the severed sections which affects their speed and direction of movement.

In space vehicle application, it is always necessary that a desired separation be effected on the first try. That is, if the amount of explosive employed on the first try is not adequate to effect separation, there is usually no opportunity to go back and use a second charge to finish the job. Hence, to guarantee that the first explosion will be the only explosion needed, an excess of explosive (above the amount calculated as being necessary) is usually provided. This excess of explosive can produce erratic forces on the severed sections and can result in a skewed separation of the sections rather than the substantially straight line relative movement between sections that is desired. In addition, the use of an excessive amount of explosive energy in a relatively concentrated area, to effectively sever the separable sections, can cause disintegration of the charge casing or associated structure and produce undesirable flying debris or shrapnel.

Nevertheless, it appears that some amount of explosive in excess of the minimum calculated amount will always be necessary in application related to space vehicles, etc. Accordingly, attempts have been made to use this excessive amount of explosive in a constructive manner, namely, to effect relative displacement of sections once their connecting structure has been severed. Hence, connecting structures have frequently been designed so that the force of the explosion that severs two bodies will act in a direction so that it also serves to separate them; and, sometimes a secondary explosive charge is even added to assist in moving one section relative to another. The effects of rapidly expanding gases from an explosion, however, are often difficult to predict with certainty, and sometimes a severed section can be pushed away from another with an undesirable tumbling motion rather than a smooth, straight line motion. Hence, the use of explosives to effect relative displacement between bodies, especially in so-called “outer space,” has not been without problems.

To avoid some of the aforementioned problems of explosive separation devices, numerous mechanical separation devices have been employed, including compression springs, spinning weights, etc. Depending on the type of mechanical device employed, problems of erratic relative movement of the separated sections have still been encountered, to a greater or smaller degree. Moreover, mechanical separation devices have frequently been of such complexity that malfunctions are common. Thus, a totally satisfactory solution has not previously existed in the prior art.

Accordingly, it is a major object of this invention to provide a means for separating two or more bodies in an outer space environment.

Another object is to provide an extremely simple magnetic separation device for moving at least one member in a smooth, uniform, substantially straight line manner relative to another member upon release of means rigidly connecting said members.

Another object of the present invention is to provide a reliable, lightweight, and inexpensive magnetic separation device that is capable of applying a separation force of sufficient magnitude between a plurality of separable sections for moving at least one section relative to the other section, and substantially eliminating the possibility of a malfunction or failure during movement of the separable sections apart.

A further object of the present invention is to provide a magnetic separation device which has substantially no moving parts.

Other objects and advantages will be apparent from the specification and claims and from the accompanying drawing illustrative of the invention.

In the drawing,

FIG. 1 is a cross-sectional view, in elevation, showing a magnetic separating device according to the invention; and

FIG. 2 is a similar view showing an alternate embodiment of such a device.

Referring initially to FIG. I, an assembly 2 is shown which includes two separable sections 4 and 6 that are rigidly held in an interconnected relationship by a releasable connecting means 8 comprising an explosive bolt release system. The separable sections 4 and 6 can be fabricated from any material, magnetic or nonmagnetic, but lightweight materials such as aluminum, magnesium, fiberglass, etc. are preferred. The separable sections 4 and 6 have respective flangelike members 10 and 12 extending in a generally transverse direction to provide the necessary space for connecting means 8. Flange member 10 is provided with a relatively flat bearing-surface 14 which is disposed opposite and adapted to contact a complementary bearing surface 16 on flangelike member 12. Member 10 has openings 18 extending therethrough in sufficient number to accommodate each of the individual fasteners that cooperate to hold the sections 4,6 together. It should perhaps be noted that, while only one connecting means 8 is illustrated in FIG. 1, it is likely that more than one would be employed on, for example, a space vehicle, with a plurality of connecting means being equally spaced around the periphery of the vehicle. Furthermore, with more than one opening 18, each is spaced so as to be aligned with an internally threaded opening 20 provided in member 12, whereby an individual fastener (exemplified by explosive fastener 22, described below) which extends through opening 18 is engageable with threaded opening 20. The flangelike members 10 and 12 are shown as being integral parts of their respective sections 4 and 6; but it should be apparent that they need not be. That is, the members 10 and 12 could be fabricated separately and then suitably fastened, respectively, to sections 4 and 6.

The releasable connecting means 8, as illustrated in FIG. 1, includes the explosive fastener 22, which is a bolt having an externally threaded portion 26 at one of its ends for engagement with threaded opening 20. An enlarged bolt head-portion 28, which includes a laterally or radially extending bearing-surface 30, is designed to contact a complementary surface 32 on member 10. Through the head and part Of the

3,582,017 shank of bolt 22 there extends an outwardly opening, centrally disposed bore 34 which is adapted to receive an explosive material or charge 36. The explosive charge 36 is provided with a primer charge 38 for firing or detonating the explosive charge 36, so as to sever the fastener 22 adjacent the interface between surfaces 14 and 16. While the illustrated connecting means 8 shows only explosive bolts, it should be noted that other types of connecting apparatus or clamps could be employed with comparable success.

The primer charge 38 is operatively associated with a resistance-bridge wire 40 which is connected through electric leads 42 and 44 to control means 46, said means including a source of electromotive force 48 operatively connected to a control device 50. A normally open switch 52 is connected in lead 44 and is interposed between the bridge wire 40 and the source of electromotive force 48. The switching mechanism 52 is provided to prevent detonation of charge 36 until a predetermined condition is detected by control device 50. The device 50 may be, for example, a temperature-sensing device, an automatic timing device, a sequence switching mechanism, an altitude-sensing device, a proximity sensing apparatus, as well as any of the other types of control apparatus which are well known in the art. The control device 50 is effective to move the switch mechanism 52 between its open position and a closed position. Thus, as long as switch mechanism 52 is held by control device 50 in the open position, the charge 36 cannot be fired. Closure of switch mechanism 52 by control device 50 completes a circuit through leads 42,44, and bridge wire 40, which ignites charges 38 and 36, thereby disconnecting section 4,6.

- Section 4 carries a magnet, in this case permanent magnet 54, in an outwardly opening recess 56 in surface 14. Similarly, the adjacent section 6 is constructed to carry a magnet such as permanent magnet 58 in an outwardly opening recess 60 in surface 16. The magnets 54 and 58 are arranged side by side with like poles immediately adjacent one another, whereby a repelling force between the magnets is realized. That is, the north pole of magnet 54 is placed opposite the north pole of magnet 58 (constituting one set of like poles), and the south poles of the magnets have a similar opposed relationship (constituting a second set of opposed, like poles). Magnets 54 and 58 are of such a size and strength that their opposed poles effectively create a resultant force of sufficient magnitude for moving sections 4 and 6 relative to each upon release of connecting means 8. The rate of separation will quite naturally depend upon the mass of the respective sections 4, 6, the strength of the magnets 54, 58, and their proximity. In the preferred construction, the separable sections 4 and 6 are fabricated from a material which has a relatively low degree of magnetic permeability. For some applications, however, it could be found desirable to position magnetic material (not shown) interjacent the opposed magnets 54 and 58, to effect a greater concentration of magnetic flux therebetween. In any event, the magnetic field between the opposed magnets 54 and 58 is such as to produce a force which causes section 4 to move in the direction of arrow 62 and section 6 to move in the direction of arrow 64.

While permanent magnets 54 and 58 have been shown and described, it is in keeping within the inventive concept to employ electromagnets as well. Such electromagnets can be continuously energized, or they can be energized just before, simultaneous with, or just after release of connecting means 8 by suitable connection with the aforementioned control means 46. If one of the magnets, e.g. magnet 54, is a permanent magnet, and an adjacent magnet is an electromagnet, the sections 4, 6 may be held together by action of the permanent magnet while the electromagnet is not energized, and then separated by mutual repulsion of the two magnets when the electromagnet is energized.

The opposite end-portions of alignment pin 66 are snugly but slidably received in aligned openings 68 and 70 which are disposed, respectively, in flangelike members 10 and 12. One purpose of the alignment pin 66 is to align openings 18 and 20 to facilitate attachment of connecting means 8. Another purpose of the pin 66 is to preclude the possibility of transverse movement of the two sections 4, 6 upon release of the connecting means 8, whereby an attractive force between opposite poles of adjacent magnets is never permitted to affect separation of the sections, and the repulsive force between like poles always exceeds any attractive force between unlike poles.

FIG. 2 illustrates an embodiment of the present invention which operates in substantially the same manner as the device shown in FIG. 1. The opposed surfaces 14, 16 of flange members 10, 12 are coated with respective layers of nonmagnetic material 72, 74, such as a suitable rubber, fiberglass, plastic, or the like. A plurality of small permanent magnets 76 are disseminated throughout and imbedded in the nonmagnetic material 72 and 74, and these magnets are uniformly oriented, end to end, such that magnetic poles of the magnets in material 72 are disposed in opposed relationship to like magnetic poles of the magnets in material 74. If desired, they may be sealed within the material 72, 74 so as to be waterproof without materially effecting their efficiency. A useful manufacturing technique is to imbed magnetizable materials in a suitable nonmagnetic material, and subsequently magnetize them to achieve the desired polarities. Alternatively, a strip or gasket of one of the so-called magnetic rubber materials (such as a rubber binder in which barium-ferrite particles are suitably oriented during extrusion or calendering) may be employed.

The separation of sections 4 and 6 can perhaps best be understood by referring to FIG. 1. The detonation of explosive charge 36 produces an instantaneous shock and pressure buildup within holes 34 to ensure uniform cutting or severance of the relatively thin, lateral wall-portion of fastener 22, thereby releasing separable sections 4 and 6. Upon release of the sections 4, 6, the like magnetic poles of opposed magnets 54 and 58 exert a repelling force of predictable magnitude to move sections 4 and 6 apart, in the directions indicated by arrows 62, 64. If an explosive connecting means is oriented to merely sever the connection between two sections and not to separate them once they are severed, the separation force realized from the magnets will be the only force acting on the sections. Under these conditions, the possibility of a skewed separation is essentially eliminated, and a smooth, substantially straightlike movement between the sections 4, 6 is achieved. The separation force of a magnetic device is, of course, independent of the environment in which it acts, and the same force is achievable in the earth’s atmosphere as is achievable in a vacuum or in outer space.

From the above description, it should be readily apparent that numerous advantages reside in the unique magnetic separation device of the present invention. This separation device is very inexpensive to manufacture, considerably reduces the possibility of failure, and provides a significant reduction in weight when compared to separating devices previously used. The magnetic separation device is perhaps most notable, however, in the reliability it provides, since no moving parts are required to effect separation of the separable sections upon release of the connecting means. For this reason, the invention is readily employed, for example, to effect a fail-safe separation of a heat shield or payload from a space vehicle.

Furthermore, unlike separation devices that rely on springs in compression, a magnetic separation device is susceptible to inspection and measurement of its stored potential energy without actuation of the device. If an access port or the like is provided adjacent the permanent magnets, their strength can be measured with suitable flux-measuring instruments, etc., without disturbing the connected sections. Hence, structures can be connected for months or even years, and the magnetic separation device tested in a nondestructive manner as often as is desired to verify its capability of providing a desired separation force when such a force is necessary. While some permanent magnets are known to lose some of their strength

3,582,017 over a period of years, electromagnets do not, and the use of electromagnets can obviate what might be considered a minor deficiency of a system using permanent magnets.

While only one embodiment of the invention, together with a modification thereof, has been described in detail herein and shown in the accompanying drawing, it will be evident that various, further modifications are possible in the arrangement and construction of its components without departing from the scope of the invention.