US1805459A - Magnetic device - Google Patents

Description

May 12, 1931.

R. R. BATCHER MAGNETIC DEVICE Filed April 27. 1929 I INVENTOR W ATT RNEY coste Patented May 12, 1931 PATENT orrlca mm a. imrcrmn, ornorms, NEW roux momma rav oli 1 Application filed April 27, 1929. Serial No. 358,732.

. My invention relates to improvements in magnetic-devices generally and, while not limited in its apphcation to any special type of magnet, is particularly adapted for'use 6 and may be a plied with material advantage to the form electro-magnet now commonly employed in loud speakers of the dynamic n such speakers, the electro-magnet con- 10 stitutes the principal item of expense, owing to its rather unusual size, the amount of copper and iron employed and the time and labor required in its construction. The pole-pieces of this type of magnet are of such formand so related as to provide a narrow annular gap between them, in which the movable coil, carried by or otherwise secured to the diaphragm of the speaker, is located, free to vibrate clear of the walls of the gap. 7 29 In order tobrin the pole pieces into the required relation to orm the annular gap, it has heretofore been the practice to employ a heavy iron pot-like casing or cylinder suitably proportioned to enclose the magnet core proper and the winding thereon. This cylindrical casing is closed at one end and the closed end is bolted or otherwise secured in centered relation to the core proper.

A removable cover plate is provided for W the op osite end of the casing and centrally thereof an opening is formed of a diameter to admit the free projecting end of the core proper and give the necessary clearance for the movable coil.

I Ordinarily thi's cylindrical casing with one end closed, is formed as, a heavy casting and both it, and its attached parts,the core proper and apertured cover platemust be carefully and. accurately machined to provide the required narrow'annular gap for the movable coil, which is mounted free to vibratetherein with just sufficient clearance to avoid touching either wall.

Recognizing that the bulk and welght, plus the labor and material costs, are serious d1sadvantages of the above described structure,

I have devised an improved construction in 'which many of the ohjeetional features are entirel avoided and a considerable saving in fl e cted, without loss of efiioiency.

. In carrying my invention into efl'ect, I first dispense with the heavy cast iron pot-like enclosing casing'and substitute for it comparatively light steel stamped up members, two of which, exact duplicates of each other, combine to form the casing and, excepting the necessary punched bolt holes therein, such members, without requiring machine work of any kind, are complete and ready for immediate assembly in a speaker unit, on leaving the stamp press.

As a lighter weight and less costly substitute for the cast, drilled and machined cover plate heretofore employed, I form the same of crossed, twin rectangular plates of comparatively light steel strip and again, excepting the necessary punched bolt holes and central opening therein,these plates are ready for assembly on leaving the stamp press.

A convenient and effective form of mounting or support for the assembled magnet, diaphragm, etc., is found in the use of a stamping, similar in all respects to the above mentioned members I employ as the enclosing casing and to extend one of the poles of the magnet. Thus applied, it serves all requirements without change or modification of any kind.

The accompanying drawings will serve to illustrate a construction suitable for carry- I ing my invention into effect but I do not wish to be understood as limiting myself to the same as various changes may be made therein or other forms employed without departing from the spirit and scope of-the invention, as outlined in the appended claims.

In the drawings- Fig. 1 is a view in elevation, partly in section, of a well known type of dynamic speaker, showing my invention applied;

Fig. 2 is a vertical section on the line a s' of Fig. 1; t

Fig. 3 is a rear elevation thereof, and

Fig. 4 is a view in perspective showing the assembly of the stamped up members.

Referring now to the drawings, a wellknown dynamic type of loud speaker is shown for convenience in illustrating the application of my invention, but it will be understood that other types may be employed, if preferred.

In the speaker shown, a large electro-magor otherwise suitably connected to a diaphragm 7. The diaphragm is shown mounted in a skeleton metal frame 8, bolted to the magnet casing.

In bringing the pole-pieces of the magnet into relation to form the annular gap, I employ two approximately U-shaped members 9, 9, stamped up from comparatively thin strip steel and arranged one within the other to form in efi'ect a square box, closed at one end and open at the other, the box thus 'formed being of such size as to completel enclose the magnet core proper andits win ing. The members 9, 9, are exact duplicates and, as assembled, to form the box-like casing, are arranged at right angles to each other, as best shown in Fig. 4. 'At the closed end of the casing, the members are bolted in centered relation, solidly to the core of the magnet, as indicated at 10 and are punched for the insertion of additional bolts 11, 11, which secure the members together.

At the open end of the casing, the ends of the members are bent over forming terminal flanges 12, 12, etc., and bolted to these flanges there is aremovable cover formed of crossed twin rectangular plates 13, 13, which are each provided with a central opening 14, of such diameter as to closely encircle the projecting end 4 of the magnet core, leaving only clearance spacein the annular ap thus formed between the pole pieces for ree movement of the movable coil 6.

As a convenient mounting or support for the electro-magnet, the diaphragm and its carrying frame, I utilize a stamped up member 15, similar in all respects to the stampings employed in forming the box-like casing described and bolt the same to the casing, as indicatedat 16, 16, and shown in Figs. 1 and 3.

The U-shaped mounting or support 15, provides amplehousing for the transformer 17, which is secured therein by small angle irons and bolts, as indicated at 18, 18. v

The circuit connections form no part of the present invention, and it will not, therefore, be necessary to describe the same in detail.

The advantages of the invention will be obvious from the foregoing description. Eliminating the heavy cast iron pot-like casing with its cast cover and the time and labor necessary in machining both to produce, with required accuracy, the narrow annular up for the reception of the movable coil eects a material saving in cost and also in the weight of the structure, as a comparatively light gage steel serves every purpose without loss of function or efliciency. Furthermore, the utilization of one of the stamped members of the casing as a mounting or support results in an additional saving in cost and enables the speaker to be firmly secured in a receiver cabinet in position with the diaphragm paralleling the usual screened opening therein.

In addition to the foregoing, there are various other minor advantages which will be apparent without further comment.

While the present description has been confined to the application of the invention to an electro-magnet, it will be understood that it is equally applicable without material modification, to a permanent type of magnet and may be so used, if desired.

Having thus described my invention, What I claim is:

1. In an electro-magnet comprising a core and a coil wound thereon, means for extending the core to bring the pole-pieces thereof into relation to form an annular gap between them, the said means consisting of 'a plurality of shaped strip members secured to the core and arranged in nested relation to form an enclosing casing for the magnet winding.

2. In an electro-magnet comprising a core and a coil wound thereon, means for extending the core to bring the pole-pieces thereof int-o relation to form an annular gap between them, the said means consisting of a plurality of strip members approximately U-shaped, secured to the core and arranged in nested relation, to form an enclosing casing for the magnet winding.

3. In an electro-magnet comprising a core and a coil wound thereon, means for extending the core to bring the pole-pieces thereof into relation to form an annular gap between them, the said means consisting of a plurality of strip members approximately U-shaped, secured to the core and arranged in nested relation, and a plate apertured to encircle the core and combining with the strip members to form an enclosing casing for the magnet winding.

4. In an electro-magnet comprising a core and a coil wound thereon, means for extending the core to bring the pole-pieoesthereof into relation to form an annular gap between them, the said means consisting of twin strip members approximately U-shaped secured to the core and arranged at right angles to each other in nested relation, and a plate apertured to encircle the core and combining with the strip members to form an enclosing casing for the magnet winding.

v5. In an electro-magnet comprising a core and a coil wound thereon, meansfor extending the core to bring the pole-pieces thereof into relation to form an annular gap between them, the said means consisting of twin members suitably shaped and arranged in nested relation at right angles to each other, the ends of the said members being bent over to form flanges, and twin plates apertured to encircle the core and combining with the strip members to form an enclosing casing for the magnet winding.

6. Means for extending the core of an electro-magnet, which consists of twin strip members secured to the core to form a continuation thereof, the said members being approximately U-shaped and arranged at right angles to each other in nested relation to form an enclosing casing around the magnet winding.

7. Means for extending the core of an electro-magnet, which consists of twin strip members secured to the core to form a continuation thereof, the said members being approximately U-shaped and arranged at right angles to each other in nested relation to form an enclosing casing around the magnet winding, and a suitable support for the encased magnet serving as a housing for an additional circuit element.

I aflix my signature.

RALPH R. BATCHER.

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