US1819140A - Reciprocating motor - Google Patents

Description

Aug. 18, 1931. c. s. WEYANDT ET AL REC IPROCATING MOTOR Original Filed Nov. 21, 1923 Patented Aug. 18, 1931 UNITED STATES PATENT cam. s. WEYANDT AND HAROLD E. FOX, or rimsnunon, rENus LvAmmnssIonons. BY MESNE ASSIGNMENTS, 'ro CENTRAL ELECTRIC moor. COMPANY, a CORPORATION OF PENNSYLVANIA micrrnoca'rmo Moron. I

yon-ice Original application filed November 21, 1923, Serial No. 676,106. Divided and this application filed May 5,

1928. Serial Our invention relates to magnetic circuit conductors serving as casings for electric tools, and more particularly to iron-clad electromagnets.

In accordance with our invention, a metallic casing of magnetic material has a discontinuous periphery for electrically insulating the respective edges of said casing from each other.

Further in accordance with our invention the magnetic casing or housing is made of low carbon silicon steel and comprises a sheet of said steel rolled or bent into conduit-like form, the loose or free edges being electrically 5 insulated from each other by a thin layer of oxide.

Our invention further resides in apparatus of the character hereinafter described and claimed.

In the accompanying drawings, Fig. 1 is a side elevational view of a tube to be used as a casing; Figs. 2, 3 and 4 are end views of tubes of different shapes; and Fig. 5 is a longitudinal sectional view of anelectric hammer of the reciprocating motor type, to which a casing embodying our invention may be particularly applied.

This application is a division of the subject;

matter in our Letters Patent No. 1,796,721,v granted March 26, 1929.

In constructing the magnetic housing constituting our invention we roll a sheet of low carbon silicon steel to substantially the desired shape and size which is required to fit the electromagnet with which the casing so formed is to be used. The loose or free side edges are then loosely welded by the heat of the metal itself to form a rigid tubular structure to permit machining or otherwise working on the tube. After the tube is machined to proper length and other desired dimensions, the loose weld is broken open to rovide a slit in the casing to eliminate the lnduced current losses that would be effected therein.

In preparing the tubes for service as casings, a sheet of silicon steel is rolled into a tube of substantially the desired shape and size as illustrated in Figs. 2, 3 and 4 and is cut to the approximate length that is desired. The sheet is preferably provided with tapered portions 2 and 3 that will overlap somewhat when the tube is rolled. The overlapped portions arethen loosely welded. However such overlapping is not essential, and theedges may simply abut each other as illustrated in Fig. 3 of the drawings and then united by the non-permanent union previously referred to.

."The surface of thelow carbon silicon steel has a thin layer of oxide thereon which pre-f fuse the two portions into a homogeneous vents a fusing weld that would otherwise substance. Only a. surface. adherence or loose weld is obtained. We employ the expression loose weld in this application to comprehend a surface adherence, between two metals,

which may be easily broken b 'a relatively small force, as distinguished rom a fusion Weld whereby the molecular structures of both metals are intimately mixed, or disposed, to, constitute a homogeneous mass.

The expression loose weld is intended to include lap welds, but-t welds and any other Weld which is merely a surface adherence of i the aforementioned character. a

The loose weld so obtained between the overlappmg portions of the tube is strong enough to maintain the tube as a rigid struccorrosive-resisting material may be applied in any well known manner, though preferably by electroplating. g a

The metal which we preferably use for the magnetic housing or casing consists of silicon steel having 2 to 4% silicon and low carbon content, preferably not exceeding 0.1%. Silicon steel of this character hashigh electrical resistance and high magnetic permeability and for a magnetic circuit is almost as good as laminated steel for reducing eddy current losses.

A tube of this metal is particularly applicable as a. casing for an electromagnet. In Fig. 5 is illustrated an electric hammer of the reciprocating motor type to which we have applied the silicon steel tube as a casing.

The hammer may comprise in general two operating coils 5 and 6. a movable piston or core 7, a barrel or guide 8 for the core 7, a tool 9 that is struck by the core to do useful work, a shock-absorbing spring 10 and a handle 11.

The coils 5 and 6 may be provided with magnetic circuits including end laminations 13 and 14 and middle laminations 15. The laminations are provided with pole tips 16 that extend into openings in the barrel 8 to within a few thousandths of an inch from the inner surface thereof which guides the movement of the core 7.

The. magnetic flux passing between the pole tips in the magnetic circuit of each coil acts upon the core to ell'ect its actuation in each direction.

In order to provide a protective casing that shall also serve as a conducting medium of low reluctance to the magnetic flux developed by both coils, we provide casing 17 having low carbon content silicon steel which also has a high electrical resistivity and tends, therefore, to diminish eddy current losses. The peripheral discontinuity of the casing still further diminishes eddy current losses by restricting the path of said currents.

Casing 17 may have beveled ends, 17a, shown substantially as a 45 bevel, for effecting snug and close engagement of the casing with co-acting end pieces 18 and 19 when the same are forced towards each other. The magnetic housing which forms a portion of the magnetic circuit or circuits may therefore be positioned with respect to other sections of the magnetic circuit or circuits so that the reluctance therein due to joints between said members may be substantially reduced.

Silicon steel has heretofore never been used in tubular form because of the difiiculty of effecting a solid or fusion weld. lVe have found. however, that a loose weld is sufficiently strong to permit machining and thereafter, in an application, such as herein illustrated, as a casing for an iron-clad magnet, the opening of the weld introduces a desirable and serviceable air gap, for electrical resistance.

Although we have particularly specified silicon steel as the metal which we employ because of its desirable magnetic and electrical characteristics, it will be readily apparent that any other metal having similar characteristics may be used. Moreover, the casing may be applied to electromagnets of difierent types without departing from the scope and spirit of the invention as set forth in the appended claims.

What we claim is:

1. In an electric motor, a reciprocatory magnetizable member, magnetic operating means associated therewith and comprising a winding and magnetic pole elements energized thereby and spaced to form an air gap, and a tube-like casing for said motor of magnetizable material, the periphery of said casing being discontinuous with the respect ve peripheral edges electrically insulated w th respect to each other by oxide of the material of said casing.

2. In an electric tool, a reciprocating element of magnetizable material, and magnetizable structure associated therewith, said structure providing with said element a magnetic circuit and comprising a longitudinallyslitted tube of low carbon steel containing from 2 to 4% silicon, and carbon not exceeding 0.1%.

3. The combination with an electric reciprocating motor, of a magnetic casing for said motor comprising a rolled sheet of magnetic metal, said sheet having its edges substantially abutting and insulated from each other by comparatively thin layers of oxide of said metal.

4:. The combination with an electric reciprocating motor, of a magnetic casing forming a part of the magnetic circuit of said motor comprising a sheet of magnetic metal rolled into substantially cylindrical shape, the edges of said sheet substantially abutting each other and coated with a comparatively thin film of oxide of said metal to form an insulating joint longitudinally of said casing.

5. In an electric motor, means for producing a magnetic field, a reciprocating element of magnetizable material, magnetizable structure associated with said element and including a cylindrical member of magnetizable material having its circumferential continuity along its entire length broken by a broken weld for preventing flow of currents therein generated by the magnetic field of said motor, said member providing with said element a magnetic circuit for said field.

6. In an electric motor, means for producing a magnetic field, a reciprocating element of magnetizable material, magnetizable structure associated with said element and including a cylindrical member of magnetizable material having its circumferential continuity along its entire length broken by a broken lap weld for preventing flow of currents therein generated by the magnetic field of said motor, said member providing with said element a magnetic circuit for said field.

CARL S. WEYANDT. HAROLD E. FOX.

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