US918498A - Revolving field-magnet structure. - Google Patents

Description

B. A. BEHREND.

REVOLVING FIELD MAGNET STRUCTURE. APPLIOATION FILED APR. 9, 1904. RENEWED JUNE 9, 1907.

91 8,498. Patented Apr. 20, 1909.

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918,498. Patented Apr. 20, 1909.

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B. A. BEHREND. REVULVING FIELD MAGNET STRUCTURE. APPLICATION FILED APR.9, 1904. RENEWED JUNB 8,1907.

Patented Apr. 20, 1909.

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WITNESSES.

UNITED STATES PATENT OFFICE.

BERNARD ARTHUR BEHREND, OF NORWOOD, OHIO, AS'SIGNOR, BY MESNE ASSIGNMENTS, TO THE BULLOCK ELECTRIC COMPANY, A CORPORATION OF OHIO.

REVOLVING FIELD-MAGNET STRUCTURE.

Specification of Letters Patent.

Patented April 20, 1909.

Application filed ,Apri19, 190;, Serial No. 202,353. Renewed June 8, 1907. Serial No. 378,002.

To all whom it may concern:

Be it known that I, BERNARD ARTHUR Barnum), a citizen of the United States, resldmg at Norwood, in the county of' Hamiltonand State of Ohio, have invented certain new and useful Improvements in Revolving Field-Magnet Structures, of which the fol-,

lowing is a. full, clear, and exact specification.

My invention relates to dynamo-electric machines, and particularly to the construction of revolving field magnets adapted for very high speeds, such as those required of steam turbine generators.

The object of my invention is to provide such a construction of all parts of the revolving structure as to enable the same to withstand the enormous strains created at yery high speeds and at the same time not in any way sacrifice the design as regards magnetic and electric requirements.

- A further object is to make the construction as simple and well designed as possible consistent with obtaining the results desired.

One feature of my invention relates particularly'to the structure of the shaft and the core by whichits strength is greatly increased and the magnetic circuits also 'im-.

proved.

My invention .further relates to. means for supporting and protecting the field coils.'

I My invention will be understood by reference to the following/description and accompanying drawings which illustrate one form of my invent-ion, and the novelty thereof will be more definitely set forth in the claims. I

Figures 1 to 6, inclusive, are .for the purpose of explaining the principles which relate to one feature of'my invention and illustrate sectional and end views of different forms of disks. Fig. 7 shows in section my improved construction of core and shaft s eed machines and only by their considera tron can the best possible des gn be obta ned.

Figs. 1 and 2 show a circular disk A which may be made of any material. I have proved experimentally, and it is also theoretically true that the bursting strains are greater at the center of the disk than at any other point. This is graphically represented in Fig. 2 in which the components of forces which tend to burst the disk when rotating at high speeds are represented by the arrows a, b, c; that is, considering a vertical section through the disk, the bursting c01nponent at the periphery may be represented by the arrow a, that at the center by the arrow 0, and at some. intermediate point by Z). The strains at the center where they are a maximum are greatly in excess of those at the periphery, where they are a minimum. Figs. 3 and 4 show a. .disk B similar to disk A in which there is a central opening C. The bursting strains on a vertical section are indicated by the arrows a, b, c, thatat the outer periphery being indicated by a, that at the inner periphery by c, andat an intermediate oint by Z). Experiment has shown that wlien there is an opening as C, there is an entire change in relation of the strains to each other and cause a marked and excessive increase in the strain at'the periphery of the central opening, which rapidly decreasesat points a short distance therefrom. This great difference in the magnitude of the strains caused by the opening in the disk may be accounted for theoretically, although very complex formulae are involved for calculating the strains. Moreover, it is ex erimentally as well as theoretically true t1at the magnitude and relations of the bursting strains are greatly changed by the presence of a central opening no larger than a pin-hole. The above leads to two requirements for obtaining strains of equal magnitude throughout all parts of the structure; first, the structure must be thinnest at the periphery and gradually increase in thickness until it is a maximum at the center; second, the structure must be one solid integral mass. This result is obtained, in the structure shown in Figs.

5 and 6 representing a disk D tapering from the periphery so as to gradually increase the thickness, which is greatest through the center. By this construction the strains on a vertical section will be practically uniform .atevery point, as represented by the arrows a", although the actual outline for this purpose is more nearly represented by the dotted lines in Fig. 5.

In applying the above principles to the revolving field structure of a dynamo electric machine, I have invented the form of core shown in Figs. 7 and 8, in which both of the above stated requirements are fulfilled. In the construction shown I provide one solid element of high magnetic permeability, which serves the function of a shaft as well as the core, being freefrom all joints and thus avoidingthe excessive strains caused by their presence. I -also taper down the endsof the coreso as to give practically uniform'strength to all parts. In the figures a core 1 is lllustrated square in section, adapted for four poles and with the slots 2 to receive the dove-tailed projections of the pole ieces. Integral with this solid core are t e tapering ends 3 which serve to greatly strengthen the central part of the catedby arrows p caused by the attached core and also serve as supports for the same.

The'construction described is of value not only with. reference to the strains created by the rotation of the core itself, but also-to overcome the great additional strains indi- 7 by the through bolts 6 between the end plates 7. The pole pieces are provided with a plurality of dove-tails 7' which engage slots cut in the core 1. Thefield winding 8 is shown in this, instance as a strip winding supported between the pole tips 9'and core 1.; Between the poles and for the purpose of supporting the windings, I provide cast metal frames 10. These are triangularbox like-pieces secured to the core 1 by the tap bolts 11, the openings 12 for the heads of the bolts being closed by the screws 13, which would also serve to keep the bolts from flying but in case of breakage. Any suitable number of frames 10 may be used, depending upon the length of the pole, five being shown in Fig. 9 spaced apart from each pther. The frames 10 are engaged by the projections 13 extending from the pole tips which assist the bolts 11 in retaining the frames in place. The end connections of the coils are supported. and protected by the casting 14 of steel, phosphor bronze or other 5 suitable material. This is U shaped in section and the winding is inclosed between the 5 arms 15 as shown in Fig. 9, the arms being 1 provided with/dovetails for engaging the core in the same way as the laminae. A spacing block- 15' is placed between the nner ends of the arms. Acover plate 16 is placed at each end .of the core to prevent sidewise movement-of the poles, the plates 16 being secured to the core 1 by end bolts 17 and radial bolts 18. The supports 14 are secured at their outer ends by means of the bolts 19 which are shown as extending through the full length of the pole piece, giving a very rigid construction. The leads '20 are brought out from the coils and connected to the usual collector rings 21, the leads being diametrically mg a more balanced structure.

It is apparent that my construction is very compact and rigid. throughout and the strength is the greatest in the central core.

where it is most needed,as above explained. My construction presents the further advantage that'the entire core serves asa'. path for the magnetic flux, being made of one solid mass of high magnetic permeability.

opposite for gi'v- It is understood that I am not limited to v the exact construction shown as changes in detail may be made without departing from g the scope of the claims.

I claim as my invention: g

1. In a revolving field structure, the com bination with an element comprising a core, polygonal in shape, of high magnetic permeability, having extensions for supporting the same, all of one solid integral mass, of field magnet poles secured to said element.

2. In a revolving field structure, the combination withan element comprising a core ofhigh magnetic permeability, having gradually tapering extensions for supporting the same, all of one solid integral mass, of field magnet poles secured to said element.

3. In a revolving field structure, the combination with an element comprising a core, polygonal in shape, of high magnetic permeability, having gradually tapering extensions for supporting the same, all of one solid'integral-mass, of field magnet poles-se cured to said element.

4. In a revolving field structure, the combination with an element comprising a core of high magnetic permeability, having gradually tapering extensions for supporting the same, all of .one solid integral mass of laminated field magnetic poles secured to said element by dovetails.

5. In a revolving field structure, the combination with an elementcomprising a core, polygonal in shape, of high magnetic permeability, having gradually tapering extensions for supporting the same, all of one solid integral mass, of laminated field magnetic poles secured to said element by dovetails.

6. In a revolving field magnet structure,

the combination with the core and field magnet poles, of means for supporting theend turns'of the windings, comprising U. shaped members inclosmg the end connect ons,

" the outer end of piece.

7 members in'closing the means for securing the inner-ends of said members to the core and means for securing said members to the pole 7. In a revolving field magnet structure, the combination with net poles, of means for supporting the end turns of the windings, comprising U shaped end connections, the arms, ofsaidU shaped members having dovethe core and field mag-- tail projections which engage the core and bolts for securing the outer end of said members to the'pole piece.

In testimony whereof I aflix my signature, in presence of two witnesses.

BERNARD ARTHUR BEHREND.

Witnesses:

LILLIAN J.BR1TT0N, SANFORD KLEIN.

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