US1043047A - Rotor for electric machines. - Google Patents

Description

R. GOLDSGHMIDT. ROTOR FOR ELECTRIC) MACHINES.

APPLICATION FILED JUNE 4, 1912.

Patented Oct. 29, 1912.

finespjf- J EW [ma/en???" UNITED STATES PATENT OFFICE- RUDOLF GOLDSCHMIDT, 0F DARMSTADT, GERMANY.

ROTOR FOR ELECTRIC MACHINES.

To all whom it may concern:

Be it known that I, RUDoLF GOLDSOHMIDT, a citizen of Germany, residing at Darmstadt, Germany, have invented a new and Improved Rotor for Electric Machines, of which the following is a specification.

Electric machines of large diameter usually comprise a magnetically operative annular mass that is supported by a radiating central portion, the magnetically operative mass being composed of laminated metal, while its radiating portion may consist of solid steel, bronze or any other suitable material.

The annular portion is attached to the radiating central portion by means of screws, dovetail joints or the like; the mode of attachment adopted being designed to prevent the annular portion, which advantageously consists of separate segments, from being torn apart from the central portion by centrifugal. force. The coefficient of expansion of the material forming the annular portion is, however, almost invariably different from, and in general, considerably lower than that of the material of which the radiating central portion is composed; and this is especially the case when the annular portion consists of very thin sheets of a hard metallic alloy. It consequently follows that in the construction usually adopted, the strain due to expansion at the circumference of the annular portion is considerably increased by the more rapid expansion of the radially extending arms of the central portion. From this it follows that while the strain on the arms is still inconsiderable, the annular portion may, when its coefficient of expansion is low, under certain conditions, be strained even to thebreaking point. The lower therefore the coeflicient of expansion of the annular portion or the more defective the connection of the dovetailed joints, the less is that portion of the strain taken up by the radial arms, and the greater is the chance that the radiating portion may fail to afford the protection intended, with the result that the annular portion may burst before the radial arms are subjected to any considerable strain. The danger of this occurring is increased by the fact that thematerial of which the annular portion is composed is usually chosen only with reference to its magnetic properties and that no regard is paid to the question of its strength.

Specification of Letters Patent.

Application filed June 4, 1912.

Patented Oct. 29,1912.

Serial No. 701,662.

Now an object of the present invention is to provide an improved construction of rotor wherein strains in its annular or rim portion due to its comparatively low'coeflicient of expansion are eliminated or mini-' mized while the strains due to its centrifugal force are practically borne entirely by the spokes of the central radiating portion of the rotor. This is effected by subdividing the annular portion into segments which are separately and independently attached to the ends or otherwise of two arms of the radiating hub portion.

A further object of the invention is to construct the rotor throughout of uniform strength thus avoiding additions to its mass which merely serve to increase centrifugal force and hence to limit the maximum rotary speed attainable.

In the accompanying drawings, Figure 1 illustrates in side diagrammatic elevation one construction of rotor according to this invention; Fig. 2 is a similar illustration of a modified construction, and Fig. 3 is a section on the line III III of Fig. 1.

In the drawings, 0. indicates the annular and b the radiating portion. The annular portion is sub-divided into separate segments 0 by means of slots s, which extend throughout the entire width of the segments. These transverse slots or gaps may either be formed in a radial direction (Fig. 1) or they may be stepped by correspondingly stepping the ends of the segments as shown at cl (Fig. 2). hen such an arrangement is adopted the strains are not borne by the annular portion abut each segment 0 thereof transmits its strains to the spokes e of the radiating hub portion 7). Under these circumstances the material of which the radiating portion 1) is composed may be selected solely with reference to its strength, while it is, moreover, no longer necessary to pay the same attention to the accurate fitting of the dovetailed joints as in constructions wherein strains arising in the spokes are transmitted to the rim. The portion. 6 may advantageously be constructed as of equable or uniform strength throughout, its spokes e tapering outwardly toward the rim a, as shown in Figs. 1, 2 and 3.

The outer extremities of the spokes 6 may be connected in any suitable manner with the segments a; in the constructions illustrated these extremities are enlarged to form dovetailed heads f, engaging with corresponding recesses in the ends of the ments, the Width of each head being greater than the combined depths of a pair of opposed recesses.

hat I claim is:

1. In a ring armature for electric inachines a hub, a plurality of spokes radiating therefrom, a plurality of segments, each at said segments being secured at its ends to the ends of a pair of adjoining spokes and being separated from the adjacent segments by transverse gaps that extend outwardly from the spokes, wherebv the strain due to eentritugat action is separately transmitted from each segment to said adjoining spokes.

2. In a ring armature for electric ma chines, a hub a plurality of spokes radiating therefrom and having dovetailed heads, a plurality of segments having undercut recesses at both ends, the opposed recesses of each pair of adjoining segments being engaged by a common spoke-heath while the Width of said head exceeds the combined depths of said recesses, so as to form a trans Yerse gap between the segments that extends outwardly from the spoke-head, Wherehy the strain due to centrifugal action is separately transmitted from each segment to the two adjoining spokes.

RUDULF GOLDSCHMIDT. Witnesses ARTHUR E. Zunrn, :KATI-IERYNE K001i.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C.

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