US1311638A - Dynamo-electric machine - Google Patents

Description

A. L BROWN.

DYNAMO ELECTRIC MACHINE.

APPLICATION man ma. 2. 1914.

1,31 1,638. Y Patented July 29, 1919.

THE COLUMBIA PIANBGIIAPK 120., WASHINGTON, u. c.

UNITED STATES PATENT OFFICE.

ARTHUR J. BROWN, OF MILWAUKEE, WISCONSIN, ASSIGNOR- TO ALLIS-CHALMERS MANUFACTURING COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF DELAWARE.

DYNAMO-ELECTRIC MACHINE.

Specification of Letters Patent.

Patented July 29, 1919.

To all whom it may concern:

Be it known that I, ARTHUR J. Buown, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented a certain new and useful Improvement in Dynamo- Electric Machines, of which the following is a specification.

This invention relates to dynamo-electric machines and more particularly to such machines when used for driving a load that may become, at times, extremely heavy, as, for instance, when the machine is used for driving the rolls of rolling mills and the like.

In the operation of rolling mills by electric motors, it is desirable to provide, between the motor and the rolls of the mill, a special form of coupling which is designed to withstand smaller torque than the shaft and other rotating parts. I11 case of an overload on the rolls, or other driven machinery, this coupling breaks, permitting the motor t run, but without load. This coupling serves a purpose very similar to that of a fuse in an electric circuit. When such a coupling breaks, it usually does so along an irregular surface, and the two portions of the coupling, having relative rotation, due to the stoppage or slowing down of the rolls, are forced apart, and. as the roll shaft is held against end-Wise movement, the motor shaft is caused to move endwise. In some cases, this end thrust on the motor is exceedingly heavy, and unless special means are provided for taking n such thrust, serious damage may result to t e motor parts. It will be apparent, then, that it is desirable that the motor be free to move endwise to a limited extent, when the coupling between the motor shaft and the rolldriving shaft breaks.

It is the object of the present invention to provide an improved construction in which a motor shaft is permitted to have endwise movement, due to excessive end thrust, such as occurs on the breaking of a driving con nection between the motor shaft and a driven shaft, and is held against such endwise movement during normal operation.

Another object of this invention is to pro vide an improved bearing for a motor shaft, capable, at times, of moving relatively to a fixed part of the motor frame or support.

These and other objects are obtained by this invention, the novel features of which will appear from the description and drawings, disclosing one embodiment of such invention, and will be particularly pointed out in the claims.

In the drawings:

Figure 1 IS a partly sectional elevation of a wound-rotor induction motor in Which the invention has been applied, coupled to a shaft which may be the driving shaft of a, rolling mill.

Fig. 2 is an enlarged vertical section of a portion of the righthand pedestal and the bearing supported thereby, shown in Fig. 1.

Fig. 3 is a view similar to Fig. l, but show ing the couplin between the motor shaft and the driven siaft broken, and the shaft and rotor of the motor forced to the right.

Fig. 4 is an enlarged section of the righthand bearing and associated parts shown in Fig. 3, the motor shaft and bearing being forced to the right.

As shown in Fig. 1, fixed supporting pedestals 8 and 9 support a wound rotor 10 of an induction motor, the rotor being mounted on a shaft 11. so as to rot-ate within a stator 12. The shaft 11 is mounted in bearings 141 supported on pedestals 8 and 9, respectively, and is connected by a coupling 15 to the shaft 16, which may be the driving shaft of the rolls of a rollin mill, or may be connected to any other esired load. Sev eral collector rings 17, here shown as three in number, are mounted on a sleeve 18, and each collector ring is connected by a flexible connection 19 to the proper point or points on the Winding of the rotor 10. The sleeve 18 fits loosely on the shaft 11, any suitable means being provided whereby the sleeve and rings may slide longitudinally of the shaft, but must rotate therewith.

A support 31 is here shown as mounted on the cap 44, carrying brush studs 32 for brushes 33 which cooperate with rings 17. The support 31 also carries one or more inwardly projecting arms, carrying rollers 35 at their inner ends. The rollers 35 are disposed in a groove formed in the sleeve 18 and engage the sides of the groove. The support 31 may be in the form of a ring held in place and extending into the groove 35, or any other construction suitable for the purpose may be used; and, further, any arrangement that is effective to maintain the brushes in contact with the collector rings connected to the rotor winding, in spite of any movement of the rotor shaft due to exoessive end-thrust, may be used instead of the construction shown.

For a detail view of the bearing 141 and its associated parts reference may be had to Fig. 2. The pedestal 9 has its upper portion recessed at 41 and is provided with an interior portion 42 adapted to form a seat. A cap or shell 44, recessed similar to the upper portion of the pedestal, is provided with a portion or seating surface 42 adapted to aline with the portion 42 of the pedestal, when the cap is secured in operative position relatively to the pedestal, as by bolts 46. The seat portions 42 and 42' may be disposed centrally of the pedestal and cap, respectively, and the two alined parts may present a smooth polygonal or cylindrical surface, to form a seat for a bearing 141, which may be of any type suitable to provide perfect alinement of the shaft 11 carried thereby. If the engaging surfaces of the parts 42 and 42" and bearing 141 are cylindrical, a feather 47 may be used to prevent rotation of the bearing in the pedestal and cap. The bearing is normally held against endwise movement relative to the pedestal and cap by means of bolts 21 engaging the cap or pedestal and the bearing, being here shown as passing through a portion of the bearing, heads or nuts on the bolts being effective to hold one or more recessed portions 48 on the bearing against one or more shoulders 49 on the cap or pedestal. A reduced portion of the shaft 11 passes through the bearing 141 and is limited to comparatively little endwise movement relatively thereto by the collars 50 and 51 on the shaft engaging portions of the bearing. A bumper collar 52 on the shaft 11, by engagement with a portion of the pedestal or cap, serves to limit the endwise movement of the shaft, when the same has been subjected to such excessive endwise thrust .as is capable of shifting the hearing.

In the construction illustrated. the motor and bearing parts are normally in the positions shown in Figs. 1 and 2. However, when the load on the shaft 16 becomes excessive and the coupling 15 breaks, this break being always along a rough or uneven surface which is generally somewhat diagonal, the shaft 11 is moved endwise, the thrust on the shaft being sufficient to cause the breaking of the bolts 21 and the endwise movement of the bearing 141 relative to the pedestal and cap, this movement occurring through the engagement of the collar 50 with the bearing. The bearing is free to move a sufiicient distance to allow the broken parts of the coupling 16 to clear each other, and its movement is limited by ongagement of the bumper collar 52 on the shaft with a portion of the cap or pedestal. Figs. 3 and 4 show the parts in the relative positions that they occupy when the coupling 16 is broken and the motor shaft has con moved endwise.

In assembling the bearing in operative position, the breakable bolts 2'1 in the cap portion of the support, may be manipulated through openings 52.

As the connection between the shaft and bearing is such as prevents appreciable relative longitudinal movement, it will be obvious that the shaft, itself, or any art connected thereto, may form the movale abutment for breakable bolts.

Although the invention is here shown as applied to a wound-rotor induction motor, it is also applicable to other forms of motors and, in fact, to a generator or any other machine, which -may be coupled to a driving source, and which it is desirable to protect from the injurious effects of excessive endwise thrust that may result on the breaking of the shaft connection between the machine and the driving means, or from any other source.

It should be understood that it is not desired to be limited to the exact details of construction shown and described, for Ohvious modifications will occur to a person skilled in the art.

It is claimed and desired to secure by Letters Patent:

In combination with a machine comprising a rotatable part mounted on a shaft, a bearing housing, a bearing for said shaft within said housing, said shaft and said bearing being held against appreciable relative longitudinal movement, and means comprising a plurality of bolts disposed within said housing and having frangible portions for preventing movement of said bearing relative to said housing and permitting only axial movement of said shaft and said bearing on the occurrence of excessive end thrust on said shaft.

In testimony whereof the si ature of the inventor is aflixed hereto in t e presence of two witnesses.

ARTHUR J. BROWN. Witnesses:

W. H. LIEBER, J. J. KANE.

(topics of this patent may be obtained for live units each, by addressing the Commissioner of Patents.

Washington, D. 0."

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