US3501660A - Steel motor foot construction - Google Patents

Description

I March 17, 1970 L. w, WIGHTMAN mL 3,501,600

STEEL MOTOR FOOT, CONSTRUCTION Filed Jan. 5, 1969 Ffa! United States Patent O 3,501,660 STEEL MOTOR FOOT CONSTRUCTION Lawrance W. Wightman and Nick Tichy, St. Louis County, Mo., assignors to Emerson Electric 'Co., St. Louis, M0., a corporation of Missouri Filed Jan. 3, 1969, Ser. No. 788,818 Int. Cl. H02k 5/00 U.S. Cl. 310-91 6 lClaims ABSTRACT OF THE DISCLOSURE Feet for supporting and anchoring an electric motor stamped and formed from steel sheet stock and welded to a cylindrical steel stator shell, the feet being arranged to provide shielding for air -vents in the lower half of the stator shell.

This invention relates to dynamoelectric machines, and particularly to the construction and arrangement of feet for supporting and anchoring large size electric motors.

In the development of low-cost steel casings for the larger size electric motors to replace the heretofore conventional cast-iron casing, the need arose for a suitable low-cost foot construction having the required strength, rigidity, and appearance and adapted to simple and economical attachment to the casing.

Accordingly, it is an object of this invention to provide a construction and arrangement which meets these requirements and comprises four steel feet formed of sheet stock and welded to the outer surface of a steel stator shell.

A further object is to provide a cylindrical steel stator shell having four supporting and attaching feet, the feet being formed of steel sheet stock and each foot having an arcuate edge portion and a straight edge portion perpendicular thereto, which edge portions lie, respectively, transversely and axially along the surface of the shell and are welded thereto.

A further object is to provide a supportipg and attaching foot adapted to be welded to a steel stator shell as one of a plurality of such feet supporting and anchoring an electric motor, which foot is formed from steel sheet stock and includes upstanding portions adapted to be welded to the stator shell and a ilat horizontal base portion having a hole therein to receive an anchor bolt, the hole being positioned in the base portion so that the base portion will ex thereby to preclude distortion of the stator shell when strain occurs upon tightening of an anchor bolt.

A further object is to provide a cylindrical steel stator shell having air vents in the lower half thereof and including four formed steel supporting and attaching feet welded thereto and arranged to shield the air vents.

These and other objects achieved in the invention will be apparent when reading the following description in connection with the accompanying drawing.

In the drawing:

FIG., 1 is a side elevational view of an electric motor having a foot construction and arrangement according to the present invention;

FIG. 2 is a side elevational view of the electric motor shown in FIG. 1, having a portion of an end shield broken away;

FIG. 3 is a side elevational view of one of the formed steel feet;

FIGS. 4 and 5 are right and left end elevational views, respectively, of the foot shown in FIG. 3;

FIG. 6 is a bottom plan view of the foot shown in FIG. 3; and

FIG. 7 is a plan view of the blank form from which the foot shown in FIGS. 3 to `6 is formed.

Referring now to the drawing in more detail, a horizontal A.C. electric motor is generally indicated at 10. The

3,501,660 Patented Mar. 17, 1970 ice motor has a casing comprising a horizontal, cylindrical, steel shell 12 into which a stator core 14 is fitted and xed and a pair of end shields 16 attached to the ends of the shell which journal and support the shaft 18 of rotor 20. The shell 12 is provided with peripherally spaced air vents 22 in the lower half thereof, and the end shields 16 are provided with vents 24 in the lower halves thereof.

Cooling air is drawn into the casing through the vents 24 in the end shields, and exhausted through the vents 22 in the shell 12 by rotor-driven blowers (not shown) positioned between the ends of the stator 14 and rotor 20 and the end shields. The periphery 26 of the stator core 14 is spaced from the wall of shell 12 by a thick steel mounting band 28 which is press iitted on the stator core and then pressed into and iiXed in shell 12. The width of the mounting band is considerably less than the length of the stator core. This arrangement permits the outlet or exhaust vents 22 in shell 12 to be moved axially inward from the ends of the shell. If the stator core 14 is press fitted directly into the shell 12, the vents 22 would have to be spaced apart axially a distance at least equal to the length of the stator.

The shell 12 is provided with four feet 30 which support the casing in spaced relationship with a floor or base and provide means for anchoring it thereto. The feet 30 are constructed from steel sheet stock of suitable thickness by blanking and forming. Each of the feet has a rectangular, flat, horizontal base portion 32, a relatively long, upstanding, flat portion 34 extending upwardly at a right angle from one side of base portion 32, and a relatively short, llat portion 36 extending upwardly at an acute angle from an adjacent side of the base portion. The tlat portions 34 and 36 being formed as extensions of adjacent sides of rectangular base portion 32 are, therefore, perpendicular to each other. The base portion 32 is provided with a clearance hole 33 to receive an anchor bolt.

The upper portion of that side of portion 34 adjacent the portion 36 is arcuate, having substantially the same curvature as the cylindrical shell 12, as indicated at 38. The portion 36 is, however, rectangular and has a straight square end 40. The feet are positioned on shell 12 with their flat portions 34 perpendicular to the axis of the shell and with their arcuate side portions contiguous with the surface of the shell. The straight ends 40 of portions 36, being perpendicular to the adjacent arcuate sides 38, extend axially and in contiguous relationship with the shell surface. The feet are welded to the shell along these contiguous sides of the foot portions. It is not, however, essential to rigidity or to secure attachment that the weld extend continuously along these contiguous portions; welding at two spaced points along the contiguous portions has been found to be adequate and is, of course, le'ss costly.

The feet 30 are arranged in pairs, each pair consisting of a left and right-hand foot positioned in axial spaced relationship and in axial alignment along one side of the lower half of horizontal cylindrical shell 12 with the vents 22 lbetween them. Preferably, each axially aligned pair of feet 30 are arranged so that their long, upstanding, transverse portions 34 are adjacent, that is, facing each other, and their shorter axially extending portions 36 remote, as shown. The two feet of each axially aligned pair may, however, be reversed from the positions shown, if desired, when greater axial spacing of the shell vents 22 requires. The left and right-hand feet are formed, however, from identical blanks, as the one shown in FIG. 7, by merely forming the portions 38 and 40 in one direction with reference to base 32 for a left-hand foot and in the opposite direction for a right-hand foot.

The lateral spacing of the pairs of feet is such that the straight sides 42 of the relatively long, upstanding, foot portions 34 are substantially tangential to the shell 12, as shown in FIG. 2. Cover plates 48 enclosing the upper half of the space between the transverse foot portions 34 and connected at their ends to the straight sides 42 of portions 34 by screws or pins 46 are provided. The foot portions 34 and cover plates 48 provide a shield for the air vents 22 in the lower half 0f shell 12, and the cover plates 48 additionally substantially improve the appearance of the construction. The cover plates 48 are preferably formed of lighter gauge sheet stock than the feet 30 and are preferably provided with perforations so as not to restrict the flow of air through air vents 22.

In assembling the feet 30 on the stator shell 12, the shell is cradled in an assembly xture which includes a base having four upstanding locating pins accurately positioned thereon with reference to the cradle axis. The feet 30 are then positioned on the xture base with the locating pins entering the anchor bolt holes 33. The feet 30 are dimensioned so that manufacturing tolerances are accumulated in variable slight spaces between the foot sur- `faces 38 and 40 and the shell wall. These surfaces are then welded to the shell, preferably at two spaced points along each surface, thereby to reduce the cost over a continuous weld. The extensive contiguous surfaces of the foot and the shell permit this economy and provide the required rigidity and security of attachment.

Stress in a greater or lesser degree is frequently set up upon the tightening of the Ibolts anchoring the motor to a floor or base. In cast-iron casings with integral cast feet and in steel casings with welded steel feet, such stresses may, in some instances, be of suflicient magnitude to distort the stator casing and seriously affect the air gap. In order to relieve such stresses and preclude distortion of the casing, the clearance holes 33 in the horizontal, rectangular, base portions 32 of the feet are positioned outwardly fromv the center of the base portion toward the intersection of the free sides thereof, as shown in FIG. 7. This provision permits the ilexing of the base portion 32 along the dot-dash line 44.

We claim:

1. A foot for supporting an anchoring an electric motor and adapted to be welded to the exterior surface of a steel cylindrical motor casing, the foot being formed of steel sheet stock and comprising a flat, horizontal, base portion of general rectangular shape having a hole therein to receive an anchor bolt, a relatively long, fiat portion extending upward at a right angle from one side of said base portion, and a relatively short, flat portion extending upward at an acute angle from an adjacent side of said base portion saidrelatively long portion having an arcuate side adjacent said relatively short portion and said relatively short portion having a straight, square, free end, the curvature of said arcuate side being substantially the same as that of the cylindrical casing to which itis to be welded, whereby when said foot is positioned on the 4cylindrical casing with said relatively long, flat portion thereof perpendicular to the casing axis said arcuate side and said straight end of said upwardly, extending foot portions will lie contiguous with transverse, arcuately extending and straight, axially extending surfaces of the casing thereby to provide extensive perpendicularly extending contiguous surfaces to be welded.

g. A foot as `set forth in lairn 1 in which said anchor bolt hole in said base portion is positionedoutward from the center thereof toward the intersection of the free sides of said base portion thereby to permit easier flexing of said base portion when Isaid foot is welded to a motor casing and pulled hard against a base by an anchor bolt.

3. A pair of feet -as set forth in claim 1, adapted to be positioned in axial spaced relationship along one side of a cylindrical steel electric motor casing and welded thereto, in which the relatively long, at and relatively short, flat portions of one foot of the pair are formed in one direction and the relatively long and relatively short, llat portions of the other foot are formed in the opposite direction with respect to the said base portion.

4. A foot as set forth in claim 1 in which the center of curvature of said arcuate side is spaced from said horizontal base portion an amount at least equal to the length of said relatively long, ilat portion and in which the side of said relatively long, ilat portion opposite said arcuate side is straight and substantially tangential to a projection of said arcuate side.

5. In an electric motor, a casing including a horizontal steel stator shell having a plurality of air vents spaced peripherally and axially in the lower half thereof, means for supporting and anchoring said motor comprising four feet welded to the lower half of said stator shell, said feet being formed of steel sheet stock and each having a at, horizontal, base portion of general rectangular shape with a hole therein to receive an anchor bolt and a long,

flat, upstanding portion extending upwardly at a right angle from one side of said base portion, said long, upstanding portions being perpendicular to the axis of said stator shell and having an arcuate side of substantially the same curvature as said stator shell contiguous with the surface of said shell and being welded thereto, the opposite side of said long, upstanding portions being straight and substantially tangential to said stator shell, said feet being arranged in pairs along opposite sides of the lower half of said stator shell with said air vents between said long, upstanding portions, and a flat cover member extending between said long upstanding portions lying flat against said straight sides thereof and attached thereto.

6. An arrangement as set forth in claim 5 in which said feet each have a relatively short, llat portion extending upwardly at an acute angle from a side adjacent to said one side of said base portion, said short, ilat portions each having a straight square end extending axially along and contiguous with the surface of said shell and being welded thereto.

References Cited UNITED STATES PATENTS 2,473,105 -6/ 1949 Luenberger 310-91 2,496,507 2/1950 Watkins 31o-258 3,441,760 4/196-9 Collens 310--91 j FOREIGN PATENTS 1,135,085 y8/ 1962 Germany.

WARR-EN E. RAY, Primary Examiner Us. c1. xn, 248-14; S10-25g

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