US 3081411 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
March 12, 1963 J. B, WILEY 3, "TIN-CAN" HOUSING FOR A DYNAMOELECTRIC MACHINE Filed Sept. 8, 1958 8 Sheets-Sheet l INVENTOR. JOHN B. Wllf Y J. B. WILEY March 12, 1963 "TIN-CAN" HOUSING FOR A DYNAMOELECTRIC MACHINE 8 Sheets-Sheet 2 Filed. Sept. 8. 1958 INVENTOR. JOHN B. mm I v BY Hi5 AUORNE Y March 12, 1963 J. B. WILEY 1,
"TIN-CAN" HOUSING FOR A DYNAMOELECTRIC MACHINE Filed (Sept. 8, 1958 a Sheets-Shet 3 i23 121 Lfl Fig. 5
INVENTOR. John 8. Way BY His Attorney March 1953. J. B. WILEY 3,
"TIN-CAN" HOUSING FOR A DYNAMOELECTRIC MACHINE Filed S t, 8'. 195a 8 Sheet s-She et 4 24s 4 I I l24r I INVENTOR.
John B. Wiley BY His Attorney March 12, 1963 J. B. WILEY "TIN-CAN" HOUSING FOR A DYNAMOELECTRIC MACHINE Filed Sept. 8, 1958 8 Sheets-Sheet 5 H k 223C 225 5&2 2|2 \N v v v 223M \--223d 71 224R w L F 6 INVENTOR.
lg John B. Wiley H/l'; Attorney March 1963 J. B. WILEY 3,081,411
"TIN-CAN" HOUSING FOR A DYNAMOELECTRIC MACHINE Filed Sept. 8, 1958 -8 Sheets-Sheet 6 Fig. 6a
INVENTOR. John B. Wiley 324r l BY March 12, 1963 J. B. WILEY 3,081,411
"TIN-CAN' HOUSING FOR A DYNAMOELECTRIC MACHINE Filed Sept. 8, 1958 8 Sheets-Sheet 7 John B. Wiley Fig.7 2%
His AI/omey J. B. WILEY March 12, 1963 "TIN-CAN" HOUSING FOR A DYNAMOELECTRIC MACHINE 8 Sheets-Sheet 8 Filed Sept. 8, 1958 00 mOOm Smwm mOmn m Qu mNm
INVENTOR. John B. Wiley 20% His Affomey TIN CAN HOUSING FOR A DYNAMOELECTRIC H MACHINE John B. Wiley, St. Catharines, Gntario, Canada, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Sept. 8, 1958, Ser. No.,759,475
7 Claims. (Cl. 310-254) This invention relates to a housing and process for making the same to support a rotating mechanism concentrically: within the housing in aligned relationship thereto. This is a continuation in-part of my copending U.S'. parent application S.N. 694,593 filed November 5, 1957, now abandoned.
An object of this invention is to provide a housing for rotating-mechanism maintained concentrically within the housing in aligned relationship thereto using a bearing and flange cover for journalling the rotating mechanism in aligned and lubricated condition relative to the housing which is mounted stationary and removable for inexpensive replacement of the entire housing and rotating mechanism. 7
Another object of this invention is to provide a machine having a rotating mechanism housed within the inexpensive canned frame construction removable with the machine in the event of defect or failure and replaceable with a new machine and frame construction for less cost than encountered in field repair under warranty.
Another object of this invention is to provide a process of producing an inexpensive yet precision made housing for a machine having a rotating mechanism that is jour'nalled and accurately aligned relative to the housing due to use of spaced bearings aligned relative to the housing during the process including steps of providing a rotor having a shaft and a stator carried within a body portion of a tin-can housing and aligning the rotor relative to the stator by means of tin-can annular members used to journal opposite shaft ends concentrically relative to the body portion of the housing. 1
Another object of this invention is to provide a process of producing an electric machine having a stator and rotor housed concentrically within a sheet metal body manufactured using rollers movable relative to dies for concentrically turning at least one end of a wrap-around body portion in alignment relative to a bearing-locating flange of a lid member by which a shaft of the rotor is rotatably journalled, the process requiring no bolting or machining except for fabrication of the shaft rotatably journalled in lubricated impregnated sintere'd metal bearingssupported by the lid members stamped and then assembled to the body portion to form an expendable or canned machine.
Another object of this invention is to providean expendable dynamoelectric machine havin g a frame formed of a tin-can sheet metal cylindrical body portion having louvers extending and opening for cooling in opposite directions from a radial median location and having stamped annular members providing a bearing-locating flange relative to which a rotor shaft is journalled by means of a bearing supported concentrically and in aligned relationship to the body portion and a stator carried therein, the stamped annular members having inwardly directed angularly displaced louvered openings terminating adjacent to fan blades carried by the rotor for circulating cooling air through the dynamoelectric machine and radially outwardly and downwardly away from the body portion.
Another object is to provide an expendable motor having a frame formed of a stamped sheet metal cylindrical body portion having radially oppositely and outwardly exatent O ice tending ventilating apertures spaced from each other adjacent to stamped annular ridges projecting radially inwardly relative to the body portion for concentrically supporting laminations of a woundstator in alignment relative to a rotor having a shaft journalled by lubricant-impregnated sintered metal bearings adjacent to a lubricating cavity formed by stamped annular members having a bearing-locating flange provided for maintaining concentricity and alignment of the rotor relative to the stator with a high degree of precision despite low-cost of manufacture of the'expendable motor.
A further object of this invention is to provide a tincan housing for a Inachinehaving a rotor and a stator supported concentrically Within a thin sheet metal wrap} around body portion with at least one end provided with a crimped-over annular beaded portion adapted to be complementary to a crimped-over annular beaded portion of an annular removable member of stamped sheet metal having an aligning portion provided substantially concentrically with a high degree of precision relative to the crimped-over portion, the rotor having a shaft journalled relative to the annular member in concentric relationship relative to the aligning portion thereof.
Further objects and advantages of the present invention will be apparent from the following description, reference being bad to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.
In the drawings: 7
FIGURE 1 is an end elevational view of an expendable dynamoelectric motor in accordance with the present invention.
FIGURE 2 is a cross-sectional View of the motor taken along line 2 -2 of FIGURE 1. I
FIGURE 3 is a fragmentary developed view of a can:
type body portion with ventilating apertures stamped therein for the motor of FIGURE 2. FIGURE 4 is a fragmentary exploded view of one end head assembly including a stamped can-type lid and sintered metal bearing that cooperate to form a lubricating cavity provided adjacent to the bearing in the motor assembled in a tin-can-type method of motor manufacture of the present invention.
FIGURES 5 and 5a illustrate rollers and dies used in one embodiment of a process for making a tin-can" housing for rotating mechanism in accordance with the present invention. I
FIGURES 6 and 6a illustrate rollers and dies used in another embodiment of a process for making a housing for a machine having a rotatingmechanism concentrically aligned in accordance with the present invention.
FIGURE 6b illustrates another embodiment of structure for joining portionsof the tin-can housing.
FIGURES 7 and 7a illustrate cooling duct structure in accordance with the present invention. 7
FIGURE 8 illustrates a cross-sectional elevational view taken along line 88 of FIGURE 6a.
FIGURE 9 shows a housing of the present invention in-' stalled in an appliance.
FIGURE 9a shows another use for a housing of the present invention with rotating mechanism.
With particular reference to FIGURE 1, there is shown an end elevational view of an electric motor produced in accordance with the present invention and generally indicated by a numeral 10. This is an expendable motor hav: ing a canned construction for minim-urn initial cost and requiring a minimum of parts and machining during manufacturing while providing concenitri citties of a body p01- tion and end assembly relative to a stator and rotor shaft far superior to concentnicitie's' achieved using either castings or pressed steel motor frames turned and machined in accordance with previous motor manufacturing methods. For example, pressed steel motor end frames as previously manufactured include complicated assemblies of several pieces for forming end closures of a motor and for providing a lubricating system for bearings provided in an assembly with the end frames to rotatably journal a motor rotor shaft. In the motor of the present invention, end lids or end head assemblies made of a simplified stamping generally indicated by numeral 12 are illustrated in the drawings. FIGURE 1 shows one such end head assembly 12 which has a broken away portion adjacent an outer periphery of the lid where an end view of a body portion generally indicated by numeral 14 is partially visible.
The body and end heads of the motor in the present invention are manufactured on can making machines of a type known to those skilled in the art of making containers for shipment and storage of [food products of both a solid and liquid nature; These can making machines produce a product commonly referred to as tin cans using a thin flat sheet metal which is formed to provide a cylindrical body with a hollow interior closed off at opposite ends by head portions or lids that are assembled to the sheet metal body by seaming, soldering, or by press fitting peripheral edges of annular head members into tight engagement with opposite ends of the cylindrical body. A press fitted type of assembly between the lids and body portion results in a temporary fastening similar to that obtained in pressing a paint can lid as a cover onto a paint container for example. In any event, the body portion 1 4 of the motor in FIGURE 1 is formed on a can making machine into a cylindrica shape that provides a hollow interior portion 15 for the motor as longitudinal edges 16 and 17 of the body 14 are joined in any suitable manner known in manufacture of can containers. The edges 16 and 17 are shown forming a butt joint which could also be soldered or otherwise fused together in the manufacture of the motor of the present invention. The stamped lid 12 is provided with a central boss portion generally indicated by numeral 18 and a peripheral covering portion 20 that has an outer radial edge 22 which is bent or formed to engage an end periphery 23 of the body portion 14 in sealing engage ment. The cover portion 20 of the lid is provided with axial openings 25 serving as ventilating passages communicating with the interior space 15 formed within the cylindrical body port-ion 14. Electrical wiring generally indicated by numeral 26 passes through a grommet or eyelet 27 inserted through an opening located at one side of the cover portion of the lid. The wiring 26 is connected with the windings provided with the stator of the motor shown in further detail in FIGURE 2.
windings generally indicated by numeral 28 are shown in FIGURE 2 as they are supported in a stator 30 which is formed of a plurality of stacked metal laminations in a usual manner by stamping out annular pieces and stacking the pieces having radially inwardly extending slot-s aligned relative to each other for receiving the windings 28 as is well known in the art of making dynamoelectric machines. Also shown in FIGURE 2 is a rotor lamination assembly 32 that is carried on a shaf 34 rotatable relative to the wound stator. The rotor 32 is preferably a squirrel-cage type of rotor having conducting metal cast extending longitudinally through slots provided in the rotor laminations aligned relative to each other and interconnected by a east end ring 36 on each of opposite sides of the rotor laminations. Also cast integral with the squirrel cage winding of the rotor are a plurality of longitudinally extending radial fins or fan blades 38 extending in opposite directions from the stacked rotor laminations. These fan blades 38 are spaced radially outwardly and concentrically relative to the shalt 34 and are positioned longitudinally of the openings 25 in the lids. As clearly seen in FIGURE 2, the openings 25 are formed by stamping sheet metal of the lids inwardly toward the space 15 within the hollow body portion 14" of the can type construction used for the motor of the present invention. [For purposes of rigidity, each of the lids 12 is strengthened in the cover portion 20 by inward y" extending flanges 39 around each of the openings 25 extending into an outwardly bent annular ring 40 spaced longitudinally away from the stator windings 28 so as to form an annular passage 41 between the ring 40 and windings 28 permitting air circulation for ventilating put-- poses around the windings contained in the canned con-- struction. The fan blades 33 rotate with the rotor 32 on the shaft 34 and create air turbulence within the canned construction for cooling of the electric motor. The fan blades 38 are cast with the rotor to be located concentrically and radially inside the windings 28 and the tan blades and rotor extend a length parallel to the-1 shaft 34 for a distance slightly less than the length of the windings 28 parallel to the shaft 34. The windings 28 are energized through Wiring 26 and .the motor of the present invention is produced having no switch in the motor body. A switch for controlling the motor is pr0- vided and mounted remote from the motor in some other portion of the device such as a refrigerator on which the electric motor of the present invention is to be used. An electric switch separate from the motor of the present invention can be quickly and easily replaced in the event of switch failure without disassembling the expendable type of motor thus decreasing the cost of rep-air and service on domestic appliance equipment such as a refrigerator. A similar separate switch arragnement can also be provided when the motor of the present invention is used for domestic equipment such as a washing machine or clothes dryer. Since a majority of motor failures experienced in field installations are attributed to switch failure, the removal of the switch from the motor proper results in less need for motor disassembly. For instances where the motor failure is not attributed to the switc the electric motor of the present invention is designed to be disposed of or thrown away in the event that failure occurs in the motor itself. In these instances, the defective motor is replaced by a new canned or expendable motor which costs less to produce than the cost of labor and repair in servicing a defective motor under a warranty that may be applicable to the motor as supplied by the manufacturer. Thus the expendable motor of the present invention is designed for minimum initial cost and can be built in various horsepower ranges for quick replacement of a complete motor unit in the event of field failure which previously has been costly in repair charges. The windings and wiring illustrated in the drawings disclose a single phase type of fractional horsepower motor made with a canned construction having a minimum number of parts involving a minimum number of machining operations during manufacturing of the expendable motor. Since any type of electrical switch may be provided for the motor serving to control the motor in any well-known manner, no switch is shown and no switch in particular is to be taken as forming part of the present invention.
In the motor assembly illustrated in FIGURE 1, any existing laminations for forming the rotor and stator can be used and mounted concentrically within the body portion 14 and lids 12 of the motor construction. The cylindrical body portion 14 as made with can making machines known in the container industry are formed having concentricities far superior to tolerances resulting from manufacture of castings and motor frames turned and machined in a manner previously known in the motor manufacturing art. Each of the lids 12 illustrated in FIGURE 2 are stamped out of flat metal sheets into a rigid annular structure having the boss and cover portions mentioned above. Each boss is provided with an outwardly extending longitudinal annular shoulder 42 which is spaced radially inwardly of the openings 25. The shoulder 42 is connected with a radial portion 43 of an inner peripheral surface extending the lboss which in turn is connected to a polygonally shaped wall '44 having a tapered or oblique structure relative to the concentric cylindrical relationship of the body portion 14 :and stator and rotor relative to the 'resilient annular mounting ring has a cylindrical outer periphery around which a metal band or grooved mounting sleeve 47 is supported for engagement by a strap or other suitable end support for mounting of the electric motor of the present invention. Since the particular mounting or band provided to clamp around the sleeve 47 does not form part of the present invention no such mounting is illustrated in the drawings. The ring 46 can be made of a rubber-like material having resilient characteristics for protecting the electric motor from shocks and vibration which can be transmitted from the device on which the motor is mounted or from the electric motor to the device on which it is mounted.
The hub is bent over to have a radial Wall 48 which terminates in a bent over flange portion 49 shaped having longitudinally and concentrically relative to the shaft 34.
The ring 49 of the hub does not form a bearing surface for the shaft but provides radial support for one end of a bearing generally indicated by numeral 50 provided to journal opposite ends of the shaft extending through each I of the lids 12. This bearing 50 is preferably made of sintered bronze -or other sintered metal that can be impregnated with oil so that a circulatory lubricating system including oil sumps and lubricating passages is not required for lubrication of shaft journalling surfaces provided between the bearing and shaft. The bearing 50 includes a cylindrical portion 52 having an end surface 53 which is press fitted into engagement with the inner surface of the ring 49 of the hub. At the end of the cylindrical portion 52 opposite the end surfaces 53 there is a radially outwardly extending annular flange or wall portion of the bearing 50 and this flange portion indicated by numeral 54 has an outer peripheral surface which is press fitted into engagement with the inner surface of the shoulder 42 provided with each lid 12. The hub of the lid 12 and bearing 50 press fitted into engagement therewith form a lubricating space or cavity 56 adjacent each of the journalled ends of the shaft 34. The cavity 56 is preferably filled with a lubricant impregnated cellulose material or other oil impregnated lubricating packing. 57 for feeding lubricant to the sintered metal bearing 50 as required. Since all free-flowing oil or lubricant from the journalling surfaces will be flowing over sintered metal through which the lubricant passed, there is little, if any, loss of lubricant because the cellulose material absorbs the free-flowing lubricant for redelivery to the journalliug surfaces when neded. Thus the electric motor of the present invention can be considered to be lubricated permanently for the life of the motor. It is noted that a cellulose type of material available commercially under a trade name Permawick can be used as a packing for the cavity 56.
Each lid 12 as stamped from thin sheet metal is pro vided with flange 42 and ring or lip 49 concentrically spaced relative to the shaft 34 such that the sintered metal bearing'St) can be press fitted in tight sealing engagement with the lid to form journalling surfaces relative to the shaft axially aligned on opposite sides of the rotor and stator assembly as well as the cavity 56. The cellulose material used as a packing in the cavity 56 replaces felt wicking systems previously provided with complicated assemblies for end frame hubs and journalling bearings for electric motor shafts where leakage of lubricant often is found to be difiicult to control. The sinter'ed metal bearing 50 is relatively porous for passage of lubricant through the journalling surfaces and the cellulose packing is effective in'soaking up and absorbing any "free-flowing lubricant or oil. Thus the stamped lid 12 provided at each end of the can-type body portion '14 for housing the stator and rotor in the motor of the present invention provide rigid support for concentrically positioning bearings 50 on opposite sides of the rotor with a minimum of parts and machining during manufacture of the motor.
Only the shaft 34 actually needs machining and the rotor larninations can be press fitted or otherwise secured to the shaft at an intermediate portion thereof. For spacing the rotor relative to the bearings 50, a metal washer 58 and a shim :59 are fitted around each of the journalling portions of the shaft 34 together with a felt or fibrous sleeve '66 and cup-shaped member 61 adjacent .a shoulder 62 at each of opposite ends of the shaft. The tfelt or fibrous sleeve '60 serves also to absorb vibration and axial shocks which may be transmitted in the motor of the present invention through the mounting thereof provided in a domestic appliance for example.
Since the bearings and packing 57 are assembled simultaneously with the hub of each of the lids, no bor-- ing or turning operations are necessary to provide lubrication of journalling surfaces for the shaft 34. Concentric spacing of the shaft 34 is attained through the bearings Siland lids 12 relative to the body portion 14 of the can motor which also concentrically supports the stator and coil assembly about an inner periphery of the body portion 14 by a very light press fit relative to the stator :laminations. If necessary a pinning operation can be added in the mmufacture of the canned motor for clamping or crimping the stator laminations into position inside the body portion 14. a
In addition to the openings 25 provided in each of the lids 12. for ventilation of the motor inside the canned construction, a plurality of radially outwardly extending ventilating apertures 65 and 66 are provided around at least one side of the body portion 14. The apertures 65 and '66 are displaced from each other angularly relative to the axis of rotation of shaft 34 as is visible in a fragmentary developed view of the body portion 14 shown in FIGURE 3. Each of the apertures '65 and 66 is stamped through an initially provided flat sheet of metal such that inwardly extending flanges 65a and 66a are formed on each of opposite sides of the stacked stator laminations as illustrated in FIGURE 2. The can making machine used in manufacturing the electric motor of the present invention operates to form the flat piece of metal that is bent into a cylindrical shape resulting in formation of the body portion 14. This formation of the cylindrical body portion effects a binding or press fitting of the stator laminations within the inner periphery of the sheet metal for the body portion 14 and abutting edges 16 and 17 described with the drawings in FIGURE 1 can be fused together or otherwise fastened or locked to each other. It is also possible to hold the body portion in a cylindrical shape by providing a cylindrical die on the can making machine for holding the body portion 14 in shape until at least one lid 12 is seamed to one peripheral edge of the body portion 14.
To further illustrate the method of manufacturing the canned type or expendable motor of the present invention,
a fragmentary exploded view of a lid 12., bearing 50, packing 57, shaft 34, and one peripheral edge of the body portion 14 are shown in FIGURE 4. The method of manufacturing the canned type or expendable motor includes the steps of stamping a lid or end head member with ventilating openings and a hub portion, providing a hearing 56 to form a cavity between the bearing and hub portion of thelid, stamping a flat sheet of metal with ventilating apertures and making a cylindrical body portion of the fiat piece for supporting a stator lamination and coil assembly, assembling the bearing '50 relative to the hub of the lid by a press fitting operation including formation of a cavity filled with a cellulose type of lubricant impreg- ,7 nated material, journalling ends of the shaft 34 in cylindrical portions of the bearings 50, and seaming or otherwise crimping and securing a peripheral edge portion of each lid to peripheral end 23 of the body portion 14 in a tin-can type of motor housing structure.
The completed motor assembly illustrated in the cross sectional view of FIGURE 2 is inexpensive to produce and provides adequate ventilation through the apertures 25 as well as apertures 65 and 66 described above. The fan blades 38 rotating with the rotor on the shaft 34 create air turbulence sufficient to circulate air around the windings 28 and within the hollow cylindrical space 15 inside the can type motor structure. The flanges 65a and 66a around openings 65 and 66, respectively, are bent radially inwardly in the form of louvers to direct a flow of air toward the windings 28 and also to serve in retaining the stator laminations of the stator 30 in a central location intermediate the lids 12 seamed at opposite sides to the body portion 14. The seaming operation as illustrated inFIGURE 2 includes a crimping of a peripheral edge of the body portion 14 with a bent over locking edge 72 of each lid 12 positively engaging the lids concentrically relative to the body portion 14 and stator and rotor. It is to be understood that other means for fastening the lids to the body portion 14 can be used. It is also possible to solder the lids in place or to press fit the lids against the peripheral edges of the body portion 14 in a manner similar to a fastening commonly found on paint can lids. If a temporary paint can lid type of fastening is used between the lids and the body portion, the can type construction for the electric motor will permit removal of one of the lids so that the windings inside the can type container can be reached for service after the motor unit has been removed from an installation in the field and brought back for possible rebuilding at the factory where the can type or expendable motor was manufactured or in a service shop set up specifically for servicing the expendable type of motors which are capable of being salvaged. However, in the majority of instances, the cost of repairing and servicing a defective motor of the expendable type having a can type structure as described above will exceed the cost of throwing away the defective motor and re placing it with a new unit of the expendable or cannedtype motor of the present invention.
FIGURE illustrates one embodiment of a provision for making a tin-can housing for a dynamoelectric ma chine having features set forth above. It is to be noted that the tin-can housing can be provided for a dynamoelectric machine or for any other type of mechanism having a rotating member which must be accurately aligned relative to a stationary portion of the machine including the housing. Further disclosure as to such additional mechanism having a rotating member is made later in the description. To illustrate the one embodiment of a method in accordance with the present invention for making tin-can housings for rotating mechanisms, a cylindrical body portion 114 is shown in FIGURE 5 after the thin sheet metal has been curved into an annular or cylindrical shape described earlier in the specification. In the embodiment of the provision illustrated in FIGURE 5 only one end of the body portion 114 is crimped relative to outer peripheral edges of a lid or end member at a time. Thus an end periphery 123 of the wrap-around body 'portion 114 is supported in an annular groove 123g provided extending laterally inwardly relative to one face 123] of a support or die 123D. The support or die 123D preferably is provided on a machine adapted for making tin-can housings for rotating mechanisms and the die 123D provides support and/or means for urging and exerting force on end periphery 123 in the direction of an arrow 123a shown in FIGURE 5. An arm or auxiliary portion 123A of the support or die is shown extending laterally from a surface opposite to the face 123 and this arm 123A can be adapted to attach the die 123D for movement by any suitable apparatus for efiecting location of the groove 123g in a position where the die is in abutting relationship relative to one end periphery 123 of the wrap-around body portion 114 of the housing.
Also illustrated in FIGURE 5 is a mandrel 123M having a main body portion 1238 provided with a surface 123E on one side adjacent to a lid or end member generally indicated by numeral 112. The lid or end member has an outer radial edge 122 which is adjacent to an outer radial edge or corner 123a of the mandrel 123M. Due to a cylindrical shape of the mandrel 123M, the corner 1230' provides a substantially cylindrical radially outer surface edge portion 123s which is adapted to be complementary relative to a shoulder portion 122s of the outer radial edge portion 122 of the lid 112. The shoulder portion 122s of lid 112 having a surface radially inwardly of edge 122 and complementary concentric outer surface edge portion 123s of the mandrel 123M are structural features comprising first cooperating means essential and important so far as success of the use of the process of the present invention is concerned for making tin-can" housings for rotating mechanisms.
Second and further essential cooperating means provided also between the mandrel 123M and lid or annular member .112 can be seen in FIGURE 5 wherein the one side or surface 123F of the mandrel 123M is contoured to be substantially complementary to one side of the annular member or lid 112. This complementary relationship between the annular member 112 and mandrel 123M includes provision for an intermediate cover portion including an outwardly bent annular ring 140 which is spaced longitudinally away from stator windings or other stationary portions of a machine having a rotating mechanism. A number of openings for Ventilating purposes can be provided if the housing is for a mechanism requiring ventilation. However, the surface 123F of the mandrel 123M need not be complementary to the openings 125 because the openings 125 can be omitted, though the first and second essential cooperating means for exercising the process of the present invention are still provided.
The mandrel 123M is provided with a third and further complementary portion including a recess 123r extending laterally inwardly relative to the mandrel and adapted to complement a central boss portion generally indicated by numeral 1118. The central boss portion 118 forms part of the lid or annular member 112 and essentiallythere is provided an annular shoulder 122S extending laterally to one side of the annular member 112 to form a radially outwardly extending surface concentrically spaced from the radially inwardly extending surface of shoulder portion 122s of the outer radial edge portion 122 of the annular member 112. It is to be understood that the annular member 112 preferably is stamped from tin-can sheet metal or other thin metal material. The stamping of the annular member 112 results in provision of the shoulder portion 122s and shoulder 1225 such that a radially outer corner 1230 and an intermediate inner corner 123C of the mandrel 123M are complementary to and concentric intermediate the shoulder portion 122s and shoulder 1228 of the annular member 112.
As described earlier, theshoulder 42 illustrated in FIG- URE 2 of the drawings is used for concentrically mounting a radially outwardly extending flange 54 of sintered metal bearing means 50. The shoulder 122$ illustrated in FIGURE 5 is comparable to the shoulder 42 illustrated in FIGURE 2. The mandrel 123M thus provides corner portions 123s and 123C integral with surface r123F on one side of the mandrel and adapted to be positioned concentrically and substantially radially in alignment intermediate a radially outer surface of shoulder 1228 of lid 112 and a radially inner surface of shoulder portion 122s of lid 112.
The shoulder 1228, inner corner 123C, outer corner portion 1230, surface 123s, and shoulder portion 122.? are substantially radially in alignment relative to each auxiliary portion 123A also indicated schematically in the drawings. Suitable means for moving and driving the rollers 124R must be provided with the apparatus that supports the rollers and a median portion 123m of the mandrel 1123M is provided integrally and indicated schematically with the mandrel for supporting the mandrel relative to the apparatus or other suitable carrier of the mandrel. The mandrel 123M can be rotated independently relative to the rollers 124R. This condition may be facilitated by coating the mandrel surface 123E with an abrasive or clutching material to increase the frictional grip thereof. The surface 123E frictionally engages one side of the lid or annular member 112 and thus effects rotation of the annular member 112 relative to the rotatably mounted or journalled rollers 124R which remain in fixed locations but can rotate about an axis of the shaft on which they are carried relative to the apparatus providing support 'for the rollers. Conversely, the mandrel 123M can also remain substantially fixed for holding the annular member or lid 1 12 in fixed relationship as the rollers 124 rotate on an axis of a shaft on which each roller is journalled and also as the rollers as agroup are rotated around an axis that passes centrally through the median portion 123m and auxiliary or arm portion 123M of the die 1231).
Due to concentric relationship of the shoulder and shoulder portions of the lid as well as the corners of the mandrel as described earlier, the rollers 124R are adapted to rotate concentrically relative to these annular corners and shoulders. As indicated by arrows 123r, the rollers 124R are adapted to be radially indexed inwardly relative to edge portion 122 of the annular member or lid 112 and engagement of the groove 124C of the rollers 124R effects a crimping or bending of the outer peripheralv edge portion 122 relative to at least one end periphery 123 of the wrap-around body portion 114. Before describing the result of the crimping or bending of the outer peripheral edge portion of the annular members relative to one end periphery 123 of the body portion, reference is made to FIGURE 5a in which there is shown a small die 123d provided with an outer peripheral edge 123e having a diameter substantially equal to a diameter of the shoulder portion 122s of the outer radial edge portion 122 of lid 112 that has been crimped by rollers 124R described with FIGURE 5. The die 123d is provided with an axially extending hollow portion or hub 123k in which one end of a shaft 134 is supported. An inner passage 1134a is provided in the hub 1231a and this passage is concentric and in a predetermined aligned relationship relative to the radially outer edge 123s of the die 123d. The'passage 134a in which the one endof the V shaft 134 is supported is provided so that a rotor assembly including the shaft can be accommodated in space Within the tin-can housing made in accordance with the present invention. It is to be understood that though a dynamoelectric mach-inc rotor isil lustrated on the shaft .134, a
rotating mechanism of any other apparatus such as a pump rotor can also be adapted to be mounted within the tincan housing made in accordance with the present invention. Further description as to other rotating mechanism that can be journalled and mounted within the tincan housing is given later. In the view of FIGURE 5a, one end of the tin-can housing has been crimped and the small die 123d provides support for this previously crimped end of the housing; The mandrel 123M and rollers 124R 10 are shown in FIGURE 5a in positions prior to indexing radially inwardly for crimping theopposite end of the housing. The features of the crimping operation are identical with the features already described and therefore identical reference numerals are used in both -F[G-" URES 5 and So for illustratingthe crimping process so far as the opposite end of the housing is concerned.
FIGURE 6 illustrates another embodiment of the process for making .a tin-can housing for a rotating mechanism in accordance with the present invention and in this embodiment opposite ends of the housing are crimped simultaneously. Mandrels are provided adjacent to opposite ends of the wrap-around body portions of the tincan housing and these mandrels are identified by reference numerals 223M and 22311. Rollers 224R are provided and are suitably journalled for permitting independent rotation of the rollers when the mandrels 223M and 223d are driven as indicated by the arrows. In this connection, it is apparent that the rollers 224R may be driven and the mandrels may rotate independently as desired. The critical locating points so far as the turning operation is concerned are indicated by a numeral 2229 for a shoulder portion of a peripheral edge 222 of each of the annular members or lids 212 and a shoulder 222$ adjacent to a hub portion of the cover or'annular member 212. As indicated by arrows 2241' the rollers are adapted to be moved radially inwardly relative to the end peripheral edge 222 substantially in the same plane with and radially in alignment with the location of the shoulder portion 222s and shoulder 2228.
In the illustration of FIGURE 6, the mandrel 223M differs slightly in configuration relative to the configuration of the mandrel 223d. This difference is illustrated because after a shaft carrying a rotating mechanism is installed within wrap-around body portion 214 of the tin-can housing, lids or annular members 212 having bearings generally indicated by numerals 250 already inserted therein are mounted onto opposite ends of the shaft for locating the opposite annular members concentrically on the shaft. The mandrel 223d does not have a corner portion 223C complementary to the shoulder 2228 because in effect a radially outwardly extending portion 254 of the bearing means 250 has a peripherally outer surface which registers against an inner peripheral surface of the shoulder 2228 and in effect the shoulder portion 222s is still concentrically and radially aligned relative tothe shoulder 2228 because the bearing means 250 maintains concentric relationship of the shoulder 222; relative to shaft 234 having one end journalled Within a hub. portion 22311 of the mandrel 223d having an outer peripheral edge portion 223e adapted to be positioned radially inside shoulder portion 222s of one annular member 212.
Inthe view of FIGURE 6, the arrows 2241' schematically indicate radially inward movement of the rollers relative to outer peripheral edges of the annular members or lids 212 and in FIGURE 6a, the arrows 324r are directed radially outwardly and indicate schematically that the rollers are removed from a position in engagement with the radially outer peripheral edges 222 of each of the lids after completion of the crimping operation as evidenced by the edges of the annular members and wrap-around body portion tightly bent into engagement with each other. It is to be understood that the crimping operation performed using the two essential locating points provided by the shoulder portion 222s and shoulder 2228 can be accomplished using the rollers and mandrels as described and providing relative rotation between the rollers and mandrels for continuously and progressively crimping peripheral edges relative to end portions of the wrap-around body portion into engagement with each other.
The views of FIGURES 6 and 6a illustrate the tin-can housing being made for a dynamoelectric machine having 1 1 The structures illustrated in FIGURES 2, 5a, and 6 shoW openings 25, 125, and 225, respectively, for ventilating purposes as the openings are provided extending axially and parallel to the shafts on which the rotors are mounted.
. The lids or annular members 312 illustrated in FIGURE 6a are each provided with openings 325 similar to openings 25, 125, and 225 but differing in that each of the openings 325 is formed by bending louvers or flange portions 325 axially and longitudinally inwardly relative to the tin-can housing with free ends 325a of these louver portions or flanges 325) projecting to a location adjacent to a radially inner end of fan blades 333 formed integral- 1y with an end ring 336 of a cast squirrel cage winding provided with a lamination assembly 332 forming a rotor carried by shaft 334.
One of the improvements in the wrap-around body portion 314 illustrated in FIGURE 6a lies in an inwardly protruding pair of flanges or shoulders 314s located on opposite sides of stator lamination assembly 330. The purpose of these flanges or shoulders 314s is to provide means for locking the stator 330 against axial or longitudinal movement or displacement within wrap-around body portion 314. The stator lamination assembly 330 has a width substantially equal to the distance between the pair of shoulders 314s and the stator assembly 330 is locked firmly into engagement between this pair of shoulders 314s as the wrap-around body portion is formed into an arcuate or cylindrical shape out of thin sheet metal in accordance with the present invention. Thus the stator is locked into a position wherein windings 328 provided in slots of the stator lamination assembly are maintained in a predetermined spaced relationship relative to annular members 312 and relative to the openings 325 formed by the louver structure or flange 325 A free edge 325:: of each of the flanges 325]" is substantially in radial alignment relative to opposite longitudinal ends of the Wind- .ings 328 provided in the stator lamination assembly.
Thus the windings 328 are terminated substantially in radial alignment with the free ends 325a of the louvers and a space 341 for passage of cooling air is provided having a width substantially equal to the distance for which the flanges are bent inwardly to one side of the lids.
Also illustrated in the view of FIGURE 6a is a modified structure of bearing means generally indicated by numeral 350. The bearing means 350 have a cylindrical portion 352 comparable to cylindrical portion 52 described with FIGURE 2. Also the bearing means 350 have a radially outwardly extending flange portion 354 providing an annular outer surface engageable against an inner periphery of flange 2223. The bearing means 350 now further provide a longitudinally extending oil control ring portion 350R located substantially half-way radially along outwardly extending flange portion 354 and extending longitudinally and axially in an opposite direction from that of the cylindrical portion 352. The
. purpose of the oil control ring portion 350R is to assure retention of lubricant provided within the bearing packing and within thee sintered metal bearing itself and the ring portion 350R provides a radial barrier against escape of lubricating fluid away from the shaft 334 surrounding washers 358.
FIGURE 6b is a fragmentary view illustrating another embodiment of cooperating structure between a wraparound body portion 414 and a lid or annular member 412. In this embodiment, the lids 412 are stamped to provide concentric locking joints comparable to the flange or shoulder portion 222s and flange or shoulder 2228 but a radially outer peripheral edge of each annular member or lid 412 is crimped individually into a bead segment 412B which is adapted to be locked behind complementary bead segment 414B of the wrap-around body portion 414. The advantage of the structure illustrated in FIGURE 6b lies in the fact that the bead segment 4128 is removable from looking engagement relative to the bead segment 41413 by using a tool such as a screw driver or other suitable. means for disengaging the bead portions relative to each other. Thus the concentricity of the tin-can housing is established prior to assembly of the annular members or lids 412 relative to the wrap-around body portion 414 while a shoulder portion 422s is provided with a predetermined concentric spacing relative to a shoulder comparable to the shoulder 222$ engaged by hearing means 350 as illustrated in FIGURE 6a.
In the illustration of FIGURE 6a the wrap-around body portion 314 is not provided with radially outwardly extending louvers but a cross sectional view taken along line 8-8 illustrates the lamination assembly 330 in a side view and also illustrates louvers for ventilating purposes differing from the passages 65 illustrates and described with FIGURES 2 and 3. Specifically, the structure shown in FIGURE 8 provides radially outwardly extending louver portions or flanges 366a and 3661) directed to provide openings 365a and 365b in opposite directions relative to each other. 7
A fragmentary developed view of FIGURE 7 illustrates the Wrap-around body portion 314 providing the louver portions 366a and 36Gb and a fragmentary section view taken along line 7a-7a of FIGURE 7 illustrates how the openings 365a and 365b extend in opposite directions as the openings are formed by stamping louver portions 366a and 366i: outwardly relative to the wraparound body portion 314. Preferably the louvers begin in opposite directions at a top median portion 366m of the wrap-around body portion 314 shown in FIGURE 8 and openings 365A and 3658 are formed adjacent to a bottom median portion 365M such that the openings 365A and 365B face each other. Adjacent to the bottom. median portion 365M a locating edge 314E is orimped or bent or otherwise suitably attached to an opposite end 314e of the wrap-around body portion 314 for securing opposite ends of the wrap-around body portion to each other.
The lamination assembly 330 is preferably formed by using a plurality of substantially rectangular shaped laminations having arcuate portions 330a and flat portions 330 The arcuate portions 330a are provided with a curvature substantially that of an inner periphery of the wraparound body portion 314 and continuous ribs or inwardly extending grooves beads or shoulders 314s shown and described with FIGURE 6a are engageable laterally against edges of outer laminations along the arcuate portions 330a. Thus each of the laminations when aligned relative to adjacent laminations provides a stator lamination assembly having a substantially arcuate peripheral edge portion engageable relative to the inner periphery of the wrap-around body portion 314 yet providing flat edge portions 330 leaving a semi-arcu'ate space 330E in each quadrant of the substantially cylindrical tin-can housing in accordance with the present invention. The purpose of the space 330E in each quadrant is to enhance ventilation and flow of cooling air relative to the lamination assembly 330. This results in an improved cooling of the lamination assembly in which windings 328 are provided and space such as 330F is of particular advantage when used with the louver portions 366a and 36Gb extending radially outwardly in opposite directions as already mentioned. Flat sides such as edge portions 330 also permit slipping a stator lamination assembly past flanged vents 65-66 into the cylinder of FIG. 2 by rotation of the stator assembly axially to lock between flanges if desired.
In FIG. 9 there is an illustration schematically representing mounting of a dynamoelectric machine having a tin-can housing in accordance with the present invention and for purposes of illustration a skirt portion 500 of an appliance such as a washing machine is outlined in a fragmentary view. This skirt portion 500 is substantially cylindrical in shape and provides vertical support for the appliance which may be portable due to use of castors or rollers 550R in a well-known manner. In any event, the skirt portion 500 is elevated a limited amount due to radially outwardly in opposite ticularly well adapted for dissipating heat from inside the tin-can housing in accordance with the present invention. As mentioned earlier, the louver portions 366a, and 3661) begin at a top median'portion 366m and extend directions :as illustrated in FIG. 8. Thus heated .air arising within the tin-can housing is dissipated and directed to flow radially out-i *wardly and downwardly as indicated schematically by arrows 366D and 366d shown in FIGURE 9. A phantom outline 51 of a dynamoelectr'c machine having a 'tin can housing in accordancewith the present invention is provided in a suitable mounting location underneath the skirt portion 560 of the appliance. Due to the use of the radially outwardly and oppositely extending louver portions shown in the drawings in FIGURES 7a and 8, heated ,air is directed downwardly into space toward a bottom edge of the skirt portion 500 where the heated air is readily dispersed from underneath the skirt portion 500.
FIGURE 9a illustrates another use of a tin-can housing made in accordance with the present invention and specifically, a fluid pump rotor 600 mounted on a shaft 634 is mounted relative to .an annular member or lid .612 provided with a shoulder 622.5 relative to which there is mounted an outer peripheralsurfaceof a radially outwardly extending flange 654 of a bearing means 650. A radially outer peripheral edge 622 of the annular member or lid 612 is crimped relative to one end portion 623 of a wrap-around tin-can body portion 614 provided for concentrically mounting a pump stator 6008 concentrically relative to fluid pump rotor 690. Specific fluid pump rotor and stator structure is not part of the present invention and therefore only a schematic illusvtration of the pump rotor and stator is made in FIGURE 9a. However, the lid or annular member 612 is provided with openings 625 which can serve as outlet passages for discharge of :any fluid forced under pressure by the cooperation of the pump rotor relative to the pump stator. Inlet openings 625i are provided in an annular member 612m snapped into engagement relative to a groove 614g provided along an inner radial periphery of the annular wrap-around body portion 614 of the tin-can housing in accordance with the present invention. The annular member 612m is provided with .a radially inner shoulder portion 1612s on a hub 612k adjacent to one portion of shaft 634 and a radially outer edge or peripheral portion 612G of =themernber 612111 is adapted to be locked relative to the groove 612g such that there is concentric spacing of the shaft 634 relative to the wrap around body portion 614 of the tin-can housing in accordance with the present invention. 7
As illustrated in FIGURE 9a, the wrap-around body portion 614 can be provided with a downwardly extending skirt portion or extension 614s adapted to fit about an outer periphery of a standpipe or conduit 614C relative accordance with the present invention. Also to be understood is that the tin-can housing 614 .can be adapted to fit onto other conduits or shapes of pipes for carrying fluid which is to be pumped from within the conduit 'to a location outside of the conduit. A die cast annular intermediate cover can be provided in place of a stamped member 625 shown in FIGURE 9w.
For a disclosure concerning formation of a wrap around body portion such as 14, 114,. 21-4, ete, reference can be made to' a U .8. Patent 1,452,143-Burke, issued April 17, 1923. Burke, particularly in FIGURES 7 and 8, shows formation of an annular wrap-around member .made of sheet metal heavier thanthat for use in accordance with the present invention. A US. Patent 1,717,- .59()-Walter, issued June 18, 1929', discloses a method and apparatus for forming a .bead relative to a can.
In FIGURE 8 there is a representation of a demountable or removable switch means generally indicated by numeral 80. The switch means 80 includesa housing 80h with a base from which terminals project and these terminals or prongs are adapted to be insertable relative *to maleor female connectors 800 which are mounted in insulating bodies -80i adapted to be locked into engagement relative to edges surrounding openings provided through the wrap-around body portion of the tin-can housing. The insulating bodies 8 0i have a flange portion .801 abutting against one side of the tin-can body portion and resilient laterally deflectable projections or tangs 89p engage an opposite side of the tin-can body portion. Another view of the switch means 80 and push-on terminal mounting means such as 80i is provided in FIG- URE 5a of the drawings. In FIGURE 5a it is apparent that the switch and terminal mounting means are located on one side of thelamination assembly. One type of switching means 80 usable with the present invention is disclosed in copending applications belonging to the assignee of the present invention including SN. 752,- 893-Shewmon, et al. filed August 4, 1958 (abandoned) as well as S.N. 752,71l-Shewmon, et al. filed August 4, 1958, now Patent 2,944,126 issued July 5, 1960. As
shown in FIGURE 8, line voltage can be supplied to the windings by way of a pair of terminal or connector mounting means including bodies 80 i and connectors 80c. Suitable wires connect the windings with the connectors 800.
As indicated earlier, the stator lamination assembly .can be snapped into place relative to the tin-can housing from either end thereof. The square configuration .of
to which the pump in the tin-can housing is mounted.
is a danger of fire .or explosion.
the laminations is such that the tin=can body portion of the housing is deformed temporarily for permitting snap-in of the lamination assembly. No snap-in lamination mounting could beetfected with round laminations and therefore square laminations are used. The body portion of the tin-can housing can be provided without ventilating passages and sealed as a totally enclosed unit if the motor is to be used in an environment where there One example of such a use would be for a motor used in an oil burner housing. An 'oil burner housing could be provided with a mounting plate adaptednto complem nt a lid end of the tincan? housing and mounting bolt apertures can he provided or formed through flanges extending laterally of the oil burner housing mounting plate. I
In addition to an advantage of accurate concentricity between stator and rotor parts in the tin-can housing, there is a very desirable cooling permitted by Euse of louvers as illustrated in the views of FIGURES 6aiand 8. Rows of louvers can be provided on both sides of the stator laminations or only on one side, but with two rows of louvers pointed downwardly and extending in opposite directions, there are two streams of directed airflow parallel at opposite ends and meeting along the flat sides of the laminations.
The tin-can housing can be made of corrosion resistant material :if necessary- Due to tin-can housing structure, there is less copper and iron and the motor runs cooler. Also the use of less metal and louvers in conjunction with a fan assures less heat reserve and quicker cooling. Cost of materialsfor making a tincan housing is relatively low. The machining operations for making motor housings are minimized. A tingap between stator and rotor parts mum.
15 .Can housing can be rotated at 1500 r.p.m. for example as end seals are effected by rollers for crimping lids to the annular body portion. An inner register point for concentricity along a central shoulder or hub is established by mandrels provided relative to an outer register point along a shoulder portion adjacent to edge of the lid crimped as described previously. concentricity can be accurately maintained to within of an inch. Air
can be kept at a mini- While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.
What is claimed is as follows:
1. An expendable dynamoelectric machine sufficiently inexpensive to produce so as to permit throw-away rather than repair of components, comprising, a plurality of stacked stator laminations carrying wound coils and a laminated rotor having a case squirrel cage winding connected at opposite sides by end rings cast integral with rotor fan blades provided radially inwardly of ends of the stator coils, a tin-can housing including a cylindrical body portion directly for supporting the stator laminations concentrically therein, said housing also including end members stamped out of thin sheet metal and fastened by seaming to opposite peripheral ends of said body portion, a hub stamped centrally into each end member including a flange and a lip concentrically located relative to each other, a sintered metal bearing pressed into sealing engagement at opposite ends relative to said flange and lip to form a cavity between said hub and said bearing, and a lubricant impregnated packing of cellulose base material injected in the cavity during en gagement of said bearing against said end member.
2. The machine of claim 1 in which said end members have openings spaced longitudinally of said rotor fan blades, the openings having peripheral flanges bent laterally inwardly of said housing to add rigidity to said thin sheet metal end members, said body portion having apertures on at least one side adjacent said stator laminations for ventilation surrounding the wound stator coil ends, said fan blades being located to rotate radially inwardly of the coil ends and serving to facilitate adequate ventilation inside said tin-can housing between the openings and apertures.
3. For a dynamoelectric machine, a housing, comprising, a cylindircal body portion formed exclusively only of a tin-can sheet metal and having louvers extending and opening for cooling radially outwardly in opposite directions from a radial median location, a pair of axially spaced and continuous ribs provided extending radially inwardly as part of said cylindrical body portion, a substantially rectangular shaped stack of stator laminations with flat side portions and arcuate portions snapped directly into an inner periphery of said cylindrical body portion at a position intermediate of and relative to said continuous ribs, a pair of stamped annular members of tin-can sheet metal directly attached to opposite end peripheral edges of said cylindrical body portion, a cast rotor including axially-extending fan blades and journalled by said members, and radially inwardly protruding flanges provided on said stamped annular members and forming louvered openings terminating adjacent to said fan blades carried by the rotor for circulating cooling air through the housing and radially outwardly and downwardly through said body portion louvers.
4. The housing of claim 3 wherein said stamped annular members have annular beads and said opposite edges of said cylindrical body also have beads adapted to be removably locked into engagement with each other and thereby establishing concentric relationship between the rotor and the stator laminations through journalling of said rotor by said annular members relative to said cylindrical body portion of tin-can sheet metal.
5. The housing of claim 3 wherein said cylindrical 16 body portion of tin-can sheet metal is fitted with insulating bodies adapted to provide a mounting for terminal means for electrical connection with a source of power as well as a switching means.
6. A dynamoelectric machine sufficiently inexpensive to produce so as to permit throw-away rather than repair of components, comprising, a plurality of stacked stator laminations carrying wound coils in slots thereof, a 1aminated rotor having a cast squirrel cage winding connected at opposite sides by end rings, rotor fan blades cast integral with the end rings of said rotor squirrel cage and located radially inwardly relative to ends of the stator coils, and a tin-can housing rather than a relatively heavy metal frame eliminated and replaced by said housing that consists essentially only of a tin-can central cylindrical body portion along an inner periphery of which said stator laminations are held by a light press fit, a pair of substantially identical lid-like annular end members stamped out of thin tin-can sheet metal and fastened by seaming directly to both of opposite peripheral ends of said central cylindrical body portion, each of said substantially identical lid-like annular end members including an integral tin-can hub portion with an annular flange and a lip concentrically located and longitudinally spaced apart as stamped centrally relative to each end member, an annular sintered metal bearing means pressed directly into sealing engagement at op posite ends relative to said flange and lip to form a cavity between each tin-can hub portion and bearing means, and a lubricant-impregnated packing of cellulosebase material injected in each cavity during engagement of said bearing means against each said end member that is seamed to said central cylindrical body portion so as to provide high concentricity of said stator laminations relative to said rotor journalled directly relative to said tin-can lid-like members by way of said annular sintered metal bearing means, said central cylindrical body portion having openings located radially outwardly from said stator coil ends and said rotor fan blades, said lid-like annular end members having axial openings substantially in alignment with said rotor fans blades for ventilating purposes.
7. In a dynamoelectric machine sufliciently inexpensive to produce so as to be disposable rather than subjected to costly maintenance of components including a plurality of stacked stator laminations carrying wound coils in slots thereof as well as a laminated rotor having a cast squirrel cage winding connected at opposite sides by end rings, the improvement which comprises a tin-can housing rather than a frame of heavy metal eliminated completely for the stator laminations and rotor including only a tin-can central cylindrical body portion along an inner periphery of which the stator laminations are held and fitted directly thereto free of any separate fastening means such as screws and the like, a pair of substantially identical lid-like annular end members stamped out of thin tin-can sheet metal and fastened by seaming directly to both of opposite peripheral ends of said central cylindrical body portion, a hub portion of tin-can metal integral centrally with each of said lid-like members and including an annular flange portion offset to one side from said lid-like member as well as an annular lip portion having a smaller radius than said flange portion, an annular sintered metal bearing means including a radially outwardly projecting annular flange adapted to fit in sealing engagement with said flange portion of said lid-like member and including a cylindrical portion integral with an inner end of said annular flange such that a free end of said cylindrical portion fits in sealing engagement with said annular lip portion so as to form an annular cavity in between each said tin-can hub portion and each said sintered metal bearing means,
and a lubricant impregnated packing of cellulose base material injected into each cavity during engagement of said bearing means against each said tin-can end memher that is seamed to said tin-can central cylindrical body portion so as to provide high concentricity of the stator laminations relative to the rotor journalled only directly relative to said tin-can integral hub portion of said lid-like members by way of said sintered metal bear- References Cited in the file of this patent UNITED STATES PATENTS Wheeler Dec. 8, 1925 Watkins Feb. 7, 1950 Fox May 6, 1952 Hansen Feb. 11, 1958 FOREIGN PATENTS Great Britain May 9, 1949 Germany Dec. 10, 1951