US2527416A - Electric motor - Google Patents

Description

Patented Oct. 24, 1950 UNITED STATES PATENT OFFICE Claims.

The present invention is concerned with small electric motors and more particularly with motors of the universal unwound armature type that may be operated either by direct or alternating current.

The invention herein constitutes an improvement upon the motors described and claimed in my prior Patent No. 2,078,896 dated April 2'7, 1937, and my prior application Ser. No. 645,647 filed February 5, 1946, and hence only so much of the construction set forth in the above identified patent and application will be described herein as is necessary to a clear understanding of this invention.

In motors of the above type wherein the cam rotates out of contact with the circuit interrupter arm following each contact closure, the repeated impact of the cam against the interrupter arm results in rapid wear and breakdown of the latter and also causes objectionable noise and undesirable vibration with resultant looseningof the parts of the motor and consequent malfunctioning of the same.

It is accordingly among the objects of this invention to provide a motor of the above type which is especially adaptable to manufacture by mass production methods and comprises a minimum number of inexpensive parts of rugged and compact construction, and which shall be easy to assemble, inherently to maintain th various constituent parts thereof in accurate position, which shall be relatively noiseless in operation and free from vibration and in which the circuit interrupter arm suffers a minimum of wear.

According to the invention, a circuit interrupter arm resiliently urged to open contact position follows and remains in engagement with a cam configuration rotating with the armature axle, said cam configuration moving the arm against the resiliency thereof into closed contact position.

In the accompanying drawing in which is shown one of various possible embodiments of the several features of the invention,

Fig. 1 is plan View of the device,

Fig. 2 is a sectional view of the device taken along line 2-2 of Fig. 1,

Fig. 3 is an end view of the device,

Fig. 4 is a perspective view of the frame with a clamp thereon,

Fig. 5 is a fragmentary plan view of a second embodiment of the device, and

Fig. 6 is a detail view on a larger scale of a mounting member in the embodiment of Fig. 5.

Referring now to the drawings, the electric motor shown in Figs. 1 to 4 comprises a frame I0 of insulating material, fashioned as a unitary piece in an appropriate mold. The frame comprises a generally rectangular open base plate II with ears l2 and it at the right side as viewed in Fig. 1. Rising from the opposing sides l4 and I5 of the base plate I I and unitary therewith are the inner and outer armature mounting blocks l6 and I! which support the armature l8. To this end, blocks l6 and I! each have an arcuate depression I8 therein and threaded openings l9 on each side of the depression [8. A clamp 2|, preferably comprising two metal strips 22 and 23 each having an arcuate bend 24 at the center thereof which forms a socket 25 when the bends 24 are in juxtaposition, holds a bushing or bearing 26 in said socket 25. A clamp 2| is affixed to each of said mounting blocks [6 and I! by screws 21 which are passed through openings at each end of strips 22, 23 and through a washer 28 and threaded into openings H3 in mounting blocks 16 and H.

The armature [8 which in the embodiment herein has two poles is built up oflaminations of soft iron held together by rivets 20 and is secured to an axle 29 passing therethrough, by a countersunk setscrew 3i pressing into a longitudinal groove 32 in the axle. The axle 29 journalled in bushings 26, extends beyond the outer mounting block H, and said extension has a cam conformation 33 formed integrally therewith having a plurality of operating protrusions 33' thereon.

The field of the motor desirably comprises a laminated horseshoe magnet structure 34 having a cross car 35 and legs 35 that terminate in pole pieces 31 conforming to the periphery of the armature 26 and affixed to the base by bolts 38 through aligned apertures in the pole pieces 31 and the base I I all as best shown in Fig. 3. About the cross bar 35 of the field extend the field coils 4|, 42 with their leads 43, 4.4 to the source of current (not shown) and their leads 45, 46 extending along the length of the magnet legs 36 to the circuit interrupter 41. These leads are preferably clamped against the legs 36 by clips 48 encompassing said leads and anchored to the legs of the horseshoe magnet 34 by the heads of the same bolts 38 which maintain said magnet on place upon the base I I. T

The field circuit interrupter 41 comprises a fixed contact 43 mounted at the end of a support arm 49. Through a washer 52, having a tip 53 to which the extremity of lead 45 is soldered, and

through an opening in support arm 49 extends screw 5| which is threaded into an opening in ear I2 to rigidly hold said contact arm 49 in place.

The movable circuit interrupter contact 56 is affixed to one end of a metal interrupter arm 51 preferably in the form of a leaf spring. The other end of arm 51 is aflixed to ear I3 by means of a screw 58 which passes through a Washer 59, the latter having a tip SI to which the extremity of lead 46 is soldered, and is threaded into an opening in said ear I3 rigidly to hold said contact arm 51 thereon so as to be parallel to mounting block I'I. As ear I3 is of greater height than ear I2 as shown in Fig. 3, contact 55 will be positioned slightly above fixed contact 48 and in registry therewith. Preferably, an insulating wear piece 63 is afiixed to the upper face of movable interrupter arm 51 by rivets 65 and is engaged by cam 33 at the end of axle 29, the resiliency of arm keeping said wear piece 63 in constant engagement with said cam.

In use it will be apparent that the field coils M, 42 when connected to the source of current by leads 43, 44 are energized whenever the interrupter contacts 48 and 56 are closed, the circuit being through coil 4I, lead 45, arm 49, contact 48, contact 56, resilient, arm 5'1, and lead 46 to coil 42.

When coils 4|, 42 are energized, the armature I8 will be swung around to bridge across the gap between the pole pieces 31 and in such position the cam 33 is moved to the position shown in Fig. 3, so that by virtue of its resiliency spring arm 51 follows and remains in engagement with cam 33, and therefore moves its contact 55 away from fixed contact 48 and so opens the circuit. By means of its inertia, the heavy armature I8 will move suiiiciently past center position so that cam 33 can again move contact 56 against contact 48, thereby closing the circuit to repeat the operation above set forth twice each revolution of the armature.

The axle of the motor described above extends longitudinally of the magnet structure, whereas the axle of the motor shown in Figs. 5 and 6 of the drawings is at right angles to its magnet structure. This motor comprises a laminated substantially V-shaped magnet structure II having legs 73 that terminate in pole pieces I2 conforming to the periphery of an armature 54. About the legs I3 of the field extend the field coils I5, 15 with their leads TI, TI to the source of current and their leads I8, I9 to the circuit interrupter 8I.

lhe armature I4 which is built up of laminations has preferably three poles P, P and P The stack of laminations is secured together by pins 84 transversely through the poles thereof, and is retained on an axle 85 therethrough by a countersunk set screw 86. The axle 85 has a triangular cam conformation 99 at one end and is journalled in and extends beyond bearings 87 in a frame comprising a pair of insulating plates 88 only one of which is shown and which are rigidly afifixed on opposing sides of the legs I3 of the magnet structure II by bolts 9| through aligned apertures therein and in the legs 13.

Plate 88 which carries the circuit interrupter 8I is rectangular in shape and has afiixed thereon a pair of mounts 92 and 93 for fixed contact 93 and resilient interrupter arm 94. Mounts 52 and 93 each comprises a bracket portion 95 afiixed to plate 88 by screws 95, and an arm 91 integral with said bracket at one end thereof and bent at right angles to the plane thereof.

As shown in Fig. 5, mount 92 is positioned on plate 88 so that arm 91 extends outwardly therefrom, fixed contact 93' being afiixed to the end thereof. Mount 93 is positioned so that its arm 91 extends in the opposite direction to arm 91 of mount 92, said arm being reversely bent as at 98 and having aflixed thereto as by rivet 98' one end of resilient metal interrupter arm 94 which is preferably in the form of a leaf spring. The free end of interrupter arm 94 carries a contact IOI which is in registry with fixed contact 93 and normally urged away therefrom by the tension of leaf spring arm 94. An insulating wear piece I02 is affixed to the face of interrupter arm 94 adjacent cam by rivets I04, the resiliency of arm 94 keeping said wear piece I02 in constant engagement with said cam 90. Leads I8 and I9 are each connected to a lug I05 as at I06, said lugs being clamped against said mounts 92 and 93 respectively by the heads of the same screws 96 which maintain said mounts in place on said plate 88.

It can be seen that the respective apices or protrusions 90' of the cam 90 register with the respective poles P, P and P of the armature, so that contact IOI will be urged against fixed contact 93' when one of the armature poles is midway between the field pieces, but will be urged away from contact 93 by the resiliency of arm 94 when two of the armature poles are aligned with the corresponding field poles.

Once the motor has been started, the opening of the contacts 93, IN interrupts the circuit, but the inertia of the moving armature carries it on to a position where the contacts again close the circuit for further impulses, three cycles of alternate impulse and inertia advance occurring for each complete turn of the rotor. The rotation of the motor is thus uninterrupted and operation will occur regardless whether on direct current or any frequency of alternating current.

In both of the embodiments herein the cam is so arranged with respect to the resilient interrupter arm that as the cam rotates and the protrusions thereon depress the interrupter arm the movable contact will be brought into engagement with the fixed contact before the peaks of the protrusions reach the interrupter arm and the latter will thus be bowed when the peak does reach the interrupter arm to insure positive engagement of the movable contact with the fixed contact thus avoiding any possibility of arcing due to faulty contact. By reason of the fact that the resilient interrupter arm is in constant engagement with the cam, there is no impact of the cam against the arm and consequently a motor utilizing such construction is relatively noiseless and suffers but little vibration so that the motor has a long life.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a small electric motor, a frame comprising a generally rectangular open base plate, a pair of ears on said base plate, mounting blocks unitary with said base plate and rising from two opposing sides thereof, a bearing clamp removably affixed to each of said blocks, a bearing affixed in each of said clamps, an armature, an axle therefor journalled at each end in. said bearings and extending beyond one of said bearings between said ears, said armature being positioned on said axle between said bearings, a field structure aflixed on said frame having pole legs straddling the other of said bearings and said armature, a cam conformation having a plurality of protrusions thereon on the extending end of said axle, a fixed contact mounted on one of said ears, a resilient circuit interrupter arm therefor having a movable contact at one end and mounted at its other end on the other of said ears, said arm being urged to circuit opening position by the resiliency thereof, and urged against said cam and following the latter, said cam periodically operating said arm with said protrusions to force said movable contact into engagement with said fixed contact.

2. An electric motor comprising a substantially rectangular insulating frame having a pair of ears on one side and an inner mounting block and an outer mounting block unitary therewith, the latter being straddled by said ears, said blocks rising from said frame on opposing sides thereof, a bearing clamp affixed on each of said mounting blocks, a bearing affixed in eachof said clamps, an armature between said mounting blocks flanked by said pole pieces, an armature axle through said armature and journalled in said bearings, said axle having a cam conformation at one end with a plurality of protrusions thereon and extending beyond said outer mounting block between said ears, a fixed contact mounted on one of said ears, a field structure affixed on said frame having pole legs straddling said inner mounting block and said armature, a field coil on said field structure, a resilient interrupter arm therefor mounted onthe other of said ears and extending parallel to said outer mounting block between said cam and said fixed contact, a movable contact at the free end of said interrupter arm in registry with said fixed contact, insulated conductors from said field coil along said pole legs and affixed at their free ends to said fixed contact and said resilient inter rupter arm, said arm being urged to circuit opening position by the resiliency thereof and urged against said cam and following the latter, said cam periodically operating said arm with said protrusion to force said movable contact into engagement with said fixed contact.

3. An electric motor comprising a substantially rectangular insulating frame having an inner mounting block and an outer mounting block rising therefrom, said mounting blocks each having an arcuate depression on the upper surface thereof, a pair of ears unitary with said frame on each side thereof and straddling said outer mounting block, a bearing clamp affixed on each of said mounting blocks, said clamps each comprising a pair of metal strips having an arcuate bend in the center thereof forming a socket therebetween and seated in the arcuate depression in said block, a bearing affixed in each of said sockets, an armature between said mounting blocks flanked by said pole pieces, an armature axle through said armature and journalled in said bearings, a set screw affixing said armature to said axle, said axle having a cam conformation at one end thereof with a plurality of protrusions thereon and extending beyond said outer mounting block between said ears, a field structure of horseshoe magnet shape having a field coil and having pole pieces affixed to the base of said frame straddling said inner mounting block and said armature, a fixed contact mounted on one of said ears, an interrupter arm mounted on the other of said ears and extending parallel to said outer mounting block between said cam and said fixed contact, and resiliently urged against said cam and following the latter, a movable contact at the free end of said interrupter arm in registry with said fixed contact and resiliently urged away therefrom, the protrusions on said cam periodically operating said interrupter arm against the resiliency thereof to force said movable contact into engagement with said fixed contact.

4. In a small electric motor, a frame comprising a generally rectangular open base plate, an armature on said frame positioned in the opening in said base plate, an axle for said armature, hearings on said frame for said axle on each side of said armature, said axle extending beyond one of said bearings, a cam configuration on the extending end of said axle, a field structure affixed on said frame having pole legs straddling the other of said bearings and an armature, and circuit interrupter means on said frame actuated by said cam configurationv 5. In a small electric motor, a frame comprising a generally rectangular open base plate, a pair of ears on-said base plate, mounting blocks unitary with said plate and rising from two opposing sides thereof, a bearing clamp removably amxed to each of said blocks, a bearing afiixed in each of said clamps, an armature, an axle therefor journalled at each end in said bearings and extending beyond one of said bearings between said ears, said armature being positioned on said axle between said bearings, a field structure afiixed on said frame having pole legs straddling the other of said bearings and said armature, a cam conformation having a plurality of protrusions thereon on the extending end of said axle and circuit interrupter means on said frame actuated by said cam conformation.

JOHN A. HANLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Aug. 14, 1940

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