US1769785A - Dynamo-electric machine - Google Patents

Description

July 1, 1930. J. D. KARLE DYNAMO ELECTRIC MACHINE 2 Sheets-Sheet l Filed June 30, 1928 July 1,1930. J. D. KARLE DYNAMO ELECTRIC MACHINE Filed June 30, 1928 2 Sheets-Sheet 2 Jo/vn/ .Karle dunha( L Md Patented July 1, 1930 UNITED STATES PATENT oFFlcr.

JOHN D. KARLE, OF ROSELLE PARK, NE'W JERSEY, ASSIGNOR T0 DEHL MANUFACTUR- JQNG COMPANY, F ELIZABETH, NEVI JERSEY, A CORE'ORATION OF NEW JERSEY DYNAMO-ELECTRIC MACHINE Application led June 30,

This invention relates to dynamo-electric machines, more particularly of the singleg phase motor type having a commutator, with short-circuited brushes and a speed-responsive commutator short-circuiting mechanism, adapting the motor for repulsion operation in starting and induction operation after a pre` determined speed has been attained.

An object of the invention is to provide m simplified and eiiicient mechanism for lifting the brushes from the commutator, after the motor has been started, to avoid unnecessary brush-wear.

Another object of the invention is to provide for quietness and freedom from Wear of the partswhen the motor is running. A further object of the invention is to provide a brush-lifting mechanism having minimum wearing pressures upon the rela-tively rotating parts in starting, thus increasing the useful life of the parts. Still further, the invention has for an object to provide a free Hoating support for the eommutator short-circuiting disk permitting it to adapt itselfto any irregularities in the commutator.

AAccording to the present improvement there is provided a brush-lifting member which is adapted to exert a yielding pressure in one direction only from a position of rest,

in which direction it engages and lifts the brush. The speed-responsive commutator short-circuiting means is arranged to kick-off or initiate the movement of said member from its position of rest. Due to this arrangement,

the action ofthe speed-responsive mechanism is independent of the vbrush-lifting mechanism and, consequently, the speed-responsive device has to press but lightly and momentarily against the brush-lifting mechanism,

to trip the latter into action.

In the accompanying drawings, Fig. 1 is a longitudinal sectional view of an electric motor emlioilying the invention; the parts of the brush-lifting mechanism boing in starting position. Fig. 2 is a similar view of the lnush-lifting elements of Fig. 1 in running position. Fig. 3 is an end view of the motor with the parts in starting position. Fig. Il is a longitudinal section on the line 4--4,

Fig. 1. Fig. 5 isa disassembled perspective 1928. Serial No. 289,383.

view of the removable brush and brush-shank elements of Fig. 4l, and Fig. 6 is a vi ew, similar to Fi g. 2, of a n'iodication ofthe invention.

yAccording to the preferred embodiment of the invention illiiistrated in Figs. 1 to 5, inclusive, 1 represents the motor frame, 2 the lield, 3 the armature and 4 the commutator carried by the armatureshaft 5. Fixed to the shaft 5 is a carrier 6 having radially disposed'cylindrical slideways 7 for the cylindrical weights 8 having conical outer ends 9. Siidabl y mounted on the shaft 5. between the carrier G and the commutator 4 is the disk 1() which is dished to provide a conical portion 11 overl-ranging the conical outer ends of the weights 8. The disk 10 is also formed with a flat rim 12 disposed in a plane normal to the shaft- 5. The disk 1() is urged by the spring 13 toward the carrier 6 and, when the motor is at rest, the disk 10 engages the narrow raised ring-shaped seat 14 on the carrier (j, closely adjacent the shaft 5.

Fixed to the disk 10 are studs 15 which pass through somewhat larger apertures in the commutatorshort-circuiting disk 16 and are surrounded by springs 17 disposed between the disks 10 and 1G and yieldingly urging the disk 1G into engagement with the heads 18 of sai d studs. The disk 16 is of the usual radially slotted construction enabling it to bear upon the ends of the commutator segments and effectively short-circuit the latter when pressed thereagainst by the action of the centrifugal weights 8 upon the conical portion 1l ofthe disk 10. The disk 1G is free to float or tilt relative to its carrier disk 10 and adapt itself to any irregularities in the commutator, or to hear evenly upon the commutator despite any unevenncss in the running of the disk 10. f

The end-bonnet 1 of the motor-frame 1 is formed with a pair of bosses 19 each of which is bored radially of the commutator 4 to receive a brush-tube bushing Q() in which is fixed a brush-tube 9.1 on the lower end of which is clamped a terminal lug band Q2 for the usual brush shortvcircuiting connection 23. Y Slidablv mounted in each brush-tube 21 a brush-holder tube 24 constituting a brushshanlf; in the socket-ed inner end of which a brusl secured by; screw 26. The brushliolder tube may be considered as apart of the brush since it is in fixed relation with the latter.

Disposed within the bruslrtube 21 is the brush-spring 27 which at its inner end is conneeted to the brush 25 and at its outer end presses the terminal washer 2S ot the brush pig-tail 29 against the cap-screw 30 which is threaded into and closes the outer end of the brush-tube 21. A pin-screw 31, threaded into the boss 19 and passing through the bushing 2O and brush-tube 21, enters a longitudinal slot 32 in the brush-shank 24. This pin tixedly positions the bushing' 2O and bruslntube 21 in the boss 19 and permits the brush-shank 24 to freely perform endwise sliding` movements. without rotation. The slot 32 is open atl its inner end to permit withdrawal of the brush from the brush-tube 21. At the outer end of the slot 32 there is a shoulder 33 which is adapted to engage the pin-screw 31, when the brush 25 has worn sutliciently, and prevent the inner end of the brush-shank 24 from scraping the commutator. The brush-shank 24 is also formed with a shoulder 34 for engagement. by the brush-lifting lever 35 which is fulcrumed at 36 on the ear 3T extending inwardly from the boss 19.

The brush-lifting lever 35 is cut away at 38 to emb ace the im 12 of the speed-responsive disk 10 and is also formed with a V- shaped notch 39, to receive the conical end of the plunger 41 which is pressed inwardly by the spring 42. The inner conical end of the plunger 40 is iattened or squared-oil` at 43 to rest upon the hump 44, Fig. 1, at one side ot the V-notch 39 in the lever when the motor is at rest. without tendency to impart motion to the lever 35. In this, the set position of the parts, the brush is bearing upon the commutator. the lever is spaced trom the shoulder 34. and the riin 12 of the disk 10 is in engagement with one wall ot the notch 38 and spaced from the opposite wall a distance substantially equal to the distance of the short-circuiting disk 16 from the commutator. and full power is stored in the spring 42.

Then the motor is started and attains a predetermined speed. the centrifugal action of the weights S upon the disk 10 forces the latter towards the connnutator and causes the short-circuiting disk 16 to be pressed against the commutator. In this movement of the disk 10, its rim 12 is carried across the open mouth or" the notch 3S without disturbing the position of repose of the lever After the short-circuiting of the commutator is effected, the further movement of the disk 10 in compressing the springs 17 and 13. causes its rim 12 to press against the inner wall of the notch and kiek oli or trip the lever into action by swinging it sutliciently to carry the hump 40 oli of the flat inner end of the plunger' 41. whereupon the spring 42 in pressing the plunger 41 into the V-notch 39. swings the lever 35 to the predetermined position shown in Fig. 2 with a snap action and lifts the brush 25. The lever 35 is thus adapted to exert a yielding pressure upon the brush in one direction only from its position of repose. Fig. 2. The speed-responsive disk 1() initiates the movement of the lever 35 from its iosition of repose. and this requires but a momentary and light pressure of the disk 16 upon the lever 35, whereby the timing of the brush-lifting action ot the lever 35 is not disturbed, relative to the time of short-circuiting of the commutator. by wear of the inner wall of the notch 38 upon the rim 12 oi the disk 10. In the running posit-ion of the parts, Fig. 2, the rim 12 of the disk 10 floats quietly in the notch 38 without engaging the walls thereof.

lVhen the power is eut off from the motor and the latter' slows down, the recovery spring 13 tei-ces the disk 10 toward the right, Fig. 2, and withdraws the commutator short-circuiting disk 16 from the commutator 4: at the same time restoring the lever 35 to or resctting it in its initial position of repose and storing power in the spring 42 for the next start-ing operation. The spring 13 is strong enough to overcome the resistance of the lnush-lever actuating springs 42, which latter are strong enough to overcome the .resistance of the brush-springs 27.

In the modification shown in Fig. 6. the parts carried by the motor-shaft are identicalv with those shown in Figs. 1 to 5. inclusive. Also. the brush and its holder. the brush-tube, bushing, stop-screw, and brushspring are identical with the like parts previously described. The modification is in the brush-lifting lever 35 Which is pivoted at 36 on the ear 37 rigid with the boss 19. The lever 35 is actuated by the spring 42' which is coiled about the screw 36 and anchored at its opposite ends to the lever 35 and screw 36. In the position of rest shown in Fig. 6. the lever 35 is held out of engagement with the shoulder 34 of the brush-shank. with full power stored in the spring 42. by the spring 13 which presses the disk 10 against the short arm 48 of the lever 35. Then the motor is started and the disk 1() moves toward the commutator, the lever 35 cannot follow the disk 10 as it is arrested by engagement of the pin 45 with the shoulder 46 of the spring-pressed latchlever 46 fulcrumed at 47 on the ear 37 After the short-circuiting disk 16 is pressed into engagement with the commutator, the disk 10. in its further movement-` trips or kicks ofi' the latch-lever 46 and releases the lever 35 which acts under the influence of its spring 42 t0 lift the brush.

The arm 48 of the lever 35 is engaged by the rim 12 of the disk 10 in re-setting the lever 35 when the motor is slowing down to a stop. The lower end of the latch-lever 46 is spaced from the end of the lever-arm 48 a distance permitting movement of the shortcircuiting disk 16 into engagementwith the f commutator before release of the lever 35 by movement of the latch-lever 46.

The brushes 25 are initially of such length that they are lifted but a short distance from the commutator by the action of the levers 35 or 35. As the brushes wear, the shoulders 34 are correspondingly lowered and the brush-lift increased. The shoulder 33 is preferably arranged to strike the stop-pin 31 before the brushes Wear sufficiently to let the shoulder 34 down upon the levers 35 or 35 in the initial positions of repose of the latter.

Having thus set forth the nature of the invention, what I claim herein is:

1. In an electric motor, an armature having a commutator, an armature shaft, speed-responsive commutator shortcircuiting means including a disk movable lengthwise of the armature shaft, a brush yieldingly engaging the commutator, a brush-lifting lever having anotch entered by the rim of said disk, a spring for moving said lever in a direction to lift the brush, and means independent of said disk for detaining said lever in one extreme position with full brush-lifting power stored in said spring.

2. In an electric motor, an armature having a shaft and commut-ator, a speed-responsive disk movable lengthwise of the motor-shaft a commutator shQrt-circuiting disk disposed between the speed-responsive disk and the end face of the commntator, a plurality7 of headed pins mounted on one of said disks and passing through apertures in the other disk, said pins being spaced equidistantly around the armature shaft, and a plurality of coil springs each surrounding a respective one of said pins between said disks.

3. In a dynamo-electric machine, rotary current-carrying means, a brush, a brushspring urging said brush into engagement with said means, brush-lifting mechanism including a brush-lifting element and a brushlifting spring for actuating said brush-lifting element in a direction to lift the brush against the pressure of the brush-spring, a speed-responsive device, means independent of the speed-responsive device for detaining the brush-lifting element in a position of repose, with full brush-lifting power stored in the brush-lifting spring, while the machine is at rest, and a connection between the speedresponsive device and the brush-liftingmechanism for tripping the latter into action.

4. In a dynamo-electric machine, rotary current-carrying means, a brush, a brush-y spring urging said brush into engagement with said means, a speed-responsive device, a self-contained spring-actuated brushdifting mechanism the parts of which are maintained in a set position of repose, independently of ysettable in a position of repose with full brush-lifting power stored in said sprin and speed-responsive means for kicking o said spring-energized brush-lifting mechanism at a predetermined speed.

6. In an electric motor, an armature having a commutator, an'armature shaft, speed-responsive commutator short-circuiting means including a disk movable lengthwise of said armature-shaft, a brush yieldingly engaging the commutator, a brush-lifting lever connected to be moved in either direction by said disk, a spring for moving said lever in a direction to lift said brush, and means independent of said disk for detaining said lever in one extreme position with full brush-lifting power stored in said spring.

In testimony whereof, I have signed my name to this specification.

JOHN D. KARLE.

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