US2292537A - Commutator short circuiting device - Google Patents

Description

Aug. 11, 1942. R. L. MORTON COMMUTATOR SHORT CIRCUITING DEVICE Filed July 17, 1940 2 Sheets-Sheet l FIG.2.

FIG.I.

FIG.3.

INVENTOR gBERT L. MRTON ATTORNE YS FIG.5.

Aug. 11, 1942. R. 1.. MORTON- COMMUTATOR SHORT CIRCUITING' DEVICE Filed y 17, 1940 2 Sheets-Sheet 2 FIG.

INVENTOR ROBER T L.MORT N 7 ATTORNEYS Patented Aug. 11, 1942 COMMUTATOR SHORT CIRCUITING DEVICE Robert L. Morton, St. Louis, Mo., assignor to Valley Electric Corporation, St. Louis, Mo., a corporation of Delaware Application July 17, 1940, Serial No. 345,92

6 Claims.

This invention relates, generally, to electromotive devices, and particularl to a mechanism for short circuiting commutators such as are commonly employed in connection with single phase alternating current motors.

Many efforts have been made to provide a commutator short circuiting device which will be actuated by centrifugal force when the motor upon which it is employed attains a predetermined speed, and while a great variety of such commutator short circuiting devices have heretofore been produced, such devices have as a rule presented some difliculty either from the standpoint of manufacturing, assembling, or operation. An especial disadvantage of many such devices heretofore employed has resided in the fact that the multiplicity of parts has rendered difficult the assembly of the devices on the m0- tor shaft; and while special skill has largely overcome such difficulties in original manufacture, it

has been extremely difficult to replace such devices upon motors.

The present invention contemplates a commutator short circuiting device in which the difficulties heretofore encountered are substantiall :1."

overcome, and provides an arrangement which is sufficiently compact and self contained that the same may be packed and shipped separate and distinct from the motor, anad assembled therewith without difficulty.

The object of the present invention, generally stated, is to provide a commutator short circuiting device which may be readily manufactured and assembled, and which is positive and certain in its action.

Another object of the present invention is to provide a commutator short circuiting device in which the contactor elements are so formed as to take maximum advantage of centrifugal force in effecting their movement into short circuiting position.

Other objects will become apparent to those skilled in the art when the following description is read in connection with the accompanying drawings, in which:

Figure 1 is a sectional view, showing the arrangement of the commutator short circuiting device of the present invention in position upon a motor shaft adjacent a commutator.

Figure 2 is a plan view of a supporting member forming a part of the commutator short circuiting device.

Figure 3 is a plan View of a pressure plate, forming a part of the commutator short circuiting device of th present invention.

Figure 4 is a plan view of a contacting ele ment, a number of which are employed in th commutator short circuiting device of the presen invention.

Figure 5 is an edge view of the contactin; member shown in Figure 4.

Figure 6 is a view constituting an inside plal view of the commutator short circuiting de vice, part being broken away to reveal the re lation of the parts.

In accordance with the present invention, gen erally stated, a supporting member in the form of a disc having a peripheral channel, is fixe| upon the shaft of a motor for rotation therewitl'. Loosely arranged in the peripheral channel 0 the supporting member is a series of contac elements, arranged to swing outwardly about circumferential axis located within the channe of the supporting member. The contacting ele ments are sector-shaped, bein thicker at thei outward extremities, which are nested in th aforesaid channel, than at their inner extremi ties; and are arranged in series substantiall; around the entire circumference of the support ing member above mentioned. The sector shap of the elements and the arrangement thereo so that the thicker portion is adjacent the axi of swinging provides a construction in which th respective contact elements become progressive 1y freer of each other as they swing outwardly The commutator contacting portion of the con tact elements is axially displaced, toward th commutator, from the plane of the periphera axis about which the series of contact element swin under centrifugal force. Each contact ele ment is provided with a bearing area agains which the rim of a pressure plate is biased in i direction tending to maintain the contact ele ments out of engagement with the commutator The contact elements of the present inventioi are especially shaped so that when in norma position (out of contact with the commutator) l substantially long portion of the element extend generally normal to the shaft of the motor. Th mass center is slightly displaced from the plane 0 the peripheral axis about which such contac elements swing, but the form is such that whel the contact elements have moved slightly fror their normal position, further movement is ac complished with a snap to the extreme outwarl position, in which the contact elements are engagement with the commutator, thereby shor circuiting the same.

When each of the contact elements is furcatec' as in the embodiment to be more fully describe ELECTRICIIY- UIHUUIF MAKERS & BREAKERS,

hereinafter, the furcation of the assembled group of contact elements provides a circumferential groove into which the edge of the pressure plate is received. The diameter of the pressure plate is such, with reference to the diametrical distance between the extremities of opposite contact elements, however, that when the contact elements are in normal position (at rest) the pressure plate is trapped in the circumferential groove just mentioned. This prevents the individual contact elements from being swung outwardly, independently of the others, and thereby prevents removal of the pressure plate unless at least half of the contact elements are swung outwardly from their normal positions. With this arrangement of parts, the pressure plate retains the contact elements in position, and the contact elements retain the pressure plate in position, all within the supporting member, thereby facilitating handling and assembling of the arrangement; as the parts cannot release themselves from each other so long as at least two opposite contact elements are held in normal position, as by pressure of the fingers, regardless of the position of the assembly.

Referring now to the drawings for an illustrative embodiment, the commutator short circuiting device of the present invention is shown in position upon the shaft I of a motor having a commutator 2 whose conductor elements 3 are arranged with their end faces 4 exposed for engagement with the commutator short circuiting device of the present invention. It is of course understood that the conducting elements 3 of the commutator are suitably insulated from each other and from the shaft and core thereof in the usual manner.

In the embodiment illustrated, a collar 5 is arranged upon the shaft I so as to rotate therewith and provide a shoulder 6 against which a disk I may be seated. It will be understood, of course, that the collar 5 may be formed as an integral part of shaft I.

In order to fix disk I upon the shaft so that it rotates therewith, a bushing 8 may be driven over the shaft against disk I, and, if desired, further positive connections may be provided. The disk I constitutes the supporting member for the various elements of the commutator short circuiting device of the present invention, and is provided at its outer periphery with an inward- 1y opening channel 9.

Arranged in channel 9 is a series of contacting elements Ili shown in detail in Figure 4, and each provided with an outer rounded portion II sized and shaped to be fitted loosely in channel 9, so as to swing about an axis within channel 9. In the embodiment illustrated, the interior cross-sectional shape of channel 9 is square, with filleted corners, and the rounded portion II of the contact element I6 is formed so as to provide a play of 0.006-7 inch within channel 9 in a direction axially of the motor.

The contact elements II) are furcated, provid-- ing a long leg or weighted part I2, and a short leg or contact part I3 with a space H therebetween. With the contact elements so shaped, they may be supported in a, manner such that the elemental mass center of the long leg I2 lies substantially in a plane normal to the shaft I, in which the axis of swinging also lies; and accordingly the weight of leg I2 is substantially ineffective as far as centrifugal action is concerned until the centrifugal force is sufiicient to displace the contact elements from their normal Cross Heierence position. When the contact elements are displaced from their normal position, however, the mass of leg I2 is acted upon by centrifugal force, and accelerates the outward swinging movement of the contact elements, thus giving the desirable snap of operation.

When the series of contact elements I0 is assembled on supporting member I, it will be apparent that the spaces I4 produce together a circular groove into which is fitted a pressure plate I5. The pressure plate I5 is freely movable axially relative to shaft I and is provided with a coil spring I6 arranged on shaft I so as to bias pressure plate I5 in a direction away from the commutator. The exterior diameter of pressure plate I5 is in excess of the diametrical distance between the inner extremities of short legs I3 of contact elements Ifl, when the latter are in their normal position, illustrated in full lines in Figure l; and is arranged with respect to the contact elements and channel 9 so as to provide an abutment limiting the inward radial movement of contact element I9 under the force of gravity when the apparatus is at rest.

Contact elements I5 are each formed with a rounded portion arranged to receive the thrust from pressure plate I5, and below convex portion is a concavity II formed in leg I2 of the contact element. The concavity I1 is provided so as to prevent engagement of the flat rim II! of pressure plate I 5 with the contact element at regions other than the convex bearing portion 50; and pressure plate I5 is flared so as to accommodate the tail of long leg I2 of the contact elements when the same swing outwardly. With the arrangement just described, pressure transmitted from plate I5 to the contact elements is limited to a line bearing at convex portion 60, regardless of the position of the contact element, and friction between the moving parts is thereby reduced. With this arrangement the thrust applied through plate I5 exerts itself upon contact elements I9 through a torque arm of substantially constant length irrespective of the angular position of the contact elements.

The disk I is provided, on its interior face, with a plurality of radially extending lugs I9 formed, in the embodiment shown, by punching and deforming. While in the embodiment shown in the drawings the disk I is provided with five such lugs, it will be understood that any desired number may be provided; such lugs I9 provide abutments through which the rotating force of disk I is transmitted direct to contact elements It], in order to positively drive the same.

When the contact elements are fitted with sufficient closeness, however, and at least three such lugs I9 are provided, displacement of the contact elements from channel 9 by radially inward movement is prevented at times during the assembly of the device when pressure plate I5 is absent. It will be observed that the sector or wedge shape of the respective contact elements precludes the radially inward movement of one or more of the same independent of the others, beyond a point where the contact elements become wedged against lug I9. When at least three such lugs I9 are provided, the contact elements may be assembled into channel 9 of disk I with sufucient looseness to permit the desired freedom of movement for convenient assembly, but nevertheless without suflicient play that the contact elements will become completely displaced from channel 9 by axially inward movement. This arrangement facilitates handling and as- Search H00 sembling of the device, at stages where pressure plate I5 is not in position. As pointed out hereinbefore, however, when pressure plate I5 is in position, the outer edge thereof is arranged so so as to limit radial inward movement of those contact elements which tend to move radially inward under the force of gravity, thus preventing the same from becoming wedged against lug I9 after installation of the assembly upon a motor.

It will be observed that the diameter of pressure plate I5 is in excess of the diameter of the circle formed by the inner termini of the series of short legs l3 of contacting elements Iii. Accordingly, in assembling the commutator short circuiting device of this invention, the entire series of contacting elements is swung outward ly about the peripheral axis extending in channel 9, so that the inner termini of legs I3 are more greatly spaced than in the positions illustrated in full lines in Figure 1. When the contact elements are thus all swung out, the distance between the inner termini of the short legs I3 of opposite contact elements It) is great enough to permit pressure plate I5 to be inserted. When the device is arranged upon a motor shaft, however, the parts are so positioned that the maximum outward movement of contact elements will not permit release of the margin I8 of pressure plate I5 from the furcation in the respective contact elements, and consequently there is no possibility of displacement of parts when in position on the motor. In certain installations, where it is of no particular importance to trap pressure plate I5 with reference to the contact elements as hereinbefore described, the short leg I3 of the contact elements may be arranged so as to permit free insertion and removal of pressure plate I5. In this case, the leg I3 is formed so as not to overhang the rim of pressure plate I5, and accordingly the confined space I4 of the furcated element shown in the drawing would then become an open space for the reception of pressure plate I5.

When a motor is equipped with the commutator short circuiting device of the present invention, the parts in the position illustrated in full lines in Figure 1; but in view of the axial displacement of the mass centers of contact elements I from the plane of the peripheral axis of rotation thereof (in channel 9), as the motor gains speed, centrifugal force acts upon contact elements IB, tending to swing the same outwardly. When th speed of the motor has reached a predetermined point, depending upon the compression strength of spring IS, the force of spring l6 will be overcome, and pressure plate I moved axially toward the commutator 3, thus permitting the contact elements II! to swing outwardly to an extent such that contact portions 20 engage the adjacent faces 4 of the commutator conductors. The shape of the engaging face 20 of contact element 59 is such that a wiping contact with the commutator face is effected, and the centrifugal force acting upon the individual contact elements maintains the same in fixed engagement with the commutator face. The respective elements are, however, fitted in the adjunct parts with uch freedom that all may accommodate themselves to irregularities, and thus maintain a firm contact at the commutator face.

When the speed of the motor is being reduced, however, the centrifugal force acting upon contact elements In gradually reduces to a point where the centrifugal action is overcome by the pressure of spring I6, at which time the contact elements I!) are conjunctively restored to the position illustrated in full lines in Figure l.

The construction of the device of the present invention is such that the contact elements II) cannot individually operate to an extent such that the commutator is engaged, but through the medium of pressure plate I5 the action of the contact elements I0 is conjugated, and consequently when one container is in engagement with the commutator, all contactors are in engagement; and vice versa. As hereinbefore stated, however, the parts are assembled with such individual freedom of action that centrifugal force acts individually upon the contact elements Ill, and the individual elements may move relative to each other and to the adjacent parts to an extent sufficient to assure firm electrical contact with the commutator face.

From the foregoing description it should be apparent that the present invention accomplishes its objects, and provides a commutator short circuiting device which may be manufactured and assembled with facility and that the device is so self-contained that displacement of the parts during handling is not liable to occur.

While in the foregoing description a full disclosure of the present invention has been made with respect to the embodiment illustrated in the accompanying drawings, it is to be understood that such disclosure is by way of illustration, and not limitive. It is apparent that many modifications and variations of the commutator short circuiting device herein disclosed will present themselves to those skilled in the art without departing from the spirit of this invention; and it is therefore to be distinctly understood that such modifications and variations, although not specifically described herein, are contemplated by and within the scope of the appended claims.

Having thus described the invention, what is claimed is:

1. A commutator short-circuiting unit comprising, a disk having a circumferential flange, a plurality of furcated sector shaped contactor elements arranged around said disk and confined by said flange against translatory movement in all. directions except radially inward, and at least three radially extending lugs on said disk and extending between certain of said contactor elements in substantially equal circumferential displacement, said elements being circumferentially held by said lugs sufficiently spaced for free independent movement but insufiiciently spaced to permit radially inward translation of any one element suflicient to free said flange without rotation.

2. A commutator short-circuiting unit comprising, a disk having a circumferential flange and an inwardly bent lip forming a channel, a plurality of furcated sector shaped contactor elements arranged around said disk each having a rounded part disposed in said channel and held thereby against translatory movement in all di rections except radially inward, and at least three radially extending lugs on said disk and extending between certain of said contactor elements in substantially equal circumferential displacement, said elements being circumferentially held by said lugs sufficiently spaced for free independent movement but insufiiciently spaced to permit radially inward translation of any one element sufficient to free said flange without ro tation.

3. A commutator short-circuiting unit comprising, a disk having an internally open peripheral channel, a series of contactors arranged about said disk, said contactors having a rounded part freely fitting in said channel and a commutator engaging part radially inward thereof, said rounded part of the contactors being embraced by said channel on three sides so that said contactor may be removed from said channel only by radially inward translation, and a pressure plate 5. A contact element for a commutator shortcircuiting device comprising, a substantially long leg having at one end thereof of a rounded hinge portion, a commutator engaging portion extending laterally from said long leg, said long leg having a rounded bearing surface radially inward of said commutator engaging part the distance between said hinge portion and the end of said long leg being substantially greater than the distance between said hinge portion and the arranged for engagement with each of said concommutator engaging part, tactors, said contactors having a rounded bearing 6. The combination with an electromotive depart arranged to receive thrust from said plate. vice having a commutator on a shaft, of a com- 4. A commutator short-circuiting unit comprismutator short circuiting device comprising, a ing, a disk having an internally open peripheral support fixed on the shaft in axially spaced rechannel, a series of contactors arranged about lation to the commutator, a series of contact elesaid disk, said contactors having a rounded part ments each having a substantially long leg with a freely fitting in said channel and a furcated part hinge portion at one end thereof and a shorter radially inward thereof, and a plate arranged in leg displaced axially from said longer leg, and the circumferential groove formed by the series means for mounting the hinge portions of said of furcated parts, the portion of said furcated elements on said support with said long leg expart between said plate and said disk being longer tending substantially radially and substantially than the other portion thereof, and the elemental perpendicular to the axis of said shaft. mass center of said longer part being substantially in the plane of said channel when in normal ROBERT L. MORTON.

position.

-;ent N0 2,292,557-

CERTIFICATE OF CORRECTION.

ROBERT L. MORTON Augus t ll, l 9Lt2 It is hereby certified that error appears in the printed specification ithe above numbered patent requiring correction'as follows: Page. 1, first page 5, second column, line 11,

DI the word "container" read --contactor-; ,line fifi, for "limitive' read limitative-; page it, second column,'line 5, claim 5, strike out "of" fore a"; and that the said Letters Patent should be read with this corection therein that the same may conform to the record of the case in 1e Patent Office. i

Signed and sealed this 15th dayof September, A. D. 19142.

Jun, line 2 9, for "anad" read "ma- Henry Van Arsdale,

Acting Commissioner of Patents.

Seal)

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