US1673518A - Short-circuiting device for motors - Google Patents

Description

June 12, 1928.

G. H. LELAND SHORT CIRCUITING DEVICE FOR MOTORS 2 Sheets-Sheet Filed April 26, 1924 m w w GEORGE/5. LELAND.

ATM RNEY June 12, 1928.

G. H. LELAND SHORT CIRCUITING DEVICE FOR MOTORS 2 Sheets-Sheet Filed April 26, 1924 A TTOP/VEK induction. motor is so constructed that it' Patent d-June 12, 1928.

- UNITED STATES GEORGE -H. LELAND, OF'IOAYTON, OHIO, ASSIGNOR OF ONE-HALF TO THE LELAND ELECTRIC COMPANY, OF DAYTON, OHIO, A CORPORATION OF OHIO.

I snon'r-crneurrme 'nnvrcr: roa morons.

Application filed April 26, 1924. I Serial No. 709,287.

This invention relates to short circuiting .devices for motors. An alternating current motorof'the typeknown as the repulslonstarts as a repulsion motor and, after it has attained approximately its operating speed, the commutator is automatically short circuited to convert it into an induction motor.

It is customary to provide a short circuiting element consisting of a series of short circuiting members arranged circumferentially of the motor shaft and movable'by. centrifugal force into engagement with the commutator bars to short circuit the latter and plates or disks'which retain the short -cir-' change the motor from a repulsion type to an induction type motor. The short circuit-- will move in advance of the others, thus pro-- ducing undesirable results. Further, the end cuiting members in position are'so mounted on the shaft and in many instances they are capable of tilting movement and unless they fit very snugly they'will wobble in the operation of the motor. While this does not 1 affect the operation of the motor it is uni mi e a shortcircuiting device'which will desirable.

One object of the present invention is to provide a short circuiting device of this character in which the several-short circuit ing elements will be operated substantially in unison. 'A further object of the invention is to provide such a short circuiting device in which the retaining disk will be maintained in a position pe endicular tothe axis of its rotation, there y causing it to run true. A further object of the invention is to provide a short circuiting device with means for so controlling the operation of the short circuiting element that the members will be moved quickly into and out of engagement with the commutator bars and the motor can have'a relatively large variation of speed without 'causin'gthe operation of the short circuiting element. a 1

A ifurth r'obje'ct of the .invention 'is to thereof and showing the short circuiting members in elevation; Fig. 3 is a detail sectional view showing the short circuiting element in its operative position; Fig.4 is anelevation of a portion of the short circuiting device, partly broken away and showing the contact members in engagement with the commutator bars; Fig. 5 is an enlarged detail View showing the arrangement and movement of the contact members; Fig. 6- is a transverse sectional viewtaken parallel with the axis of the commutator showing the tilting of the end plate; Fig. 7 is a detail sectional view showing a slightly modified form of the device; Fig. 8 is a detail view of a portion of the commutator shown in Fig. 7; and Fig. 9 is a sectional detail view of a slightly modified arrange: ment of the weights and contractile band.

. In these drawings I have illustrated one embodiment of my invention, together with minor modifications thereof, but it will be understood that this particular embodiment has been chosen for the purposes of illustration only and that the device may take various-forms without departing from the spirit of'the invention.

In these drawings I have not illustrated the motor as a whole but have shown only a portion of the shaft 1 of the rotor and the commutator which is mounted on that shaft. The rotor and stator, with their associated parts, may be of any' usual or suitable construction. The commutator comprises a body portion or core 2 which is rigidly secured to the shaft 1 and which has mounted thereon a circumferential series of commutator bars 3 which are insulated one from the other and from the body' of the commutator in the usual manner. The ends ofthe commutator bars are preferably flush with the corresponding end of the bod I orcore of the commutator so as to providh .a straight flat surface over which the short circuiting-members are moved as hereina-fier appear. In applying my mventlon PATENT OFFICE- to this commutator I provide a series of short circuiting members which are arranged circumferentially of the shaft 1 adjacent to the end of the commutator 2 and are mov able by centrifugal force into contact with the commutator bars, this movement being resisted by a suitable yieldable device. The short circuiting members are connected one with the other in such a manner that the movement of one or more of the short circuiting members into engagement with the commutator bars will cause the simultaneous movement of all the members into short circuiting relation to the commutator bars. Preferably the short circuiting members are mounted for pivotal movement about axes parallel with the axis of the shaft 1. In the present instance the inner ends of the short circuiting members have no outward or radial movement but as the outer or contact portions ofthe members move radially the inner port-ions are caused to move circumferentially of the shaft and the connect- ;ing means between the several members will cause this circumferential movement to be imparted simultaneously to all the members.

,It will be obvious'that the short circuiting members may take various shapesand forms and that they may be mounted and connected one to the other in various ways but, in the particular embodiment here illustrated, the short circuiting element comprises a series of arms 4 which are curved or otherwise so shaped that they will nest snugly tator.

. portion one against the other, when in their contracted positions. The outer portion of each arm or short circuiting member extends at an angle to the body portion of the arm, as shown M75, and preferably is arranged substantially radially to the axis of the commu- The inner end of the arm or short circuiting member is, in the present instance, supported in engagement with the shaft 1. This inner portion may, if desired, be ofIa greater width than the body portionof the arm so as to provide a laterally extending 6 which projects into a recess 7 formed in the adjacent end of the commu. tator core 2. The inner'portion of each arm or member 4 is provided on eachside with a a lu 8, these lugs being formed in the present evice by forming recesses 9 in the opposite edges of the enlarged portion of the arm, the recesses in the respective edges of the several arms being so arranged that.

when the short circuiting element is assembled these recesses will form annular grooves in the opposite sides thereof. Mounted in these recesses to engage the lugs 8 are suitable retaining members, here shown in the form of rings 10 which have their inner edges,notched, as shown at 11. to receive the corners of the respective lugs 8. The inner corner of each lug, that is, the corner diagonally opposite the corner which is seated in the recess 1110f the retaining trifugal, force, into engagement with the; commutator bars and this radial movement.

of the outer portions 'of the arms will cause the inner portions thereof to move circumferentially of the shaft 1, as is clearly shown in Fig. 5. The retaining rings 10 connect the several short circuiting arms one to the other so that the circumferential movement imparted to the inner portion of one arm by centrifugal force will be transmitted to all the arms and the several arms of the short' circuiting element will be. caused to move 'circumferentially of the shaft simultaneously and this circumferential movement I of the inner ends of the arms will cause the outer portions of the arms to move radially into contact with the commutator bars. It will be apparent, therefore, that should one or more of the' short cir:uiting members. or arms tend to move eith er toward'or from the commutator in ad ance of the other members this movemensw ill be restrained until the force is suificient to impart movement to all the members, thereby causing the contact portions of all the members to engage the commutator bars substantially simultaneously.

The movement of the short circuiting 7 members toward the commutator bars is re- Y sisted by a suitable yieldable device which is of such a character that itwillthold the short circuiting members in their retracted or innermost positions when the motor is idle or moving at a low speedzbut' which, when the speed of the motorhas reached a predetermined speed, will yield to permit the short circuiting members to move into contact with the commutator bars. This ieldable device maytake various forms h ends connected oneto the other to; form a ring no i at. I I have, in the present construction, employed which extends about and is in constant contact with the outer edges of the contact portions 5 of the short circuiting arms. The

short circuiting members-are held against movement. axially of the shaft by the circumferential contractile member, 12 which is retained in position thereon by an end plate or disk 13 which is mounted on the shaft and extends outwardly beyond the ends of the short circuiting members. The retaining disk 13 is spaced such 'a:distance from the adjacent end of the commutator that the short circuiting members have free movement between the disk and the commutator but are held against any appreciable movement axially of the commutator. The outer edges of the contact portions 5 of the short circuitingmembers are preferably inclined away from the commutatorv and toward the shaft and to thus present to the yieldable member 12 a conoidal surface so that the pressure of the yieldable member will tend not only to press these short circuiting members toward their innermost positions but will also tend to press them yieldingly and with equalized pressure against the end of the commutator so that they will at all times be in firm contact therewith. I have here shown the contact portions of the short circuiting members as having projections or noses extending beyond the edges thereof to contact with the end of the commutator and these projections move over the end of the commutator with a sliding movement and thus keep the ends of the commutator bars and contact members clean and bright, thereby providing tric contact between the same.

Means may, if desired, be provided for so controlling the outward movement of the short circuiting members as to prevent any movement thereof until the motor has reached a predetermined speed and to then release the short circuiting members and permit them to move quickly into contact with the commutator bars, and likewise to prevent the contractile band from moving the short circuitingmembers inwardly until the speed of the motor has been reduced to a predetermined extent, the bars being then moved quickly to their innermost or inoperative positions. In the present device, these results are accomplished by providing the end plate or disk 13 with concentric grooves 15 and 16, which grooves are separated by a rib 17. The groove 15 is so arranged that when the contractile band is in its innermost position it will be seated in 'that groove and the rib 17 will resist the outward movement of the band and of the short circuiting members. When the speed of the motor is such that the centrifugal force will move the contractile band out of the groove 15 the resistance to its movement will be so reduced that it will move quickly to its outer position, in which position it will be seated in the grove 16, thus permitting the short circuiting members to mfove quickly into contact with the commutator bars. When the contractile member is seated in the outer recess or groove 16 the rib 17 will resist its inward movement and prevent it from moving the short circuiting members inwardly until the speed of the motor has been materially reduced at which time the band will ride over the rib 17 and move the short circuiting members quickly to their inoperative positions. By thus resisting the perfect elcc- I inward movement of the contractile band the speed of the motor may be reduced to a point considerably below the speed which is necessary to effect the short circuiting of the commutator before the short circuiting members will be moved out of engagement with the commutator bars. Consequently the motor may operate as an induction motor with a relatively wide variation of speed.

As has been stated if the end plate or disk 13 is not fitted snugly onto the shaft 1 it may havea tiltingmovement thereon and willtend to wobble and not run true when the shaft is rotated, particularly at the lower speeds. have found, however, that by giving the outer edges of the contact members 5 a curved shape, as shown at 18, so that the inclination of these edges increases as they approach the commutator the contactile spring 12 may be caused to act upon the disk 13 in such a way as to maintain the same perpendicular to its axis of rotation. In Fig. 6 of the drawings, the disk 13 is shown in full lines in tilted position. It will be apparent that in this position the contractile spring 12 has been moved up the curved surface of the short circuiting element and that the resistance to this movement of the band or spring 12 increases as it approaches the commutator. Consequently when one portion of the disk 13 tends to move the hand toward the position shown in Fig. 6 the resistance to that movement is greater than the forcev exerted on the other portion of the disk by the band and which tends to move said other portion away from the short circuiting element. As a result the spring tends to hold the disk in a vertical position and to cause it to run true.

It is not essential to the operation of the device that the inner ends of the arms or short circuiting members should be of in- Inn creased width so as to enter a recess in the 'contactportions t ereof and the inner lugs 8, and the recesses 21 are formed inthe lateral edges near the inner ends thereof; The retaining rings 22 are identical with those above described and the operation of the short circuiting device is exactly the same as heretofore set forth. However, in that form of the device, first described the laterally extending portions 6 of the arms contact with, the circumferential wall of the recess 7 of the commutator to hold the arms against radial movement and when these laterally extending portions are omitted I prefer to provide some other means for limiting the outward movement of the arms. As shown in Figs. 7 and 8, the commutator bars 23 are provided with projections 24.- at their outer edges which extend toward the short circuiting members and form a flange which ment in which the contractile band serves as a short circuiting element and to this end the inclined outer portions of the weight members are inclined toward the commutator so that the band will be causedlobear firmly against the face of the commutator.

While I have shown and described one embodiment of my invention I wish it to be understood that I do' not desire to be limited to the details thereof as various modifications may appear to a person skilled in the art. For example, it will be understood that the annular series of pivoted Weight members may include all or a part only of the Weight members which are comprised in the short circuiting element, as it will be readily apparent that substantially the same results will be secured in either instance.

Having now fully described my invention what I claim as new and desire to secure by Letters Patent is 1. In a short circuiting device for the commutator of an electric motor, an annular short circuiting element comprising a series of members movable in a substantially radial direction to effect the short circuiting of said commutator, and means for causing said members to move in unison in the direction to effect the short circuiting of said commutator.

2. In a short circuiting device for the commutator of an electric motor, an annular short circuiting element comprising a series of separately mounted members movable by centrifugal force to effect the short circuiting of said commutator, yieldable means to 'resist said movement of said members, and

an operative connection between the several short circuiting members to cause them to move in unison. 3. In a short circuiting device for the commutator of an electric motor, a short circuiting element comprising an'annular series of members arranged for movement about individual axes substantially parallel with but spaced from the axis of said commutator to effect the short circuiting of said commutator.

4. In a short circuiting device for the commutator of an electric motor, an annular series of elongated members pivoted at their inner ends on axes substantially parallel to the axis of said commutator, and means to cause said members to be moved in unison about their individual axes to effect the short circuiting of said commutator.

5. In a short circuiting device for the commutator of a motor, a short circuiting element comprising a plurality of elongated members each pivotally supported on an axis substantially parallel with the axis of said commutator and spaced from the bars of said commutator and each having a portion arranged out of line with the axis thereof, said portions of said members being movable outwardly to effect the short circuiting of said commutator, and means acting on said members to resist the movement thereof:

6. In a short circuiting device for the commutator of an-electric motor, an annular series of substantially spiral shaped members mounted for movement into positions to effect the short circuiting of the commutator.

7. In a short circuiting device for the commutator of a motor, an annular series of substantially spiral weight members pivotally mounted at their inner ends on axes substantially parallel with the axisof said commutator and movable by centrifugal force into positions to effect the short circuiting of said commutator.

8. In a short circuiting device for the commutator of a motor, an annular series of substantially spiral weight members pivot ally mounted at-theirinner ends on axes substantially parallel with the axis of said commutator and movable by centrifugal force into positions to effect the short circuiting of said commutator, and an annular member connected with the inner end of said spiral weight members to cause them to move in unison.

9. In a short circuiting device for the commutator of an electric motor, an annular series of substantially spiral Weight members pivotally supported on axes substantially parallel with the axis of said commutator and located in juxtaposition to the lateral face of said commutator, said members having their exterior margins shaped to collectively provide a conoidal surface, and a circumferentially arranged yieldable member engaging said conoidal surface to press said members against the face of said commutator as they open outward under the influence of centrifugal force and to restrain the centrifugal action thereof;

10. In a short circuiting device for the commutator of a gnotor, an annular short circuiting element arranged concentrically of the axis of said commutator and comprising a plurality of elongated members each having its innerend pivotally supported at a point spaced from the bars of said commutator for movement about an axis substantially parallel with .the axis of said commutator and each having an outer portion arranged out of radial alinement with said inner end, said outer portions of said members being movable by centrifugal force to effect the short circuiting of said commutaradial direction, and a device actin on said short circuiting members to yiel ably resist the movement of said outer portions thereof.

11. In a short circuiting device for the commutator of a motor, an annular short circuiting element arranged concentrically of the axis of said commutator and comprising a plurality of elongated members each having its inner end pivotally supported at a point spaced from the bars of said, commutator for movement about an axis substantially parallel with the axis of said commutator and each having an outer portion arranged out of radial alinement with said inner portion, said outer portions of said members being movable by centrifugal force to effect the short circuiting of said com-.

mutator, the pivotal portion of each of said members being movable circumferentially of the axis of said commutator to permit the outer portion thereof to move in a substantially radial direction, and means for connecting the inner portions of the several members one' to the other to cause them to move circumferentially of said axis in unison, and means acting on said/members to yieldably resist the movement thereof.

12. In a short circuiting device for thecommutator of a motor, a short circuiting element comprising a plurality of elongated members each plvotally mounted at its inner end .on an axis substantially parallel with the axis of said commutator and spaced from said commutator bars, the axes of the several members bein arranged in a circle described about the axis of said commutator, the inner ends of said members being movable about the axis of said commutator, an

' annular member extending about the axis ofv said commutator and connected with the inner portion of each of said members to cause said portions of said members to move in vunison about the axis of said commutator,

each of said members having at its outer end a portion arranged out of radial alinement with the pivoted inner end thereof, said portions being movable to effect the short circuiting of said commutator, and means to yieldably resist the movement of said members.

13. In a short circuiting device for the commutator of a motor, a" short circuiting element adapted to rotate with said commutator and comprising a series of elongated members each pivotally su vported at I its inner end on an axis paralle with the axis ofjsa'id commutator and spaced from resist the movement of said members toward said commutator bars.

14. In a short circuiting device for the commutator of an electric motor, an annular series of elongated members movable about axes substantially parallel to the axis of said commutator to efiect the short circuiting of said commutator, and means for interconnecting the inner ends of said members to cause them to rotate in unison about the axis of said commutator as said members are moved into positions to effect the short circuiting of the commutator.

15. In a short circuiting device for a. motor, the combination with a shaft, and a commutator secured thereto, ofa pluralit of elongated short circuiting members eac having its inner end pivotally supported adjacent to said shaft and having its outer end arranged out of radial alinement with said inner end and adapted to be moved by displacement with relation to said shaft and to cause the same to move in unison about the circumference of said shaft, and means to yieldably resist the movement ofsaid short circuiting members about their respective axes.

16. In a short circuiting device for a motor comprising, a shaft and a commutator, a plurality of short circuiting members each having its inner portion supported on said shaft and provided at one edge thereof with a lug, a mug extending about the lugs on the several short circuiting members and having notches to receive the respective lugs to hold the same against radial displacement with relation to said shaft and to cause the same to move in unison about the circumference of said shaft, each of said members having its outer portion arranged out of radial alinement with the inner portion thereof and adapted to be moved by centrifugal force to effect the short circuiting of said commutator, said movement of said outer portions of said members causing the inner portions thereof to move circumferentially of said shaft, and means to yieldably resist the movement of said short circuiting members about their respective axes.

17. In a short circuiting device for a motor comprising a shaft, a commutator, a lurality of elongated short circuiting mem ers each having at its inner end a part engaging said shaft and forming a fulcrum about which said member may be moved, each of said members having a recess in each edge thereof, the recesses in the respective edges of the several members being arranged in line one with the other, annular members mounted in the recesses in the respective edges of the several short circuiting members and having notches to receive the inner walls of the respective recesses, each of said short circuiting members having at its outer end a substantially radial portion arranged out of radial alinement with the inner portion thereof and movable'in a substantially radial direction to effect the short circuiting of said commutator.

18. In a short circuiting device for a motor comprising a shaft, and a commutator mounted on said shaft, a short circuiting ele' ment arranged circumferentially of said shaft and comprising a series of short circuiting members movable outwardly by centrifugal force to effect the short circuiting of said commutator, a disk mounted on said shaft to hold said short circuiting element against axial displacement with relation to said commutator, the radius of said short circuiting element being less at that side adjacent to said disk than at the side adjacent to said commutator and the outer edges of said short circuiting members being curved, and a contractile band encircling the outer edges of said short circuiting members and engaging said disk.

19. In a short circuiting device for the commutator of a motor, a retaining member mounted about the axis of said commutator and spaced therefrom, an annular series of weight members confined between said commutator and said retaining member,

each pivotally supported at its inner end on an axis substantially; parallel with the axis of said commutator and adapted to move outwardly by centrifugal force to. effect the short circuiting of said commutator, and a circumferentially arranged contractile band engaging said We ght members to control the centrifugal actlon thereof, a part of said short circuiting device having an annular armature of an electric motor, the combina-,

tion with a commutator connected, with the armature, and a retaining member mounted f in spaced relation to the lateral face of the commutator, of an annular series of weight members interposed between said commutator and said retaining means and having their outer margins shaped to collectively provide a concave'conoidal surface, and a circumferentially arranged contractile band also interposed between said commutator and said retaining means and engaging sa d conoidal surface to provide varying longitudinal pressure on said retaining member as the distance between said member and the face of said commutator may vary.

In testimony whereof, I aflix my signature hereto.

GEORGE H. LELAND.

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