US2499122A - Centrifugally operated switch - Google Patents

Description

Feb. 28, 1950 w. 2. WEST, JR., ET AL 2,499,122

CENTRIFUGALLY OPERATED SWITCH Filed July 30, 1948 2 Shhs-Sheet l Feb. 28, 1950 w. 2. WEST, JR., ET AL 22 CENTRIFUGALLY OPERATED SWITCH Filed July 30', 1948 2 Sheets-Sheet 2 Patented Feb. 28, 19 50 UNI TED CENTRIFUGXLLY OPERATED swr'ron Willis Z. West, In and MorganF. Gamble, Winston-Salem, N. 0.

Application July- 30, 1948,Seria-l No. 41,534

. 1'7 Claims. (Cl. 200-80) Our invention "relates to .a switch \of {the WP;

actuated by centrifugal force to open or closez-ra circuit.

An important'object of theinvent-ion iszto provide a switch of the abovementioned character,

to be mounted upon thearmature shaft of ,a motor, and having means for electrically connecting the switch terminals :when :thearmature shaft is at :rest, orsrotating slowly,. and"to.break the electrical connection between the terminals when the rotational speed of theyarmature -shait increases. 3

A further object of the invention is to provide a switch of the above.mentionedcharacter havin a centrifugally operated icontact element which has its radial outward movement orgaosed by-ya spring which also serves to center thecontact element, providing a clearance between the, contact element and the adjacent relatively stationary parts. 1

A further object of the invention is to provide means for holding a band spring .in position, which band spring acts "against. thezcontact :element and will permit of the .readyremoval .ofthe band spring so that band springs of'varying strength may be employed, depending upon the rated rotational speed 'of the aarm'ature shaft or the like.

A furtherobject of the invention is toprovide a clearance between the radial zoutward'portion of the rotary contact carrier andth'e adjacent relatively stationary parts, reducing friction and vibration to the minimum.

A further object of the invention 'is' to provide a switch of the above mentionedwcharacter.having a completely closed housing, excluding dust and reducing sparking to 'theminimum.

A furtherobject of the inventionis to provide a switch of 'theabove mentioned character which will operate properly when mounted upon the armature shaft of? a motor or the like, irrespective of the relative rotary position that the contact elementhas with respect to the armature shaft.

A'further object of the invention is toprovide a switch of the above mentioned character which may be installed upon the armature 'shaft or the like without the necessity of making adjustments requiring the services ;of a skilled mechanic.

A further object-of the invention is to provide :a

switch of the above mentioned character which is extremely simple in construction, cheap to manufacture, and compact.

Other objects and advantages ofthe invention will be apparent during the courseiof the following description.

.In the accompanying drawings, forming .a part of this application, and .in which .like numerals are designated to designatellikeparts throughout the same,

Figure .1 is aperspective view of a rotary switch embodying my invention,

...Eig=ure .2 is an endelevation of the same,

Figure 3 is a horizontaltransverse section taken on line 3---3 ofFigure 2,

Figure 4 a vertical section taken on line 4 of Figure 3,

,Figure 5 .is'a similar view taken on line 55 of Figure 3,

Figure-Bis an explodedperspective view of the switch,

-on line- 9-9 of Figure .7, and

vl 'igure 10.is a diagrammatic view of a slight -modification.

In the drawings, wherein for the purpose of illustration is shown a preferred embodiment of my invention, the numeral I0 designates a .Jmaterialand which may have an internal diam- ,formed in the'bottom of the main groove.

eter sothat the sleeve may have a pressed fit upon the armature shaft 1 l of a motor. A metal :sleeve, not shown, may have a; pressed fit within the insulating sleeve Ill foraccominodating armature shafts of smaller diameters. A rotary ,annular carrier i2 is provided, formed of in- ,sulating material and made integral with the insulating sleeve l0 and secured thereto by an annular. portion l3. Arranged upon the insulating sleeve l0 and having a pressed fit thereon, or

otherwise rigidly secured thereto, are metal con tact orslip rings l4, preferably engaging the annular portion l3 and separated thereby. The

annular carrier 12 is provided with an annular particularly Figure .4, which receives a radially movable contact segment or element It, formed of .suitable metal. Thiscontact segment .01 ele- Jnentris provided with contacts l9, formed of silver orgthe like, and welded to the .same, and these'contacts are adapted to engage with contectsJm-welded upon the innerends .of the contact or slip rings [4, as shown. The recess or passage l'l extends through the opposite ends of the carrier I2 and extends radially inwardly beyond the bottom wall of the main groove IS. The recess or passage ll is only slightly longer than the contact segment so that it retains the contacts 19 in cooperative relation to the contacts 20. The passage l1 extends throughout a minor portion of the length of the main groove l5. The outward radial movement of the contact segment or element I8 is opposed by a band r etractile coil spring 2|, seated within the annular groove [6 and engaging within a circumferential groove 22 formed in the periphery of the contact segment or element [8. The groove 22 is at the longitudinal or axial center of the segment or contact element l8. The band spring 2| not only opposes the radial outward movement of the contact segment or element I8, but retains the" same axially centered with respect to the rotary carrier l2 whereby the outer axial faces of the contact segment are retained slightly within the ends of the carrier 12.

A cylindrical housing 23 is provided, formed of insulating material, and this housing is provided at one end with a brush holder ring 24, also formed of insulating material and formed integral therewith. The opposite end of the cylindrical housing 23 is open and is adapted to receive a companion brush holder ring 25, having a snug removable fit therein. The brush holder ring 24 is provided upon its inner face and at its center with an annular rib 26 for slidably engaging the end of the annular carrier l2, and the brush holder ring 25 is provided upon its inner face and at its center with an annular rib 21, for slidably engaging the opposite end of the annular carrier 12. By this arrangement there is a slight clearance between the radial outer portion of the carrier and the brush holder rings, thereby reducin the friction and vibration to the minimum. The spring 2| retains the contact segment or element I8 axially centered with respect to the carrier l2 and holds it out'of contact with the ribs 26' and 21.

The brush holder ring 24 is provided with a radially circumferentially extending recess 28, having a curved 'end or bottom and receiving a segmental contact 29 formed of carbon orthe like. This contact has an inner curved face for engagement with the adjacent contact or slip ring M. The contact segment is urged inwardly and is retained in permanent contact with the ring by'a bow spring 30, which may be formed of a copper alloy and this bow spring is electrically connected with an insulated wire 3| by solder or the like. This insulated wire passes through a radial opening 32. The brush holder ring 25 has a radial recess 33 corresponding to the recess 28, and receiving a contact segment 34, corresponding to the contact segment 29 and held in permanent contact with the adjacent slip ring I4 by a bow spring 35, corresponding to the bow spring 30. The bow spring 35 is connected with an insulated wire 36 by solder or the like, and this wire passes through an opening 31. The wire 36 also passes through a notch 38 formed in the housing 23.

When the parts are assembled, as shown in Figure 8, the inner ends of the slip rings l4 are disposed inwardly of the brush holder rings '24 and 25. When the brush holder ring 25 is re moved, the unit including the insulating sleeve rated from the brush holder ring 24 and removed from in the housing. The annular recess l5 faces toward the removable brush holder ring 25 and this renders it convenient for removing the contact segment [8 and spring 21, by removing the brush holder ring 25 without removing the entire unit including the sleeve ID from the housing, although the unit may be removed for this purpose, if desired.

The housing 23 has oppositely arranged openings 39 to register with oppositely arranged openreceive the inwardly bent ends 4| of a U-shaped resilient keeper 42, whereby the housing and ring ment, not shown, such as a piece of wire which is secured to a stationary part of the motor. This prevents the entire housing from turning.

The operation of the switch is as follows:

The sleeve I0 is applied to the armature shaft II for rotation therewith. The motor may be of the split phase type or of the capacitive type. The split phase motor has a starting stator winding, and a running stator winding. As is well known, in starting a motor of this type, the current is first supplied to the starting and running stator windings, and when the motor speed increases, the current to the starting stator winding is cut off. The present switch is employed to supply current to the starting stator winding to start the motor, and to cut the current off when the motor speeds up. When the motor armature shaft is at rest, the switch embodying this invention is in the normally closed condition, Figure 8. The band spring 2| forces the contact segment or element l8 radially inwardly and its contacts 19 engage the contacts 20 of the slip rings Hi, thus closing the circuit between the slip rings and connecting the brushes 29 and 34 for closing a circuit leading to the starting stator winding. As the speed of the armature shaft H increases, the unit including the slip rings M has its rotational speed correspondingly increased, and the contact segment or element I8 is thrown radially outwardly, within the recess of the carrier i2, by centrifugal force. The contact segment I8 moves outwardly against the force of the spring 2i, and the contacts I9 disengage the contacts 20, thus opening the circuit to the starting stator winding. When the speed of rotation of the armature shaft is again reduced sufliciently or when it is brought to rest, the contact segment 18 will return to the closed position.

- The switch is a completely self contained unit, as all parts are assembled as a unit, when the sleeve I0 is pressed upon the armature shaft II'. The loop 43 of the keeper 42 is secured by means of a wire or the like to a stationary part, such as a bolt of the motor housing. The placing of the sleeve Ii] upon the armature shaft and connecting the loop 43 to a stationary part, are the only manipulations which need be made, in installing the switch, and these do not require the services of a skilled mechanic or electrician. It is entirely immaterial what radial position the annular'brush holder rings assume, with respect to the slip rings [4. Since the brushes 29 and 34 are arranged upon opposite sides of the carrier, there is no tendency for the switch to shortcircuit across the inner ends of the slip rings, due to carbon dust or the like. Further, the brushes are enclosed, and there issubstantially no tendency for sparks to be produced, due to en ages improper contact between th'ebrushes and slip rings. Byvirtue of the brush holder rings slidably rotatably receiving the slip'ri'n'gs [4, these rings are kept clean for proper contact with the brushes. The housing 23 and brush holder rings '24- and 25, produce a dust-proof casing, enclosformed of few parts which are not liable to disapplied to the contact segment and thesegment returned to the operative position. "By varying the strength of the spring 2|, the switch will operate to open the circuit speed.

While in the preferred embodiment of the 'inat a selected rotational vention the circuit is closed when the contact segment i8 is in the inner position, however we contemplate making a slight modification in the construction whereby the circuit would be opened when the contact segment I8 is in the inner position and the circuit closed when the contact segment is in the outer position. As shown in Figure 10, the carrier 52 is equipped with contacts 44, connected by wires 45 with the slip rings l4.

These contacts correspond to the contacts l9, Figure 8. Contacts 4'! are formed upon the outer circumference of the contact segment. The contact segment is moved outwardly by centrifugal force against the action of the spring 2|, and disengages the same when the contact segment moves radially inwardly. All other parts of the switch will remain identical with those shown and described in connection with the first form of the invention.

It is to be understood that the form of our invention herewith shown and described is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of parts, may be resorted to, without departing from the spirit of our invention or the scope of the subjoined claims.

Having thus described .our invention, we claim:

1. A centrifugal force actuated switch comprising an insulated sleeve to bel mounted upon an armature shaft or the like, axially spaced slip rings mounted upon the sleeve, an insulating carrier disposed adjacent to the inner ends of the slip rings and rotatable with the insulating sleeve, said carrier having a circumferentially extending main groove passing through one end of the same and terminating short of the opposite end of the carrier and a radial passage leading into the ends of the circumferentially extending groove, the inner ends of the slip rings projecting into the passage, a contact segment arranged within the passage, contacts electrically connected with the slip rings and arranged for co-action with the contact segment, a spring band arranged within the circumferential recess and engaging over the contact element in the passage, the arrangement being such that the contact segment and spring band may be removed laterally through the main groove without disturbing the carrier.

2. A centrifugal force actuated switch comprising an insulated sleeve to be mounted upon an armature shaft or the like, axially spaced slip rings mounted upon the sleeve, an insulating carrier formed integral with the sleeve and including a reduced radial portion forming grooves between 6 the carrier and sleeve, said grooves receiving the ends of 'the' slip rings; said carrier having a circumferentially extending main groove passing through one end thereof and terminating short of the opposite end of the carrier an'd'a radial passage leading into the ends of the circumferential main groove and having a circumferentially extending spring holding groove in the bottom'of the main groove, a contact segment arranged within the passage'for co-action with the slip rings and moved by the action of centrifugal force, said contact segment being provided upon its periphery with a circumferentially extending spring holding groove, a spring band held within the groove ofthe carrier and engaging within the groove of the contact-segment to oppose the outjward radial movement of the contact segment and to axially center the contact segment, brush holder-rings formed of insulating material and rotatably receiving the slip rings, brushes carried by the brush holder rings and contacting with the slip rings, and a mechanical device connecting the brush holder rings, the arrangement being such that the spring band and contact segment maybe removed laterally through the main groove without disturbing the carrier.

3. A centrifugal force actuated switch comprising an insulated sleeve to be mounted upon an armature shaft or the like, slip rings mounted upon the sleeve, an insulating carrier formed integral with the sleeve and arranged adjacent to the inner ends of the slip rings, said carrier having a circumferentially extending maingroove passing through one end thereof and terminating short of its opposite end and a radial passage leading into the ends of the circumferential main groove, a contact segment arranged within the passage and moved by the action of centrifugal force, a spring band held within the circumferential recess and engagingover the contact segment to oppose its outward radial -movement, brush holder rings formed of insulating material and rotatably receiving the slip rings and provided adjacent to their centers and upon their inner faces with ribs to contact with the inner portion of the carrier and-provide aclearance between the radially outer portion of the carrier andthe brush holder rings, brushes carried by the brush holder rings and contacting with the slip rings, and a mechanical device connecting the brush holder rings.

LA centrifugalforce'actuated switch comtudinal center, said carrier having a circumferentially extending recess means open at one end, slip rings mounted upon the sleeve and projecting axially beyond the ends of the carrier, a contact segment mounted within the recess means to be actuated by centrifugal force, a spring band within the recess means and engaging the contact segment to oppose its outward radial movement, a housing for enclosing the carrier, 9, brush holder ring permanently secured to one end of the housing and rotatably receiving one slip ring, a brush carried by the brush holder ring and contacting with the adjacent slip ring, a removable brush holder ring for insertion within the opposite end of the housing and rotatably receiving the adjacent slip ring, and a brush carried by the second brush holder ring and contacting with the adjacent slip ring, the arrangement being such that the contact segment and spring band may be removed laterally from the recess means without disturbing the carrier.

5. A centrifugal force actuated switch comprising an insulating sleeve, an insulated carrier formed integral with the sleeve near its longitudinal center, said carrier having a circumferentially extending recess means which extends axially through one end of the carrier, slip rings mounted upon thesleeve and projecting axially beyond the ends of the carrier, a contact segment mounted within the recess means to be actuated by centrifugal force, a spring band within the recess means and engaging the contact segment to oppose its outward radial movement, a housing for enclosing the carrier, a brush holder ring permanently secured to one end of the housing and rotatably receiving one slip ring and having a recess formed therein, a brush arranged within the recess of the brush holder ring and contacting with the adjacent slip ring, the open end of the housing being arranged near the end of the carrier through which the recess means passes, a removable brush holder ring for insertion within the open end of the housing and rotatably receiving the adjacent slip ring and having a radial recess, a brush within the radial recess of the last named brush holder ring to contact with the adjacent slip ring, and a keeper having parts for interlocking engagement with the housing and the removable brush holder ring arranged therein, the arrangement being such that the contact segment and spring band may be removed laterally from the recess means without disturbing the carrier.

6. A centrifugal force actuated switch, comprising an insulating sleeve and an insulating carrier formed integral therewith, said insulating carrier having a main circumferentially extending groove passing through one end thereof and terminating short of the opposite end, said main groove having top and bottom Walls, said carrier having a circumferentially extending passage leading into the ends of the main groove and passing through the opposite ends of the carrier, the main groove being open at one end only while the passage is open at both ends, axially spaced slip rings mounted upon the sleeve and extending outwardly beyond the ends of the carrier and having parts extending into said passage, a contact segment arranged within the passage for co-action with the slip rings, a spring band arranged within the main groove and passing over the contact segment to control its outward radial movement, brush holders mounted upon the slip rings, and brushes carried by the brush holders to engage the slip rings, the arrangement being such that the contact segment may be pressed upon one sidefor shifting it and the spring band laterally from the main groove and passage of the carrier. 7. A centrifugal force actuated switch, comprising an insulating sleeve and an insulating carrier formed integral with the sleeve, said insulating carrier having a main circumferentially extending groove passing through one end thereof and terminating short of its opposite end, said main groove having top and bottom walls, said carrier having a circumferentially extending passage leading into the ends of the main groove and passing through the opposite ends of the carrier, the passage extending through the minor portion of the length of the main groove, the main groove being open at one end only while the passage is open at both ends, said passage extending radially inwardly beyond the bottom wall of the main groove, axially spaced slip rings mounted upon the sleeve and extending outwardly beyond the ends of the carrier and having their inner ends projecting into the passage, contact points carried by the inner ends of the slip rings and arranged within the passage, a contact segment arranged within the passage and having contact points for co-action with the contact points of the slip rings, the contact segment being only slightly shorter than the passage so that the end walls of the passage retain the contact points of the contact segment in cooperative relation with the contact points of the slip ring, a spring band arranged within the main groove and passing over the contact segment to control its outward radial movement, brush holders mounted upon r the slip rings and brushes carried by the brush holders to engage the slip rings, the arrangement being such that pressure may be applied to one end of the contact segment to force the contact segment from the passage and the spring band from the main groove.

WILLIS Z. WEST, JR. MORGAN F. GAMBLE.

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

UNITED STATES PATENTS Number Name Date 704,575 Pintsch July 15, 1902 2,459,984 West et a1. Jan. 25, 1949

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