US2459984A - Centrifugal force operated switch - Google Patents

Description

Jani, 25 949V w. z. WEST, JR., ETALl CENTRIFUGAL FORCE OPERATED SWITCH 2 Sheets-Sheei l Filed Feb. l5, 1947.

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MRGAN F. GAMBLE ATTOMEY Jan. 25%19497 w. z. WEST, JR., ET AL 45%984 EEEEEEEEEEEEEEEEEEEEEEEEEEEE CH eb. l5 3.947

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MORGAN F.GAMBLE A 7" TORNEV NVENTORS Patented Jan. 25, 1949 UNITED STATES PllTllNTy OFFICE Willis'Zeb` West, Jr., and Morgan F..Gamble, Winston-SalemN. C.

Application February 13, 1947, SeriaiNm 728,350

7 Claims. (C1. 20G-80) Our: invention relates to a switch of the type actuated by centrifugal force.

An. important object of our invention is to provide 'a switch of the character mentioned, to be# mounted upon the armature shaft lof a motor, andhaving lmeans for electrically connecting the switch terminals when the armature shaft isat rest, or rotating slowly, and to break the electrical connection between the terminals when the rotational speed of the armature `shaft increases.

A further object of the invention is toprovide a centrifugal force-actuated switch which is eX- tremely simplified in design, constituting a completely sel'l-containedr unit, Well adapted `for installation without adjustment, thereby dispensing with the necessity of the services of askilled mechanic. l

A further object ofthe invention is to provide a normally closed switch, having mechanical means actuated by centrifugal force for opening the switch.

A further object of the invention is to provide a. switch which isadapted to operate properly when mounted upon the armature shaft of a` thereby enabling it to have an exceptionally. long and, Vusei'ul life. n y 1 Other objects and advantages of the invention will be apparent during the course of the following description. l

In the accompanying drawings, forming a part of this application, and in which like numerals are employed to designate likepartsithroughoutthesame, s

Figure 1 is a perspective view ci an assembled'switch embodying our invention,and showing the same applied to the armatureshaft of a motor, partsomitted,

lligure 2A is acentral vertical section1 taken on line 2 4. of Figure l, and showing, stationary holdingL bracket,

AIifigure 3 is avertical transversesection taken online 3--3 `oflig'ure 2,` n K Figure 4 isa vertical transverse-section', similar to Figure 3, and showing the switchfin theV open position,

Figure' 5 is a perspective view of a metal sleeve, I

Figure 6 is` a perspective view of an insulating sleeve,-

FigureA l isa perspective' viewof slip rings,

Figure 8fis a perspective view of an annularV housing, part in section,

Figure 9 isa perspective View of conductingv segments,

Figure' 10r is a perspective view of a carbon: brush and brush holder, and',

Figure 11= is a. perspective view of a brushholder ringV bracket'.

Iii-the drawings, where` for the purpose of illustration, is shown a preferred' embodiment of our The insulating sleeve I3* andthe'metal sleeve- I2 are of-the'same length, and: their ends are flush.

Rigidly mounted luponthe' insulating sleevev I3`V are Contact orslip lrings I4, formed of any' suitable electrical conducting material, such as copper or steel. These slip rings I4 have a tight press iit'upon the insulating sleeve I3', and their outerends are iiush with the ends of'Y the sleeves I2 and |32` The slipv rings; I4` may be staked'v in place upon the insulating sleeve I3, if desired, to

further assure anv integralassembly ofthe sleevesA I2 and I3 'with the slip rings, "I'he sliprings I 4 are of the samelength, and their inner ends are spaced apart, forming an annular passagewv or' groove Iibetween them, at the longitudinal center ofthe sleeve |21 The numeral IB- designates an annular ring or housing, formed of: suitable insulating material. cludes a circumferential wall and parallel annularendsill, formed integral therewith, and forming an-fanrmlarV recess: I1. housing7 Itvl'ias ai-m'ainl axial opening or bore IBl, `for receiving ltlfier-adjacent' inner ends of the sleeve, preferably' This sleeve I2" is` This annular housing I 6 in- The4 annular' slip rings I. and the slip rings have aI press t within this bore, for causing the annular housing iii to rotate with them. The ends Vi of the annular housing I8 are arranged equidistantly upon opposite sides of the groove I5.

Arranged within the annular recess Il of the housing IIB, are a plurality of circularly curved current conducting lsegments I9, having circumferentializgrooves 20 provided therein. The conducting segments I 9 are preferably four in number, and rwhen they are disposed inwardly, and in engagement with the inner ends of the slip rings, they constitute a substantially continuous annular conducting element, see Figure 3. The conducting segments I9 have free sliding engagement between the ends il of the annular housing I6, and are adapted to move radially within the annular recess I1. Arranged within the circumferential grooves 29 of the segments i9, is an annular helical extension spring 2|. This annular spring 2Iholds the conducting segments I9 in the innermost position, as shown in Figures 2 and 3. and in engagement against the inner ends of the slip rings I4, see Figure 2. This is the position of the conducting segments I9 when the switch is in its normally closed condition.

The numeral 22 designates annular brush holder rings, slidably mounted upon the slip rings I4, and arranged upon opposite sides of the annular housing I6, in close'spaced relation thereto. The brushing holder rings 22 are free to rotate with respect to the housing I6. The brush holder rings 22 are formed of a suitable insulating material, and are of slightly larger outside diameter than the annular housing I6, `see Figure 1. Each brush holder ring 22 has a cylindrical radial opening 23 formed therein, for receiving in tight press t engagement a cylindrical tubular brush holder 24. Each brush holder ring 22 is further provided with a pair of small diametrically oppositely arranged openings 25, for a purpose to be described. These openings 25 are preferably arranged at right angles to the axis of the opening 23. Each brush holder 2d is preferably formed of copper, or the like, and has a main' cylindrical opening 26 formed in its inner end and this opening 26 leads into a smaller screw threaded opening 21, through the outer endof the brush holder. Ar-

ranged within each main opening 26, is a cylini drical carbon brush 28, having a small outer cylindrical extension 29. Each brush 28 is free to move radially within the recess 26. Also disposed within each recess 26 is a small helical compression spring 30, preferably formed of a copper alloy, or the like. yEach spring 30 engages Vover the cylindrical extension 29 Vof the brush 28, and the inner Vend ofthe spring engages against the outer end of the cylindrical brushZB. The outer end of each spring 39 engages against outer end of the main opening 25, andthe spring forces its associated brush 28 radially inwardly, to hold the same in contact against outerperiphery of the adjacent slip ring I'4.` Each screw threaded opening 2l' receives a binding post orterminal screw 3|, under the heads of which may be connected the ends of the wires 32 and 33,-to be connected to the terminals of the switch. EachV terminal screw 3l is electrically7 connected with its associated brush 28, through the spring 3U; and also through the brush holder 24.

*Disposed upon the external cylindrical surfaces off-the brush holder rings 22, andspaced slightly radiallyfrom the annular housing I 6 (see ure 2), is a substantially semi-cylindrical or Fig-v which extends starting stator winding.

U-shaped bracket 34. The bracket 34 is preferably formed of sheet metal, and it therefore possesses a required degree or" resiliency, permitting it to `be mounted upon the brush holder rings 22. The bracket 34 has diametrically oppositely disposed and laterally spaced pairs of radial extensions or fingers 35 at its ends, and formed integral therewith. These ngers 35 engage within the small openings 25 of the brush holder rings 22, and thereby secure the rings 22 together, as a unit, which is slidable or rotatable upon the slip rings It. The bracket 32% prevents axial movement of the brush holder rings 22 upon the slip rings. The bracket 3@ is spaced radially outwardly from the annular housing i, sufciently to allow the housing to rotate freely with the sleeve l2, and associated elements. rEhe bracket 34 is'provided with a depending or radial knuckle 36, spaced equidistantly from its ends; and this knuckle Se receives portions or eXtensions 31 of a suitable stationary holding device or bracket 38, which is rigidly secured to the associated motor casing, not shown.

The operation of the switch is as follows:

The sleeve I2 is applied to the armature shaft S of a motor. The motor may be oi 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 oi. 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 position, Figure 3. The annular spring 2l forces the conducting segments it radially inwardly and against the inner spaced ends of the slip rings i4, thus closing the circuit between these rings, and supplying current to the The starting winding is, of course, connected into the circuit by means of the wires 32 and 33. As the speed of the armature shaft S increases, the unit including the slip rings Ill has its rotational speed correspondingly increased, and the conducting segments I9 are thrown radially outwardly, within the annular housing I6, by centrifugal force. The segments I9 move outwardly against the force of the spring 2i, and assume positions as shown in Figure 4 of the drawings. The conducting segments are now out of electrical contact with the slip rings I4, and the circuit through these rings is broken. The starting stator winding is now cut out of the circuit, and remains cut out as long as the motor remains upto speed.

The switch is a completely self contained unit, as all the parts are permanently assembled, when the sleeve I2 is pressed on to the armature shaft S. The knuckle 36 of the bracket ifi is secured to the stationary holding bracket 3B, and the wires 32 and 33 are connected to the terminal screws 3 I. These are the only manipulations which need be made, and they do not reduire the services of a skilled mechanic or electrician. It is entirely immaterial what radial positions the brush holders 24 assume, with respect to the slip rings i4. Since the brushes 2e are arranged longitudinally exteriorly of the annular housing i there is no tendency for the switch to short circuit across the inner ends oi the slip rings, due to anregen carbon dust, on'the like. Further` the brushes 28ersenclosed,v and there is substantially no tendencyffor-"spalrksf'to be produced, due to improper contact between the brushes an'dt-slipfrings, if improper conta-ctv shoulcboccur. Bywirtue of the brush holder rings 22 slidablyrotatably engaging thevslipv rings I4, these rings arekopt rclean for proper'contact with the'r brushes" 28. The switch is extremely .simple inf construction, strong and durable; it comprises few parts, and these are not liable tor` derangement. n

Itis 'to'be understoodthat'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, what we claim is:

1. A centrifugal force actuated switch, comprising axially spaced slip rings to be mounted upon the armature shaft of a motor, means to insulate the slip rings from such armature shaft, an annular insulating housing mounted upon the slip rings to rotate therewith and to bridge the space between the same and providing an annular recess, conducting segments arranged within the annular recess and adapted to move radially therein, an annular spring arranged. within the annular recess and engaging upon the conducting segments to hold the same in electrical contact with the spaced slip rings, brush holder rings slidably mounted upon the slip rings axially out wardly of the annular housing, brush holders carried by the brush holder rings, and brushes arranged Within the brush holders for engage ment against the slip rings.

2` A centrifugal force actuated switch, comprising a sleeve to be pressed on to the armature shaft of a motor to rotate therewith, an insulating sleeve rigidly mounted upon the sleeve, axially spaced slip rings rigidly mounted upon the insulating sleeve flush with the outer ends of the insulating sleeve and sleeve and forming an annular recess between their inner ends, an :annular insulating housing mounted upon the slip rings for rotation therewith and covering the annular recess, circularly curved conducting segments disposed Within the annular housing and adapted to move radially outwardly' when acted upon by centrifugal force, resilient means associated with the annular housing and engaging the conducting segments to counteract the effect of centrifugal force, brush holder rings slidably mounted upon the slip rings upon opposite sides of the annular housing, brushes mounted upon the brush holder rings to slidably engage the slip rings while the same rotate, and a U-shaped bracket mounted upon the brush holder rings to secure the rings together as a unit and to hold the rings against rotation while the armature shaft rotates.

3. A centrifugal force actuated switch, comprising axially disposed slip rings having their inner ends spaced, means to support the slip rings and to insulate the same, an annular insulating housing mounted upon the slip rings for rotation therewith and covering the inner spaced ends of the slips rings and providing an annular recess adjacent to the inner spaced ends of the rings, electrical conducting elements arranged within the annular recess and adapted to move radially therein when acted upon by centrifugal force, yielding means associated with the annular housing and engaging the conducting elements to op posethe effect of centrifugal force upon the conducting elementa'brushholders arranged out wardly of the annular housing and mounted upon the slipr` rings, brushes carried by the brush holders and engaging the slip rings, yielding means associated with the brush holders to move the brushes inwardly, and a bracket mounted upon the brush holders and spaced from the annular housing to secure the brush holders together as a relatively stationary unit.

4. A centrifugal force actuated switch, comprising axially disposed slip rings having their inner ends spaced apart, mea-ns to support the slip ringsI and to insulate the same, an annular insulating housing mounted upon the slip rings for rotation therewith and covering the inner spaced ends of the slip rings and providing an annular recess, an electrical conducting element arranged within the annular recess and adapted to move radially therein when acted upon by centrifugal force, yielding means associated with the annular housing and engaging the conducting element to oppose the eifect of centrifugal force, brush holders arranged axially outwardly of the annular housing and slidably mounted upon the slip rings, brushes carried by the brush holders and engaging the slip rings, springs arranged within the brush holders and engaging the brushes to move the same inwardly, a cylindrically curved bracket mounted upon the brush holders and spaced radially from the annular housing to secure the brush holders together as a unit, and means including a projection integral with the bracket for holding the unit stationary relative to the slip rings.

5. A centrifugal force actuated switch, comprising a rotatable insulating sleeve, axially spaced slip rings mounted upon the sleeve, an insulating housing having opening means to receive parts of the slip rings and rotatable theree withs parts of the slip rings being uncovered within the housing, a radially movable conducting element mounted within. insulating housing to co-act with the slip rings, resilient means to oppose the outward radial movement of the conducting element, brush hoider members hav ing openings for rotatably receiving the slip rings and disposed upon opposite sides of said housing, and brushes carried by the brush holder members to engage the slip rings.

6. A centrifugal force actuated switch, comprising a rotatable insulating sleeve, axially spaced slip rings mounted upon the sleeve, an insulating housing having opening means to receive parts of the slip rings and rotatable with the slip rings, parts of the slip rings being uncovered within the housing, a radially movable conducting element mounted within the insulating housing for coaction with the slip rings, resilient means to oppose the outward radial movement of the conducting element, brush holder members having openings for rotatably receiving the slip rings and disposed upon opposite sides of said housing, brushes carried by the bru-sh holder members to engage the slip rings, and means to prevent the outward axial movement of the brush holder members.

7. A centrifugal force actuated switch, comprising axially disposed slip rings having their inner ends spaced apart, means to support the slip rings and to insulate the same, an annular insulating housing mounted upon the slip rings for rotation therewith and covering the inner spaced ends of the slip rings and providing a recess, an electrical conducting element arranged within the recess and adapted to move radially therein when acted upon by centrifugal force, yielding means associated with the annular housing and engaging the conducting element to oppose the effect of centrifugal force, brush holders arranged axially outwardly of the annular housing and slidably mounted upon the slip rings, brushes carried by the brush holders and engaging the slip rings, springs arranged within the brush holders and engaging the brushes to 10 move them inwardly, and a bracket mounted upon the brush holders to secure them together as a unit.

WILLIS ZEB WESTLJR. MORGAN F. GAMBLE.

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

UNITED STATES PATENTS v Number Name Date 1,024,807 Y Ray Apr, 30, 1912 FOREIGN PATENTS Number Country y Date France Jan. l23, 1913

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