US2999139A - Centrifugal switch devices - Google Patents

Description

Sept. 5, 1961 LEE 2,999,139

CENTRIFUGAL SWITCH DEVICES Filed Feb. 6, 1958 3 Sheets-Sheet 1 FIG. 2

F1 G. 7 143 a 744- 132 5g lNSULAT/ON 7 IN V EN TOR.

ROYAL LEE NEY Sept. 5, 1961 R. LEE 2,999,139

' CENTRIFUGAL SWITCH DEVICES Filed Feb. 6, 1958 3 Sheets-Sheet 2 FIG. 11 FIG. 15 43 350 FIG. 12 a J43 .35] 345344377 552K /1Z6a GM 55$ 727 365 L- 26b as; 323{ l 565' E 336 g,

3Z4 7 326 524 525 .15 J50 a l! FIG. 367 9 I; .lll $366 240 517 568 364527 320 INVEN TOR.

BY ROYALLEE 427 mp 7 ATTORNEY R. LEE

CENTRIFUGAL SWITCH DEVICES Sept. 5, 1961 3 Sheets-Sheet 3 Filed Feb. 6, 1958 FIG. 21

FIG. 22

INVENTOR. ROYAL LEE ATTOR 2,999,139 CENTRIFUGAL SWITCH DEVICES Royal Lee, Elm Grove, Wis, assignor to Lee Engineering Company, Milwaukee, Wis., a corporation of Wiscousin Filed Feb. 6, 1958, Ser. No. 713,728 7 Claims. (Cl. 200-80) The present invention relates to speed-responsive apparatus and more particularly to centrifugal switch devices.

An object of the invention is to provide an improved centrifugal switch which can readily be constructed in relatively small sizes while still possessing satisfactory operating characteristics and aifording a substantial range of speed adjustment, the switch device being adapted to embody one or more switch sections and being especially suitable for use in miniature and other equipment where space is limited.

Another object is to provide a centrifugal switch device including compactly arranged loading or biasing spring means and improved means for mounting the same and adjusting the spring tension.

Still another object is to provide a centrifugal switch device having a rotary member on which any one of a number of interchangeable loading spring units or subassemblies, including spring units with different spring rates, can be expeditiously mounted to complete the device, thus facilitating manufacturing operations.

A further object is to provide a centrifugal switch device which is of simple, durable and inexpensive construction and which is reliable in operation.

The invention further consists in the several features hereinafter described and claimed.

In the accompanying drawings, illustrating certain embodiments of the invention,

FIG. 1 is an end View, on a greatly enlarged scale, of a centrifugal switch device constructed in accordance with the invention, parts being shown in section;

FIG. 2 is a sectional view taken generally on the line 22 of FIG. 1;

FIG. 3 is a sectional detail view taken generally on the line 3-3 of FIG. 1;

FIG. 4 is a perspective View of a contact-carrying loading spring;

FIG. 5 is a schematic wiring diagram of a motor speed controlling system in which the centrifugal switch device may be used;

FIG. 6 is an end view of a modified form of centrifugal switch device, parts being shown in section;

FIG. 7 is a side view of the switch device of FIG. 6, parts being shown in section on the line 7-7 of FIG. 6;

FIG. 8 is a schematic wiring diagram of a motor speed controlling circuit in which the centrifugal switch device of FIG. 6 may be used;

FIG. 9 is an end view of another modified form of centrifugal switch device adapted for use in various circuits, including motor starting and overspeed control circuits;

F155. 10 is a detail sectional view taken generally on the line Itl-10 of FIG. 9;

FIG. 11 is an end view of a further modified form of centrifugal switch device;

FIG. 12 is a sectional view taken generally on the line lib-12 of FIG. 11;

FIG. 13 is a detail sectional view taken generally on the line 1313 of FIG. 11;

FIG. 14 is a detail sectional view taken generally on the line 1414 of FIG. 11;

FIG. 15 is a perspective view of a contact-carrying spring unit;

nited States Patent 6 FIG. 16 is a perspective view of a contact-aligning tool for use in assembling the switch device of FIG. 11;

FIG. 17 is an end view of a still further modified form of centrifugal switch device;

FIG. 18 is a fragmentary end view of an additional modified form of centrifugal switch device;

FIG. 19 is an end view of still another modified form of centrifugal switch device;

FIG. 20 is a sectional view taken generally on the line 29-22% of FIG. 19;

FIG. 21 is a detail sectional view taken generally on the line 21-21 of FIG. 19;

FIG. 22 is a detail sectional view taken generally on the line 22-22 of FIG. 19, and

FIG. 23 is a detail sectional view taken generally on the line 2323 of FIG. 19.

Referring to FIGS. 1 to 5 of the drawings, 15 designates a rotatable shaft, such as the shaft of an electric motor 16, FIG. 5, the speed of which is to be controlled or regulated. Mounted on the shaft 15 is a rotatable member comprising a disk 17 of insulating material. The disk is rigidly secured to the shaft in any suitable manner and is here shown to be pressed onto a knurled portion of the shaft, which is satisfactory in the case of a small diameter shaft.

The disk 17 carries thereon one or more centrifugal switch sections or mechanisms 19, two switch sections being shown in the present instance. The switch sections each comprise a pair of cooperating circuit-controlling contacts 2t} and 21, the contact 20 being mounted on a metal post or bracket 22 secured to the disk, as hereinafter described, and the contact 21 being carried on a. centrifugally-iniiuenced loading or biasing spring member 23 hereinafter more fully described. The posts or brackets 22 are disposed near the periphery of the disk at diametrically opposite points and in parallel relation to the axis of the shaft, and each comprises a head 24 and a shank or stem 25 coaxial therewith, the head bearing against the front face of the disk, and the shank extending tightly through the disk. A clamping washer 26 surrounding the rear portion of the shank is secured against the rear face of the disk by an upset annular flange 27 on the shank, and the rear end of the shank forms a tubular wire terminal 28. The contact 20 is carried on the end of a screw 29 which is threaded transversely through the post head 24, the latter being split diametrically, as at right angles to the axis of the screw, to provide a pinching or looking action on the screw so as to retain the screw in adjusted position.

Each loading spring member 23 is in the form of a U-shaped or reversely bent leaf spring comprising inner and outer arms 33 and 31 connected by a semi-cylindrical bight 32 which is pivotally carried on a metal post or bracket 33, hereinafter described, secured to the disk. The spring arms extend in a generally tangential direction with respect to the disk, and the spring member is angularly displaceable in a plane normal to the axis of the disk. The movable contact 21 is secured to the free end portion of the inner spring arm 39 and is urged against the post-supported contact 2% under adjustable pressure by applying an inward flexing force on the outer spring arm 31, as hereinafter described.

The outer arm 31 of the U-shaped spring member 23 includes an outwardly bent or angular end portion 34 having therethrough a longitudinal slot 35. A post or bracket 36 is rigidly secured to the front face of the disk and carries a reaction member in the form of an adjusting screw 37 with a reduced inner end or tip 38 and an annular abutment shoulder 39 of conical or spherical shape at the base of the tip, the tip fitting in the spring slot 35 to resist lateral shifting of the spring, and the annular shoulder 39 bearing against the outer face of the spring 3 to tension or flex the spring. The post 36 includes a head 4%) and a shank or stem 41 coaxial therewith, the head bearing on the front face of the disk, and the shank extending tightly through the disk and riveted thereto at 42, FIG. 3; The post head 4% is split diametrically to provide a pinching and retaining action on the screw 37. Inward displacement or" the screw 37 turns the spring member about the post 33 and brings the spring-mounted contact 21 against the cooperating contact 29 under a selected pressure. The contact 21 forms a large part of the centrifugally-infiuenced mass of the spring arm 36.

Each post or bracket 33 is rigidly secured to the insulating disk 17 near the periphery thereof and extends parallel to the axis of the shaft. The post comprises a head 43 and a shank or stem 44 coaxial therewith, the head bearing on the front face of the disk, and the shank extending tightly through the disk. A clamping washer 45 surrounding the-rear portion of the shank 44 is secured against the rear face of the disk by an upset annular flange 46 on the shank, and the rear end of the shank forms a tubular wire terminal 47. The post head 43 is cut away, as with the aid of a hole saw, to form a central pintle 4S and a concentric semi-cylindrical flange 49 spaced therefrom to provide a concentric arcuate slot 50 with an end wall 51. The bight 32 of the U-shaped spring member 23. pivotally fits over the pintle 48 to turn thereon through a limited angle and is confined in the arcuate slot by the semicylindrical flange 49, which extends about the outer side of the bight. The pintle 43 has a reduced front end 52 carrying a washer 53 riveted thereto, thus axially confining the spring bight between the slot and wall 51 and the washer.

During rotation of the disk, the contact-carrying spring arm Bttis urged outwardly under the influence of centrifugal force, thus causing separation of the contact 21 from the contact 2% at a predetermined speed dependent on the tension of the spring. A metal stop pin 54 is rigidly carried by the disk to limit the outward displacement of the inner spring arm 30. in some instances the stop pin may form a switch element cooperating with the spring, as in cases where the switch is used in an overspeed control or indicating circuit, or when the switch is used in speed-regulating systems requiring closing of contacts upon increase of speed, as in motors including shunt field windings or brake windings. For this purpose the spring and stop pin carry respective cooperating contacts 55 and 56.

The centrifugal switch device of FIG. 1 may be used in various control systems, including motor speed regulating systems one known form of which is shown in PEG. 5. In this system the motor 16 is'of the series or universal type with a rotatable armature S7 and field windings 58, and is connected to supply conductors 59. The armature winding is opened at diametrically opposite points, and the two centrifugal switch sections 19 are interposed in the winding at these points to complete the armature circuit. Preferably, a contact-protecting capacitor 60 is shunted either across each set of switch contacts 2% and 21, as shown, or across the motor brushes. The centrifugal switch device is carried on the motor shaft and no slip rings are required, the switch terminals 28 and 47, FIG. 2, being directly connected to the armature winding. The two switch sections are adjusted to open at the same speed.

In the operation of the motor speed regulating system of FIG. 5, the motor on starting accelerates to the governed speed, whereupon the centrifugal switch contacts 20 and 21 separate and interrupt the armature current, thus preventing further increase in motor speed. A very slight deceleration or drop in motor speed then causes reclosing of the centrifugal switch contacts, and the cycle of operation is repeated. Each spring-mounted contact vibrates at a high frequency, say 50 to 500 cycles per second, thus insuring good speed regulation.

It is preferred to-rotatethe switch-carrying disk 17 in a counter-clockwise direction as viewed in FIG. 1, as this provides an anticipating effect which improves speedgoverning action. At the critical speed each sprin mounted contact 21, which is in trailing relation to the cooperating fixed contact 2%, will tend to leave the fixed contact upon a very slight momentary acceleration in motor speed, being subjected to bothradial and tangential inertia action.

The reversely bent loading spring member 23 for each switch section provides a relatively long effective spring length in a small compass, enabling the spring to be used on a rotor of relatively small diameter while providing a substantial range of speed adjustment. By way of example, the rotor may be inch in diameter for use in miniature and other equipment where space is limited.

The modified form of centrifugal switch device shown in FIGS. 6 to 8 includes an insulating disk 117 fast on a rotatable shaft 115, such as the shaft of an electric motor 116, FIG. 8, the speed of which is to be controlled. The disk carries thereon a pair of centrifugal switch sections 119, generally similar to the switch sections 19 of FIG. 1, and the rear face of the disk is provided with slip rings 126a, 126b, and 12:60 on which brushes 127 bear. An insulating sheet 117' underlies the slip rings. Each switch section comprises a pair of circuit-controlling contacts 26 and 21, the contact 20 being carried on the end of a screw 29 engaged in the split head 124 of a metal post or bracket 122 secured to the disk, and the contact 21 being carried on a centrifugally influenced loading or biasing spring member 123 which is pivotally mounted on a post or bracket 133 secured to the disk, as hereinafter described. The two posts 122, which are generally similar to the posts 22 of FIG. 1, have respective shanks riveted to washers 126 countersunk in the insulating disk 117 and are electrically connected to the respective slip rings 1126b and 125s by connector straps 124 and rivets 125". The pivot posts 133 are electrically connected to the outermost slip ring 126a, as hereinafter described. However, in cases where the slip rings are omitted the posts 122 and 133 will have wire terminals as in FIG. 2.

Each loading spring member 123 comprises a shaped or reversely bent leaf spring having inner and outer arms 13% and 131 connected by a semi-cylindrical night 132 which is pivotally carried on the post or bracket 133, as hereinafter described. The spring member 123 is generally similar to the spring member 23 of FIG. 1 except that the inner arm 139 has riveted thereto at 165 an extension-forming radiator plate 164, such as of an aluminum alloy, which carries the contact 21 and provides for heat dissipation. The outer arm T31 of the spring member includes an angular end portion 134 with an opening 135- A headed screw 137 passes through the opening 135 and a registering opening 135 in the radiator plate and is threaded through the split clamping head T42 of an anchor post or bracket 135 riveted to the disk, the anchor post having a riveted shank 14f and being generally similar to the contact-carrying post 122. The screw 137 has a transversely slotted square head with a conically or spherically shaped shoulder T39 engaging the outer arm of the leaf spring, the sliding fit of the screw in the spring arm opening 135 resisting lateral shifting of the spring. Inward dis placement of the screw 137 turns the spring member about the pivot-forming post 133 and brings the centrifugally influenced spring-mounted contact 21 against the cooperating contact 2% under a selected pressure. A metal stop pin 154 is rigidly carried by the disk to limit the outward displacement of the plate-carrying spring member under centrifugal force.

Each pivot post or bracket 133 comprises a cylindrical shank or stem 144 and a surrounding pintle-forming sleeve or bushing148, the shank having a tight fit in the disk and a riveted connection with the outermost slip ring 126a,. and: the sleeve having an annular base flange 151 bearing against the front face of the disk. At its :3 front end the shank 144 has an integrally formed head or cross bar 152 provided with a rearwardly projecting lug 14 9 extending parallel to the shank, a slot 150 being formed between the lug and the sleeve. It is preferred to stamp the headed shank from metal plate stock, the rounded portions of the shank being coined to shape. A washer 153 surrounds the shank and is interposed be tween the shank head and the front end of the sleeve 148. The semi-cylindrical bight 132 of the U-shaped leaf spring pivotally fits over the pintle-forming sleeve 148 to turn thereon through a limited angle. The spring bight 132 is axially confined between the sleeve base flange 151i and the washer 153, and is radially confined by the head lug 149 at the outer side of the bight.

By way of example, the centrifugal switch of FIGS. 6 and 7 is shown to be used in the motor speed regulating system of FIG. 8, which is generally similar to the system disclosed in my United States Patent No. 1,630,394 for Speed Governors for Electric Motors, issued May 31, 1927. In this system the motor 116 is of a variablespeed series or universal type with an armature 157 and field windings 153 and is connected to supply conductors 153. The two switch sections, which in this case are set to operate at different selected speeds, are connected in series in the motor load circuit through a selector switch 162. The switch sections are shunted by a protective capacitor 160 or protective resistor 161, or both.

The operation of the centrifugal switch device of FIGS. 6 to 9 is generally similar to that of FIGS. 1 to 5, the spring-mounted contact of the selected switch section vibrating at the governed speed. During motor operation under the control of the high-speed switch section, the outward displacement of the movable contact of the other switch section will be limited by the associated stop pin 154. Each slip ring may be either continuous or split into semi-circular segments, as is well understood in this art.

The modified form of centrifugal switch device shown in FIGS. 9 and 10 includes an insulating disk 217 fast on a rotatable shaft 2-15, as in FIG. 1. A single switch section 215 is carried on the disk at one side of the axis thereof, and a vaned counterweight 236 is secured to the disk at the other side of the axis. The disk carries a contact-mounting post 22 and a spring-mounting post 33, like those of PEG. 1, and a spring-adjusting post 236 generally similar to the post 22. The disk also carries a stop-forming and contact-carrying post 54 like that of FIG. 1. A U-shaped or reversely bent leaf spring 223 has inner and outer arms 23!? and 31 and a b ight 32, the spring being pivotally mounted on the post 33, as in FIG. 1. The outer spring arm 31 includes an apertured angular terminal portion 34 engaged by an adjustable abutment screw 37 threaded in the post 236, the latter being split, as in the axial plane of the screw, to provide a pinching action on the screw. The spring 223 is similar to the spring 23 of FIG. 1 except that the inner leg 23% of the spring is troughed or otherwise shaped to provide a snap action, the main switch contacts 29 and 21 opening at one speed but closing at a somewhat higher speed. To facilitate the snap action, a pin 257 is mounted on the disk near the post 33 and between the spring arms, the pin being engageable with the centrifugally deflected spring arm 231).

The centrifugal switch device of FIG. 9 may be used in various circuits, such as for motor starting, overspeed protection, and speed indication.

In some instances, the centrifugal switch device of FIG. 9 may include a second switch section, as in FIG. 1, in place of the counterweight 236. The additional switch section may be a duplicate of the switch section 219, or it may be of different construction, such as the switch section 19 of FIG. 1.

The modified form of centrifugal switch device shown in FIGS. 11 to includes an insulating disk 317 fast on a rotatable shaft 115, such as the shaft of the electric motor 116 of FIG. 8, the shaft having a knurled portion 18 as in FIG. 2. The disk carries thereon at its front face a plurality of centrifugal switch sections or mechanisms 319, hereinafter described, two switch sections being shown. As in the device of FIG. 7, the rear face of the disk is provided with slip rings 126a, 126b, and 1260 on which brushes 127 bear. An insulating sheet 117, such as of fibre, underlies the slip rings.

Each switch section 319 comprises a pair of cooperating circuit-controlling contacts 320 and 321, the contact 324 being mounted on a metal post or bracket 322 rigidly secured to the front face of the disk near the periphery of the disk, and the contact 321 being carried on a centrifugally-infiuenced loading or biasing spring member or unit 323 which is fulcrurned 0r swingably mounted on the disk, as hereinafter described. The contact 32% is here shown to be carried on an end of a stem 329 which passes through a cut-away head portion 324 of the post 322, the other end of the stem being tubular and riveted to the post head, as best seen in FIG. 14. The post 322 includes a shank 325 which is riveted to a washer 326 countersunk in the rear face of the disk.

Each loading spring unit includes a U-shaped or reversely bent leaf spring having inner and outer arms 330 and 331 connected by a semi-cylindrical bight 332, and further includes a hing -forming leaf spring 363 which is fastened to the spring arm 330 in parallel relation thereto and has an end portion secured to a disk-carried pivot post or bracket 333, as hereinafter described. The inner spring arm 330 has riveted thereto an extensionforming radiator plate 364, such as of an aluminum alloy, which carries the contact 321 and provides for heat dissipation. Preferably, the anchored end portion of the radiator plate is interposed between the spring arm 330 and the hinge-forming leaf spring 363 and is riveted at 365 to both of these spring parts. The spring parts 330, 331, and 363 and the contact-carrying radiator plate 364 form a unit or subassembly, as shown in EEG. 15, which is mounted on the disk as hereinafter described.

The pivot post or bracket 333 is rigidly secured to the insulating dis 317 near the periphery thereof and extends parallel to the axis of the shaft. The post comprises a cylindrical head 343 and a shank or stem 344 coaxial therewith, the head bearing on the front face of the disk, and the shank extending tightly through the disk. The shank is here shown to be riveted to the outermost slip ring 12611, and the head has a band of knuriing 345, FIG. 12, around its base portion, forming teeth which bite into the insulating disk. The outer end of the head 343 is provided with a narrow diame'trically extending slot 356 which extends therethrough in an axial plane and has a straight inner end wall 351. The slot 350 intersects a solder well 352 centrally formed in the outer end face of the head. The slot 350 snugly receives the anchored end of the hinge-forming leaf spring 363. In assembling the switch, the end of hinge-forming leaf spring 363 is inserted in the slot 356 and bottomed against the inner end wall 351 of the slot, and is then firmly secured in the slot by a fusible metal or solder connection 353 extending in the solder well 352.

The spring arm 330 and the hinge spring 363 extend in a generally tangential direction with respect to the disk, and these spring parts are angularly displaceable in a plane normal to the axis of the disk. The movable contact 321 on the radiator plate 364 is urged against the post-supported contact 321 under adjustable spring pressure by applying an inward flexing force on the outer spring arm 331, as hereinafter described.

The outer arm 331 of the U-shaped spring member includes a bent or inwardly offset end portion 334. A post or bracket 336 is rigidly secured to the front face of the disk at the outer side of the outer spring arm 331 and carries a reaction member in the form of an adjusting screw 337 which is threaded transversely through the post head 342 and bears on the spring end portion 334.

The post head 342 is split diametrically, as at right angles to the axis of the screw, to provide a pinching or locking action on the screw 337 for retaining the screw in adjusted position; Inward displacement of the screw 337 turns the spring assembly about its spring hinge under a selected pressure. The disk carries a stop pin 354 to limit the maximum centrifugally-influenced displacement of the radiator plate. The contact 321 and radiator plate 364 form a large part of the centrifugally-influenced mass of the loading spring unit.

During attachment of the movable contact subassembly 323 to the post 34-3 to cooperating contacts 321 and 321 are suitably aligned as by a jig or tool 366 one form of which is shown in FIG. 16. The tool comprises a spring fork 367 carried on a handle 363, the arms of the fork having outwardly divergent free ends 369 and confronting cylindrically curved jaw portions 37G to engage and align the contacts. While the contacts are held in alignment by the tool the hinge spring ass is soldered in the slotted post 333, the soldered connection 353 extending into the solder well 352 of the post and providing a good electrical joint between the spring and the post. The screw 337 is then adjusted to obtain the desired speed setting of the centrifugal switch, and may be adjusted at intervals to accommodate wear on the contacts or to provide different speed settings. The con tacts seat against each other, and the adjustment of the switch does not disturb the seating fit. The attachment of the loading spring unit to the disk completes the assembly of the switch.

The centrifugal switch device of FIG. 11 may be used in various control systems, including the motor-speed regulating system shown in FIG. 8, hereinbefore described. When the switch device is used in a speed regulating system, the switch contacts vibrate at a predetermined speed of rotation of the rotary member.

In the event that the contact-carrying loading spring unit or subassembly requires replacement, it is only necessary to unsolder the spring hinge connection and substitute a new spring unit. The fixed contact 320 on the disk can also be easily replaced, the riveted head of the shank 329 being filed off or pinched off. Various interchangeable contact-carrying spring units 323, including units with difierent spring rates, can readily be kept in stock, thus facilitating manufacture.

The further modified form of centrifugal switch device shown in FIG. 17 includes an insulating disk 4-17 fast on a rotatable shaft 415, as in FIG. 11. A single switch section 419 is carried on the disk at one side of the axis thereof, and a vaned counterweight 236 is secured to the disk at the other side of the axis, as in FIG. 9. The switch section comprises a pair of cooperating contacts 42d and 421 which are arranged to close on increase of speed, as for use on an overspeed control or indicating circuit, or when the switch is used in speed-regulating systems such as motors including shunt field windings or brake windings. The disk carries at its front face a loading spring unit 423 similar to that of FIG. 11 except that it includes a radiator plate 464 carrying the contact 421 at its outer side. The cooperating contact 429 is carried on a post 422 similar to the post 322 of FIG. 11. The loading spring unit includes a reversely bent leaf spring 339 331 and a hinge leaf spring 363, as in FIG. 11, the latter spring being secured to a slotted anchor post 333, asin FIG. 11. The switch device further includes a post 335 with a reaction screw 337 bearing on an offset end portion 334 of the spring arm 331, as in FIG. 11. The disk carries a post 466 with a slotted head 467 carrying a stop screw 368 bearing against the inner side of the contact 421 to limit the inward deflection of the radiator plate by the reaction screw 337. The stop post 466 is similar to the post 336. The contact post 422 is connected to one of the slip rings by a riveted connection including a connector strap 324, and rivet 325, as in FIG. 11.

When the switch device of FIG. '17 is at rest the con tacts 420 and 421 are open, as'seen in this view. At a certain speed of rotation, determined by the adjustment of the reaction screw 337, the contacts will close. When the device is used in a speed regulating system, the movable contact 421 will vibrate at the governed speed to open and close the switch.

The contact-carrying loading spring unit 423 is readily mounted on the disk 417 in the same manner as the unit 323 of FIG. ll. Loading spring units with various spring rates may be provided, as in thedevice of FIG. 11.

The centrifugal switch device shown in FIG. 18 is similar to the device of FIG. 11 except for the provision of a modified form of loading spring unit 523 for each switch section 513, the latter including cooperating switch contacts 320 and 321, as in FIG. 11. Each loading spring unit includes a U-shaped or reversely bent leaf spring having inner and outer arms 530 and 531 connected by an arcuate bight 532 which extends about the slotted post head 3-43 in spaced relation to this head. The loading spring unit 523 further includes a hinge-forming leaf spring 363 which is fastened at one end to the spring arm 530, as by rivets 365, and is secured at its other end to the slotted post head 343, as in the device of FIG. 11. An extension-forming radiator plate 364 is secured to the hinge spring, as in the device of FIG. 11, the radiator plate carrying the contact 321 near its free end. The outer arm 531 of the U-shaped spring member includes an angular end portion 534 against which a reaction screw 337 bears, the screw being adjustably mounted in a headed post 336, as in FIG. 11. The remaining structure of the device of FIG. 18 is like that of FIG. 11.

The centrifugal switch device of FIG. 18 can be used in various control systems, including the motor speed regulating system of FIG. 8.

The modified form of centrifugal switch device shown in FIGS. 19 to 23 includes a shaft-mounted insulating disk 3-17 provided with slip rings, as in FIGS. 11 and 12, and carrying a pair of centrifugal switch sections 619, hereinafter described, disposed at opposite sides of the shaft axis. Each switch section 619 comprises a pair of cooperating circuit-controlling contacts 320 and 321, as in FIGS. 11 and 18, the contact 320 being mounted on a metal post or bracket 322 rigidly secured to the front face of the disk, and the contact 321 being carried on a centrifugally influenced loading or biasing spring unit 623 which is fulcrumed or swingably mounted on the disk, as hereinafter described. Each loading spring unit includes a hinge-forming leaf spring 363 and attached contact-carrying radiator plate 364, as in FIGS. 11 and 18. The hinge-forming leaf spring 363 is secured to the radiator plate 364 by rivets or studs 365 and 665 the latter having a head 666 with a peripheral groove 667, FIG. 23, for a purpose hereinafter described. The leaf spring 363 is secured to a post or bracket 633 generally similar to the post 333 of FIGS. 11 and 18. The post 633 comprises a cylindrical head 643 and a shank or stem 344 coaxial therewith, the head bearing on the front face of the disk, and the shank extending tightly through the disk and being riveted to the outermost slip ring 126a. The post head has a band of knurling 34-5 around its base portion, as in the device of FIG. 12. The outer end of the post head is provided with a diametrically extending slot 65f? with a straight inner end wall 651, and is further provided with a solder well 352, as in the device of FIG. 11. The anchored end of the leaf spring 363 is secured in the slot by a fusible metal or solder connection 353, as in FIG. 11. In addition, the post head 643 is preferably provided with a shallow peripheral groove 648 of cylindrical shape.

Each loading spring unit further includes a U-shaped or reversely bent biasing leaf spring having inner and outer arms 63C and 631 connected by an arcuate bight 632 which extends about the post head 643 in bearing relation thereto and fitsin the peripheral groove 6 18.

The inner spring arm 630 has a keyhole slot 649 which detachably receives therethrough the stud head 666, the edges of the reduced end of the slot engaging in the stud head groove 667 behind the outer portion of the stud head. The outer spring arm 631 includes an end portion "634 having formed therethrough a longitudinal slot or aperture 635. In some instances the spring end portion 624 may be bent, as in the devices of FIGS. ll and 18.

A post or bracket 336 is rigidly secured to the front face of the disk, as in FIG. 11, and carries a reaction member in the form of an adjusting screw 637 with a reduced inner end or tip 638 and an annular abutment shoulder 639 of conical or spherical shape at the base of the tip, the tip fitting in the springopening 635 to resist lateral shifting of the spring, and the annular shoulder 639 bearing against the outer face of the spring to tension or flex the spring. The movable contact 321 secured to the radiator plate is thus urged against the post-supported contact 326 under adjustable pressure.

The arms of the 'U-shaped leaf spring member 636, 631 are here shown to have a concavo-convex or troughed cross-section so as to provide an approximately constant spring rate. In its free condition the leaf spring member 639, 631 is substantially straight. In mounting this leaf spring member the slotted end of the arm portion 63b is hooked onto the peripherally grooved rivet head 666. The spring member is then bent around the peripherally grooved anchor post 633, and the apertured or slotted end of the outer spring arm 631 is engaged over the reaction screw tip 638. The spring arms 630 and 63-1 retain their troughed cross-section, but the bight portion 632 assumes a generally semi-cylindrical shape and rockably fits in the peripheral groove 648 of the anchor post, the spring bight being laterally confined by the side walls of the groove. In some instances the U-shaped biasing spring member may be formed of fiat spring stock, as in FIGS. 4 and 18, in which event the spring member is U- shaped or V-shaped in its free condition.

Various interchangeable biasing springs of different thickness, material or shape may be provided to complete switch assemblies requiring different operating characteristics. Since such switch assemblies can be identical except for the readily mounted biasing springs, manufacturing operations are facilitated. The centrifugally deflected contact-carrying arms of the switch assemblies are also readily replaceable.

I claim:

1. In a speed-responsive device, a rotatable member, centrifugal means carried by said member including a centrifugally displaceable swingable arm, a stud rigidly secured to and projecting from said arm in the plane of swinging displacement of said arm and from a region of said arm between the opposite sides of said arm, said stud having an outer shoulder-forming head portion, biasing spring means including a resilient arm having an end portion with a keyhole slot releasably interengaged with said stud on said swingable arm to exert a biasing force on said swingable arm opposing centrifugal displacement of said swingable arm, said keyhole slot having an enlarged portion for admitting therethrough said stud head portion and a reduced portion normally engaged behind said stud head portion, and switch means responsive to centrifugal displacement of said swingable arm, said arms being movable in a plane normal to the axis of rotation of said rotatable member.

2. In a speed-responsive device, a rotatable member, centrifugal means carried by said member including a centrifugally displaceable swingable arm, biasing spring means including a resilient arm connected to said swing able arm to exert a biasing force on said swingable arm opposing centrifugal displacement of said swingable arm, said biasing spring means including a deflectahle portion adjacent to the outer side of said swingable arm, said arms extending from a connecting portion joining said arms, means for pivotally supporting said swingable arm on said rotatable member adjacent to said connecting portion, reaction means carried on said rotatable member engaging said deflectable portion of said biasing arm means, and switch means responsive to centrifugal displacement of said swingable arm, said swingable arm, biasing spring means, pivotal supporting means, reaction means and switch means being all disposed at one side of a diameter of said rotatable member.

3. in a speed-responsive device, a rotatable member, centrifugal means carried by said member including a centrifugally displaceable swingable arm, biasing spring means including a resilient arm connected to said swingable arm to exert a biasing force on said swingable arm opposing centrifugal displacement of said swingable arm, said arms extending from a connecting portion joining said arms, means for pivotally supporting said swingable arm on said rotatable member adjacent to said connecting portion, said biasing arm having an aperture therein, a reaction member carried by said rotatable member engaging said biasing arm and having a portion extending in said aperture, and switch means responsive to centrifugal displacement of said swingable arm, said swingable arm, biasing spring means, pivotal supporting means, reaction member and switch means being all disposed at one side of a diameter of said rotatable member.

In a speed-responsive device, a rotatable member, centrifugal means carried by said member including a centrifugally displaceable swingable arm having a spring hinge connection with said member, biasing spring means connected to said swingable arm comprising a reversely bent leaf spring member one end portion of which is secured to said swingable arm, reaction means carried on said rotatable member engaging the other end portion of said leaf spring member to exert a biasing force on said swingable arm opposing centrifugal displacement of said swingable arm, and switch means responsive to centrifugal displacement of said swingable arm, said swingable arm, biasing spring means, reaction means and switch means being all disposed at one side of a diameter of said rotatable member.

5. In a speed responsive device, a rotatable member having a projection with a slot therein and a well-forming recess in the outer end thereof communicating with said slot, a centrifugally displaceable swingable arm having a resilient hinge-forming leaf spring portion secured in said slot by a fusible metal connection extending into said recess and slot, biasing spring means connected to said swingable arm for opposing centrifugal displacement of said swingable arm, and switch means responsive to centrifugal displacement of said swingable arm.

6. In a speed-responsive device, a rotatable member having a projection, a centrifugally displaceable swingable arm secured at one end to said projection and swingable about an axis substantially parallel to the axis of said rotatable member, a reversely bent biasing leaf spring member forming a pair of defiectable arms and a bight portion connecting said arms, said bight portion extending about said projection, and said biasing spring arms extending on opposite sides of said swingable arm, one of said biasing spring arms having an end portion connected to said swingable arm, said leaf spring member having a troughed cross-section over a substantial portion of its length, reaction means on said rotatable member engaging the other of said biasing spring arms to exert a biasing force on the first of said biasing spring arms opposing centrifugal displacement of said swingable arm, and switch means responsive to centrifugal displacement of said swingable arm.

7. In a speed-responsive device, a rotatable memher having a projection, a centrifugally displaceable swingable arm secured at one end to said projection and swingable about an axis substantially parallel to the axis of said rotatable member, a reversely bent biasing leaf spring member forming a pair of defiectable arms and a bight portion connecting said arms, said bight'portion bearing on said projection, and said biasing spring arms extending on opposite sides of said swingable arm, one 5 of said "biasing spring arms having an end portion connected to said swingable arm, reaction means on said rotatable member engaging the other of said biasing spring arms to exert a biasing force on the first of said biasing spring arms opposing centrifugal displacement 10 of said swinga-ble arm, and switch means responsive to centrifugal displacement of said swingable arm.

References Cited in the file of this patent UNITED STATES PATENTS Cloud Apr. 26, Groot June 22, Thunberg et al. June 19, Anderson Nov. 11, Spang Apr. 14, Vasold Mar. 23,

FOREIGN PATENTS Germany Sept. 12, Germany Mar. 25,

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