US2182977A - Centrifugal switch - Google Patents

Description

Dec. 12, 1939. v Q E E I 2,182,977

CENTRIFUGAL SWITCH Filed Oct. 23, 1936 2 Sheets-Sheet 2 INVENTOR .Ca/vzzz J. Warn E7:

' BY 12g, 7 I M fwffav 1,42 ATTORNEYS Patented Dec. 12, 1939 UNITED STATES' PATENT OFFICE 2,182,977 I CENTBIFUGAL SWITCH Calvin J. Werner, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich, aoorv poration of Delaware Application mm as,

18 Claimsating positions and for operating in a way such as to allow the switch to move quickly to another position when the speed of the shaft reaches a predetermined value. meansalso operates reversely to quickly return the switch to its normal position when the speed of the shaft is decreased to a certain value. This quick movement is generally known as snap ac-. tion. This snap action of the switch is accomplished by a speed responsive device includin a rod extending radially from the shaft, a weight slidable on the rod' and a weight controlling spring that is so designed that its rate of buildup is less than the rate of build-up of the force of the weight due to centrifugal action. By this arrangement the weight is moved from a lesser to a greater radius with a quick action when the shafthasreachedacertainspeed;andthe weight will move from the greater to the lesser V radius when the speed of-the shaft is decreased to a certain value.

Further objects and advantages of the present invention will be apparent-from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly ShOWD. j

In the drawings:

Fig. 1 is a fragmentary longitudinal sectional view of ,the electric motor segment with a centrifugal switch embodying the present inven tion.

mgzisasectionalviewtakenontheline2- -2 of Fig. 1. Fig. 3 is a fragmentary sectional view similar to Fig. l showing the switch in itsoperative position.

4 is a sectional view taken of Fig. 3.

Fig. 5 h a fragmentary longitudinal sectional on the line 4-4 A view of a motor showing a modified form of a centrifugal switch.

The speed responsive 193s, SerialNo. 101.121

(01. zoo-so) V Fig. 6 is a view'similar to Fig. 5 showing the switch in its operative position.

Figs. '7 and 8 are sectional views taken on the lines 1-! and 8-8 of Figs. 5 and 6 respectively.

Fig. 9 is a diagram illustrating the action of 5 the speed responsive means.

Referring to the drawings, a field frame 20 carries a stator frame '2! which in turn carries stator windings 22 and 23. The frame 20 supports end members 24 which provide suitable 1o bearings, not shown, foran armature shaft 25 which supports a rotor 25.

The shaft 25 is provided with a transverse opening 21 through its axis to provide a bearing surface for a rod 28 of a centrifugal device 29. 15

This centrifugal device comprises the rod 28 which is free to slide through the opening 21, a laminated weight SI and a cam or washer 32 -of hard felt'or similar fibrous material; The

weight and thecam are supported on the rod 28 between ahead provided bythe'rod and one side of the shaft 25. .On the other side of the shaft), spring 33'surrounds the rod 28, one end of the spring bearing against the shaft 25 and the other end bearing against an adjustable nut' 5 34 to restrain the centrifugal action of the weight until a certain predetermined speed of the shaft 25 has been reached. The spring 33 normally urges the weight'members 3| toward the motor shaft as shown in Fig. 1. When the shaft is rotating above a predetermined speed, the weight 3| and the cam 32 are moved radially outward against the tension of the spring 33, as shown made of suitable insulating material. The plate 40 also supports a pair of stationary terminals 39 and 40. Cooperating movable contacts ll and 42 adapted to engage the stationary contacts 39 and respectively, which are supported on a plate or lever'member 43. The member is pro,- 45 vided with spaced openings on its vertical dimension and is supported on the insulating bushings 21a and 38a. The openings are of greater-dimensions than the bushings'so as to provide a loose connection between the lever and the bushings. 3 x

The lower end 44 of the plate 43 is of dish form providing a conical portion 45 and a.fla t portion 45. The flat portion is provided with an opening 41 which is of greater dimension than u the line a3'ba.

movlhg radially therewith.

lever while thecontacts are in engagement.

When the motor is at rest, the spring 33 urges the weight and the cam 32 toward the shaft 25, see Fig. 1. In this position the cam 32 will engage the flat portion 46 to urge the dish portion of the actuating plate 43 toward the endmember '24 and hold the contact 42 of the switch 35 in good electrical engagement with the contact terminal 40. When the motor shaft 23 is rotated and reaches a" certain speed the force of the weight 3|, due to centrifugal action, is equal to or slightly greater than the resisting effort of the spring 33. This creates an unstable condition, therefore the weight 3i will move outwardly to a greater radius and cause the switch to operate with a snap action to open the starting circuit. This is accomplished due to the fact that the spring 33 is so designed that its rate of build up is less than the rate oi build up of the force of the weight 3!! due to centrhiugal action. Tish causes the weight to move to a. greater radius with a quick action. A act weight takes place when the spee of decreases to cause the switch to be o close the starting circuit a action. The action of the weight 36 w et the spring 33 can he understood to the diagram shown in horizontal base line represents R2, R3 and R4 oi weight 32, i e redo the distance from the center o the center of the mass or tile the weight 35 when the shaf fl-l-bl, rte-ha and ice-ha represent, the law of action of the weight at v namely, 1100 R. "P. 3. 1., lZ-Eil P. R. l. M, respectively. the 351 is to start move outwardly from the shaft 25 at 1300 R. P. ill, the spring 33 so constructed that its law of action will conform to the line 413-221 which has a slope less than In other words, the spring 33 is so designed that its rate oi build-up is less than the rate of build-up oi the force of the weight 3i due to centrifugal action. it will be observed by comparing the slopes of lines (ls-b1 and Irabs that, once the weight starts to move away from the shaft, it will move quickly to its outer position designated by the vertical line from point R4. Having-once moved to the radius R4 the weight 3| willremain at that radius until the shaft speed is reduced to slightly below 1100 R. P; M. whereupon the spring 33 becomes efiective quickly to niove the weight 3! toward the shaft 25 so that its radius returns to the "value Ra To summarize, the weight 3| moves rapidly from radius R1 to radius Rcwhen the shaft speed has increased to 1300 R. P. M; and the weight 3| will move from radius R4. to radius R1 quickly when the shaft speed has decreased to 1100 R; P. M. This operation of the weight II is used to efiect rapid movements of a switch actuating plate or contact carrier 43 between its two extreme positions oi operation. In this way switch contacts controlled by the plate 43 are caused to be engaged or separated quickly by a movement which is generally called a snap shown in Fig.3.. when the weight 3| and the cam 32 are in this position, the spring 48 moves the end of the lever member adjacent the spring 43 toward themember 24 using the contacts 44 and 42 as a pivot for the plate until the contact 4| engages the contact 33, then the pivot for the plate is shifted to the contacts 4| and 39 which causes the contact 42 to break quickly from the contact 43 to open the starting circuit of the motor. By this arrangement, the contacts not only break quickly, but the contact points are kept clean and free of surface deposits that result from arcing at the contact points.

Referring to Figs. 5 to 8 inclusive, the modification of the centrifugal device and of the switch structure are shown. The centrifugal device mounted on the shaft 25 comprises a rod 50 having a knurled portion 50. In this instance, the knurled portion is forced into the transverse opening it provided by the shaft 35 to firmly hold the rod to theshait. A fan 52 is secured on one side of the shaft by the rod in order to maintain a circulation oi air within the motor frame. The fan comprises two arms Si l and an intermediate arcuate portion 55 complementary to the circumference of the shaft 25. The arouatc portion is provided with an opening through which a poition oi hnurl on rod protrudes 35 riveted over, at 513, to firmly hold the fan on (in the other side of the shaft, the red 56 is smooth and extends radially from shat-t slidably supports a weight having an flange 6i upon which rests a member 62 made of hard felt or similar fibrous materiel. The provided with an is egral ilazoge 53, said forming a stop for cup= red having an annular flange 65 to terpcsed between the'inner side of the seat and cam (32 normally hold the weight and cam mom or toward the 25. or cork washers it are supported on red, one being disposed between the cup-shaped member W and the weight and another washer being disposed between the weight and the shaft. .The. washers serve to prevent noise which might occur if the weight was to engage metal parts while the shaft is rotating. s 4

The switch construction shown in Figs. 5 to 8 inclusive, is similar to that previously described with the exception that the plate 36a supports only one set of stationary terminals, namely, 43a. The actuating plate or lever 43a supports a set of movable contacts 42a and is provided with a set of spherical shaped bosses 10 which provide a pivot for the lever during the separation of thecontacts.

' Now referring to Figs. 5 to 8 and when' the motor is at rest the spring 66 holds the weight I and the cam member 62 adjacent the shaft 25, see Fig. 5. While the centrifugal device is in this position the cam 62 engages the flat portion 43 to urge the dish shaped portion of the In a seat for a coil spring "55 ire is equal to or slightly greater than the resisting effort of the spring 6' and allows the weight to move outwardly to a greater radius with a-quick action and causes the switch to be opera-ted with a quick action. This quick action of the switch is accomplished in the following manner: As 'the cam 62 moves outwardly with the weight it to a greater radius, the spring will move the end of the lever member a adjacent the spring toward the insulating plate "a. when this happens the contacts a and 42a act as a pivot for the plate a until the bosses ll engage the plate 38a. When this occurs the pivot for the lever a is shifted from the contacts to the bosses II and the adjacent surface of plate 36a and causes the contacts a and 42a of the switch to be separated quickly by a movement which is generally called a snap action.

It is obvious that the constructions of the switches disclosed and the meansby which the switches are operated are such as-to provide an efiicient contact engagement in either position of the switch shown .in Figs. 1 to 4 while that construction shown in Figs. 5 to 8 the contacts must be well closed or fully opened, and that the centrifugal devices for actuating the movable switch member will operate to produce a rapid breakin of the contacts, thus reducing to a minimum the tendency to are when the contacts are separated. I

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A centrifugal switch comprising in comhination; a stationary frame; fixed and movable contacts carried by the frame; a rotary shaft 'journaled in the frame; a speed responsive device radially supported-from the shaft for normally holding the movable contact in one of its operating positions, said device including a rod extending through the shaft, a weight carried by the rod and spring balanced so as to .be speed responsive; and means carried by the weight for ,controlling the movable contact.

2. A centrifugal switch comprising in combination; a stationary frame; fixed and movable contacts carried by the frame; a rotary shaft v iournaledhn the frame; a speed responsive tie-- i nation; a shaft; a frame-.member providing a bearing for the shaft; a stationary contact insu- .latingly supported on the frame member; a movablecontact pivotally supported from the frame member; spring means tending to urge the movable contact away from the stationary contact; speed responsive means radially supported on "the shaft; means associated with speed responsive means for normally holding the movable contact in engagement with the stationary contact and adapted to 'move radially outwardly after a certain predetermined speed permitting the spring 15 to separate the contacts.

4. A centrifugal switch comprising in combination; a stationary frame; fixed and movable contacts carried by the frame; a rotary shaft journaled in the frame; a speed responsive device supported on the shaft to normally hold the movable contact in engagement withthe fixed contact, said device including a rod fixed to the shaft and having one end thereof extending radially from the shaft; a weight slidable on the rod; a spring for restraining the weight against centrifugal force up to a predetermined value;

and means carried by the weight for controlling a the movable contact.

5. A centrifugal -switch comprising in combination; a stationary support; a rotary shaft journalled in the support;'a fixed terminal carried by the support; a plate loosely carrledby the support; a contact carried by the plate; a spring acting upon the plate and tending to urge the contact out of engagement with the terminal; a speed responsive device radially supported on the shaft -to-normallyhold the movable contact in.

' engagement with the terminal, said device including a weight adapted to move radially from the shaft; resilient means for restraining the movement of the weight against centrifugal force up to a predetermined value; and means carried by the weight and engaging the plate to normally hold the contact carried thereby in engagement with the terminal and to place the spring under compression and permitting the spring to actuate the plate to separate the contact from the terminal when the weight has moved radially a.

predetermined distance.

6. A centrifugal switch comprising in combination; a rotary shaft; a support; a fixed terminal insulatingly supported on the support; a movable plate pivotally supported on the support, said plate carrying with a contact, a spring tending to move the plate andthe contact from the terminal; speed responsive means carried by the shaft to control the movable contact, said means including aslidable weight adapted to move radially with respect to the shaft; a disc carried by the weight; and resilient means normally urging the weight toward the shaft and the disc against the plate whereby the contact is normally held in engagement with the terminal, and said disc permitting the spring to move the plate to separate the contactfrom the terminal when the weight has moved outwardly a certain distance in opposition to the resilient means by centrifugal force.

'7. A centrifugal switch comprising in'combi-' duced by rotation of the shaft to permit the con-. tact carried by the movable member to form a pivot therefor until' theboss engages the support whereby the 'pivot for the movable member is shifted to cause the contacts to break quickly. v 8. In a device of the character described, the combination comprising, a support; spaced terminals carried by the support; a lever loosely mounted on the support and carrying spaced contacts adapted to engage the terminals, the

contacts being arranged on the lever that one or the other acts as a pivot for the'lever depending 7 upon the position of the lever; a. rotary shaft; speed responsive device supported from the shaft for normally holding one of the contacts in engagement with a terminal controlling the lever; and spring means for shifting" the lever to change the pivotal point of the lever in accordance with the speed of the shaft. r

9. A centrifugal switch comprising in combination; a support; spaced stationary terminals mounted on the support; a lever loosely mounted on the support and carrying contacts adapted to engage the terminals, the contacts being spaced that one or the other engages a terminal to form a pivot for the lever depending on the positionof the lever; a rotary shaft; and means carried by the shaft and responsive to centrifugal force induced by rotation the shaft for normally holding one of the con cts in engagement with a terminal; and resilient means for actuating the lever after 'a predetermined movement of the speed responsive device.

10. A centrifugal switch comprising in combination; a support;, spaced stationary terminalscarried by the support; a shaft rotatably mounted with respect to the support; a movable lever mounted on the support and carrying contacts adapted to engage the terminals, the contacts,

being so arranged on the lever that one or the other acts as a pivot for the lever depending upon the position of the lever; and speed responsive means radially supported-from the shaft for normally holding one of the contacts lo. engagement with a terminal; and resilient means for shlltlng the lever to change the ivotal point thereof alter V a certain recliol movement of the speed respon-' sive means.

ll. lo a switch; the comhlnotlon comprhlng; a support; spaced termlhols carried thesupport; a lever loosely mounted on the support and carrying spaced contacts, the contacts helng so arranged on "the lever that one or the other es pivot for the lever depending upon the oosltion of lever; a shaft; a device by the shell; and responsive to the speed or the for nor holding one oi the contacts to engagement with one or" terminals; and soclatecl with the lever and operable a cer= teln recllal movement or the device to the lever causing another contact to engage another terminal whereby the first mentioned contact is separated quickly from its terminal.

12. In a device of the class described, the combination comprising; a support; a terminal insu= latingly carried by the support; a lever loosely mounted on the support and provided with a boss and carrying a contact, salol contact and boss being so arranged on the lever that. elther the boss or the contact provides a pivot for the lever depending upon the position or the lever; a shaft; a device carried by the shalt and responsive to the speed oi the shaft for normally holding the contact in engagement with the terminal; and

spring means acting on the lever alter a certain radial movement or the rlevlce to shltt the lever causing the boss to engage the support whereby the contact is separated quickly from the terminal.

13. The combination of e motor governor hay-- ing a weight member adapted totrovel radially in. a certain path and to control on electrlc power circuit connected with the motor; a movohlc switch member normally helcl lo a clrcuit closed position by the weight member; and resillent means normally held under compression when said member is in its normal posltlon said resilehle o lent means operating to move the switch member to its open position when the weight member has moved outwardly a predetermined distance by centrifugal force.

14. A centrifugal switch'comprising in combination; a shaft; a stationary support; a plurality of fixed terminals carried by the support; a spring urged movable member slidably mounted on the support; a plurality of contacts carried by the member and providing pivot points for the member; and means carried by the shaft for normally holding one of the contacts in engagement with a terminal, said means being responsive to centrifugal force produced by rotation of the shaft for permitting the engaged contact to form a pivot for the member until another contact engages means normally holding the movable contact in engagement with the terminal; a spring for separating the movable contact rrom the terminal when sald means has moved radially outward a certain distance ln response to the rotational speed oi the shaft; and means associated with the movable cool: it and cooperating with the support to cause movable contact to separate quickly Zrom termlnol.

155. A stvlteh comprising in commnotion; a fixed a movehle contact; a rotate-kale me moons carried by and move rotatable member, said means normehy holncnt tlonory contact; and resilient means for seporatm movable contact from the stollonory contact when the first mentioned means has moved r outward a certain dislance response to speed of the rotatable meroher.

17. A centrifugal sv ltch comprising in combi nation; at contact; a movable contact; a o responsive clevlce carried by the shalt oncl hoclu g port adopted to travel radially or the shaft, salol part normally holding the movable contact in engagement with' the stationary contact, and spring means for separating the movable contact from the stationary contact when the part is moved outwardly a predetermined distance in response to the rotational speed of the, shaft.

18. In astarting switch, for an electric motor having a stationary frame and a rotor therein, the combination with a pmr offixed terminals carried bythe frame; a lever loosely mounted relative toth'e fixed terminals and carrying spaced contacts, said contacts forming pivots for the lever on the fixed terminal contacts; centrifugally distance CALVIN J. WERNER.

- movable contact in engage

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