US2663771A - Centrifugal device - Google Patents

Description

Dec. 22, 1953 R. J. HARTZ CENTRIFUGAL DEVICE 2 Sheets-Sheet 1 Filed March 26, 1952 INVENTOR. RAYMOND J. HARTZ ATTORNEY Dec. 22, 1953 R. J. HARTZ CENTRIFUGAL DEVICE 2 Sheets-Sheet 2 Filed March 26, 1952 INVENTOR. RAYMOND J HA rz ATTORNEY starting windings.

Patented Dec. 22, 1953 CENTRIFUGAL DEVICE Raymond J. Hartz, Cuyahoga Falls, Ohio, assignor to Jack & Heintz, Inc., Cleveland, Ohio, a. corporation of Delaware Application March 26, 1952, Serial No. 278,731

Claims. (Cl. 200-80) This invention relates i general to actuating devices and more particularly to automatic centrifugally responsive actuating devices carried by rotatable shafts, so as to be eiiicient as a governor, switch actuator, power control or for other control purposes.

As an example of an application of centrifugally responsive actuating devices carried by rotatable shafts, it has been found that in such electrical machines as single-phase induction motors, it is important that the switch be controlled within close limits with respect to the speed of the armature shaft. In such motors, after starting, the torque tends to fall off quickly at a speed less than that rated running speed if the starting winding is kept in circuit with the running winding. It is therefore important that the starting winding be positively cut out at a precise given speed in order to prevent the motor torque from falling off quickly after a predetermined running speed and the heavy current load on the motor winding from overheating. Gradual breaking of the switch increases the resistance through the switch so as to cut down the current through the This causes the motor speed to fall off so as to make it diiiicult to cut out the starting windings at the proper point in the speed of the motor.

It is therefore an object of the invention to provide a simplified centrifugally responsive actuator carried by a rotatable shaft which will operate with a snap action at a constant and predetermined speed of rotation of the shaft, as distinguished from a, gradual and progressive action.

Another action is to provide such a device in the form of a combined single unit that is inherently flexible and capable of assuming a normal predetermined shape and which responsive actuator includes a centrifugally weighted portion,

rather than separate weight members movable l relatively thereto, so as to involve the minimum number of parts, obtain quiet, frictionless and positive snap action in response to centrifugal forces for accomplishing the intended purpose of the. actuating device.

With the foregoing and other objects in view,

the invention resides in the combination of parts trated in the accompanying drawings, in which: Figure 1 is a view in side elevation, partly broken away and in section of one form the invention may take as applied to an electric motor switch, showing one half of an electric motor and 2 switch, and in which the switch is shown in open position;

Figure 2 is a view similar to and complementary with Figure 1, showing the switch in closed position.

Figure 3 is a fragmentary View in side elevation of one half of the motor shaft with the actuating device in section and shown in position for opening the switch of Figure 2;

Figure 4 is a view similar to and complementary with Figure 3, showing the actuating device in position for closing the switch of Figure 1;

Figure 5 is an end view of one half the actuating device shown in position for opening the switch of Figure 2;

Figure 6 is a view similar to and complementary with Figure 5, showing the actuating device in position for closing the switch of Figure 1; and

Figure 7 is a diagrammatical view of the windings of the motor.

Referring more particularly to the drawings, and as one example of utility of the actuating device of the present invention, an electric motor is illustrated as being enclosed in a housing I for a stator 2 and an associated squirrel cage armature 3 inside the stator and carried by an armature shaft 4.

For supporting the switch, there is provided an insulating plate 5 secured by bolts 6 to stationary housing posts 1. The switch includes contacts 8 and 9. Contact 8 is carried by a leaf spring [0 that is secured to plate 5 so that contact 8 remains stationary. Also carried by plate 5 is a leaf spring I I that carried the other contact 9. Ring 20 has bonded thereto a cup l3 of rubberlike material which is also bonded to a metallic collar I4 that is rigidly secured to the motor shaft 4. Approximately midway between the inner collar l4 and the Outer ring 20, the rubber cup I3 is shown to have imbedded therein a series of metallic weights it. As an alternative, the cup may be made of a relatively thin strip of flexible material with a thicker and larger mass of the same material concentrated in the bowed portion.

The inherent flexible nature of the rubber cup !3 insures it to normally assume its natural cup shape, as shown in Figure 2, so as to force the linearly movable contact 9 into engagement with contact 8. This occurs when the motor is at rest, as shown in Figure 2.

As shown in the diagrammatical view of Figure 7, the switch contacts 8 and 9 are connected one to a conductor l6 and the other to a conductor l 7. Thus, the switch contacts control the current supply of a starting winding I 8 of the 3 motor, the running winding of which is shown at I9.

Instead of employing movable weights and guideways therefor for frictional radial ball movement in response to the centrifugal force created upon motor shaft rotation, the weights l5 are embedded in the rubber cup I3. When at rest, and also upon starting of the motor, the cup assumes its normal shape so that the movable contact 9 is in engagement with contact 8 and this continues switch contact engagement through a relatively slow motor shaft speed. When, however, a predetermined motor shaft speed is reached, the centrifugally responsive weights l5 fly radially outwardly to deform the cup as shown in Figures 1, 3 and 5 to withdraw ring of the cup from ring l2 of the movable contact .9, permitting spring II to remove movable contact 9 from the stationary contact 8, as shown in Figures 1, 3 and 5, to open the switch. Upon resumption of a slower speed, or stopping, of the motor, the inherent resilient characteristics of rubber cup l3 results in the resumption of its normal cup shape and the automatic reengagement of contacts 8 and 9 and the closing of the switch, as shown in Figures 2, f and 6.

The construction specifically shown in the drawings makes for simplicity and accuracy and efficiency in performance. The weights being embedded in the rubber cup, there is no relative movement therebetween and hence no element of friction nor distortion nor chance of misalignment. The action is a positive snap action both I in closing and opening of the switch, as contrasted to a slow and gradual action that occurs when relatively movable parts are employed in the actuating device and when the element of friction between the weights and their suppQrts and guideways is present. This is true whether the ring 20 that is carried by the bowed portion of the flexible cup is used to control the operation of the shaft of the machine by engagement with mechanical, electrical or magnetic control means carried by the stationary supporting plate 5. It is to be understood that the disclosure of the actuating device, constituting this invention, as applied to a switch control for electric motors is by way of illustration and not with the intent to restrict its scope to be in combination therewith. -'-The construction may also be modified so that the device to be controlled, or actuated, by the centrifugal device is responsive either to linear or radial movements of the cup, as desired. As previously stated, the cup may be made of relatively thin flexible material with a denser and heavier section in the bowed portion to be eentrifugaliy responsive and to replace the embedded weight members. The machine to be controlled by the device may be arranged to be responsive to movements of the cup in an axial, linear or radial direction, or combination thereof. It is adapted not only to function as a centrifugal switch, but also as a governor, speed control or a power control device.

I claim:

1. In a machine having a rotatable shaft, control means for controlling the rotation of said shaft, a centrifugally responsive actuating device for actuating said control means and including a flexible normally cup-shaped member inclfiding a centrally aperturd ring secured to said shaft and a bowed portion free of said shaft to permit linear movement of said bowed portion ax a of ai shaft, he we porti n of sai flexible member having a centrifugally responsive weighted portion, means carried by said bowed portion, normally in engagement with said control means when said shaft is at rest and in relatively slow speed rotation, for engaging said control means in response to centrifugal outward movement of said weighted portion and consequent axial linear movement of said bowed portion, in response to a predetermined speed of rotation of said shaft, to control the speed of rotation of said shaft.

2. In a machine having a rotatable shaft, control means for controlling the rotation of said shaft, a centrifugally responsive actuating device for actuating said control means and including a flexible compressible, normally cup-shaped member including a centrally apertured ring secured to said shaft and a bowed portion free of said shaft to permit linear movement of said bowed portion axially of said shaft, the bowed portion of said flexible compressible member having a centrifugally responsive weighted portion, means carried by said bowed portion, normally in engagement with said control means when said shaft is at rest, and in relatively slow speed rotation, for engaging said control means in response to centrifugal outward movement of said weighted portion and consequent linear movement of said bowed portion, in response to a predetermined speed of rotation of said shaft, to control the speed of rotation of said shaft.

3. In a machine having a rotatable shaft, control means for controlling the rotation of said shaft, a centrifugally responsive actuating dev ce f act ti g sai co trol m a a i ding a rubber like deformable normally cup-shaped membe n ludi g cen l y ap rtures; g secured to said shaft and a bowed portion free of said shaft to permit linear movement of said bowed portion axially of said shaft, centrifugally responsive weights rigid with the bowed portion o s fl ible m be m ans arrie by aid bowed p rtion, normally n engag ment with said c l m ns when sa d sha t i at rest and, i relatively slow speed rotation, for engaging said contr l m a s n r sp o entr ugal utward movement of said weights and consequent axial linear movement of said bowed portion, 78- sp se to a pre min p ed of. rotati n of d s a o co rol h speed of rota ion of said shaft.

c t i ugal i ch for le tr cal meohino ha i g a rot le shaf in ludin a stationary ontact an a s tio ry upp rt herer a fl ible memb r having an inner r secur d t said shaf and a bowed por ion rryin a co act linea y movab b s id embe w th p t t aid t ona y ontact for closin and p ni g of said switch, a e es of centrifugally responsive weights rigid with the bowed portion of said flexible member, said switch being normally closed when said shaft is at rest and also in relatively slow rotational speed, said weights upon said shaft arriving at a predetermined speed of rotation, being adapted to linearly move said bowed portion axially of said shaft so as to withdraw said contact carried thereby from engagement with said stationary contact to open said switch. 7

5 A centrifugal switch for an electrical machine having a rotatable shaft, including a stationary contact and a stationary support therefor,

V a rubber-like deformable cup-shaped member having an inner ring secured to said shaft and an open concave surface facing said stationary contact and carrying a contact linearly movable by said member with respect to said stationary contact for closing and opening of said switch, a series of centrifugally responsive weights embedded in the bowed portion of said cup shaped member, said switch being normally closed when said shaft is at rest and also in relatively slow rotational speed, said weights, upon said shaft arriving at a predetermined speed of rotation, being adapted to linearly move the bowed portion of said cup-shaped member into temporary deformation to withdraw said contact carried thereby from engagement with said stationary contact to open said switch.

RAYMOND J. HARTZ.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,584,703 Hollerith Feb. 5, 1952 2,616,682 Greenhut Nov. 4, 1952

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