US2561560A - Centrifugal guided speed responsive device - Google Patents

Description

July 24 1951 s. s. BROWN 2,561,560

CENTRIFUGAL GUIDED SPEED RESPONSIVE DEvIcE Filed Oct. 16, 1947 3 Sheets-Sheet 1 INVENTOR STEFFEN 5. BROWN BY 4 www www ATTORNEYS v July 24, 1951 s. s. BROWN 2,561,560

CENTRIFUGAL GUIDED SPEED RESPONSIVE DEVICE Filed Oct. 16, 1947 5 Sheets-Sheet-Z NVENTOR STEFFEN S. BROWN July 24, 1951 s. s. BROWN 2,561,560

CENTRIFUGAL GUIDED SPEED RESPONSIVE DEVICE Filed Oct. 16, 1947 5 Sheets-Sheet 3 5511 Tg. ,1E

INVEN'roR STEFFE N 5. BROWN ATTURNEYS Patented July 24, 1951 CENTRIFUGAL GUIDED SPEED RESPONSIVE DEVICE Steffen S. Brown, Dayton, Ohio, assignor to The Brown-Brockmeyer Company, Dayton, Ohio, a

corporation of Ohio Application October 16, 1947, Serial No. 780,291

This invention relates to switches and to actuators therefor, and particularly to a centrifugal vactuator for a switch.

In the construction of many devices, such as electric motors, it is common to include a switch `which operates in response to a predetermined motor speed for opening a circuit. Switches of this type are employed in connection with split phase motors for opening the starting winding Acircuit at a predetermined motor speed to eliminate the loss of power in the starting winding and to permit the motor to operate as a pure repulsion motor when running under load.

The particular object of this invention is to provide an improved type of centrifugal actuator for a switch of this nature.

Another object is to provide a centrifugal switch actuator which is very simple to assemble and which is therefore inexpensively mounted in a motor.

A still further object is the provision of a centrifugal actuator in which the several parts can easily be manufactured by mass production methods.

A still further object is the provision of a centrifugal switch actuator which is substantially fully enclosed thereby protecting the mechanism of the actuator from dirt.

A still further object is the provision of a centrifugal actuator for switches and the like which is unusually small and which therefore can be mounted in a small space.

In the operation of electric motors having centrifugal switches therein it is necessary that the switch open and close sharply. It is also important that once open the switch will remain open until the motor speed falls to a predetermined value.

Accordingly, it is a still further object of this invention to provide a centrifugal actuator for a switch which has a precision snap action and which does not flutter or hunt when the motor speed is reduced due to heavy loads being imposed thereon.

These and other objects and advantages will become more apparent upon reference to the following description taken in connection with the accompanying drawings in which:

Figure 1 is a vertical section taken along the axis of an electric motor having mounted therein a centrifugal switch and actuator according to this invention;

Figure 2 is an enlarged sectional View taken through the switch actuator and showing the internal construction thereof;

9 Claims. (Cl. 264-17) Figure 3 is a transverse section through the actuator and is indicated by the line 3--3 on Figure 2;

Figure 4 is another transverse section through the actuator and is indicated by the line 4 4 on Figure 2 and shows the switch device which is operated by the actuator;

Figure 5 is a side view of the switch mechanism of Figure 4;

Figure 6 is a section indicated by the line 6--6 on Figure 5 and shows the relative positioning of the contacts of the switch;

Figures '7 and 8 are views of the weights in the centrifugal actuator;

Figure 9 is a view of one of the cup shaped members in which the weights are positioned in the assembled actuator;

Figure 10 is a perspective View of a washer which is employed in the actuator for retaining the weights in their proper relative position; and

Figures 11 and 12 are sectional views through the switch and actuator showing the parts in different operative positions.

Referring to the drawings, in Figure l there is illustrated a typical electric motor consisting of a stator l0 having windings l2 therein which includes starting and running windings.

The stator is mounted in a motor frame I4 which includes the end covers i6 and I8 secured to the motor frame lin any well known manner. Each of the motor end covers includes bearings 20 which journal a shaft 22 that supports a rotor 24 within the stator IU.

The shaft 22 may also carry a fan 26 for circulating cooling air within or through the motor frame if desired.

The end. cover I8 may have mounted therein a condenser as at 28 which is in circuit with the starting winding and which is to be employed during the starting period of the motor,

The circuit through the condenser 28 and the starting winding of the stator is established through a switch mounted at 30 in the end cover I6.

This switch is better seen in Figures 4, 5 and 6 wherein it will be seen to comprise a mounting panel 32 of insulating material which is secured to the cover I6 and which has secured thereto the spring arm 34. The arm 34 is riveted to the panel at 36 and has a connection made therewith by the wire 38. The other end of the arm 34 carries a contact 40 which is continuously urged away from the contact 42 on the panel 32 by the resilienci7 of the arm 34. A stop bracket 44 is provided for limiting the movement ot the contact 4d away from the contact 42.

Iih 4i! and 42 are normally mainf- .ent by the pressure on the arm 34 of the flange 45 of a cup shaped member 48 which lorlns a part of the actuator assembly generally indicated at 5i] in Figure l. and shown more in. detail in Figure 2.

'.iiie cup shaped member 48 has an inner sleeve which is slidably splined to the shaft 22 by the spline means 54 and which is continu ously urged toward the left in Figure 2 by the compression spring 55. The compression spring 56 bears betw the member 48 and a washer 58, the said washer being retained in position on the shaft by the snap ring 66.

Also mounted on the shaft 22 is a second cup shaped member 62 which opens toward the member 48 and which telescopes therewith as at 64. The member i2 is retained in position on the shaft 22 by the snap ring 66.

Mounted within, the cup shaped members 48 and 62 are the Oshaped weights 68 which have their adjacent faces abutting as at l0. It will be obvious in Figure 2 that the Weights engage the members at the bottoms of the recesses therein and that theJ outer surfaces of the weights are divergent with the walls of the cup shaped members toward the open sides thereof. The weights, together with the members in which they are .mounted thus form a toggle like arrangement.

The adjacent faces of the weights are provided with spherical. protuberances and recesses indicated at 12, and best seen in Figures '7 and r8, and which provide a pivot axis about which the weights may pivot relatively.

mentioned before the weights are substantially C-shaped, as shown in Figure 8, and the faces ol the said weights below the pivot axis formed by the protuberances and recesses 12 are divergent as will be seen from the dotted line indicated at 14 in Figure 2.

'For uniform action of the actuator there are preferably two sets of weights therein. This provides for an actuating thrust on each side of the actuator members and prevents the binding thereof on the shaft 22.

For maintaining the two sets of Weights in their proper relative positions each of the said weights has a projection extending from the .back thereof at E6 which. is receivable in a notch of a washer 8f).

This washer is illustrated in Figure 1G and it will be observed that the notches so disposed therein that the two weights in each member will be retained at exactly 180 degrees from each other.

The tips of the G--shaped weights are also provided with projections as at 82 which projections are shorter in height than the projections T6 by the thickness of the washer S0. The projections 32 thereby provide stops for stopping the weights in their innermost position.

It will be evident upon reference to Figure 2 that the center of gravity of each of the several weights GB is well within the point about which it pivots on its associated cup shaped member. The last mentioned points are indicated n Figure 2 at 84 and are the points of engagement of the projections l5 with the cor-t ners of the members. These points, or lines, form the point axes for the several Weights when they throw out in the i'nembers due to centrifugal :forces acting thereon.

Due to the relative location of the center of gravity of each weight and the point about which it pivots in its cup shaped member, the action of the switch is extremely rapid because once the weightsconunence to move, not only is the moment arm of the weight thereof about the said pivot point increased, but the center of gravity is moved out further from the center of the shaft and thereby increases the amount of centrifugal force. Thus, the movement of the weights outwardly in the actuator is in the nature of a snap action and having moved out, the weights will remain, in their outermost position until the speed of the motor has been reduced to substantially less than that which was required to throw them out.

In operation, rotation of the shaft 22 will drive the member 48 directly through the spline means at 54. When rotation of the actuator commences the members 48 and 62 thereof are urged together by the spring 56 and this also maintains the weights in their inner positions as shown in Figure 2.

When the speed of the shaft 22 has reached a certain value the weights 68 will commence to move outwardly, pivoting in the members 48 and 62 at the point B4, and relative to each other about the pivot axes dened by the protuberances and recesses 12.

As soon as outward movement of the Weights has commenced, the increasing radial distance outwardly of the centers of gravity thereof, and the increasing moment arm through which the centrifugal force on the weights act, causes the said weights to snap into their outermost position.

The movement outwardly of the weights increases their elective axial length within the actuator due to the toggle arrangement of the said weights. This will bring about movement of the member 4B rightwardly and permit the spring arm 34 to disengage the contacts 40 and 42.

It will be noted that at this time there are no rotating parts in engagement with stationary parts. Thus, all wear on the flange of the actuator member 48 and the arm 34 will take place in the relatively brief period that is required for the motor to come up to speed. This promotes long life of the actuator and quiet operation of the motor.

It will be apparent that engagement of the weights 68 by the washers 80 prevents the circumierential displacement of the Weights in each member due to acceleration thereof during the starting or stopping of the motor shaft.

Relative displacement of the weights in one member relative to those in the other members is prevented by the interengagement of the weights through the aforementioned protuberances and recesses 12.

It will be understood that this invention is susceptible to modification in order to adopt it to different usages and conditions and, accordingly, it is desired to comprehend such modications within this invention as may fall within the scope of the appended claims.

I claim:

l. In a centrifugal actuator, a pair of members mounted on a shaft and adapted for rotation therewith about a predetermined axis, each member having side and circular bottom walls integrally formed to denne a corner, said members being spaced apart, said side wall of each member extending toward the other thereof dening a substantially enclosed weight receiving space, a. p

pair of weights between said members one plvotally abutting the corner of one member and the other pivotally abutting the corner of the other member, said weights also abutting each other, said weights forming a, pivot axisvtherebetween at their point of abutment, and means urging said members toward each other.

2. In a centrifugal actuator, spaced members each having side and bottom walls integrally vformed to define a corner, said side wall of each member extending toward the other thereof dening a substantially enclosed weight receiving space, a weight positioned Within each member in said space and in abutting pivotal engagement with the corner of the member in which it is positioned, yielding means urging said members toward each other and holding the weights in abutting engagement with each other, and interfitting parts on the weights for forming an axis for relative pivoting movements therebetween, said axis being inwardly of the engagement of the weights and corners, the arrangement being such that relative pivoting movements of said weights outwardly will move said members apart.

3. In a centrifugal actuator, a pair of members adapted for being mounted in spaced relation on a shaft and rotated therewith, said members each having side and bottom walls defining a corner, said side wall of each member extending toward the other thereof defining a substantially enclosed weight receiving space, weights positioned in said space and inwardly of said corners, one of said weights being in abutting pivotal. engagement with the corner of one member and another of said Weights being in abutting pivotal engagement with the corner of the other member, yielding means urging said members toward each other andholding said weights in abutting engagement with each other, and intertting parts on said weights forming a pivot axis for relative pivoting movements therebetween, said axis being inwardly of the aforementioned corners on said members, the arrangement being such that outward movement of said weights will urge said members apart and means for preventing relative circumferential movement between each weight and its member.

4. In a centrifugal actuator, a pair of spaced cup-shaped members each having side and bottom walls defining a corner, said side wall of each member extending toward the other thereof defining a substantially enclosed Weight receiving space, a C-shaped weight positioned within each member in said space and in abutting pivotal engagement with the corner of the member in which it is positioned, yielding means urging said members toward each other and holding said weights together, and abutment means on said weights forming an axis for relative pivoting means thereof in response to a predetermined centrifugal force acting thereon, said axis being substantially nearer to the center of said actuator than the aforementioned corner of said members, the opposed faces of said weights each being formed of two planar areas at angles to each other so that one corresponding pair of said areas are contiguous for each of the inner and outer positions of said weights while the other pair thereof are divergent.

5. In combination with a shaft, a rst cu-pshaped member mounted on said shaft, a second cup-shaped member slidably mounted on said shaft, said members each having side and bottom walls dening a corner, a weight positioned within each member, a projection on a corner of each weight and abuttingly pivotally engaging the corner of its associated member, resilient means urging said members toward each other and maintaining said weights together, intertting abutment means comprising a protuberance on one weight and a recess in the other' lmounted inv each of said members, a projection on a corner of each of weights abuttingly pivyotally engaging its associated member at the corner between the side and bottom walls thereof, resilient means for urging said splined member toward said cup-shaped member and for urging said weights together, interengaging abutment means on said weights for relative pivoting movements between one pair of weights and the other pair of weights, said axis being disposed substantially nearer to the axis of said shaft than the aforementioned corners, said weights being operable when thrown outwardly from said shaft by centrifugal force to move said members apart and when moved inwardly toward said shafts to permit said members to move toward each other, and means in said members preventing relative circumferential movement between each weight and its member.

'7. In a centrifugal actuator, a pair of spaced members mounted on a shaft and adapted for rotation therewith about a predetermined axis, said members each being of cup-shape and having side and bottom walls defining a corner, said side wall of each member extending toward the other thereof defining a substantially enclosed weight receiving space, a pair of weights in said space, one of said weights being in abutting pivotal engagement with the corner of one member and another of said weights being in abutting pivotal engagement with the corner of the other member, interiitting parts on said weights for forming an axis for relative pivoting movements therebetween whereby pivoting movement of said weights outwardly will move said members apart and means resiliently urging said members toward each other and means including an element in each member adapted to receive a portion of one of the weights to prevent relative circumferential movement between each weight and its member.

8. In a centrifugal actuator, a pair of spaced members mounted on a shaft and adapted for rotation therewith about a predetermined axis, said members each being of cup-shape and having side and bottom walls defining a corner, said side wall of each member extending toward the other thereof defining a substantially enclosed weight receiving space, a pair of weights in said space, one of said weights being in abutting pivotal engagement with the corner of one member and the other of said weights being in abutting pivotal engagement with the corner of the other member, and interfitting means comprising a protuberance on one weight and a recess in the other weight for forming an axis for relative pivoting movements therebetween, and means urging said members toward each other.

9. In combination: a shaft, a member slidably splined to said shaft and having an annular recess therein, a cup-shaped member mounted on said shaft having its open side facing said recess and teiescoping said recessed member, each of said members having a side and circular bottom wall formed integral to define a cerner, a pair of C-shaped Weights mounted in each of said members, a projection on a corner of each weight abuttingly pivotally engaging its associated member at its corner, resilient means for urging said splined member toward said cup-shaped member for urging said weights together, interengaging abutment means on said weights for relative pivoting movements between one pair of Weights and the other pair of weights, said Weights being operabie when thrown outwardly from said shaft by centrifugal force to move said members apart and when moved inwardly toward said shaft to permit said members to move toward each other, and means in said members preventing relative circumferential movement between said each weight and` its member, said last named means including a washer element carried by each member and having openings therein through which the projection on the corner of each weight extends.

STEFFEN S. BROWN.

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

UNITED STATES PATENTS

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