US2788206A - Centrifugal mechanism - Google Patents

Description

L. E. STAAK CENTRIFUGAL MECHANISM April 9, 1957 Filed July 24. 1953 2 Sheets -Sheet 1 Fig.1.

Inventor: Louis 13.5taa

l is Attorney.

April 1957 L. E. STAAK 2,788,206

CENTRIFUGAL MECHANISM Filed July 24, 1953 2 Sheets-Sheet 2 Inventor: Louis E. SteaK,

by AZ/ l is Att orney United States Patent CENTRIFUGAL MECHANISM Louis E. Stank, Fort Wayne, Ind., assignor to General Electric Company, a corporation of New York Application July 24, 1953, Serial No. 370,084 4 Claims. (Cl. 264-45) This invention relates to speed responsive devices and more particularly to centrifugal mechanisms for actuating switches.

In order to provide for starting single phase induction motors, the stator of the machine is conventionally provided with a main or running field exciting winding and a starting field exciting winding physically displaced from the running winding and often electrically displaced, as by a capacitor connected in series therewith. This arrangement provides the requisite rotating field necessary for initially starting an induction motor.

Since the starting winding is not needed after the motor has come up to speed, it is conventional to provide means for disconnecting the starting winding from the power sup ply line at a predetermined speed. One common Way of effecting disconnection of a starting winding in response to a predetermined motor speed is to provide a centrifugally actuated mechanism mounted on the shaft of the motor which will open a switch in the circuit of the starting winding when the motor reaches the desired speed. These centrifugal mechanisms are characterized by the provision of weight members which move under the influence of centrifugal force responsive to the rotation of the shaft thereby actuating the associated switch. It is necessary that these centrifugal mechanisms have a snap action, i. e. that they shift suddenly from the switch closed to the switch opened position at the desired speed and it is also desirable that the switch opening action be accomplished at a higher speed than the switch closing action.

In the past, in order to provide these characteristics, centrifugal mechanisms have been characterized by their complexity, difficult assembly, and relatively high cost. it is therefore desirable to provide an improved cenincorporating the desirable features set forth above.

Further objects and advantages of this invention will become apparent and the invention will be better understood by reference to the following description and the accompanying drawings, and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In accordance with this invention, a pivot member is provided mounted on the shaft and a pair of weight members are pivoted on the pivot member. A push collar is provided mounted on the shaft for sliding movement thereon and spring means, such as a coil spring arranged on the shaft between the push collar and the pivot member, is arranged to bias the push collar to a first position. The push collar has an annular flange portion adapted to actuate the associated switch and a hub portion on the side of the flange portion adjacent 2,788,206 Patented Apr. 9, 1957 the pivot member. The hub portion has a pair of oppositely disposed projections formed thereon and connected to the flange portion with each of the projections having an axially extending slot formed therein extending from the flange portion through a portion of the axial length of the projection. Each of the weight members is provided with a pair of arms respectively having inwardly extending projections formed thereon, these projections being respectively seated in the push collar projection slots so that movement of the weight members under the influence of centrifugal force responsive to rotation of the shaft moves the push collar against the spring to a second position. Each of the push collar projections also has a peripheral arcual slot formed in one side thereof respectively communicating with the axial slots thereby permitting ready assembly of the Weight member arm projections in the axial slots by rotation of the push collar. This arrangement therefore provides an improved centrifugal mechanism having only five component parts.

In the drawing, Fig. l is a side elevational view, partly in section, showing a single phase alternating current motor provided with the improved centrifugal mechanism of this invention;

Fig. 2 is an exploded perspective view of the improved centrifugal mechanism of this invention;

Fig. 3 is a side elevational view showing the centrifugal mechanism of this invention with the shaft in a stand-still condition;

Fig. 4 is a similar view showing the mechanism in its actuated position after the shaft has reached the pre determined speed; and

Fig. 5 is an end view of the improved centrifugal mechanism of this invention taken along the line 55 of Fig. 4.

Referring now to the drawing, there is shown a single phase alternating current induction motor 1 having a stator core member 2 mounted in a shell member 3. A suitable starting winding 5 and a running winding 4 are arranged in slots (not shown) in stator member 2. A squirrel cage rotor member 6 is arranged within stator core 2 and is mounted on shaft 35.

In order to provide for disconnecting the starting winding 5 at a predetermined speed, a centrifugal mechanism 7 is provided which actuates a suitable switch 8. The connections between the switch 8 and the starting winding 5 are conventional and will not be further shown or described. Centrifugal mechanism 7 includes a U-shaped pivot member 9 having a central portion 10 with a hub portion 11 formed thereon for mounting on shaft 35. Pivot member 9 has arms 12 extending at right angles to central portion 10 parallel with shaft 35 and on either side thereof. Arms 12 of pivot member 9 form pivot plates, and have axially extending slots 13 respectively formed in the ends thereof and laterally extending pivot projections 14 extending on either side, as will be hereinafter described.

A pair of weight members 15 are provided. These Weight members are generally U-shaped in configuration with a pair of spaced apart weight arms 16 respectively joined to a pair of spaced apart actuating arms 17. Actuating arms 17 are joined by a connecting portion 13 which has a bent-over projection 19 formed at the center thereof. Actuating arms 17 are provided with inwardly extending projections 24) respectively formed on the ends thereof. Weight members 15 are respectively mounted on pivot plates 12 with projections 19 being arranged in slots 13 and with the weight arms 16 and actuating arms 17 respectively arranged on either side of shaft 35. It will be seen that the ends 21 of projections 19 respectively are engageable with the outer surfaces of pivot plates 12.

A push collar22tis provided formed ofsuitable insulating material, such as a molded plastic, and having an annular flange portion 23 for actuating switch 8 and a hubportion 24 on the side of the flange 23 adjacent the pivot member d. Hub 24 has extension portion '35 the interior of which is splined as at 26, thereby to permit push collar 22 to slide axially on the shaft 35. A coil spring 27 is provided arranged around shaft 3:3 and over extension portion 25 of push collar hub 24 with one end abutting hub 24 and the other end abutting pivot member 9.

A pair of oppositely disposed projections 2% are formed on hub portion 24 of push collar 22, each having an axial slot 2? formed therein extending outward from flange 23 throughout a portion of the axial length thereof. Each projection 23 also has a peripheral arcual slot 30 formed in the same side thereof communicating with and substantially perpendicular to the axial slot 29. In order to permit molding of the push collar 22, the annular flange 23 has a pair of oppositely disposed openings 31 formed therein respectively communicating with axial slots 2? and radial slots 3d.

In order to assemble the improved centrifugal mechanism of my invention, the projections 29 on actuating arms 17 of weight members are initially positioned in slots 39 in hub portion 24 of push collar 22 and the collar is then rotated until the projections line up with the axial slots 29. it will then be seen that the coil spring 27 will force the push collar 22 away from the pivot member 9 thus respectivel locating the projections 29 on actuating arms 17 and weight members 15' in the recessed portions 32 of slots 29 thereby locking the device in assembled relation.

Annular flange 23 of push collar 22 engages a pair of arms 33 of switch 3 thereby closing contacts 34 when the shaft 35 is stationary or has not come up to the desired speed, as shown in Figs. 1 and 3. In this position, surface 36 of Weight member 15 is in pivotal engagement with the edges of pivot projections 14. When the shaft 35 reaches the desired speed, the weight arms 16 of weight members 15 fly outwardly under the influence of centrifugal force, pivoting about projections 14, and the actuating arms 17 thus move push collar 22 toward the pivot member 9 against the force of spring 27, as shown in Fig. 4, thus allowing arm 33 of switch 8 to move toward its unbiased position thereby opening contacts 34 to disconnect the starting winding 5. Movement of coller 22 in response to the movement of weight arms 16 is stopped when surface 36 of member 15 lies flat against the back side of projections 14 as in Figure 4.

It will now be seen that the improved centrifugal mechanism of this invention includes only five component parts all easily and inexpensively manufactured and that the device is readily assembled by merely positioning the projections 29 of actuating arms 1'7 on the same side of shaft 35 in the corresponding peripheral arcual slot of push collar 22 and then rotating the push collar until the projections 20 are seated in recess 32 at the end of axial slot 29. It is therefore seen that this mechanism is characterized by its simplicity and ease of assembly. Furthermore, the device provides good snap action and a substantial differential in shaft speecs between opening and closing.

While I have shown and described a particular embodiment of this invention, further modifications and improvements will occur to those skilled in the art. I desire that it be understood therefore that this invention is not limited to the form shown and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A centrifugal mechanism for actuating a switch and adapted for use on a rotatable shaft; comprising a pivot member fixed to said shaft, a pair of weight members pivoted on said pivot member, each of said weight members having a pair of arms respectively arranged on either side of said shaft, a push collar mounted on said shaft for sliding axial movement thereon, and spring means arranged to bias said push collar to a first position, said push collar having an annular flange portion formed thereon adapted to actuate said switch and a hub portion on the side of said flange portion adjacent said pivot member, said hub portion having a pair of oppositely disposed projections formed thereon and connected to said flange portion, each of said projections having an axially extending slot formed therein extending from said flange portion through a portion of the axial length of said projection, each of said Weight member arms having an inwardly extending projection formed on tie end thereof, the said projections on said weight member arms on the same side of said shaft being respccti' ly seated in oneof said push collar projection slots whereby said push collar is prevented from rotation relative to said shaft and movement of said weight members under the influence of centrifugal force responsive to rotation of said shaft moves said push collar against said spring means to a second position, each of said push collar projections having a peripheral arcual slot formed in one side thereof, said arcual slots each having one end communicating with an axial slot and having its other com iunicating with the edge of the push collar projection in which it is formed thereby permitting assembly of said weight member arm projections in said axial slots by rotation of said push collar.

2. A centrifugal mechanism for actuating a switch and adapted for use on a rotatable shaft; comprising a pivot member fixed to said shaft, a pair of weight members pivoted on said pivot member, each of said weight members having a pair of arms respectively arranged on either side of said shaft, a push collar mounted on said shaft for sliding axial movement thereon, and spring means arranged to bias said push collar to a first position, said push collar having an annular flange portion formed thereon adapted to actuate said switch, and a hub portion on a side of said flange portion adjacent said pivot member, said hub portion having a pair of oppositely disposed projections formed thereon and connected to said flange portion, each of said projections having an axially extending slot formed therein extending from said flange portion through a portion of the axial length of said projection, each of said weight member arms having an inwardly extending projection formed on the end thereof, the said projections on said weight member arms on the same side of said shaft being respectively seated in one of said push collar projection slots whereby movement of said weight members under the influence of centrifugal force responsive to rotation of said shaft moves said push collar against said spring means to a second position, each of said push collar projections having a peripheral arcual slot formed in the same side thereof, said arcual slots each having one end communicating with an axial slot and having its other end communicating with the edge of the push collar projection in which it is formed thereby permitting assembly of said weight member arm projections in said axial slots by rotation of said push collar, said push collar flange having axial openings therethrough respectively communicating with said axial slots.

3. A centrifugal mechanism for actuating a switch and adapted for use on a rotatable shaft; comprising a pivot member fixed to said shaft, a pair of weight members pivoted on said pivot member, each of said weight members having a pair of arms respectively arranged on either side of said shaft, a push collar mounted on said shaft for sliding axial movement thereon, and spring means arranged between saidpush collar and said pivot member for biasing said push collar to a first'position, said push collar having an annular flange portion formed thereon adapted to actuate said switch and a hub portion on the side of said flange portion adjacent said pivot member, said hub portion having a pair of oppositely disposed projections formed thereon and connected to said fiange portion, each of said projections having an axially extending slot formed therein extending from said flange portion through a portion of the axial length of said projection, each of said weight member arms having an inwardly extending projection formed on the end thereof, the said projections on said weight member arms on the same side of said shaft being respectively seated in one of said push collar projection slots whereby said push collar is prevented from rotation relative to said shaft and movement of said weight members under the influence of centrifugal force responsive to rotation of said shaft moves said push collar against said spring to a second position, each of said push collar projections having a second slot formed in one side thereof, said second slots each having one end communicating with and substantially perpendicular to an axial slot and having its other end communicating with the edge of the push collar projection in which it is formed thereby permitting assembly of said weight member arm projections in said axial slots by rotation of said push collar.

4. A centrifugal mechanism for actuating a switch and adapted for use on a rotatable shaft; comprising a pivot member fixed to said shaft, a pair of weight members pivoted on said pivot member, each of said Weight members having a pair of arms respectively arranged on either side of said shaft, a push collar mounted on said shaft for sliding axial movement thereon, and a coil spring arranged on said shaft between said push collar and said pivot member for biasing said push collar to a first position, said push collar having an annular flange portion formed thereon adapted to actuate said switch and a hub portion of the side of said flange portion adja ent said pivot member, said hub portion having a pair of oppositely disposed projections formed thereon and connected to said flange portion, each of said projections having an axially extending slot formed therein extending from said flange portion through a portion of the axial length of said projection, each of said weight member arms having an inwardly extending projection formed on the end thereof, the said projections on said weight member arms on the same side of said shaft being respectively seated in one of said push collar projection slots whereby said push collar is prevented from rotation relative to said shaft and movement of said weight members under the influence of centrifugal force responsive to rotation of said shaft moves said push collar against said spring to a, second position, each of said push collar projections having a second slot formed in one side thereof, said second slots each having one end communicating with and substantially perpendicular to an axial slot and having its other end communicating with the edge of the push collar projection in which it is formed thereby permitting assembly of said weight member arm projections in said axial slots by rotation of said push collar.

References Cited in the file of this patent UNITED STATES PATENTS 2,041,161 Brown et al. May 19, 1936 2,095,755 Libby et a1 Oct, 12, 1937 2,149,108 Welch Feb. 28, 1939 2,305,093 Leflar et; a1. Dec. 15, 1942 2,512,405 Willits et al June 20, 1950 2,538,410 Bretch Ian. 16, 1951 2,573,968 Hammell et a1. Nov. 6, 1951

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