US1214081A - Centrifugal switch. - Google Patents

Description

H. M. SCHEIBE.

CENTRIFUGAL SWITCH,

APPLICATION FILED DEC. 19', I913.

1,214,081 Patented Jan. 30, 1917.

, 2 SHEETS-SHEET I- ATTORNEY H M.SCHEWE.

CENTRIFUGAL SWITCH.

APPLICATION FILED DEC.I9.19I3.

1,214,081. Patented Jam. :30, 1917.

2 SHEETS-SHEET 2.

ATTORNEY BY r UNITED STATES PATENT OFFICE.

HAROLD SCHEIBE, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

CENTRIFUGAL swrrcn.

Specification of Letters Patent.

Patented Jan. 30, 1917.

Application filed December 19, 1913. Serial No. 807,661.

To all whom it may concern:

Be it known that I, HAROLD M. SoHEIBE, a citizen of the United States, and a resident of Cambridge, in the county of Middlesex and State of Massachusetts, have invented a new and useful Improvement in Centrifugal Switches, of which the following is a specification.

My invention relates to centrifugal switches and particularly to such switches as are employed in connection with fan motors of the induction type, or similar devices, to control the connections of an auxiliary starting winding.

The primary object of my invention is to provide a device of the above indicated character which is simple in construction and which requires less attention and repair than switches heretofore constructed.

bers which are acted upon by centrifugal force to break the circuits of auxiliary wind I ings at predetermined speeds. As the speed of the motor increases, a critical speed is reached at which the centrifugal force is just suiiicient to overcome the pressure of a spring or other retaining means. Because of the slight pressure of the contact members, arcing will occur until the contact members are finally separated. The effect of this excessive arcing is not only to shorten the life of the switch by destggying the contact members, but to so corr e the surface of these members as to render the switch ineffective after a comparatively short period of use.

In my invention, I avoid the defects above mentioned and thus provide a switch which does not require frequent attention and repair by persons skilled in the electrical art. I accomplish this result byconstructing a switch which operates with 'a' Centrifugal switches, as at present constructed, usually comprise weighted mem- The above and other advantages will be apparent from a description of the details of my invention in connection with the accompanying drawings in which Figure 1 is a front view, in elevation, of a single-phase induction motor with my invention applied thereto, parts being broken away. Fig. 2 is a side view of a portion of the motor shown in Fig. 1, partially in elevation and partially in section on line IIII of Fig. 1. Fig. 3 is a view in elevation showing the details of the stationary contact devices of the switch and related parts, with parts broken away. Figs. 4 and 5 are views of details of the switch. Fig. 6 is a diagrammatic view of the electrical circuits of the motor. Fig. 7 is an end view in elevation, of a modification of the switch. Fig. 8 is a view in section on line VIII- VIII of Fig. 7.

Referring now to Figs. 1 and 2, a single phase induction motor 1 comprises a stator 2, a rotor 3, a shaft 4 and an end casing 5. As illustrated diagrammatically in Fig. 6, the stator is provided with a main winding 6 and with an auxiliary winding 7 which serves as a shading coil in starting the motor. The connections of the coil are controlled by a centrifugal switch which comprises a stationary ortion and a rotatable portion. The stationary portion of the switch is mounted within the casing 5 and comprises two concentric contact rings 8 that are connected to and insulated from the casing 5 and are insulated from each other. The rings 8 are connected to the respective terminals of the auxiliary winding 7. The rotatable portion of the switch comprises a circular base plate 9 that is provided with a concentric circular opening 10 to receive the shaft 4. Thebase plate 9 connected to and insulated from the rotor 3 by means of insulating disks 11 and 12, the latter being connected to the rotor by suitable screws or studs 13. Two curved weighted members 14 and 15, that are disposed on opposite sides of the shaft 4, have pivotal supports indicated at 16 and 17, respecshown in the drawing, the outer end of the member 14 engages the bent portion 29 and thus limits the inward movement of the members. The weighted members 14 and 15 are operatively connected by gear teeth coact with the stationary rings 8. The base plate 9 is provided with inwardly extending lugs 25 which coact with projecting arms 26 on the levers 23 to rock the levers upon the pins 22 when the weighted members 14 and 15 move outwardlyin response to centrifugal force. The levers 23 are severally provided with a portion 27 which projects beyond the pivotal support and the two portions are connected by a spring 28. The spring 28 acts to oppose bothv the outward movement of the weighted members 14 and 15 and the rocking movement of the levers 23.

Normally, the various parts are in the relative positions shown in Figs. 1 and 2, with the contact pieces 24 in engagement with the rings 8. The auxiliary winding 7,

' diagrammatically shown in Fig. 6, which serves as a shading coil for starting, is short circuited by the centrifugal switch. When the motor circuit is closed and the motor reaches a predetermined speed, the weightarms 26, having relatively short lever arms,

impart quick movement to the contact pieces 24 which are at the ends of the relatively longlever arms 23, and the disconnection of the several members is thus accomplished with a' minimum of arcing. The sparks occur upon the outer portion of the rings 8,

leaving the inner portionot the surface free from any corrosion to affect its normal operation. Upon a decrease in speed, the spring 28 draws the members 14 and 15 inwardly and also rocks the levers 23 to bring the contact pieces 24 into engagement with the rings 8 at their outer portions. lUpon amper a further decrease in speed, the contact pieces 24 are moved inwardly upon the several rings to their respective normal paths of contact and the mechanism is again in its starting position.

A modification of my invention is shown in Figs. 7 and 8 in which like numerals are used to indicate corresponding parts. in this form of my invention, three concentrically disposed contact rings 8 are employed. The rings may be connected in any suitable manner to the terminals or to intermediate points of an auxiliary motor winding (not shown). A pivoted lever 23 bears a contact piece 24 which coacts with the middle ring. A second pivotal lever 23 carries, at its outer end, a bar 30 which bears contact pieces 24 to coact with the respective outer rings. The bar 30 has a pivotal support at 31 on the lever 23 in order to insure perfect contact between each of the pairs of engaging contact members. A spring 32 retains the bar 30 in an operative position.

The operation of the form of switch illustrated in Figs. 7 and 8 is similar in every way to the operation of the switch shown in Figs. 1 to 6. The switch is composed of comparatively few parts and these may be formed by pressing thus rendering the construction simple and inexpensive. The manner of operation renders the switch particularly desirable because of the relatively long period during which it may operate without impairment of its eflectiveness or without repair or replacement of its operatma ing parts.

It is understood that such changes and modifications may be made as fall within the limits of the appended claims.

I claim as my invention:

1. The combination with a stationary contact member, and a rotatably and pivotelly mounted contact member, or means for causing successive radial and axial movements of said rotatable contact member.

2. The combination with a stationary contact member, and a coacting rotatably and pivotally mounted contact member, oi? means for causing separate radial and axial movements of said movable contact member 5 at a predetermined speed.

3. The combination with a stationary contact member, of a rotatably and pivotally lltili mounted contact member coacting therewith, and means for actuating said movable 0 contact member in a path that comprises substantially a right angle.

4. The combination with a rotatable member, and a weighted member connected thereto and having a radial movement, of a stationary contact member, a pivotally mounted contact member carried by said weighted member, and means for causing an axial movement of said pivotally mounted contact member.

5. The combination with a rotatable base member having a projecting portion, and a member pivotally mounted on said base member, 0 a contact member pivotally mounted on said second member and having an arm for engaging said projecting portion at a predetermined speed, and a stationary contact member for engagement by the movable contact member.

6. The combination with a rotatable member, a weighted member carried by said rotatable member and adapted to be thrown outwardly by centrifugal force, of acontact member pivotally mounted on said weighted member, means for causing an axial movement of said contact member at a predetermined speed, and a second contact member for coacting with the other contact member.

7. The combination with a member having a projecting portion, and a weighted member pivotally mounted on said rotatable member and adapted to be actuated by centrifugal force, of a contact member pivotally mounted on said weighted member and provided with an arm for coacting with said projecting portion, and a second contact member coacting with the pivotally mounted contact member.

8. The combination with a plurality of concentric annular contact members and a rotatable plurality of rotatably and pivotally mounted contact pieces adapted to coact with the same, of means for causing a radial movement of said pieces on said members and an axial movement of said pieces at a predetermined speed.

9. The combination with a plurality of concentric annular contact members and a plurality of relatively movable coactin contact pieces, of means for rotating sai movable contact members and for causing said movable contact members to move parallel to the axis of rotation at a predetermined speed.

10. The combination with a plurality of annular contact members, concentrically arranged in the same plane, and a plurality of coacting contact pieces pivotally mounted to rotate in a plane parallel to that of said members, said pieces being adapted to move radially outwardly in response to centrifugal force, of means for moving said pieces axially at a predetermined speed.

In testimony whereof, I have hereunto subscribed my name this first day of December, 1913.

HAROLD M. SCHEIBE.

Witnesses:

GEO. H. OLSON, FRED F. FRANCIS.

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