US3251958A

US3251958A - Centrifugal governor having resiliently mounted slip rings

Info

Publication number: US3251958A
Application number: US276920A
Authority: US
Inventors: Craig E Ebner
Original assignee: Litton Industries Inc
Current assignee: Litton Industries Inc
Priority date: 1963-04-30
Filing date: 1963-04-30
Publication date: 1966-05-17
Anticipated expiration: 1983-05-17

Description

C- E. EBNER May 17, 1966 CENTRIFUGAL GOVERNOR HAVING RESILIENTLY MOUNTED SLIP RINGS Filed April 30 1963 F l G. 2.

F I G.

F I G. 4.

INVENTOR. CRAIG E. EBNER F I G. 3.

gnifd 24% ATTORNEY United States Patent Office 3,251,958 CENTRIFUGAL GOVERNOR HAVING RESlLlENT- LY MOUNTED SLIP RINGS Craig E. Elmer, Philadelphia, Pa., assignor, by mesne assignments, to Litton Industries, Inc., Beverly Hills,

Califi, a corporation of Delaware 1 Filed Apr. 30, 1963, Ser. No. 276,920 4 Claims. (Cl. 200-80) This invention relates to improvements in a governor, and more particularly concerns a speed governor for electric motors of the miniature type.

It is an object of this invention to provide a governor which is stable under shock, and which has longer brush and governor life.

It is another object to provide a governor which is easily adaptable for rotation in both clockwise and counter-clockwise directions, and which is adapted to operate with accuracy in a wide range of temperatures and humidity.

It is another object to provide a governor which fits snugly on a motor shaft without splitting, and which eliminates the noise and shock caused by a governor which fits loosely on a motor shaft.

It is another object of this invention to provide a governor having means for preventing movement of the governor reed in a plane perpendicular to the face of the governor base. 7

It is another object to provide a governor having means for securely mounting the governor posts on the governor base and preventing any rotation of the governor posts.

Other objects and advantages of this invention, including its simplicity and economy, as well as the ease with which it may be adapted to existing equipment, will further become apparent hereinafter and in the drawings, in which:

FIG. 1 is a view in side elevation and partly in section of a governor constructed in accordance with this invention;

FIG. 2 is a view in front elevation of the governor shown in FIG. 1;

FIG. 3 is a view in front elevation of a governor adapted for counter-clockwise rotation, whereas the governor shown in FIGS. 1 and 2 is adapted for clockwise rotation; and

FIG. 4 is a view in section taken as indicated by the lines and arrows 4-4 which appear in FIG. 2.

Although specific terms are used in the following description for clarity, these terms are intended to refer only to the structure shown in the drawings and are not intended to define or limit the scope of the invention.

Turning now to the specific embodiments of the invention selected for illustration in the drawings, there is shown a speed governor for electric motors comprising a disc-shaped ceramic base 11, a ceramic hub 12 extending from the base 11 and formed integral therewith, and an opening 13 extending through the hub and base and adapted to receive a motor shaft. A pair of slip rings 14, 15 are mounted on hub 12 and are connected by

electric conductors

16, 17 to

posts

21, 22.

A reed 23 has one end mounted on one side of post 22 and has an electric contact 24 mounted on the other end.

Post 21 has an adjusting screw 25 positioned therein which includes an electric contact 26 mounted on its Patented May 17, 19 66 In some applications, such as for high rotational speed, only one counterweight 31 is necessary.

Base 11 is made of a ceramic material which is advantageous because it has a low coeflicient of thermal expansion, and also is a good insulator. Metals have previously been used in the construction of the bases of governors because of their low coeflicient of thermal expansion, but the use of metals presented serious problems of how to properly insulate the electrical elements of the governor. Such insulation problems are eliminated by the use of ceramic materials in the base and hub of the present governor.

The outer periphery of hub 12 is of stepped construction so as to provide a pair of

shoulders

32, 33, with shoulder 32 having a larger inside diameter than shoulder 33. This construction aids in the assembling of the unit and insures that

slip rings

34, 35 are properly positioned. Slip ring 35 has a larger diameter than slip ring 34 and abuts shoulder 32. Slip ring 34 abuts shoulder 33.

Making the base 11 and hub 12 of a ceramic material created some problems in obtaining a snug fit with a motor shaft.v If shaft opening 13 were too tight, the ceramic would split. On the other hand, if the shaft opening 13 were too loose, it would slap against the motor shaft and cause shock and noise. This problem was solved by providing a liner 36 inside shaft opening 13. Liner 36 is made of a resilient material, such as an epoxy resin, and serves to cushion the governor on the motor shaft and to provide a snug fit.

Four pairs of holes 37 are formed in base 11 and are positioned about degrees apart around its base. These holes 37 are adapted to receive dowel pins 38 from

posts

21, 22, and from counterweights 31. They aid'in properly positioning these elements of the governor.

Each

post

21, 22 is provided with a pair of dowel :pins 38 which extend into holes 37 and are flared at the end. The pair of pins 38 prevent the posts from rotating, and the flared end of the pins prevents the posts from pulling out of base 11. In assembly, the ends of pins 38 are flared over to prevent the posts from pulling out of base 11, but initially the flare does not fit tightly against the ceramic material of the base. To tighten pins 38 in base 11, a film of resilient material, such as epoxy resin, is introduced by capillary action into the space between the flare and the base to form a liner 39. If the ends of pins 38 were forced into tight contact when they were being flared over, the ceramic material of the base might split.

Similarly, slip rings 14, 15 are tightened onto hub 12 by introducing, through capillary action, a film of epoxy resin, or other resilient material, into the space between rings 14, 15 and hub 12 to form a liner 40.

Posts

21, 22 have sides 41 with planes that are converging in the direction toward the periphery of base 11. A pair of flanges 42 are formed at the top and bottom of each of the post sides 41, and the anchored end of reed 23 is positioned between post flanges 42 to prevent movement of the reed in the plane of sides 41.

A wedge 43 is provided to hold the anchored end of reed 23 in position against side 41 when screw 44 is tightened.

Posts

21 and 22 are identical in construction and may be reversed in position. A pair of stop holes 45 are formed in base 11. Stop member 27 is mounted in one hole 45 for clockwise rotation, and in the other hole 45 for counter-clockwise rotation of the governor. FIG. 2 shows the governor adapted for clockwise rotation (as indicated by the arrow), and FIG. 3 shows the governor adapted for counter-clockwise rotationtalso indicated by an arrow), with reed 23 being mounted on the other side of post 22, counterweights 31 being mounted in the opposite holes 37, and stop member 27 being mounted in the other stop hole 45. The direction of

screws

44 and 25 is also reversed.

In operation, the governor is mounted on a motor shaft and is rotated therewith.

Contacts

24, 26 remain together until the rotation exceeds a pre-s'et speed, Whereupon centrifugal forces bend the reed 23 and

separate contacts

24, 26 by moving reed contact 24 outwardly. When the rotational speed drops below the pre-set value, the contact 24 moves inwardly to return to its normal position in contact with contact 26.

The single reed construction of the governor gives more stability under shock than a double-reed type of governor. Moreover, it is more easily adjusted than the double reed type since the adjustment is made directly against the reed contact 24 (by rotating adjusting screw 25), and the whole length of the reed is utilized (since it flexes at its anchored end, instead of at the middle of the reed as in double-reed governors). In conventional double-reed type governors, the adjustment screw is positioned at the middle of the reed.

The slip rings 14 provide for longer governor and brush life as compared to a split commutator type of electrical connection. The slit in a split commutator is rough and tends to rub the brushes and wear them away quickly.

Further, if the commutator slit becomes filled withelec- It is to be understoodthat-the form of the invention herewith shown and described is to be taken as a present- 1y preferred embodiment. Various changes may be made in the shape, size and arrangement of parts. For example, equivalent elements may be substituted for those illustrated and described herein, and other resilient materials may be used in place of the epoxy resin. Also, parts may be reversed, and certain features of the invention may be utilized independently of the use of other features, all without departing from the spirit or scope of the invention as defined in the subjoined claims.

The claimed invention:

1. A speed governor for electric motors comprising a disc-shaped ceramic base, an integral ceramic hub extending from said base, said base and hub having an opening formed therethrough for receiving a motor shaft, the outer periphery of said hub being of stepped construction so as to provide a pair of shoulders with the shoulder that is positioned closer to said base having a larger inside diameter than the other shoulder, a pair of slip rings mounted on said hub with each slip ring abutting one of said shoulders, a liner made of resilient material lining said shaft opening, a pair of posts mounted opposite eachv other on said base, said posts having sides with planes that are converging in the direction toward the periphery of said base, a pair of flanges formed at the top' and bottom of each of said post sides, a reed with one end mounted on one side of one of said posts and positioned between the post flanges to prevent movement of the reed in the plane of the post side, an electrical contact mounted on the other end of the reed, an adjusting screw positioned in the other post, and an electrical contact mounted on the end of the adjusting screw and adpated to contact the reed contact.

2. A speed governor for electric motors comprising a base made of ceramic material, an integral ceramic hub extending from said base, said base and hub having an opening formed therethrough for receiving a motor shaft, the outer periphery of said hub being of stepped construction having a pair of shoulders with the shoulder that is positioned closer to said base having a larger inside diameter than the other shoulder, a pair of slip rings mounted on said hub with each slip ring abutting one of said shoulders, each slip ring being mounted on a liner of resilient material on said hub, a liner made of resilient material lining said shaft opening, means mounted on said base for opening electrical contacts in response to the rotational speed of said base, and electric conductors connecting said slip rings to said means.

3. A speed governor for electric motors comprising a base, a hub extending from said base, said base and hub having an opening formed therethrough for receiving a motor shaft, the outer periphery of said hub being of stepped construction having a pair of shoulders with the shoulder that is positioned closer to said base having a larger inside diameter than the other shoulder, said base and hub being integrally formed of ceramic material, a pair of slip rings mounted on said hub with each slip ring abutting one of said shoulders, each slip ring being mounted on a liner of resilient material on said hub, means mounted on said base for opening electrical contact-s in response to the rotational speed of said base, and electric conductors connecting said slip rings to said means.

4. A speed governor for electric motor comprising a disc-shaped base of ceramic material, a hub extending from said base, said base and hub having an opening formed therethrough for receiving a motor shaft, the outer periphery of said hub being of stepped construction so as to provide a pair of shoulders with the shoulder that is positioned closer to said base having a larger inside diame-v ter than the other shoulder, a pair of slip rings mounted on said hub with each slip ring abutting one of said shoulders, a liner of resilient material holding said rings tightly on the hub, a liner madeof resilient material, lining said shaft opening, said base having formed therein four pairs of holes positioned about 90 degrees apart around the periphery of the base, a pair of posts mounted opposite each other in a pair of said holes, each of said posts having a pair of dowel pins extending into said holes and flared at the end, said pair of dowel pins preventing rotation of said post and said flared ends preventing pull-out of the post from the base, a liner of resilient material holding the posts tightly in the ceramic material of the base, said posts having sides with planes thatare converging in the direction toward the periphery of said base, a pair of flanges formed at the top and bottom of each ofsaid post sides, a reed with one end mounted on one side of one of said posts and positioned between the post flanges to prevent movement of the reed in the plane of the post side, an electrical contact mounted on the other end of the reed, an adjusting screw positioned in the other post, an electrical contact mounted on the end of the adjusting screw and adapted to contact the reed contact, a stop member mounted on said base behind said reed, a weight mounted on said reed, and a counterweight mounted on said base.

References Cited by the Examiner UNITED STATES PATENTS 618,910 2/1899 Seng 2671 1,731,892 10/ 1929 Ferris 310-232 2,857,451 10/1958 Barclay 174-52 2,927,172 3/ 1960 Chichester et al. 200- 2,936,331 5/1960 Sillers 17477 2,997,559 8/ 1961 Caton 200--80 2,999,139 9/1961 Lee 200-80 3,009,996 11/ 1961 Lee 200-80 3,119,916 1/1964 Holden 200-168 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCI-IAEFER, Examiner.

H. A. LEWITTER, Assistant Examiner.

Claims

3. A SPEED GOVERNOR FOR ELECTRIC MOTORS COMPRISING A BASE, A HUB EXTENDING FROM SAID BASE, SAID BASE AND HUB HAVING AN OPENING FORMED THERETHROUGH FOR RECEIVING A MOTOR SHAFT, THE OUTER PERIPHERY OF SAID HUB BEING OF STEPPED CONSTRUCTION HAVING A PAIR OF SHOULDERS WITH THE SHOULDER THAT IS POSITIONED CLOSER TO SAID BASE HAVING A LARGER INSIDE DIAMETER THEN THE OTHER SHOULDER, SAID BASE AND HUB BEING INTEGRALLY FORMED OF CERAMIC MATERIAL, A PAIR OF SLIP RINGS MOUNTED ON SAID HUB WITH EACH SLIP RING ABUTTING ONE OF SAID SHOULDERS, EACH SLIP RING BEING MOUNTED ON A LINER OF RESILIENT MATERIAL ON SAID HUB, MEANS MOUNTED ON SAID BASE FOR OPENING ELECTRICAL CONTACTS IN RESPONSE TO THE ROTATIONAL SPEED OF SAID BASE, AND ELECTRIC CONDUCTORS CONNECTING SAID SLIP RINGS TO SAID MEANS.