US2400136A

US2400136A - Carbon pile regulator

Info

Publication number: US2400136A
Application number: US509454A
Authority: US
Inventors: William J Rady
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1943-11-08
Filing date: 1943-11-08
Publication date: 1946-05-14
Anticipated expiration: 1963-05-14

Description

CARBON FILE REGULATOR Filed Nov. 8, 1943 2 Sheets-Sheet 1 GD 73 73 o D 60 o m M ,8 1% 7/ fir: a Q4. munumnm /3 i 5 I; I

g L w mu M u u Z 15 INVENTOR WJIImmJ Eddy M W M ATTORNEYS y 4, 1946. w. J. RADY 2,400,136

CARBON FILE REGULATOR Filed Nov. 8, 1943 2 Sheets-Sheet 2 mvEnTToR Wzllmm J Eddy ATTORNEYS Patented May 14, 1946 2,400,138 CARBON PILE REGUIATOB William J. Bady, Anderson, Ind, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application November 8, 1843, Serial No. 509,454

6 Claims.

This invention relates to regulators for electric generators by which the voltage of the generator is maintained within prescribed limits. More particularly the present invention relates to a carbon-pile regulator comprising a stack of carbon discs connected in the generator field circuit and subjected to spring pressure and electromagnetic means responsive to generator voltage for varying the pressure between the discs.

It is well known that the operation of a regulator is aii'ected by variations in the resistance of the electromagnet coil due to changes in temperature. Temperature responsive devices have been added to compensate for this variation in resistance. An object of the present invention is to provide compensation without adding a temperature responsive compensating device. In the disclosed embodiment oi the invention. this object is accomplished by efl'ecting, in response to increase of temperature of the regulator, a reduction of the modulus of elasticity of the control spring by an amount which compensates substantially for the increase in the resistance of the electromagnct coil due to increase in its tempenture. In this connection, it is a further object so to retard the transfer of heat to the spring that it will not be heated faster than the electromagnet coil. Therefore, during change from environment temperature to operating temperature. the variation in regulating voltage will beminimized.

A further object is to provide for the complete enclosure of the working parts of the regulator in order to exclude foreign matter therefrom. while providing free relative movement between other parts due to variations in temperature.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embdi ment oi the present invention is clearly shown.

In the drawings:

Fig. i is a side elevation of the regulator;

F183. 2 and 8 are end views looking respectively in the directions of arrows and 8 of Fig. 1.

F18. 4 is a side View of the armature and sprin assembly.

Fig. 6 is a longitudinal sectional view on line H of Fig. 2, and is drawn twice the size of the preceding views.

Fig. 6 is a graph in which curves are plotted to show the eiiect or temperature increase upon a carbon pile regulator.

Referring to Fig. 3. there is a base II to which screws Ii secure a bracket I! attached by screws II to a heat-dissipating shell or radiator it. Referring to Fig. 2, screws ll secure to the base lo t e arms it of a clamp bracket which, b the tightening 01 a screw i1 cooperating with a out II, is caused to embrace tightly a magnetizable magnet shell 20 (Fig.

Shell supports a magnetizable plate 2i carrying an adjustable magnetizable core 12 supporting a metal tube 23 insulatingly supporting a main magnet coil 14 and an equalizer coil 25. Coil 2| is used when a plurality oi generators using similar voltage regulators are connected with the same storage battery.

Core 22 cooperates with armature 26 which is part of an assembly comprising spacer 21, spring discs 28 having blades 28a. spacers 2|, metallic disc Janos-conducting discs SI of mica, and

terminal plate I! attached to legs I! of a strut 16. This assembly is secured together by screws :1 and 14. Spring blades fla'epgage each other and the blades of the left hand disc 28 enga a ring I of copper or other 'non-magnetizable metal of good thermal conductivity.

Blades an urge the strut "against a metal disc 31 attached to a. carbon button I! thus placing a stack of carbon discs under compression. Discs II are housed in a refractory tube 40 enclosed by the radiator ll. Q

The magnet housing 20 is tied-to the remote end flange ill: of radiator N by studs 0 screwed into housing ll and having threaded ends 42a passed through holes in flange Ida and receiving nuts 0. Terminal plate II, attached by screws 5! to radiator I4. is insulated from the radiator It by a non-conducting plate 5i and from the screws 82 and metal washer 0G by insulating washers I4 and sleeves 08. Plate carries a screw it attached to a metal disc Ii, attached to a carbon button It which receives the pressure exerted byspring blades Ila on the stack of carbon discs ll. Screw BI is adJustI-ble to vary the normal pressure of blades 21a and the normal gap between armature it and core 12. The tubular screw-receiving portion I of plate 50 is split at I (Fig. i) to provide a screw-thread clamp which is tightened by a screw H. After screw It is ad- Justed, it is covered by a cup I having an ear I attached by a screw ll used to secure to plate It a wire clip I! attached to a wire 00.

The carbon stack is connected in series with the held of the generator to be regulated. Magnet coil N is in a circuit connected across the terminalg of the generator. said circuit including a fixed resistance unit 18 (Fig. 3) and a variable resistance unit ll controlled by a knurled disc 12.

The armature assembly is enclosed by a housin I h vin a flange Ii engaging a glass-fabriccovered metal ring I! received by a shoulder I! provided by magnet housing 20. Housing 00 has a flange I4 bearing against a glass-fabric-covered metal ring it received by a shoulder It provided by radiator I4. Housing II is resilient to provide for movement of the left end oi radiator i4 relative to magnet housing ll. 'mbe N. which expands faster than radiator ll, clears ll of housing 8| and bears again ll of a ring ll having resilient branches tachedto housing .0.

Screw ltsecurestoplate fltheclip "oia wire I! which passes through a bushing II attached to housing II and crimped arolmd the insulation wire ll.

Since the housing the iiangc the iianse ii atflistiedtothatendoi radiator II which is remote therefrom, expansion of radiator ll does not aflect the resistance 0! the carbon pile. Furthermore temperature variations in the carbon-pile do not materially ail'ect the pressure thereon because the materials 01 the studs 42, strut it and disc 31 are so chosen that the studs I! spend substantially the same amount as the combination of carbon-pile, disc 31 and strut it.

The resistance of coil 24 increases as its temperature increases and its pull per volt on the armature it decreases. In order that regulation for the same voltage may be obtained'as the temperature oi the coil It increases, heat from the carbon-pile causes the blades Ila to expand thereby causing their moduli of elasticity to decrease at a rate which compensates for the increase in resistance in the coil fl. 1n other words, for a given temperature increase, the coil 2| and the blades Ila become proportionately weaker so that the regulator, whether cold or hot, will regulate for the same voltage.-

In this connection it is important that the spring blades Ila should not be heated faster by the carbon pile, than the coil 14 is heated by the passage or electric current. Retardation (or transfer of heat by conduction from the carbon piletothespringslseflectedbythesmallcrosssectional dimensions or the legs ll oi strut SI and by the thick mica insulating disc II.

The heating of the blades as is limited due to the fact that the copper ring ll is continually drawing out the heat from the blades and passing heagdto the housing II from whence it is dissipa In order to demonstrate the functions of the heat-retarding strut 8i and the heat-absorbing ring ll, reference is made to Fig. 6 in which line A-B represents the voltage for which the neulatorissetandiineA-Crepresentsthcincrease oi regulated voltage due to heating the mag et coil by electric current. Line a-n represents the decrease in regulated voltage due to increase of spring temperature. Values 0 and D are those which exist at the end 0! the warm-up period when the dlfl'erential oi magnet coil and spring temperatures is practically constant thereafter. The ideal condition will exist ii line -0 is the exact opposite of line 5-0. the values D and C being the same and the slopes ot-tlrs lines denotlng rates of change oi voltage due to temperature increase being the same. The function of the 8H istoabsorbheatiromthespringsand topassitontothehousingwithwhichthering islnclocecontactinordcrsotolimittheheating of the springs that D, the final decrease in regulated voltage due to increase of spring temperature, will substantially equal C, the final increase in regulated voltage due to increase of coil temperature. The function of the strut ii is so to limit the rate 0! transfer of heat from the carbon pile to the springs that the rate oi spring temperature increase is commensurate with the rate of coil temperature increase whereby the rate oi. regulated voltage decrease due to spring temperature increase, as reprcsaitod by A-D is commenby A-C. While the mica surate with the rate of regulated voltage increase due to coil temperature increase. as represented insulating disc Ii has a retarding eflect, it would not be eilective to obtain a result approaching the effect represented by A-D without the strut 36 with its legs it which have relatively small cross-sectional dimenaions and which provide relatively large radiating surfaces. Without the strut 38, heat from the carbon-pile would be transferred so rapidly to the springs that the decrease in regulated voltuse due to spring temperature increase would be that represented, for example, by dash line A-E-D with the result that, during the warmup period, there would be a sag in regulated voltage as represented, for example, by dot-dash line A--F-B.

While it is known that mice will retard transier of heat, a. body oi! mica having thickness sumcient to obtain an effect approximately the eiIect represented by line A-D. could not be used since mica softens with increase of temperature and its thickness would be substantially reduced under the ressure of the springs; and the distance between the carbon-pile and the springs and the armature would be changed.

In view of the foregoing, it is apparent that the use of the metal strut 38 makes it possible to use a mica disc of moderate thickness suitable for electrical insulation. Strut 38 so retards the heat transfer to the mica disc II that the softening eiIect or temperature increase therein is negligible. A strut having a plurality o! spaced legs is relatively strong for the amount of material used in its construction. The cross-sectional dimensions of the legs are reduced to the minimum require ment of the spring pressure to be transmitted. The legs have relatlveLv large heat-dissipating surfaces inside as well as outside so that not all the heat in the fiat base of the strut passes into the plate 81. The strut N is therefore better adapted for the purposes oi the present invention than a tubular strut such as disclosed in my Patent No- 2,354,542 while its elongation with increase in temperature compensates to a material degree in compensating i'or elongation of the studs 4!.

While the embodiment oi the present invention as herein disclosed, constitutes a preferred form. it is to be understood that other forms m ht be adopted. all coming within the scope of the claims which (allow.

What is claimed is as i'ollows:

l. A carbon pile regulator comprising a housjuxtaposed carbon discs forming a stack loca within the housing; a refractory liner for aligning said discs; an electrode engaging one and of the stack and fixed relative to one end of the housing; an electrode engaging the other end 0! the stack and movable relative to the other end of housing: a frame located adjacent the last mentioned end of the housing in spaced relation thereto; an electromagnct supported by the frame; an armature cooperating with the electromagnet and attached to the movable electrode; biasing means for urging the armature toward the stack; a member for transmitting motion from the biasing means to the movable electrode adiacent thereto; a flexible closure having sealin engagement with the frame and the housing for completely enclosing the movable parts of the regulator so that same are not exposed to foreign matter; and resilient member supported by the closure and having a suspended central poriion engageable with the liner to permit free movement of the liner relative to the closure.

2. A carbon pile regulator comprising a casing; a refractory tube supported within the casing; juxtaposed carbon discs forming a stack or pile located within the tube; an electrode engaging one end of the pile and fixed relative to one end of the casing: an electrode engaging the other end of the pile and movable relative to the other end of the casing; a frame located adjacent the last mentioned end of the casing; means for securing the frame to the casing in spaced relation thereto; an electromagnet supported by the frame; an armature cooperating with the electromagnet and attached to the movable electrode; resilient means operatlvely connected with the frame and with the armature for urging the armature toward the pile; a member for transmitting motion from the resilient means to the movable electrode adjacent thereto; and a, flexible enclosure disposed between casing and the frame for completely enclosing the movable parts so that same are not exposed to foreign matter, said enclosure providing a cylindrical portion coaxial of said tube and engageable therewith to permit free movement of the tube relative to the enclosure.

3. A carbon pile regulator comprising a housing having one end relatively fixed and the other end free of obstruction to elongation or contraction due to temperature change: a stack of car bon discs located within the housing; an electrode attached to the relatively fixed end of the housing and engaging one end of the stack: a movable electrode engaging the other end of the stack; a frame located adjacent the free end of the housing: means for securing the housing to the frame in spaced relation thereto; an electromagnet supported by the frame; an armature cooperating with the electromagnet and attached to the movable electrode; resilient means operatively connected with the frame and with the armature for Alrging the armature toward the pile: a member for transmitting motion from the resilient means to the movable electrode adjacent thereto; a pair of fabric rings one supported by the housing the other by the frame; a flexible member disposed between the housing and the frame for completely enclosing the movable parts of the regulator so that same are not exposed to foreign matter, said enclosure providing a cylindrical portion at each end thereof with each cylindrical portion engaging one of the fabric rings to form effective seals between the enclosure and the housing and the frame.

4. A carbon pile regulator comprising a housing including a refractory liner: said housing having one end relatively fixed and the other end free of obstruction to elongation or contraction due to temperature change; a stack of carbon discs supported within the housing; an electrode engaging one end of the stack and fixed relative to one end of the housing: an electrode engaging the other end of the stack and movable relative to the other end of the housing; a frame located adjacent the last mentioned end of the housing in spaced relation thereto; an clectromagnet supported by the frame; an armature cooperating with the electromagnet and attached to the movable electrode; biasing means for urging the armature toward the stack; a member for transmitting motion from the biasing means to the movable electrode adjacent thereto; a pair of insulated covered rings.

one supported by the frame and the other by the housing; a flexible cover disposed between the frame and the housing for completely enclosing the movable parts of the regulator, said cover having annular flange portions at each end thereof with each flange engaging one of the rings to provide seals to prevent foreign matter from entering the interior of the cover: and a resilient member having arms attached to the interior of the cover and having a cylindrical portion engageable with the liner to permit free movement of the liner relative to the cover.

5. An electrical regulator comprising a frame, a stack of resistance discs supported by the frame, force applying means for compressing the stack and comprising an abutment member mounted on the frame in close contact therewith, spring means bearing on the abutment member and means for transmitting force from the spring means to the stack, electromagnetic means for opposing the spring means and comprising a. magnet coil supported by the frame and an armature connected with the spring means, said force-transmittin means including a strut of relatively small crosssectional dimensions and relatively large heat dissipating surface area and providing for a relatively low rate of transfer of heat from the stack to the spring means. said abutment member having relatively high thermal conductivity and relatlvely large area of contact with the frame, said force-transmitting means by virtue of its ability to limit transfer of heat from the stack to the spring means and said abutment member by virtue of its ability to extract heat from the spring means cooperating so to limit the temperature increase of the spring means, in rate and amount, that the corresponding decrease in modulus of elasticity of the spring means is proportional to the increase in resistance of the magnet coil whereby, during the warm-up period, variations in regulated voltage due to temperature variation are minimized.

6. An electrical regulator comprising a frame, a stack of resistance discs supported by the frame. means for applying pressure to the stack and comprising leaf spring members, a fixed abutment member mounted on the frame and in close contact therewith and having relatively high thermal conductivity and relatively large area of contact with the frame, and means for transmitting force from the springs to the stack and including a strut having spaced legs of relatively small crossserional dimensions and relatively large heat disslpating surface area and providing for a relatively low rate of transfer of heat from the stack to the springs, electromagnetic means for opposing the springs and comprising a magnet coil supported by the frame and an armature connected with the springs, said force-transmitting means by virtue of its ability to limit transfer of heat from the stack to the springs and said abutment member by virtue of its ability to extract heat from the springs cooperating so to limit the temperature increase of the springs, in rate and amount, that the corresponding decrease in modulus of elasticity of the springs is proportional to the increase in resistance of the magnet coil whereby, during the warm-up period, variations in regulated voltage due to temperature variation are minimized WILLIAM J. RADY.