US2441059A - Electric regulation - Google Patents

Description

May 4, 1948.' J. CR EVEL|NG 2,441,059

ELECTRIC REGULATION Filed June 12, 1944 I 76 80 82 as 54 K9 2 6 7 E- az f3 3121 69 24 S 86 a I 'NVENTOR Patented May UNITED STATES PATENT OFFICE ELECTRIC REGULATION John L. Creveling, near Tucson, Ariz.

Application June 12, 1944, Serial No. 539,931

22 Claims. 1

My invention pertains to that class of electric regulation wherein the voltage upon or the current in an electric circuit is to becontrolled automatically.

An object of my invention is to provide a sensitive regulator having relatively wide range which may be of small dimensions and cheaply built.

Another object is to provide an automatic regulator which shall come into action only when its services are required. Other objects will be pointed out in the specification or obvious therefrom to those skilled in the art.

As my invention is particularly applicable to systems wherein the dynamo or generator subject to intermittent operation and wide changes in speed is employed to charge a. storage battery and supply lamps or other translating devices it will be described with particular reference to such a system.

Fig. I is a more or less diagrammatic representation of a system included in my invention, showing some parts in elevation, some in section, and some in diagram.

Figs. II and III are partial sections and partial elevations of a portion of the structure of Fig. I on larger scale portraying features which cannot be seen in Fig. I.

Figs. IV and V are mere diagrams of conventional devices which will be used in pointing out some of the particular features of the present invention.

Fig. VI is a. partial section and partial elevation of one type of structure included in my invention.

Fig. VII is a top plan of a portion of the structure of Fig. VI.

Fig. VIII shows a modification that may be made in the structure generally portrayed in Fig. VI.

Fig. IX is a partial elevation and partial section of a portion of a structure included in my invention and in many respects similar to that of Fig. VI.

Fig. X is a top plan of a portion of the structure of Fig. IX.

Fig. XI is a section showing a modification that may be made in the structure of Fig. IX.

Fig. XII shows a modification that may be made in the structure of Fig. IX.

Referring to Fig. I of the drawing which includes a structure I have found very useful in laboratory work on account of its general flexibility and easy adjustability. I represents a generator or dynamo subject to intermittant operation and varying speed.

The generator I is shown as provided with a field coil 2 having connected in series therewith the carbon pile 3 as by wires 4 and 5.

The carbon pile 3 is mounted upon the base 6 of insulating material and is preferably held in proper position by vertical insulating rods (not shown). Base 6 is provided with a back plate.

or vertical member 1 and support member 8 provided with a metal plate 9 having a smooth upper surface which serves as a bearing for the rocker shaped portion of lever l I pivotally carrying the'adjustable pressure plate l2 bearing upon the pile 3. The adjustable spring [3 tends to depress the left hand end of lever II' and compress the pile 3 and, when the generator is idle or running at sufficiently low speed and the elements of the structure are in the positions indicated, to revolve the lever about the pivot I4 and thusto lift the rocker portion from the bearing plate 9 until arrested by the adjustable screw I5. Under these conditions the pile 3 will be tightly compressed and of low resistance and may even be short circuited as by contact members I6 and I! and wires I8 and [9 by proper adjustment of screw IT.

The right hand end of lever H is perforated to allow the sleeve 20 to pass therethrough without contact while the sleeve in turn is bored to slide over the threaded stem 2| carrying the armature 22 operated by an electro-magnet, in this instance shown as of the iron-clad type having the shell 23, adjustable core 24 and' 'voltage winding 25. The magnet is secured to the base Gas by screws (not shown) and is here shown as having the winding 25 connected across the generator circuit as by Wires 2B and 21 through a resistor 28 which may be used for adjustment or to provide temperature compensation in a manner now well known in the art. The magnet is also here shown as provided with a magnetic shunt 29 which, by being made of material having its permeability decreased by increase in temperature, may be employed for temperature compensation in a now well known manner if desired.

* 3 i5 and thus assist spring l3 in compressing the pile 3, owing to contact of the adjustable ball faced nut with the end of the lever II. The sleeve 26 carries a member 34 provided with knife edges on opposite sides of the sleeve adapted to engage suitable notches on each side of lever II when the stem 2! is moved downwardly so that when suiiicient downward movement has been given to armature 22 any further movement will draw lever H downwardly about pivot l4 and break contact with screw l5 and bring the rocker portion of the lever to bear upon the plate 9, whereupon any further downward movement of the armature 22 will cause the short-circuit contact iii-ll to be broken and the pressure upon pile 3 to be decreased in an obvious manner Therefore, proper operation of tnearmatur 22 may be caused to regulate the generator for-constant voltage throughout speed changes above the minimum speed required to generate thevoltage desired to carry. I v

In" Fig. I the generator is shown as having' its lower brush connected by'wire "35 with one side of storage battery 36andl'amps or other'translating devices 3! while'the upp'erbrush is shown as connected as by wir'e38 "withfone side of any suitable automatic" switch; the mere presence cf'which is indicated at39, which has its opp'osite side connected with the freete'r'rninals 'of' the battery and translatingdevices as by wire 40. Wire 4!] has in series therewith the current coil 4|, of a clapper type magnet 'supp'or't'edinany suitable manner (not shown) and having the armature 12 which, when attracted mayrotate against the effort of adjustable 'spring43 tobring the leverd-G in contact withthe adjustable nut 45 upon the tail rod 30and'thusass1stthe magnet 23-24-25' and :lowerthe voltage uponthe generator in such mannenas'will prevent the desired maximum current to be delii'rer'ed bythe generator from being exceeded.

The lever H is maintaine'dinproper'relation to the other parts bymeans ofthe-fiexible strip 46 shown in Fig. IIhavingits upper'right hand end attached to the lever by s'crew"4'l'and its lefthand end attached to the plate 9 by the screw 48. The strip '48 is confined-within the-channel 49' shown more-plainly in the" sections-appearing in Fig. III, which are taken'a'long'the lines ap-' pearing above the same inFig. II and viewed in the directions indicated by-'the arrows. This arrangement'permits'the lever to rock freely upon the plate 9 and even to be lifted'alimited' distance above the same as indicatedin Fig. I. As the lever II is rocked upon the plate 9 under the influence of armature 22 its point of contact changes so as to change'theposition of the fulcrum of the lever in such n'ranruer as to compensate for the changes in pull exerted by the magnet 232425 dueto approachiof the armature and also to compensate for any changes in the effect of the springsl3 and 32 as well' as the elasticity of the pile. H U

Fig. VI shows a more compact commercial type of voltage regulator wherein the carbon pile 3 is shown as compressed between theadjustable plug 59 and the pressure-plate 5| and insulated therefrom as indicated. H

The pile is held in position, by the surrounding tube 52 having thin walls of ceramic or other insulating material capablefof withstanding relatively high temperatures withoutlos'ing itsinsulating character. I p

This tube which may 'beja' Inere coat of heat resisting enamel is carried bythebodyportion 53 having heat conducting'and dissipating fins f the pile as low its regulating cation of-the pile 3 through the contact of plate 5| with the posts 58 carried by the member 59 (shown in Fig. VII) bearing upon the upper side of spring 55.

The armature 22 is here shown as carried by the rod Gil passing through the perforated "discs of pile 3 and drawn upwardly by the corn- 'pression spring "3! acting against the adjusting nut 62 and, as the member 63 (shown in dotted lines'inFig. VII) bears upon the lower side of spring 55, spring 5! tends to assist spring 55 in compressing the pile *3.

The voltage"winding25 is here'shown as surrounding the-adjustableholid core24 carried by the shell 23 which may be adjusted with respect to-the armature-asbythe threads at '83 engaging'thebbdyportion53. If armature 2?. is drawn downwardlyiny magnet -23-2 i-25 it will be opposed only by spring-e4 until the adjustable nutEEi'strikesi-the -upp'er sideof member 58 and then-further' downward movement will be oppos'ed'by spring'fiii and tend to release the pressure upon the pile -so as-to raise its r sistance to 'co'nt'rol'theg'eneratarvoltage if conncctedin 's'eries'with its'fieldas by'means-of pigtails 6S. Them'emb'er -59 'has its lower surf ace so formed thatas it is drawn downwardly it extends its bearing from the cente'r of '-the spring toward theendsthereof in 'such'm'anner as to increase the resistance offered by the spring to compensate for the increase inpull of the armature due to approach toward the magnet.

In"Fig 'VI-II there isshown an adustable magnetic shunt 61 which may be incorporated in the structure of FigfVPandwhich has portions 68 extendingi'around the outer 'edge of the armature asfar-as desired. This tends quitestrongly to hold the armature from being-drawn downwardly diiringthe init'ial energization of the magnet While'the' armatureis in theposition shown. The position of the shunt-may beadjusted by means of the threaded arrangement at 69. V In FlgIX a portion of-the carbon pile is shown atB' ascontained w'ithin"the tube 52 which is carried by the body portion 53 and the pile may have-its position-"adjusted as by a screw plug similar to 5 U in Fig. VI. Here the pile is shown as o frelativelythick-discs as used for relatively lower voltage and as-restin'gupon the member Tihshown in top plan in Fig. X. Member 10 rests upon-thespring H- and is connected with member 12 as-by screws "13 while a flexible member 14 at right angles to spring II is clamped together with spring 'H between members 10 and i2. The'flexible member 14 may be either another spring similar to II or merely a readily bendable memberserving principally to maintafin'th'e partstncentralpositions as desired.

Spring Handmember'IA have depending portions which rest'upon the'ledge 15' and together tend to compress the pile'3. The armature 22 is carried -b'ythe rod 16 'passing through the hol- Ibfw magnet corefifandlprovided with a head 17 within the'pocketmfin" the member 12. The armature is pressed upwardyby the leaf spring 19 which holds the armature I: in the position shown when the winding- (not shown) within the shell 23 is deenergized.

The leaf spring 19 rests upon ledges 80 of the shell BI and is perforated to receive the tail rod 82 of rod 16 to hold the latter in central position while the tail rod 82 if depressed will strike the flexible member 83 and break the contact at 84 which may be connected to short-circuit the pile in an obvious manner if desired. In this structure member has its lower surface soformed as to increase its bearing upon spring II and member 14 to compensate for approach of the armature toward the magnet.

In Fig. XI there is shown another means of supporting the spring H of Fig. IX which may -be used instead of the ledge 15 of Fig. IX. Here a spring ring 85, split as indicated at 8,6,iis sprung into an annular channel in the body portion 53.

Before taking up the operation of the present invention it will be noted that, with-a carbon pile regulator of conventional prior art type as indicated in Fig. IV, if we consider both the solenoids deenergized the pile will of course be under the maximum pressure and its resistanec will be at its minimum value. In a system employing a generator which operates intermittently and at variable speed it is .of: course-very desirable that the pile shall remain under maximum compression until the voltage or current to be limited by the regulator reaches the full maximum desired value, so as to allow the field to build up rapidly in starting and to obtain full generator output at as low speed as possible.-

If we assume the pile of Fig. ,IV connected as is pile 3 in Fig. I and the solenoid at the left connected across the generator as is-"the winding 25 in Fig, I and the right-hand solenoid inoperative, then, as the generator voltage rises from zero to its desired maximumgvaluesome of the pressure upon the pile will be relieved throughout this process, even though no very marked change in the position of the lever may be noticed, and this drawback of course is aggravated by the elasticity ofthe pile. This is a great disadvantage in this type of regulator.

If we assume the left-hand solenoid to be inoperative and the one at the right to be connected as above mentioned then the pile will remain at maximum compression untill, suiiicient voltage is reached to lift the core into contact with the lever, but from this point;.on the action will be the same as in the previous case. As it is desired that the maximum pressure upon the pile shall be quite heavy this means that the solenoid core will encounter considerable resistance to upward movement when it comes in contact withthe lever and on this account must be brought into contact .at a .voltage usuallyvery much below that to be limited and that, therefore, throughout a large portion of therlse in voltage to full value the pressure upon the pile will be relieved as in the-first case, even though this" is not true at the veryrlowest speeds, at which time the voltage is nowhere near the value to be limited, and the effect even upon a connected core like the one at the left would the least and of little moment.

Now, if we increase the power of the solenoid, and therefore its size, it will be affected less by the added load upon contact with the lever and may be arranged to bring its core into contact at more nearly the voltage value to be limited and thus grow better and. better: as a regulator as the size of the:so.lenoid is 'increased.;.. How;

6. ever, there is a practical limit to size and power of the solenoid which necessitates the core acting against the lever for a considerable portion of the time while the voltage is rising to full value and this at the most undesirable time when the voltage is approaching full value and the solenoid is thus strongest and most able to hold the voltage from reaching its full value at the instant speed.

Now, in the structure of the present invention, instead of the usual solenoid as the one at the right in Fig. IV, having substantially constant force throughout its useful range for a given excitation, there is employed an iron-clad magnet of the general type indicated in Fig. V. This type of magnet is capable of exerting a very strong pull upon its armature throughout a very limited distance and as here used manipulates the pile to perform its regulating function by slight movement of the armature while separated from the magnet by a small airgap, say for example, while the armature has its lower face within the space indicated as a in Fig. V.

Thus, while the magnet is actually performing regulation it is caused to do so against heavy spring pressure capable of compressing the pile suiilciently to lower its resistance to very low value when not affected by the magnet which of course is a very valuable feature. On the other hand, since the pull upon the armature decreases so rapidly upon its movement away from the magnet, a relatively light spring is capable of holding the armature from approaching the magnet if the air gap is increased only a reasonable amount, as for example, when the armature occupies the position indicated in Fig. V. These features are utilized in the present invention to make the regulator perform much as the one shown in Fig. IV would, if the lefthand solenoid were suppressed and the right-hand one were of reasonable dimensions as usual until the core came in contact with the lever and then were transformed into a very powerful one capable of at once operating against a heavy spring to affect the pile upon very slight increases in excitation.

That is, if the armature be in the position shown in Fig. V it can be held in that position by a light spring until the voltage across the magnet reaches substantially the value to be limited, and when this value is reached it will be descend, and while passing through the space indicated at b the pull per ampere turn will be transformed from weak to strong and the magnet Will be capable of at once operating to effect the regulation against a strong spring upon very slight changes in excitation, as will be seen from the following description of the operation of the invention.

An operation of the system of Fig. I is substantially as follows:

With the generator at rest and theparts in the positions shown in the translating devices may be supplied by the battery in the usual manner.

If the generator be started and its speed gradually increased, the field will build up quite rapidly as the pile 3 is short circuited and the generator voltage will soon equal that of the battery and cause the switch 39 to close and connect the generator with the battery and translating devices,

'adjustmentof spring 32 and the air gap be ampere.

tweamthearmaturell and the. magnetyl can: cause the; armature to be drawn downwardly and the knife edges 2|] to be'brought into contact with the lever II at a voltage slightly below; equalto, orslightly above'the maximum desired to have held across. the generator. When. this occurs, lever II will be drawn down into contact with. the. plate 9, breaking the short circuit at l6l'i and the pile 3 will now be able to con, trol the generator voltage throughout. further increases in speed if. properly manipulated. Thepullupon the armature per ampere turn in: the magnet may now be severalv times that when the armature was in the position shown inthe figure and therefore if properly utilized: will cause the. regulator to respond to very'small changes in; voltage across the magnet, while able to operate against quite strong pressure exerted by spring 13 capable of placing the pile 3 under'heavycompression when allowed to do so.

I now soadjust the member l2"that thecon.- tact of-the. lever II with the plate 9 isxat such point as properlyto compensate for furtherape. proach ofthe armature toward the magnet and adjust the'spring 13 to give the d'esiredvoltage and this will be held constant'withinvery. narrow limits throughout furtherchanges in. speed so long as they take place above that speed necessary togenerate the chosen value. If at any time the chosen voltage tend to cause a greater currentthan desired, the series coil 4| will rotate its armature against the effort of spring 43- and cause lever 44 to engage nut 45 and assist mags net 239-24925 and lower the voltage to prevent the maximum desired current from being ex,

ceeded.

It is here to be noted that the screw l has a support which is adjustable upon the upright 1 so: that the screw may have such position as not to interfere with the rocking movement of lever H within the limits of useful operation, and that no. attempt has been made in the drawing to portray the exact curvature of the lever I l or the exact position of the armature 22 with respect to. the magnet.

If the parts are so arranged and adjusted'that. the armature 22 moves the knife edges into contact with the lever H at a voltage. slightly below the *full value to" be maintained, a slight rise in voltage to full value will take place before the magnet assumes the regulation, while if the above armature action takes place at thev desired maximum voltage, the magnet will at once take up the regulation while if the voltage be allowed slightly to exceed the desired value before the said armature-action takes place, it may be caused to at once lower the voltage. to the. proper value and hold it within very narrow limits.

InEtl'ie structure of Fig. VI the initial movement of the armature 22 proceeds as in Fig. I until the nut 55 strikes the member and then the relatively strong spring 55 is encountered and the regulation brought about in' a manner believed obvious in View of the foregoing. Here the shap.-. ingof; the lower sideof the member 59. causes it so to vary the action of the spring as to effect much the same result as the shifting of the point of contact of lever H in Fig. I while sliding of theen'ds of the sprin upon its support is avoided.

by the flexibility of the brackets 56.

In the modification shown in Fig. VIII the excitation required to bring the armature into operative position may be materially modified by themmetic ShLllIt BI GB which will tend to hold a. the; armature-inc itswinoporative position until overpowered; and then will suddenly release thesame and have little further eflectupon its operation it properly-proportioned.

Thooperation o1 the-structure of Fix. IX is believed to; be so. plain from the foregoing that itieonlyneoessaryto point out that the armature hasrita-initial". movement opposed by the spring 18. against the; effort of. which it brings the head 1101 0118: r0416. intocontactwith the lower portion. 01* member :12 to-affect the action of spring 'lliandliliuponthc pile and-that during its initial movementzltopensthe contact at 84 which may be used to short-circuit the pile in an obvious manner-flashed. In this embodiment sliding actionotspring H upon. its supports is avoided by the shapihg of the spring as indicated.

IKEIQ-LXIETthmrod N is shown as resting upon themember TI -which in turn rests upon the spring 1 II- and has; itsrlowcn surfaceso shaped as to comprimate-as; rnuchasv desired for the increase in pullupcnthoarmaturo due to approach toward the magnet; And,- it is of course plain that insteadot arr-ordinary. tension spring at 32 in Fig. I 1 and anordinary'compression spring at 6| in Fig. VI; I mayuao-any desired type of spring mechanismrwhich.v will bringaboutthe same action as the memberl'lfshown in Fig. XII if desired so to do.

I donot here limit myself to any of the exact constructlonsvshownnor. to any of the particular modes. of operation herein described, which have beenset forthimarely toillustrate a few embodiments of. my'invcntion, which is as set forth in the following" claims.

I- claim:

1-. Regulating means including a regulating element, meansxtonding to reduce the resistance of said element; means for increasing the resistance of" said element andautomatic means including'a-magnotic shunt for. rendering said resistance increasing, means inoperative under predetermined conditions.

2;. Regulatlngjmeans including a regulating element, means tending toreduce the resistance of said element, meanstending to increase the resistance of said. element in response to an in-- crease in an.- electrical quantity, and means for rendering :said resistance increasing means inoperative also. affected bychanges in said quantity and including a magnetic shunt.

3. Means for regulating a generator including a regulating elementfon affecting the output of a generator, means, tending to affect said element to. increase the. generator output, means for varying the affect: of said last mentioned means in response to. fluctuationsin a function of said output and separately -movalzde automatically operated .meansv for affecting the element and simultaneously delaying the action of said varying means 'also -aflected by. said function.

4., Regulating means including a regulating element, meansafor aflceting said element in a given sense, .elcctrmmagnetic means for affecting said elementin anopposite sense, and means for opposing the operation. of the electro-magnetic meansaflecting the. element and responsive to the effect of excitation of the electro-magnetic means.

5. Regulating means including a regulating element, resilient means for affecting said element ins. given sense, alectro=magnetic means for affooting the element in an opposite sense against the o! the resilient means and means for opposing the initial. operation of the electromagnetic means affecting the element and responsive to an effect produced by excitation of the electro-magnetic means.

6. Regulating means including a regulating element, resilient means for affecting said element ina given sense, electro-magnetic means for affecting the element in an opposite sense against the effort of the'resilient means, means for com trolling the initial operation of the electro-magnetic means responsive to the effect of excitation of the electro-magnetic means and means automatically affecting the further operation exerted by" the electromagnetic means by varying the opposition of the resilient means.

7. Regulating means including an element the effect of which is variedby variations in pressure thereupon, means tending to exert pressure upon said element and means for controlling the pressure thus exerted comprising an electro-magnet having a useful field of rapidly diminishing strength with respect to distance, an armature for said magnet, means for exerting pressure upon the element and holding said armature in a relatively Weak portion of the field of said magnet including a lost motion device permitting the armature to move into a strong portion of said field upon predetermined excitation of said magnet and means whereby the armature may affect the element while in said strong portion of the field.

8. Regulating means including an element the effect of which is varied by variations in pressure thereupon, means tending to exert pressure upon said element and means for controlling the pressure thus exerted comprising an electro-magnet having a useful field of rapidly diminishing strength with respect to distance, an armature for said magnet, means for compressing said element and holding said armature in a relatively weak portion of the field of said magnet permitting the armature to move into a strong portion of said field upon predetermined excitation of said magnet and means whereby the armature may affect the element only while in said strong portion of said field.

9. Regulating means comprising a carbon pile, means for exerting pressure upon said pile, means for controlling said pressure including an electromagnet having a useful field of which different portions vary materially in strength per ampere turn, an armature within the field of said magnet means whereby the armature may affect the pressure, means for holding said armature in a weak portion per ampere turn of said field until a predetermined field strength has been reached and then allowing the armature to move into a strong portion per ampere turn of said field to render operative the means whereby said arma ture may affect the pressure upon said pile while in said strong field.

10. Means for regulating a generator, comprehending an element for affecting a generator output in response to changes in pressure applied to said element, means for exerting pressure upon said element, and means for modifying the pressure exerted thereby including a magnet affected by a function of the generator output, an armature affected by said magnet, means for preventing said armature from affecting said pressure upon said element below a predetermined value of said function and then permitting said armature to move into pressure relieving position, said change in position greatly increasing the magnetic effect per degree of fluctuations in said function in said magnet upon the armature,

11. In a regulator including a carbonpile', a spring, a member bearing upon said spring and transmitting pressure to said pile, said member extending its bearing upon said spring to increase the effect of said spring upon movement of said member to decrease the pressure upon said pile,

12. An electric regulator comprising a carbon pile, a spring, a member bearing upon and trans' mitting pressure from said spring to said pile, .an armature for affecting said member, an electro:- magnet for affecting said armature, said member being adapted progressively to vary its effect upon said spring when said member is moved by said armature.

13. An electric regulator, including an electroinagnet having a field of rapidly diminishing strength per ampere turn at distances therefrom, an armature in'said field, means for moving said armature away from said magnet and holding said armature in a weak portion of said field per ampere turn until said field attains a certain strength and then permitting said armature to move into a strong portion of said field per ampere turn and means whereby said armature mayperform a regulating function only while in said strong portion of said field in response to fluctuations in the strength of said portion of said field.

14. For use in an electric system having a generator and. a load circuit supplied thereby, a regulating element for affecting the output of'the generator, 'means for operating said element including an electro-magnet having a field affected by a function of said output, an armature in said field, means tending to hold said armature in a weak portion of said field and allowing it to move into a strong portion thereof only upon predetermined strength of said field, means whereby said armature may affect said element only while in the stronger portion of. said field, means opposing movement of said armature only while in said strong portion of the field, and movable means whereby said opposing means increases its opposition as said movablemeans is moved toward saidmagnet.

15. For use in an electric system having a generator and a load circuit supplied thereby, a regulating element for aifecting the output of the generator, means for operating said element including an electro-magnet having a field affected by a. function of said output, an armature in said field, means tending to hold said armature in a weak portion of said field and allowing it to move into a strong portion thereof only upon predetermined strength of said field, means whereby said armature may affect said element only while in the stronger portion of said field, means opposing movement of said armature only while in said strong portion of the field, means whereby said opposing means increases its opposition as said means is moved toward said magnet, and means for assisting said magnet in response to another function of said output.

16. An electric regulator including a regulating element responsive to changes in pressure thereupon, a spring supported substantially at its ends, a member bearing upon said spring at substantially its mid-portion and transmitting pressure to said element, and electro-magnetlc means for moving said member to alter the pressure upon said element, said member being adapted to alter its bearing upon said spring when said member is affected by said electromagnetic means.

17. An electric regulator including a regulatthereupon. a spring supportedsubstantially at itsends, amember bearing upon said spring at substantially its. mid-portion and transmitting pressure tosaid element, and electro-magnetic means-for moving said member to alter the pres-- sure. upon said element, said. member being adapted to alter its bearing upon said spring duringsaid movement.

18; Regulating. means including a regulating element, ,a strong spring affecting said element, an electro-magnet. having, a field of rapidly diminishing. strength. with respect to distance from said magnet, an armature in said field, means operated by said armature capable of aiiecting said element only when the armature is in.,a. strong portion of saidfield, relatively Weak means for holding the armature in a Weak portion of said fielduntil a strong portion of said fl'eldis substantially capable of operating the armature against theefiort of the above mentioned-strong-spring. and then allowing the armature to moveinto. said strong. portion to atfect. the, regulating element against the effort oithev strong. spring uponslightxohanges in the excitation. of. said magnet.

19. Regulating. meansincluding a regulating element, main and auxiliary means each capable of. automatically increasing the initial pressure upon said'element, an electro-magnet, and an armature for said magnetthe movement of which inresponse. to attraction by the magnet is cpposed first-by one. and then by both of the com pressing means.

20. Regulatingmeansincluding a regulating element, main and auxiliary means each reducing. theinitial; resistance of said element, an electro-magnet, and an armature for said magnet. the movement of. which in response to attractionby the magnet is opposed first by one and. then. by both of. the resistance reducing means.

21. Re8u1ating..means,including a regulating element, means for reducing the electrical resistance of said element offering strong mechanical resistance against movement to cause increase in the electrical resistance of said element, an electro-magnet having a field of rapidly decreasing strength per ampere turn with respect to distance from said magnet, an armature in said field, means-whereby motion of the armature may increase the resistance of the regulating element, means for holding said armature in a relatively Weak portion of said field per ampere turn until a strong portion of said field per ampere turn is substantially capable of operating the armature to aflect the element against the strong mechanical resistance and then permitting the armature to moveinto said strong portion of said field per'ampere turn to become able to operate the resistance increasing means.

22. A compressible pile type of regulator, including means for exerting heavy pressure upon the pile, means for controlling the pressure including an armature, a magnet having a field with rapid decrease in strength with respect to distance capable of. attracting the armature to overcome the pressure exerting means only when in a strong. portion of said field and means for holding said armature in a weal; portion of said field until said strong portion 25 of substantially sufficient strength to aflect the compressing means and then allowingthe armature to move into said strong portion of the field. to become able to affect the compressing means.

JOHN L. CREVELING.

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

UNITED STATES PATENTS Number Name Date 1 1,162,174 Krauss Nov. 30, 1915 1,356,099 Turbayne Oct; 19, 1920 1,394,148 Creveling Oct. 18, 1921 1,700,041 Grob Jan. 22, 1929 1,939,870 Wike Oct. 18, 1921 2,268,718 Newton Jan. 6, 1942

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