US2478835A - Carbon pile regulator - Google Patents

Description

Aug. 9, 1949. w. J. RADY ETAL CARBON FILE REGULATOR Filed Aug. 8, 1945 a/ &4 ATTORN EYL I I VENTOR S BY W T Patented Aug. 9, 1949 UNITED STATES PATENT FICE GARBGN FILE REGULATOR Application August 8, 1945, Serial No. 609,670

Claims. (01. 201-51) This invention relates to carbon-pile regulators for controlling either the voltage or the current produced by a variable speed generator.

An object of the invention is to provide means for compensating ifOI' the effect upon the regulator caused by expansion of carbon-pile discs due to temperature increase.

A further object is to provide means for stabilizing the operation of the regulator particularly when there is a sudden change in load upon the generator regulated thereby.

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

In the drawings:

Fig. 1 is a longitudinal, sectional view of a regulator embodying the present invention;

Fig. 2 is a sectional view of a thermal responsive unit which compensates for expansion and contraction of the carbon-pile due to changes in temperature.

Referring to Fig. l, a suitable mounting base, not shown, supports brackets Ei and ii which support a tubular frame i2 of magnetizable material having a partition 53 having a central opening M which receives the central magnetizable core attached to a magnetizahle plate is attached to the frame 82. Core 65 supports a nommagnetizable sleeve ll which insulatingly supports magnet coils lo and iii. If the regulator is used lfO'l regulating voltage, the coil 58 will be connected across the generator erminals and coil I8 is used as an equalizer coil when a plurality of voltage regulators are used for controlling generators which charge a common storage loattery. In case of the current regulator, the coil I8 is responsive to battery charging current.

The frame 12 supports a plurality of studs the right ends of which are attached to a radiator 2| having heat dissipating fins 22. Radiator 2i encloses an electrically insulating ceramic tube 23 of good thermal conductivity enclosing a plurality of carbon discs which are in contact with electrodes 25 and 25. Electrode 25 contacts a metal disc 27 attached to the end of a screw 28 threaded through a boss 29 provided by a plate 36, insulatlngly supported by the radiator 2!. Boss 29 is cut part-way by a saw cut 36 to provide a part 29a which can be caused to spring toward the part 29 by turning a screw, not shown, which passes through a plane hole in the part 29a and is screw-threaded into the part 23. A cap 32 attached to the plate 3% in any suitable manner protects the outer end of the screw 28. Electrode 26 is in contact with a metal disc 35 attached to the base of a strut 36 having a plurality of legs 3? of relatively small cross-sectional dimensions and providing a relatively great heat radiating surface. the strut legs iii are connected with a terminal plate 38 to which a terminal screw attaches a wire 9. The wire 48 and the plate are connected into the circuit of the generator field coil.

The partition 53 and the core l5 provide pole faces adjcent to an armature M which is maintained in central location by a plurality of spring lingers d2 extending radially from and integral with plurality of discs made of spring metal such as stainless steel. The discs are separated by spacers The left hand disc 53 is separated from armature ll by a disc The right hand disc is separated by metal spacer from a mica spacer El located between the discs 45 and terminal plate The metal discs are secured to the armature t! by screws 48 and it, the

latter serving also to secure the plate 33 and the mica disc ii to the other discs and to the armature. As shown screws til are insulated from the plate 38. The ends of the spring fingers are spaced slightly from the cylindrical wall 52a of frame i2 and bear against ring of non-magnetizable metal and having good thermal conductlity. Ring is in good thermal contact with the wall lid, so that heat extracted by the member 5-9 from the sp ing fingers 42 will be readily transmitted into 1 ie frame iii.

Between the member it-l and the partition l3 there is located (ll-SC iii of resilient non-magneb izable metal which is attached to the armature [i l, a spacer ring and a inagnetizable metal disc 555. Between the discs 5i and air is trapped for a purpose to be described later. The spring fingers :2, being normally biased toward the ring cause the armature ll to be urged toward the right thereby causing pressure to be exerted through the strut legs upon the carbon discs 2%. Obviously, the initial pressure upon the discs can he regulated by turning the screw In order to exclude dust from the movable parts of the regulator, the fra he provides a re= cess defined by a ledge 55 w .ch receives a seal ring of glass covered music wire 55 against which s the flange of a housing having a contrai in MS right wall defined by the por tion which bears a glass covered inusic wire ring ill in a recess provided by radiator 25. To the interior of the right wall of housing 58, there are attached a plurality of resilient arms 62 extending radially from a ring 63 having an annular flange 64 bearing against the left end of the refractory tube 23. As the temperature of the regulator increases, radiator 2| will expand faster than the tube 23 thereby deflecting the portion 59 of the housing relative to the flange 64 of ring 63 which remains in contact with the tube due to the bias of the resilient arms 62. Housing 58 supports a grommet 65 through which the wire 40 passes.

In copending application of William J. Rady, Serial No. 509,454, filed November 8, 1943, issued as Pat. #2,400,136, May 14, 1946, the strut legs 3'! and the ring 5!] cooperate together so as to limit the rate of temperature increase of the spring fingers 42 that rate of decrease of modulus of elasticity of the spring fingers will be commensurate with the rate of increase of the resistance of the magnet coil 18 due to the effect of passage of electric current therethrough. Therefore, during the warm-up period of the regulator, there will be practically no variation of regulated voltage; and, at the end of the warm-up period when equilibrium between the differential of spring temperature and magnet coil temperature is reached, the regulation will remain practically the same as at the outset. In other words, the heating of the spring fingers 42 is so controlled as to compensate for the heating of the magnet coil.

The present invention provides compensation for increase in thickness of the carbon pile discs as temperature increases. To provide this compensation, there is inserted between two of the carbon discs a compensating unit iii shown in section in Fig. 2. The unit in comprises two dished washers H and 72 having fiat annular surfaces adapted to engage the adjacent carbon discs such as 24a and 24b and having pockets 13 and M respectively for receiving the head 15 of a rivet and a washer 16 over which the rivet is formed at 11. In order that there may be relative movement between the discs H and 12, the rivet i5 is not swedged so tightly as to take up all the clearance. Fig. 2 shows that normally there is a small gap 18 between the parts H and '12 which are maintained in extended relation by a bimetal washer 19 comprising two dished rings, namely, ring 80 of metal having higher temperature coeiiicient of expansion and a disc 8| of metal having lower temperature coefiicient of expansion. The unit i is preferably located near the right end of tube 23 where it will be likely to be the most responsive to temperature changes in the carbon pile. As the temperature increases, the thickness of the carbon discs 24 increases, thereby tending to increase the pressure between the discs and thus interfering with regulation. However, the unit 10 operates to offset the tendency to increase the all-over length of the carbon pile since, as temperature increases, the bimetal member l9 tends to bend toward a more flattened position thereby permitting the gap 18 to be decreased so that the all-over length of the carbon pile including the unit in will remain the same regardless of temperature.

In order that the regulator will not otherwise be affected by changes in temperature, the studs 20 and the strut 36 are made of metal having practically zero temperature coemcient of expansion such as Invar metal.

When the load on the generator is suddenly diminished, there is a tendency to increase its voltage suddenly, thereby causing a sudden increase of pull of the magnet of the regulator.

If the armature were free to respond to the sudden pull of the magnet, its amplitude of oscilla tion would be abnormal and would tend to oscillate an unusual length of time before returning to equilibrium. Abnormal oscillation of the armature is resisted in the following manner. Normally disc 5| oifers small resistance to movement of the armature, but increases in stiffness rapidly as the armature moves an abnormal distance toward the diaphragm thereby tending to reduce motion toward the magnet. The compression of the air between the discs 5| and 53 also reduces this motion. If the armature still moves too far toward the magnet, the generator field current is over-reduced, generator voltage drops abnormally, and magnetic pull on the armature decreases suddenly with the result that springs 42 are permitted quickly to move the armature away from the magnet. As disc 5| rapidly approaches the ring 50, air between these parts is rapidly compressed and motion of the armature away from the magnet is reduced. Thus, by preventing normal oscillation of the armature under these conditions, stability of operation is obtained. At the joint between the ring 52 and the discs there is a restricted flow of air out of and into the space between the discs.

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

What is claimed is as follows:

1. An electrical resistance regulator comprising a stack of discs of resistance material, electrodes between which the stack is confined, one electrode being movable relative to the other, spring means acting through the movable electrode to apply pressure to the discs, an electromagnet having a coil responsive to an electrical function, an arma ture connected with the movable electrode and at-- tracted by the electromagnet in opposition to the spring means confined within the stack, and means for preventing the all over length of the stack of discs, said means compensating for changes in the thickness of the discs due to change in temperature whereby the force applied by the spring means to the stack is unaifected by varia tion of the temperature of the stack.

2. An electrical resistance regulator comprising a stack of discs of resistance material, electrodes between which the stack is confined, one electrode being movable relative to the other, spring means acting through the movable elec- 55 trode to apply pressure to the discs, an electromagnet having a coil responsive to an electrical function, an armature connected with the movable electrode and attracted by the electromagnet in opposition to the spring means, and an 60 electrically-conducting spacer of variable thickness located between certain discs to offset the tendency to increase the all over length of the stack, said means having temperature responsive means for adjusting its thickness to compensate 65 for change in the thickness of the discs due to change in temperature whereby the force applied by the spring means to the stack is unaffected by variation of the temperature of the stack.

3. An electrical resistance regulator comprising 70 a stack'of discs of resistance material, electrodes between which the stack is confined, one electrode being movable relative to the other, spring means acting through the movable electrode to apply pressure to the discs, an electromagnet having a 75 coil responsive to an electrical function, an armabimetallic washer located between the other washers and operating to become more flat with temperature increase whereby the thickness of the spacer decreases to compensate for increase in the thickness of the discs due to increase in temperature whereby the force applied by the spring means to the stack is unaffected by variation of the temperature of the stack.

4. An electrical resistance regulator comprising a stack of discs of resistance material, electrodes between which the stack is confined, one electrode being movable relative to the other, spring means acting through the movable electrode to apply pressure to the discs, an electromagnet having a coil responsive to an electrical function, and having flat pole faces, an armature parallel with the pole faces and connected with the movable electrode and attracted by the electromagnet in opposition to the spring means, and means for resisting abnormal oscillation of the armature comprising substantially parallel discs located in the gap between the armature and pole faces and extending substantially beyond the periphery of the armature and an annular spacer located between the discs and adjacent to their peripheries, the central portion of one of the discs being urged by the armature toward the other disc when the armature is attracted toward the pole faces whereby abnormal motion is resisted by the increased stiifness of the moving disc and by the compression of the air between the discs.

5. An electrical resistance regulator comprising a stack of discs of resistance material, electrodes between which the stack is confined, one electrode being movable relative to the other, spring means acting through the movable electrode to apply pressure to the discs, an electromagnet having a coil responsive to an electrical function, and having flat pole faces, an armature parallel with the pole faces and connected with the movable electrode and attracted by the electromagnet in opposition to the spring means, means for resisting abnormal oscillation of the armature comprising substantially parallel discs located in the gap between the armature and pole faces and extending substantially beyond the periphery of the armature, an annular spacer located between the discs and adjacent to their peripheries, the disc nearest the armature being attached thereto, a ring surrounding the armature and adapted to be engaged by the disc attached to the armature, the central portion of the disc attached to the armature being urged thereby toward the other disc when the armature is attracted to the pole faces whereby abnormal motion in that direction is resisted by the increased stiffness of the moving disc and by the compression of the air between the discs and whereby abnormal motion away from the pole faces is resisted by compression of air between the moving disc and the ring.

WILLIAM J. RADY. LYMAN A. RICE.

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

UNITED STATES PATENTS Number Name Date 1,728,045 Dubilier Sept. 10, 1929 1,894,842 Appleberg Jan. 17, 1933 2,045,289 Bolin June 23, 1936 2,342,008 Newton Feb. 15, 1944 2,354,542 Rady July 25, 1944 2,393,952 Austin Feb. 5, 1946 2,395,007 Leupold Feb. 19, 1946

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