US3344372A - Time delay tube reset device - Google Patents

Description

Sept. 26, 1967 R. B. HEILMAN TIME DELAY TUBE RESET DEVICE 4 Sheets-Sheet 1 Original Filed Jan. 18. 1963 IM 7 .5 mm m mnmfim v mnD Mn 5 m H A R u Sept. 26, 1967 HE|LMAN 3,344,372

TIME DELAY TUBE RESET DEVICE Original Filed Jan. 18, 1963 4 Sheets-Sheet 12 Ill ' INVENTOR RAYMOND B. HEJLMRN ah kmw H/ 5 QTTORNEYJ Sept 1967 R. HEILMAN' ,37

TIME DELAY TUBE RESET DEVICE Original Filed Jan. 18. 1963 4 Sheets-Sheet a nut-1o SUSPENSION STRUCTURE 3o BROKEN numv HERE AND PAQTLY' OMHTED FOR CLHQITY INVENTOR. RAYMOND B. Helmmu R. B. HEILMAN TIME DELAY TUBE RESET DEVICE 7 Original Filed Jan. 18, 1963 Sept. 26, 1967 4 Sheets-$heet 4 INVENTOR m Wm m8 B n W 9 5V M W V! A R Y B United States Patent 3,344,372 TIME DELAY TUBE RESET DEVICE Raymond B. Hellman, Trenton, N.J., assignor to Heinemann Electric Company, Trenton, N.J., a corporation of New Jersey Original application Jan. 18, 1963, Ser. No. 252,404, now Patent No. 3,234,344, dated Feb. 8, 1966. Divided and this application Oct. 21, 1965, Ser. No. 499,766

8 Claims. (Cl. 335-28) ABSTRACT OF THE DISCLOSURE A reset device is provided for an armature means of a circuit breaker in which the reset device is operatively connected at one end portion to the armature means and is actuated by the circuit breaker linkage mechanism during movement of the latter from the contacts closed to the contacts open position.

This application is a division of my copencling patent application, Serial No. 252,404, filed January 18, 1963, now Pat. No. 3,234,344.

Background of the invention Summary of the invention In one embodiment of the invention the electromagnet comprises -a coil which surrounds, in part, a movable tube formed of nonmagnetic material except for a tube end cap or pole and a movable core within the tube. The interior of the tube is divided into two spaces by a flexible, expansible member or bellows, the movable magnetic core being disposed in one of the spaces in which is also a fluid whose volume and viscosity varies with temperature. The movable core divides the space containing the fluid into two smaller spaces and movement of the core toward the coil (and the tube magnetic cap or pole) is retarded by a spring and the dash pot action of the fluid which passes through orifices from the underside of the core to the upper side thereof. The expansion and contraction of the fluid, due to the arrangement of the various parts, varies the size of one of the orifices as the temperature varies and'also varies the initial position of the core (relative to the coil), to compensate, to some degree, for the changes in temperature of the fluid and the tube so as to control the variation in time delays, as the temperature varies, for a given overload current within the range of currents in which a time delay is desired.

The foregoing and other objects of the invention, and the best mode in which I have contemplated applying such principles will more fully appear from the following description and accompanying drawings in illustration thereof.

' Brief description of the drawings In the drawings:

FIG. 1 is a sectional view, partly in elevation, of a circuit breaker embodying the present invention, illustrating the contacts open position;

FIG. 2 is an enlarged sectional view of the movable tube illustrated in FIG. 1, showing the internal details thereof for the contacts open position and the normal temperature; a

FIG. 3 is a sectional view taken along the line 3-3 in FIG. 1 but part of the suspension structure for the movable tube has been broken away for illustrative purposes and the mechanism is illustrated in the trip free position;

FIG. 4 is a partial view taken along the line 44 in FIG. 3 but in FIG. 4 some of the suspension structure for ijhleG movable tube is illustrated which is not illustrated in FIG. 5 is a fragmentary diagrammatic view showing the contacts in the open position and illustrating primarily the movable contact arm engaging the tube reset spring for automatically resetting the movable tube when the contact arm moves toward the open position;

FIG. 6 is an end elevation view taken along the line 6--6 in FIG. 5; and

FIG. 7 is a view similar to FIG. 5 but illustrating the contacts in the closed position and the movable contact arm disengaged from the tube reset spring to allow the tube to move down during electromagnetic tripping.

Description of the preferred embodiment Referring to the drawings, there is illustrated a circuit breaker 10, including an outer case 11 and terminal structures 12 and 13 extending therefrom. The terminal structure 12 is connected within the case by a conductor 14 to a coil 15 forming part of an electromagnet 16 which,

on predetermined overload current conditions, moves axially a tube 2%, the latter being partly of magnetic material and functioning in the manner of an armature for the solenoid coil 15. The tube 20 controls a linkage mechanism 21 of the circuit breaker for automatically (on predetermined overload conditions) opening the contacts 22 and 23 by pivoting the contact 22 out of engagement with the stationary contact 23. For opening the contacts, the movable contact 22 is carried by a movable contact arm 24 pivoted at the right on laterally projecting feet 25, the arm 24 being electrically connected by a flexible conductor 19 to the coil 15. Manual opening and closing of the contacts 22 and 23 is efiectuated by a handle 28, whereas electromagnetic tripping of the contacts to the open position is effectuated by the pivotal movement of a lock 29 (FIG. 4) upon suitable downward movement of the tube 20 and pivoting of the counterweight suspension structure 30 (FIGS. 3 and 4).

The linkage mechanism 21 comprises two groups of links referred to for convenience as the handle toggle or first group 31 and the main toggle or second group 32. The linkage is more fully described and claimed in a copending patent application filed on December 24, 1962, by Raymond B. Heilrnan and Harold H. Bahr, Serial No. 246,699, now Patent No. 3,242,286.

Briefly, however, pivotal counterclockwise movement of the handle 28, starting from the open contacts position of FIG. 1, causes the handle toggle links 31 comprising the handle link 33 and a link of varying length 34 (joined together by a knee pintle 42) to move to the right and the handle force to be transmitted by a coupling link 35, from the link of varying length 34 to the knee pintle 41 of the main toggle 32, the latter comprising the toggle links 37 and 38, and the catch link 39. The lower link 38 is, in turn, connected to the movable contact arm 24, whereby movement of the handle link 33 results in the movable arm 24 being rotated in counterclockwise direction, closing the contacts 22 and 23. In the closed position of the contacts, the catch link 39 is restrained from movement by a lock 44 carried by a cradle 45. In turn, the cradle 45 is restrained by the lock 29 from moving in the counterclockwise direction (due to the bias imposed on the cradle 45 by the catch link 39) from the force of the opening springs 48.

When the tube 20 moves downwardly a sufl'icient distance, upon predetermined overloads, the tube 20 pivots clockwise (FIGS. 1 and 4) the counterweight suspension structure 30 sufficiently to engage the lock 29 and rotate the latter in the clockwise direction also. Suflicient clockwise rotation of the lock 29 results in the release of the cradle 45, whereby the catch link 39 is released and the upper end of the catch link 39 moves in the clockwise direction under the bias of the opening springs 48. This clockwise movement of the catch link 39 causes the toggle formed by links 37 and 38 to collapse to the left (FIG. 1); due to the pressure of the opening springs 48, whereupon the contacts open. During the collapse of the main toggle links, the knee pintle 42 of the handle toggle is moved overcenter (toward the left) sufliciently for the spring 51 (carried by the link of varying length 34) to help reset the mechanism.

Referring to FIG. 2, the tube 20 comprises a generally cylindrical case 55 of nonmagnetic material, preferably stainless steel, defining a shoulder 56, which divides the case 55 into a lower case part 57 of smaller diameter than the upper case part 58. The lower case part 57 is closed and completely sealed by a nose (cap or pole) piece 60, of magnetic material, welded to the case part 57 and having an axial opening through which extends an elongated pin 62 of nonmagnetic material, also preferably of stainless steel and welded to the lower end of the nose 60 (to completely seal the tube). The upper end of the tube 20 is closed by a cap 63, of nonmagnetic material and preferably of stainless steel, and welded to the upper case part 58 and a bellows 65 to seal the space 66.

The interior of the tube 20 is divided by the expansible, flexible member or belows 65 into the first space 66, completely filled with a fluid, and a second space 67, the bellows being formed of a thin metallic material and preferably from nickel. The first space 66 comprises a lower part 68, an intermediate part 69 (between the shoulder 56 and the lower end of the bellows 65) and an upper annular part 70 circumferentially surrounding the space 67. Disposed within the intermediate space 69 and extending into the lower space at all times, a suflicient distance to be surrounded in part at all times by the coil 15 and its magnetic frame 71, is a movable core or armature 72 of magnetic material and comprising an elongated annular lower tube 73 and an integral annular upper piston 74.

The core 72 moves axially relative to the tubular case 55 of the tube 20, and is guided in such movement by the sliding fit between the annular tube 73 and the inner surface of the tubular case part 57 and the sliding fit between the piston 74 and the inner surface of the upper tubular case part 58, the latter two jointly defining an annular orifice 75. The piston 74 carries and has attached in spaced relation thereto, preferably by spot welding, an

ifice plate 76 housing a floating annular orifice valve 86, the plate 76 having a centrally formed orifice 77 and the valve 86 an orifice 87 for jointly with a metering pin 80, controlling the rate of fluid flow between opposite sides of the piston 74 during axial, downward movement of the core 72.

The metering pin 80 for the orifice 87 depends from and is secured to a lower plate 79 secured to and carried by the bellows 65, the orifice plate 76 being biased by a core spring 81 toward the bellows plate 79 at all times. The core spring 81 is seated at its lower end against the magnetic nose 60, extends into the axial opening 82 of the core 72, and is seated at the upper end against a shoulder 83 formed on the core 72, the spring 81 resisting downward movement of the core and returning it to its initial position after electromagnetic tripping. After electromagnetic tripping, the floating annular valve 86 provides for the fast return of the fluid into the space 69.

The metering pin 80 is concentric with the upper portion of the pin 62, the metering pin 80 being provided with a longitudinal opening 85 into which the pin 62 slidably fits for guiding the metering pin 80- during movement 4 of the latter. As illustrated, the core spring 81 is also concentric with the pins 62 and 80 and with the lower" portion of the core 72 and the spring 81 is intermediate the pin 80 and the core 72.

The bellows plate 79 is biased downwardly at all times against the fluid within the space 66 by an axial spring 88 centrally positioned within the bellows 65. A threaded hole 90 is provided in the cap 63 to receive a threaded plug 96 which bears against the upper end of the spring 88 to thereby adjust, within certain limits, the force exerted downwardly by the spring 88 on the bellows plate 79 and the fluid.

To limit upward travel of the core 72 and properly seal the space 66, the upper end of the case part 58 has an inner surface which defines two annular shoulders 92 and 93 separated by a cylindrical wall 94. A cylindrical sleeve 95, concentric with the upper tubular case part 58, interfits with and abuts, a portion of the inner surface of the case part 58 and has an upper bent rim .97 lying upon the shoulder 92, as illustrated in FIG. 2, the lowermost terminal portion 98 of the sleeve acting as a stop to limit upward movement of the core 72 by abutment therewith of the upper periphery of the orifice plate 76.

The bellows 65 is generally of cyindrical shape with a closed, lower, horizontal end to which the plate 79 is secured and which defines with the length-wise convolutions a cylindrical space of variable volume, as determined,

by the volume of the fluid within the space 66, the bellows 65 being of one piece construction.

The bellows 65 has an upper, flexible end portion 99 which extends upwardly between two hollow (for flexibility), stainless steel rings 101 and 102, each of one piece construction. The cap 63 is provided with two shoulders 108 and 109, the vertical surface of shoulder 108 biasing the ring 102 radially outward against the bellows end portion 99, the latter being urged against the ring 101, which is in turn urged against the inside of the upper case 58. Vertically upward movement of the ring 102 is restrained by the horizontal surface of shoulder 108 and downward movement by the outwardly rolled edge portion which forms an annular lip-like ledge, as illustrated in FIG. 2, below a horizontal plane through the center of the ring 102. The horizontal surface of the shoulder 109 biases another part of the bellows end 99, downwardly against the ring 101, after the bellows end has been turned at approximatey a 90 angle, as illustrated in FIG. 2, while downward movement of the ring 101 is prevented by the rim 97.

The bellows end 99 then extends horizontally beyond the ring 101 and lies between the shoulder 93 and the horizontal surface of shoulder 109, the bellows end 99 being then again turned at 90 angle to extend upwardly between the rim of the cap 63 and the rim of the upper case part 58. An interference fit is provided'between the cap 63, the bellows end 99, and the inner rim surface 119 of the upper case part 58 and the cap is pressed into position to preliminarily seal the space 66. The final step in sealing the space 66 is to weld the extremity of bellows end 99 annularly with a bead type weld to the outer periphery of the cap 63 and the upper case part '58, as illustrated.

The coil 15 is formed by a suitable number of turns of wire electrically insulated from each other and wound upon a non-magnetic metal tube 111. The magnetic frame 71 for the coil 15 is provided by an open ended almost completely annular tube, of L-shape in cross section, ex-- cept for the slot 114 (FIG. 2). That is, the frame 71 includes an integral top wall with an opening to receive the case part 57 and the frame extends down around the coil 15. The top, horizontal wall of the frame 71 has an annular lip 118, as best illustrated in FIG. 2, which stands up with a thickness approximately the same as that of the piston 74 of the core 72, to aid in completing the magnetic circuit when the tube 20 and core 72 are in their lowermost positions.

The bottom of the coil 15 is closed by a magnetic pole or bushing 115 which also extends within the cylindrical space defined by the nonmagnetic tube 111 about which the coil is wound. The pole 115, FIG. 1, is of L-shape in cross-section, ends slightly above the middle of the length of the tube 111, has a slot (not shown) extending axially similarly to slot 112, and the pole 115 closes the bottom of the coil, except for a radial continuation (of the aforementioned slot) through which the flexible conductor 19 extends. The tubular part of the bushing 115, adjacent its juncture with the horizontal part of the bushing 115, FIG. 2, is formed on its outside surface, i.e., facing the coil, with an annular, undercut, half-moon shaped recess 117. The presence of the bushing 115 with the undercut recess 117 extending into the cylindrical space defined by the tube 111, as described, was found to significantly raise the overload current value at which the instantaneous overload tripping took place.

Secured to the pole 115 is a bearing 116 through which extends the lower part of the pin 62 for guiding the tube 20 during movement and for limiting upward movement of the tube 20 by engagement of the reset plate 142 with the bearing 116.

The nose 60 and pin 62 interfit with the pole piece 115, as illustrated, to define an air gap Z of variable size dependent on the axial position of the tube 20 and an annular space between the nose 60 and the pole piece 115 of constant radial size regardless of the axial position of the tube. Similarly, the piston 74 (of the core 72) overlies the top surface of the frame 71 to define an air gap between the latter and the lower surface of the piston 74 of varying size dependent on the axial position of the tube 20 and an annular space between the tube 73 and the coil 15 of constant radial size regardless of the axial position of the tube 20.

The counterweight suspension structure 30 (FIGS. 3 and 4) is formed by spaced plates 120 and 121 which are pivoted intermediate their ends on pintles 122 (FIG. 4) secured to arms 123, the latter being welded at their right hand ends to the frame plates 124 of the mechanism. The spaced plates 120 and 121 are also pivotally connected by pintles 126 to the tube 20, the pintles 126 being secured to the right of pintles 122 and to the tube 20 by a strap which frictionally and tightly engages the outer surface of the tube 20 and is carried thereby. Springs 128 are provided to bias the pintles 126 above or below the pintles 122, the springs 128 having their right hand ends connected to the counterweight plates 120 and 121 between pintles 123 and 126. The counterweight structure 30 is further described and claimed in a separate patent application filed January 18, 1963, by Ronald Nicol, Serial No. 7

252,413, now Pat No. 3,221,122.

As illustrated :in FIGS. 1 and 5 to 7, coiled about a pin 140 (secured to the spaced frame plates 124) is a reset torsion spring 141 for the tube 20. The reset spring 141 has one end secured to a reset plate 142 which is in turn secured to the lower end of pin 62 of the tube 20. The other end of the reset spring 141 is disposed to the left of an extension 143, the latter being secured to the right hand portion of the arm 24, FIGS. 5 and 7, and having a lateral portion 144. The extension 143 and the associated end of the reset spring 141 are arranged relative to each other so that in the closed position if the contacts, FIG. 7, the lateral portion 144 is spaced from the near end of reset spring 141, the spring 141 being relaxed at this time and applies no bias to the tube 20. When the mechanism moves from the contacts closed to the contacts open position, whether by manual movement of the handle 28 or electromagnetically by release of the cradle 45 (by the pivotal lock 29), the lateral portion 144 engages the associated end of the spring 141 and depresses it, causing the other end of the reset spring 141 to exert a force upwardly upon the pin 62 of the tube 20 which is sufiicient, upon deenergization of the coil 15 (that is, extinction of any arc that may form) to reset the tube 20 by 6 moving it upwardly sufficiently for the pintles 126 (of the counterweight structure 30) to move above the center of pintles 122, at which time the suspension springs 128 also help to move the tube 20 up to its reset or open contacts position.

When the mechanism is in the contacts open position, as illustrated in FIG. 1, manual closing of the contacts is accomplished by manually moving the handle 28 counterclockwise about the pintle 152 of the handle link 33. This movement of the handle 28 forces the handle toggle knee pintle 42 to move the sliding link down against the upward bias of the handle toggle spring 51 (the latter being carried by the L-shaped link 154 which pivots about pintle 153) and further compresses the spring 51, moving the pintle 42 from the left of a center line con meeting the pintles 152 and 153, toward the right thereof. The L-shaped link is also connected to link 33 by floating link 148 through pintles 42 and and the L-shaped link 154 carries the pintle 155 about the pintle 153 in a manner to maintain the floating link 148 and the coupling link 35 in force transmitting relation and the L-shaped link 154 performs this same function during electromagnetic tripping. Continued counterclockwise movement of the handle 28 causes the knee pintle 42 to move through the center line between the pintles 152 and 153 and to the right hand side thereof, the line of action of the handle toggle spring 51 now moving from the left to the right of the line between pintles 152 and 153, whereby the toggle spring 51 now moves the handle toggle links to the right, with a snap action, until the handle link 33 abuts against the right stop pin 157, FIG. 1, the handle toggle spring 51 remaining more compressed when the handle link 33 abuts the right stop pin 157 than when it abuts the left stop pin 158.

When the linkage is turned to the closed position of the contacts, the toggle links 37 and 38 go overcenter to the right and the spring force of the opening springs 48 tend to rotate the catch link 3) clockwise, but rotation of the catch link is restrained by the lock lip 44 carried by the cradle 45.

At predetermined current conditions above a current level at which instantaneous tripping of the circuit breaker is desired the electromagnetic fiux is sufiicient about the magnetic nose 60 and magnetic core 72 to create a pull on the tube 20 which moves it sufficiently downwardly to pivot the counterweight structure 30 and the lock 29 (including the latters inturned latch 160, FIG. 3) out of engagement with the upper end of the cradle 45 at which time the catch link 39 is released by the lock lip 44. The toggle formed by links 37 and 38 now collapses to the left and the movable 'arm24 moves to its contacts open position under the bias of the opening springs 48 and a contact force spring 162, FIG. 1.

Upon the occurrence of overload currents above a certain percentage in excess of the rated load but below the aforementioned higher, instantaneous trip current value, the tube 20 provides time delays between the occurrence of the overload current and the opening of the contacts. These time delays vary for the same overload current value depending on the temperature of the tube 20' but the variation due to temperature changes is reduced, i.e., compensated, by the arrangement ofthe tube 20.

That is, when the coil 15 is energized, a magnetic field is established in the magnetic frame 71 and about the below the aforementioned higher, instantaneous trip cur-' rent, this magnetic field does sufficiently attract the armature 72 to start movement thereof toward the coil 15, against the bias of the core spring 81 and the damping effect of the fluid within the space 66.

Such movement of the core 72 forces the fluid to flow in the annular orifice 75 between the piston 74- and the inner surface of the tube case part 58 and also to flow upwardly through the orifice 87, the valve 86 being at such time against plate 76. As the magnetic core 72 moves downwardly toward the coil, the magnetic force on the core 72 and on the magnetic nose 60 increases, due to the fact that the reluctance of the circuit is being lowered since the equal gaps, indicated as X and W in FIG. 2, are being decreased. When the core moves downwardly sufliciently, that is, as the piston 74 approaches or contacts the shoulder 56 and the lower end of the core tube extension 73 approaches or contacts the nose 60, the magnetic force on the magnetic nose 60' becomes great enough to overcome the upward force of the counterweight structure 30 and the magnetic force now moves the entire tube 20 through the equal gap distances, indicated as Y and Z, in FIG. 2, between the shoulder 56 and the top of the magnetic frame 71 and between the nose 60 and the lower pole 115. This movement of the tube 20 carries with it the arm 165 of the counterweight structure 30 which strikes the pivotal lock 29 to pivot the latter sufliciently to release the cradle 45 and thereby release the catch link 39, whereby the main toggle links 37 and 38 collapse to move the arm 24 to the open contacts position.

When the counterweight structure 30 so moves, once the pintle 126 of the counterweight structure passes below the horizontal plane through the center of pintles 122, the spring 128 of the counterweight structure 30 also helps to move the time delay tube device 20 downwardly with a snap action, since the spring 128 now biases the pintle 126 downwardly also.

The closer the current values approach the instantaneous trip value, the faster will the core 72 move toward the coil 15, because the strength of the magnetic field is then greater and this will in turn increase the magnetic field so as to achieve a force 011 the magnetic nose 60 which is sufiicient to move the tube 20 downwardly without the need for the movable core to move through any or all of the entire gap distances, labeled X and W in FIG. 2. Thus, an inverse time delay results, that is, long time delays at smaller overloads and shorter time delays at larger overloads.

Upon the occurrence of short circuits or extremely high overloads above the instantaneous trip current value, the tube 20 moves downwardly without any movement of the core 72. That is, the current at such times creates a sufiiciently high magnetic pull on the magnetic nose 60 with aid of force on fluid by magnetic core 72 to instantaneously move the tube 20 downwardly for instantaneously tripping open the circuit breaker.

The movable core 72, the fluid completely filling the space 66, and the bellows 65 are arranged so that the piston 74 is at the predetermined distance X above the shoulder 56 at the normal ambient temperature of 75 F., this dimension being checked after assembly of the tube 20 by X-rays (but before welding together the cap 63, the case rim 119, and the bellows end 99). If necessary the tube is disassembled and refilled to insure that the amount of fluid, and, hence, the volume of the space 66, is the amount required to result in the predetermined distance X, within the tolerance desired.

When the ambient temperature varies from 75 F., the volume of the fluid within the space 66 changes and the viscosity of the fluid also changes.

The metering pin 88 has an outside surface to compensate for the temperature changes, the pin outside surface comprising three stepped tapers and a cylindrical portion at the lower end, of a diameter larger than any of the tapered surfaces, the smallest tapered diameter being at the end of the pin 80 attached to the bellows 65 and the largest diameter at the opposite end, as illustrated in FIG. 2. Upward movement of the core 72 is stopped by the lower end 98 of the aluminum sleeve 95 at a predetermined temperature but it should be noted that at temperatures above this predetermined temperature the bellows may continue to contract, to a position determined by the springs 88 and 170, moving the pin 80 upwardly, even though further movement of the core 72 is prevented. Contraction of the bellows 65 is at all times initially resisted by the spring 88, but to further resist the upward force on the bellows 65 (exerted by the fluid) the second spring 179 is placed within the first spring 88 (seated upon the bottom of the bellows and engageable with the plug 96), the second spring 170 being of shorter axial length than the first spring and coming into action only after the bellows 65 has contracted an amount equal to the difference between the length of the two springs 88 and 17 0.

Thus, assuming the existence of the normal temperature of F. and an overload current in the range toproduce a time delay before the opening of the contacts, the movable core 72 will move downwardly and the fluid will flow upwardly through the orifices 75 and 87. The orifice 75 is of fixed size but the orifice 87 varies in size as the core 72 moves becoming smaller as the core 72 moves down until the piston 74 abuts the shoulder 56 after it has travelled through the distance X, FIG. 2.

But when the temperature of the fluid increases above the normal temperature, the volume of the fluid increases and its viscosity decreases, contracting bellows 65, and the metering pin and the core 72 move upward. Upon an overload current within the time delay range suflicientto initiate downward movement of the core 72, the fluid flows upwardly through the orifices 75 and 87. The orifice 87 is of the same size, initially as during the position of the core 72 for the 75 F. normal temperature up to the aforementioned higher predetermined temperature but above this predetermined temperature the orifice 87 is smaller, due to the fact that upward movement of the core 72 has stopped but not that of the pin 80. At temperatures above 75 F., when the core 72 has moved through a distance equal to the distance X for the normal 75 F. temperature, the size of the opening between the orifice 87 and the pin 80 decreases from the size existing at the end of travel of the core 72 at the normal temperature. Such reduction in size jointly with the longer distance through which the core '72 must travel at the increased temperature, compensates for the decreased viscosity to provide a time delay, at temperatures above the normal temperature, which approximates the time delay period at the normal temperature for a given overload, in the range of overload values where a time delay is desired.

When the ambient temperature decreases from a temperature above 75 F. to the normal 75 value, the fluid in the space 66 and the force of the springs 88 and return the metering pin 80, the bellows 65, and the movable core 72 to the normal 75 F. position, as illustrated in FIG. 2.

If the ambient temperature drops below 75 F., the

fluid decreases in volume and increases in viscosity and the core 72 moves (at the decreased temperature) relative to the metering pin 80 less than at the normal 75 F. temperature because contraction of the fluid causes the bellows 65 to elongate and moves the core 72 down (against the force of spring 81) to an initial position closer to the nose 60 than the normal position of the core 72 at the normal temperature. Also, elongation of the bellows 65 under pressure of spring 88, as the fluid contracts, results in lowering of the pin 80 so that a smaller outside surface diameter defines with the valve 86 a larger orifice 87 during the end of the downward travel of the core 72 SO that ultimately a larger orifice 87 exists (after the core 72 moves its full amount) than exists at the end of core travel at the normal temperature, thus compensating for the increased viscosity of the fluid at lower temperature.

The tapers of the pin 80 and its largest diameter are determined relative to the rate of change which the fluid undergoes in its viscosity as the temperature varies.

In summary, when the fluid temperature decreases from normal, a larger orifice 87 results between the metering pin 80 and the valve 86 (relative to the opening at the normal temperature) for the fluid to flow through, because the lower temperature contracts the fluid causing the bellows to expand, thereby lowering the pin 80 and the core 72, this larger opening resulting at the time movement of the core 72 ends during a time delay period. Similarly, when the fluid temperature increases from normal, at the end of core travel, a smaller orifice 87 will result between the pin 80 and the valve 86 because the higher temperature expands the fluid (against the springs within the bellows) raising the pin 80 and the core 72.

Thus, it is seen that when the fluid temperature decreases and its viscosity increases, since the orifice 87 is larger and the travel of the core 72 toward nose 60 is less, time delay compensation has been made for the increased fluid viscosity for overloads in the time delay range. Similarly when the fluid temperature increases and its viscosity decreases, since orifice 87 is now smaller and the travel of core 72 toward the nose 60 is longer, time delay compensation has been made for the decreased fluid viscosity for overloads in the time delay range.

The method used to exclude all of the air from the space 66 when filling it with silicone oil is described here inafter. Initially the various parts are preconditioned by immersing them in a beaker containing silicone oil and heating them for about one hour at about 400 F., in an assembly chamber by heat from the electrical heating coil of the assembly fixture to be used subsequently in the assembly of the tube. Thereafter, the air is evacuated by the use ofsuitable pumps from the assembly chamber. The pumping continues until bubbling activity from the assembly chamber subsides to a low rate at which time the assembly chamber is returned gradually to atmospheric pressure and room temperature. Subsequently the assembly chamber is again evacuated and this process is repeated until no bubbles are observed at temperatures of about 400 F. All of the moisture and some of the absorbed gases in the silicone oil and metal parts are removed by this alternating procedure of heating and pumping.

The first step is to immerse the case 55 completely in a suitable quantity of silicone oil contained in an assembly fixture (not illustrated) which is placed within the assembly chamber. The core spring 81, the core 72 including its valve 87 and plate 76, the sleeve 95, the ring 101, and the bellows 65 are then submerged in the silicone oil, in almost the desired final axial position relative to the case 55, and aligned, at such time, by a guide sleeve wall forming part of the assembly fixture. At this time some of the silicone oil is displaced into the reservoir forming part of the assembly fixture. (The guide sleeve wall is concentric with the case 55 and forms an axial continuation of the cylindrical wall 94.) This placement of the parts in the case 55 is accomplished within the assembly chamber at a vacuum pressure of about 2 millimeters (mm.) of mercury and at a temperature of about 400 F. produced by the electrical heating coil forming part of the assembly fixture. During this operation the space 67 (enclosed by the bellows 65) becomes filled with silicone oil also.

The second step is commenced at a temperature of about 400 F. and a vacuum pressure of 2 mm. of mercury or less. When a satisfactory level of evacuation is achieved, evidenced by only an occasional small bubble, the temperature is reduced to about 300 F. With the space 66 sealed jointly by the bellows end 99, the ring 101, the guide wall and a positioning sleeve having a circular surface for holding firmly the bellows end 99 against the upper surface of the ring 101, air at atmospheric pressure is allowed to return at a slow rate into the assembly chamber. Entrance of such atmospheric air tends to further insure that the bellows 65 will be firmly seated against the silicone oil in the space 66 with no air bubble between the two. Thereafter, the assembly chamber is returned to a vacuum pressure of 2 mm. or less and the temperature is stabilized at about 300 F. At such time the ring 101, the sleeve 95, the. core 72 and the bellows 65 are jointly moved downwardly by a press which forcefully moves downwardly and positions the sleeve rim 97 (of sleeve against the shoulder 92, i.e., the final desired position illustrated in FIG. 2. During such movement to the final position, some of the silicone oil between the bellows 65 and the case 55 is displaced through a small port in the guide sleeve into the reservoir, further insuring the complete filling of the space 66. Also, a plunger is placed within the bellows 65 to resist the tendency of the bellows to compress, while it is moved downwardly against the silicone oil.

The bellows 65 is made so that at the temperature of 300 F., the bellows is neither extended nor compressed by the silicone oil within the space 66. This neutral position was selected for the filling of the space 66 to avoid the use of devices to extend or contract the bellows to correspond to its length at some other temperature.

The third step is commenced with the fixture and the tube at about 300 F the assembly chamber being gradually brought to atmospheric pressure and the guide sleeve and positioning sleeve are thereafter removed. The fluid which has entered the space 67 is also removed at this time and the springs 88 and 170, the ring 102, the cap 63 and the plug 96 are placed in approximately the correct axial position. The assembly chamber is then reclosed and brought to a temperature of about F. and a vacuum pressure of about 10 mm. of mercury. The cap 63 and thering 102 are then forcefully driven by the press until the ring 102 is just past the center of the ring 101, to the position illustrated in FIG. 2. Simultaneously, the cap 63 is pressed into position against the bellows end 99 and within the rim 119 to jointly seal the space 66 due to the interference fit therebetween. Thereafter, the tube 20 is removed from the assembly chamber and the weld about the cap 63, the bellows end 99 and the rim 119 is made to permanently insure the seal for the space 66.

Thus, no air is allowed into the space 66 which could accommodate expansion and contraction of the silicone oil and all such expansion and contraction is reflected in a changed length of the bellows 65.

Hence, a tube has been provided in which only the core and the nose are of magnetic material, the remainder being of nonmagnetic materials, functioning in the nature of an armature for the coil and providing instantaneou tripping at certain overloads and time delay tripping at other overloads. Further, the positions of the core and the metering pin changes, as the temperature changes, so that the time delay will approach the time delay at the normal temperature for the same current value.

Also, a small quantity of the same kind of silicone oil as is placed in the space 66 may be placed in the space 67 so that when the temperature increases sufiiciently to vaporize the silicone oil in the space 67 the downward force on the bellows 65 is sufliciently in excess of the upward force on the bellows 65 to maintain the latter in contact with the silicone oil in the space 66, minimizing the tendency of the silicone oil within the space 66 to vaporize and maintaining any vaporization of it to a minimum. Further, to create such a vapor force within the space 67, the threaded connection between the plug 96 and the cap 63 is hermetically sealed, such as, referring to FIG. 2, by circumferentially brazing the joint between the plug and the cap at the junction of the upper horizontal surface of the cap 63 and the threaded portion of the plug 96.

Having described this invention, I claim:

1. In a circuit breaker the combination of an electromagnet including a coil, magnetic armature means actuated by said coil upon predetermined electromagnetic conditions and movable from a first position to a second position, a pair of separable contacts, a movable arm carrying one of said contacts, a torsion spring having one end operatively connected to said armature means, said spring having a second end in the path of movement of said movable arm from the. contacts closed to the contacts open positions, and said movable arm flexing said second end during movement of the movable arm from the contacts closed to the contacts open position for loading the spring at which time the first spring end biases and returns the armature means to its first position.

2. In a circuit breaker, the combination of a linkage mechanism and an electromagnetic means comprising a coil and a movable armature movable between first and second positions, a pair of separable contacts one of which is carried by said linkage mechanism, said lrinkage mechanism including a movable arm carrying one of said contacts to an open contacts position, spring means positioned relative to said movable arm and armature so as to be responsive to the positions of said movable arm and armature for movingsaid armature to its first position upon movement of said movable arm to the open contacts position.

3. In a circuit breaker, the combination of a case, an electromagnetic means supported Within said case and comprising a coil and an armature movable linearly from a first position to a second position and back to said first position, a pair of separable contacts within said case, a movable arm carrying one of said contacts between contacts closed and open positions, a spring supported within said case, said spring having a first portion securedto said armature, said spring having a second portion in the path of movement of said movable arm and engaged there-by as said movable arm carries the movable contact from the contacts closed to the contacts open position but said second spring portion being 12. spaced from the movable arm when the movable arm is in the contacts open position and when the movable arm moves from the contacts open to the contacts closed position, said movable arm flexing said spring during.

engagement therewith and thereby loading said spring whereby a force is placed by said first spring portion upon said armature returning said armature to its first position.

4. The structure recited in claim 3 wherein said spring is a torsion spring and is supported on a pin within said contacts, and spring means :operatively connected to said electromagnetic means and engaged by a part of said mechanism only during opening of said contacts to automatically reset said electromagnetic means following tripping of said mechanism.

8. The structure recited in claim 7 and further including frame plates, said mechanism being mounted between said frame, said spring means being mounted intermediate said frame plates.

References Cited UNITED STATES PATENTS 2,620,382 12/1952 Ryan 335-28 2,809,251 10/1957 Findley 335-18 2,849,558 8/ 1958 Chapman 200-67 BERNARD A. GILHEANY, Primary Examiner.

H. BROOME, Assistant Examiner.

Claims (1)

1. 2. IN A CIRCUIT BREAKER, THE COMBINATION OF A LINKAGE MECHANISM AND AN ELECTROMAGNETIC MEANS COMPRISING A COIL AND A MOVABLE ARMATURE MOVABLE BETWEEN FIRST AND SECOND POSITIONS, A PAIR OF SEPARABLE CONTACTS ONE OF WHICH IS CARRIED BY SAID LINKAGE MECHANISM, SAID LINKAGE MECHANISM INCLUDING A MOVABLE ARM CARRYING ONE OF SAID CONTACTS TO AN OPEN CONTACTS POSITION, SPRING MEANS POSITIONED RELATIVELY TO SAID MOVABLE ARM AND ARMATURE SO AS TO BE RESPONSIVE TO THE POSITIONS OF SAID MOVABLE ARM AND ARMATURE FOR MOVING SAID ARMATURE TO ITS FIRST POSITION UPON MOVEMENT OF SAID MOVABLE ARM TO THE OPEN CONTACTS POSITION.

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