US2943172A - Electric switch incorporating an automatic circuit breaker - Google Patents

Electric switch incorporating an automatic circuit breaker Download PDF

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Publication number
US2943172A
US2943172A US741207A US74120758A US2943172A US 2943172 A US2943172 A US 2943172A US 741207 A US741207 A US 741207A US 74120758 A US74120758 A US 74120758A US 2943172 A US2943172 A US 2943172A
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Prior art keywords
contact
circuit breaker
wire
casing
current
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US741207A
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English (en)
Inventor
Richard C Ingwersen
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Mechanical Products Inc
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Mechanical Products Inc
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Priority to US741207A priority Critical patent/US2943172A/en
Priority to NL238421A priority patent/NL100555C/xx
Priority to GB16279/59A priority patent/GB862259A/en
Priority to DEM41763A priority patent/DE1126975B/de
Priority to FR796893A priority patent/FR1226392A/fr
Application granted granted Critical
Publication of US2943172A publication Critical patent/US2943172A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
    • H01H71/10—Operating or release mechanisms
    • H01H71/12—Automatic release mechanisms with or without manual release
    • H01H71/14—Electrothermal mechanisms
    • H01H71/18—Electrothermal mechanisms with expanding rod, strip, or wire
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H73/00—Protective overload circuit-breaking switches in which excess current opens the contacts by automatic release of mechanical energy stored by previous operation of a hand reset mechanism
    • H01H73/22—Protective overload circuit-breaking switches in which excess current opens the contacts by automatic release of mechanical energy stored by previous operation of a hand reset mechanism having electrothermal release and no other automatic release
    • H01H73/30—Protective overload circuit-breaking switches in which excess current opens the contacts by automatic release of mechanical energy stored by previous operation of a hand reset mechanism having electrothermal release and no other automatic release reset by push-button, pull-knob or slide
    • H01H73/306—Protective overload circuit-breaking switches in which excess current opens the contacts by automatic release of mechanical energy stored by previous operation of a hand reset mechanism having electrothermal release and no other automatic release reset by push-button, pull-knob or slide the push-button supporting pivotally a combined contact-latch lever

Definitions

  • This invention relates to improved electric circuit breakers and/or electric switches having automatic overload current protection.
  • circuit breakers in electrical circuits are, of course, old and well-known, and such devices are widely used to protect electrical circuits against overload current conditions. While various types of circuit breakers have heretofore been devised, many of them that have achieved commercial acceptance include bimetallic elements which expand, or deflect in response to heating so as to permit a movable contact of the circuit breaker to move out of engagement with a stationary contact and thus open the electric circuit. In such circuit breakers, the bimetal member usually acts as a latch and must be relatively strong mechanically in order to retain certain of the circuit breaker part-s in a desired relationship during normal circuit operation.
  • circuit breakers are generally not practicable for use in low current applications, or in applications where relatively rapid overload response is required.
  • the need for mechanical strength requires that the bimetal member be of relatively large size, and, therefore, relatively insensitive, requiring relatively large currents to actuate it.
  • the thermal inertia of a relatively large member limits the response time of the device to a relatively long interval.
  • bimetal members of sufficiently high electrical resistance to be actuated by a current of five amperes or less do not have sufiicient mechanical strength to act as a latch or retaining element.
  • circuit breakers In aircraft electrical systems in particular, the use of fuses is not satisfactory because of the necessity of carrying spare fuses to replace any fuse which might blow out. Circuit breakers, on the other hand, can be manually reset after a current overload condition, and replacement breakers need not be carried. This is, of course, important in that several hundred circuit breakers are used on most modern aircraft.
  • Another object of this invention is to provide a circuit breaker of the aforementioned type which will operate almost instantaneously upon occurrence of current overload.
  • Another object of this invention is to provide a circuit breaker of the aforementioned type which is relatively unaffected by ambient temperature variations.
  • Figure 1 is a longitudinal sectional view of an electric circuit breaker according to a first embodiment of the invention and illustrating the circuit breaker in its closed position;
  • Fig. 2 is a sectional view of the circuit breaker illustrated in Fig. 1 taken along the line 2-2 thereof;
  • Fig. 3 is a view similar to Fig. 1 illustrating the circuit breaker in its manually opened position
  • Fig. 4 is asectional view of the circuit breaker illustrated in Fig. 3 taken along the line 4--4 thereof;
  • Fig. 5 is a longitudinal sectional view of a circuit breaker according to a'second embodiment of this invention.
  • Fig. 6 is a sectional view of the circuit breaker illustrated in Fig. 5 taken along the line 6--6 thereof;
  • Fig. 7 is a fragmentary longitudinal sectional view showing a modified form of the circuit breaker shown in Fig. 5;
  • Fig. 9 is a sectional view of the circuit breaker illustrated in Fig. 8 taken along. the line 9-9 thereof;
  • Fig. 10 is a fragmentary view similar to Fig. 8 illustratingthe circuit breaker in its; open, or tripped.
  • Fig. 11 is a longitudinal sectional view of a circuit breaker representing a fourth: embodiment of the in e tion, showing the circuit breaker inits; closed po it on;
  • Fig. 12 is a cross-sectional. view of. the circuit breaker shown in Fig. 11, taken generally along the. line. 12-42 thereof;-
  • Eig. 13 is. a longitudinal sectional view generally simi lartothe view of Eig; 11', but shOWingthe circuit-breaker in its open position;
  • Fig. 1.4. is a fragmentary cross-sectional; view taken along the line l t-14 of Fig. 1.1...
  • Circuit breakers include, overload. sensitive elements comprising one or more relatively fine; Wires. arranged. in, the electrical circuit within the circuit breaker and mechanically tensioned. The arrangement; is such that when the wires are heated by a predetermined overload current, theyexpand, causing the release of a. latch mechanism which normally retains the contacts in; a closed position.
  • the circuit breakers of the present invention are lightweight and extremely compac They may e made responsive to; relatively small. currents. and. to. have extremely rapidreaction. to irc it; overloa s. The over oad. sensi ive wires. bein Of relatively; mall; gauge... have. a. relatively high. resistance and very small thermal inertia. They can, therefore, be heated. to the. tripping temperature. by relatively small currents, andboth the. reaction and the; recovery times are. rela ively hort.
  • the circuit. breaker illustrated therein includes a hollow casing 11 which may be made of plastic or other suitable material and is preferably formed, in two halves secured togetherby suitable fastening devices 13. Supported in and projecting fromthe casing 11 are terminals 15; and 17 which are adaptedto be connected in an electric circuit so that current flows, from one terminal through the circuit breaker to, the. other; terminal, and so that if the circuit breaker moves to itstripped, or. open position due to current overload or manual. actuation, current: flow through the circuit. is. interrupted.
  • a fixed contact 19 is disposed withintheeasingll and connected with the terminal 172 A, plunger; 21 is-slidably supported in the casing for-in? and out movement.
  • a plunger extensipnmemberlIa isconnected to the lower, or outer end of? the plunger and projects beyond, the casing 11, through a recessed collar-like member; 25,. whichabuts the bottom of the; casing and. is. fixed. with respect thereto.
  • a knob 27 is secured to the outer endof the plunger ex-- tension 23;. by means of;- a; screw 29.
  • a pair ofplastic spacers or ring-like members 311and. 32 are disposed between the plunger extension .23 and the. knob 27.
  • the knob 27 and the spacers 31 and 32 are all differently colored.
  • the ring-like member 31 is, normally confined within the collar 25,.and the member 32 and knob 27 are exposed when the plunger is in its normal contact closed position as illustrated in Fig. 1.
  • the knob and both members 31 and 32 are visible as illutrated'in, Fig. 3.
  • the plunger moves inwardly, as will be hereinafter described, so that only the knob 27 is visible, with the members-31 and 32-being confined within the collar member 25.
  • the-userof the switch can determine at a glance whetherthe contacts are open or closed, and if open-whether manuallyor, automatically so positioned.
  • the plunger 21 is urged inwardly by a spring 33, the upper, endcffwhich abuts: the bottom of the plunger 21, and thedower end of which is supported. in a spring seat member 35-fixedtothe casing near the bottomthereof.v
  • a generally U-shaped spring 39 supported in the casing 11, and opposed laterally projecting flanges. 37, adjacent to the lower end of the plunger 21, cooperates to releasably retain the plunger in its out position when it has been manually moved to such position. That is, when it is desired to manually open the switch, the user may grasp the plunger knob. 27 and pull it outwardly, thus moving the plunger 21 downwardly and compressing the coil spring 33'.
  • An arm 43 is pivotally supported at4'5 on the plunger 21.
  • a contact 47 is carried on one end of the arm in position to engage the fixed contact 19.
  • a coil spring 49 is connected between the; arm 43 and the. plunger: 21, tending to pivot the contact carrying end of the armaway from the fixed contact 19 so as. todisengage the contacts.
  • the contact 47 is, however, normally'retained in engagement with the fixed contact 19 by means of. a lever 51, having a latching shoulder 53 adjacent to its upper end, and pivotally supported in. the casing 11 by a pivot pin
  • The; lever 51 is of a generally Lshapedconstruction, and the vertical leg thereof is considerably longer. thanthehorizontal. leg 57 so. that. a. limited, movement of the. horizontal leg 57- will-cause.
  • a currentcarrying wire 63 is provided, theupper end-of; which is: connected with the terminallS andthe lower endofwhich is connected with an abutmentiplate 65.
  • the wire 63 extends.- through a hollow casing, or.
  • this circuit breaker can be used to control overload current conditions in circuits carrying less than five amperes and in circuits carrying one-half ampere or less. Thus, this circuit breaker can be used in low current carrying circuits and actuates rapidly upon the occurrence of an overload current condition.
  • the knob 27 In order to reset the switch to its contact closed position, and assuming that the wire 63 has returned to its normal unexpanded position, the knob 27 is manually pulled outwardly and the contact carrying arm 43 will slide along the angular face 81 adjacent to the upper end of the lever 51, and pivot the lever 51 in a clockwise direction until the arm shoulder 59 drops below the lever latching shoulder 53. The knob 27 is then released to allow the spring 33'to move the plunger 21 back inwardly and to pivot the arm 43 to bring the contact 47 into engagement with the contact 19. The engagement of the lever and the contact arm and the engagement of the contact will retain the spring 33 in a partially compressed position so that the elements of the switch will be held in the position shown in Fig. 1.
  • the knob 27 is pulled outwardly until the flanges 37 engage the detents 41 on the spring 39, thus moving the contact carrying arm 43 outwardly to the position illustrated in Fig. 3, in which position both the ring members 31 and 32 are visible to the user, indicating that the switch has been opened by manual actuation.
  • FIG. 5 Another circuit breaker representing a second embodiment of the invention is illustrated in Figs. 5 and 6.
  • This circuit breaker cannot be manually actuated from its closed to its open position and therefore is not a switch in the conventional sense. It is only a circuit breaker, subject to actuation due to overload current conditions and subject to being manually reset.
  • a casing 111 is provided which may be made of plastic and in two halves as previously described.
  • a pair of terminals 113 and 115 are supported in the casing and are adapted to be connected in an electric circuit, so that when the circuit breaker contacts are closed, current can flow through the circuit breaker.
  • a fixed contact 117 is connected with the terminal 113.
  • a plunger 119 is supported in the casing for in and out movement relative thereto, and a coil spring 121 acts against the inner end of the plunger to normally retain the same in its outermost position.
  • a contact carrying arm 123 is pivotally supported at 125 on the plunger 119 and carries adjacent to one end thereof a contact 127 which normally engages the fixed contact 117.
  • a spring 129 extends between the arm 123 and the plunger 119, urging the arm 123 in a counterclockwise direction to move the contact 127 away from the contact 117.
  • a lever 131 In order to normally retain the contact 127 in engagement with the contact 117, a lever 131 is provided which is pivotally supported near its lower end on a pin 133 supported in the casing 111.
  • a pawl 135 is pivotally supported at 137 on the upper end of the lever 131 and is yieldingly held in engagement with a shoulder 139 on the arm 123 by means of a leaf spring 141.
  • a coil spring 143 stretched between an anchor in the casing 111 and the lower end of the lever 1'31, urges the lever to swing in a clockwise direction to move the pawl 135 away from the contact carrying arm shoulder 139.
  • Such movement is, however, normally prevented by means of a current carrying wire 147 which has one end thereof connected with the lever 131, and the opposite end connected with an angled-shaped plate 149 which rests upon a plate 151 which is in current carrying engagement with the terminal 115.
  • One leg of the plate 149 has a slotted aperture 153 therein, while the opposite leg has a threaded aperture to receive a stud 155, the head of which is seated in the casing sothat rotation of the stud will cause movement of the plate 149 toward or away from the lever 131.
  • a suitable pin or stud 157 extends through the slot 153 in the plate 149 and into the plate 151 so that by adjusting the stud the tension on the wire 147 and the calibration of the circuit breaker can be adjusted.
  • the terminal 115 is electrically connected with the terminal 113 through the plate 151, the plate 149, the wire 147, the lever 131, a pigtail 159, the current carrying arm 123, contact 127 and contact 117.
  • the wire 147 will heat and expand as previously described thus permitting the spring 143 to swing the lever 131 in a clockwise direction to move the pawl 135 out of engagement with the contact carrying arm shoulder 169, whereby the spring 129 will swing the arm 123 in a counterclockwise direction mov-.
  • the device of this embodiment is only a circuit breaker and not a circuit breaker and switch.
  • circuit breaker illustrated in Fig. 7 of the drawings is substantially identical to that illustrated in Figs. 5 and 6 except that it is designed to carry a much higher current than the device shown in Figs. 5 and 6. This is accomplished by providing a shunt wire 171 between the plate 151 and the current carrying arm 123. Therefore, a considerable portion of the current will flow through the shunt 171 and a much smaller portion will flow through the wire 1 47.
  • circuit breaker which is adapted to be connected with two diiferent' electrical circuits.
  • One of the circuits would be a primary electrical circuit to be protected, and when this primary circuit is interrupted by the circuit breaker a secondary circuit is closed to energize a bell, buzzer, light or the like, so that when the primary circuit is broken, the buzzer, bell, or light will be energized to indicate that current flow through the primary circuit has been interrupted.
  • Such a circuit breaker is especially useful, for example, in telephone centralofliceequipment or the like.
  • the circuit breaker includes a casing 211 made of plastic or the like, preferably molded in two halves which are secured together by suitable fastening devices or the like 213.
  • a terminal 215 is supported in the upper end of. the circuit breakercasing 211 and is normally enclosed by a snap-on cover 217, and the terminal 215 is adapted to be connected with a conductor in a primary circuit.
  • a second terminal 219 is provided in the lower portion ofthe casing'211 and likewise is adapted to be" connected in the primary circuit.
  • a fixed contact 211 is disposed in the casing 211 and connected with the terminal 219.
  • a movable contact 223 is carried by an arm 225 which is pivotallysupported at 227 ona plunger 229 which is sup ported in the casing for in and out movement.
  • the plunger 229 has a knob-like extension 231 connected therewith and projecting through the lower end of the casing, and a coil spring 23 3 is disposed between the knob and the bottom of the casing to normally retain the plunger in its out position.
  • a coil spring 235' is connected between the contact carrying arm 225' and the plunger 229 tending to rotate the arm in a counterclockwise direction to move the contact 223 out of engagementwith the contact 221.
  • the contact 223 is normally held in engagement with the contact 221 by a lever 237 which is of a generally inverted L shape and is' pivotally supported in the casing at 239.
  • a pawl 241 is pivotally connected to the lower end of the lever 237 and has a latching shoulder 242 which normally engages the under side of a shoulder 243 on the contact carrying arm 225 to retain the same in its generally horizontal position with the contact 223 in engagement with the contact 221.
  • leaf-type spring 245 normally retains the upper portion of the pawl in engagement with lever 237, but the pawl can pivot in a counterclockwise direction on the lever to permit resettingof the circuit breaker, as will hereinafter appear.
  • the upper horizontal leg portion 247 of the lever 237 carries a stud or fastener device 249 to which the lower end of a current carrying wire 251 is connected.
  • the upper end of the wire 251 extends through the casing 211 and isconnected with the terminal 215' so that normally current in the primary circuit can flow from the terminal 215, through the wire 251, the lever 237, the pawl 241, the arm 225, the'contact 223 and the contact 221, to the ter minal 219.
  • a coil spring 253 has its upper end engaging the wall of a recess in casing 211 and its lower end engaging the top of the lever horizontal arm 247, and tends to rotate the lever 237 in a clockwise direction so as to move the pawl latching shoulder 242 out of engagement with the.
  • a conductive contactwasher 257 is mounted on the inner end of the knob 231 and is insulated from the plunger 229.
  • the inner end ofthe terminal 255 lies along the wall ofthe casing 211 adjacent tothe knob 231, and a contact member'259 secured to the terminal 219' also extends close to the knob 231, being spaced from the terminal 255 and normally electrically separated therefrom.
  • the conductivewaslrer 257 bridges across the inner end of the terminal 255 and the contact member 259 when the plunger is in its extended position, completing the secondary circuit between the terminal 219 and the terminal 255.
  • A. circuit breaker representing a fourth embodiment of theinvention is illustrated inFigs'. 11-14 and includes two hot wires 390 and 302 connected tin series to provide. a circuit breaker of extremely compact construction and great sensitivity. This circuit breaker includes a somewhat different mechanical latchingarrangement from the circuit breakers shown in the preceding figures.
  • The. circuit breaker shown in Figs; 11-14 is mounted within a housing 334, which may be made of any desired material having sufiicient strength and rigidity such as,
  • a pair of terminals 308 and 310 are fixed in the housing 304 and extend therefrom for connecting the circuit breaker in an external circuit.
  • a fixed contact 312 is secured to the inner end of the first terminal 308.
  • the second terminal 310 is connected by means of a pigtail 314' to one end of the first hot wire 300.
  • the two hot wires 300 and 302 are electrically and mechanically connected together at their upper ends, as viewed in the drawings, by a pivoted lever 3'16, and the lower end of the. second hot wire 302 is" is mounted for limited in and out. sliding movementwithin.
  • thev housing 304 and extends into a guideway 328 atthe upper end of the housing 304.
  • a pin 333wfixed1 to the housing304 extends through a slot 330 near. the upper end of the inner plunger forlimiting the travel: thereof.
  • the innerplunger 326 carries a pin 334- which extends through a slot 336 in the outer plunger 338.
  • the outer plunger 338 extends throughtheforward 79' wall of the housing 304, and a knob 340, preferably of an insulating material such as plastic, is secured to its outer end exteriorly of the housing 304 for manual actuation of the device.
  • the outer plunger 328 is urged outwardly by a compression coil spring 342 seated within the knob 340 and hearing at its inner end against a fixed abutment plate 344 within the housing.
  • the inner plunger 326 is urged outwardly by a tension coil spring 346, one end of which is connected to the contact carrying arm 324, near the left-hand end thereof as viewed in Figs. 11 and 13.
  • the other end of the spring 346 is connected by means of an insulating link 347 to a lever 348, which is pivoted ona fixed pivot 350 adjacent to the plungers 326 and 338.
  • the lever 348 carries a roller 352, which is urged into notches 354 and 356 in the inner plunger 326 and the outer plunger 338, respectively, by the tensioned spring 346.
  • the spring 346 is sufiiciently strong so that when it is tensioned to the position shown in Fig.
  • the notch 356 of the outer plunger 338 is relatively gently sloped so that when the tension of the spring 346 is relieved, the sloping side of the outer plunger notch 356 earns the roller 352 laterally out of both of the notches 354and 356, thus releasing both of the plungers 326 and 338 for outward movement responsively to the urging of the biasing spring 342.
  • the outward force of the biasing spring 342 is then transmitted to the inner plunger 326 through the pin-in-slot connection 334, 336', between the two plungers.
  • the inner plunger 326 is moved slightly inwardly, and the slot 330 at the innermost end of the inner plunger and the connecting slot 336 are shaped accordingly to permit such inward travel of the inner plunger beyond its normal position without obstruction by the respective pins 333 and 334.
  • the contact carrying arm 324 is normally held against rotating responsively to the urging of the spring 346 by a latch 360 formed at one end of a lever 362 pivoted within the housing 304.
  • the latch 360 engages the end of the contact carrying arm 324 opposite from the movable contact 322, and normally holds the contact carrying arm against the urging of the spring 346, thus keeping the movable contact 322 in full pressure engagement with the fixed contact 312."
  • the lever 362 as perhaps best shown in Fig. 14, fits loosely within a notch 364 defined by a guide member 366, which also encloses a spring 368 arranged to urge the lever 362 laterally toward the contact carrying arm 324.
  • the lever 362 is in the form of a bellcrank and has a relatively short arm 370 positioned adjacent to one end of the second hot wire 302,
  • the arrangement is such that when the hot wires 300 and 302 expand responsively to a current overload, the bellcrank arm 370 is moved downwardly, as viewed in the drawing, by the hereinafter described action of the spring 384, thus tripping the circuit breaker.
  • the sequence of action is as follows:
  • the circuit breaker illustrated in Figs. 11-14 is also manually actuatable, and may be opened manually by pulling outwardly upon the knob 340 with sufilcient force to overcome the force on the spring 346 and to cam the roller 352 out of the plunger notches, thereby opening the contacts even though the lever 362 is in its normal, non-overload position.
  • the hot wires 300 and 302 in the present embodiment of the invention are arranged in series, both electrically and mechanically, thus providing an increased sensitivity for actuating the circuit breaker responsively to relatively small overload currents. Also, the increased sensitivity provided by the use of two hot wires permits the use of a greater latching arrangement between the latch 360 and the contact carrying arm 324 than is possible with a single short length hot wire. overload, the two hot wires 300 and 302 provide twice the elongation of a single hot wire, and thereby provide twice as much movement of the latching lever 362.
  • lever biasing spring 368 as shown in Figs. 11 and 13 to work against the long arm of the lever 362 is of importance and of advantage in connection with the resistance of the circuit breaker to vibration and physical shock.
  • the hot wires 300 and 302 are enclosed within separate glass tubes 372 and 374 mounted adjacent to each other in a unitary assembly 380 within the housing 304.
  • the first hot wire 300 is fixed at one end to a conductive plug-like member 376, which is fitted within and rests upon the forward end of the first tube 372, and to which the pigtail 314 is attached to'connect the hot wire assembly to the second terminal 310.
  • both of the hot wires 300 and 302 are fixed to the lever 316, which is pivoted on a fixed pivot 378.
  • the forward end. of the second hot wire 302 is fixed within a plug-like member 382 which is slidably fitted within the forward end of the second glass tube 374, and is urged forwardly by a spring 384 fitted around the tube 374 and seated between 'a rearwardly facing shoulder on the plug 382 and the forward end of a mounting block 386, through which the tubes 372 and 374 extend.
  • the spring 384 is fitted around the outside of the tube 374 and is thereby protected to a large extent against the heat dissipated by the hot wire 302 within the tube, thus avoiding excessive heating of the spring, which might otherwise alfect the temper of the spring and weaken it.
  • the reliable service life of the circuit breaker is thus improved since the spring 384 retains its initial resilience and operating force indefinitely.
  • the hot wires 300 and 302 are normally heated to relatively high temperatures when they are subjected to;
  • the hot wire assembly 380 constitutes a separate rially reducing manufacturing costs, and also permitting For a given current ready and simple replacement in the event it is desired to change the current carrying capacity of the circuit breaker.
  • the subassembly 380 is firmly fixed within the housing 304 by means of appropriately positioned ledges and notches (not separately designated) molded into the housing.
  • a screw 331 may be used to secure the mounting block 386 to one portion of the housing 304.
  • the bellcrank arm 370 of the lever carries an adjustable abutment member 388, which may be threaded as illustrated for ready adjustment, and which is positioned adjacent to the plug member 382.
  • An aperture 39b is provided in the forward wall of the casing to permit manual adjustment of the abutment member Elfib for adjusting the response of the circuit breaker to a preselected current overload value.
  • the spring 384 is restrained under compression by the hot wires 300 and 302, which are thereby tensioned, and when the hot wires 300 and 302 expand responsively to current overload heating, the spring 384 drives the plug member 382 forwardly, that is, downwardly as viewed in the drawings, pushing upon the abutment memher 388 and pivoting the lever 362 in a clockwise direction to release the contact carrying arm 324, and thus to open the circuit breaker as hereinabcve described.
  • the spring 384 is substantially stronger than the biasing spring 368 and is sufiiciently strong to drive the lever 362 clockwise against the urging of the biasing spring 368 and to compress the biasing spring 368, as
  • the circuit breaker When the circuit breaker is tripped responsively to a current overload, it initially arrives atthe position shown in Fig. 13, wherein the extension arm 32% rests upon an abutment shoulder 392 formed in the housing 304, and both the inner and outer plungers 326 and 338, respectively, are moved to their out or retracted positions. Immediately thereafter, the hot wires 300 and 302 start to cool, withdrawing the plug member 332 to its initial, or normal position, compressing the spring 384 and permitting the latch biasing spring 353 to advance the lever 362 back to its normal position where it can be engaged by the contact carrying arm 324.
  • the circuit breaker may again be closed merely by pushing inwardly upon the knob 340 to drive the plungersinwardly until the roller 352 falls within the notches 354 and 356 to retain the plungers in their advanced position.
  • the contacts 312 and 322 cannot be held closed under continuing current overload conditions merely by holding the knob 340 in its advanced position.
  • the circuit breaker will not automatically recycle under such circumstances, because after it is once tripped responsively to current overload, its contacts 312 and 322 cannot again be closed until after the inner plunger 326 has travelled outwardly to bring the contact carrying'arm 324 past the latch 36h.
  • All of the circuit breakers according to the present invention are of the trip free type, being arranged so that they cannot be manually held closed by means of the reset buttons if a current overload condition persists in the circuit, and so that they will not automatically recycle it the reset buttons are manually held in the on" position.
  • the arrangement is such that after the circuit breaker opens in response to a current overload it can be reset only after the overload responsive element has recovered from the overload shock, and recovery of the overload responsive element cannot by itself cause the contacts to close even if the reset button is retained in its closed position during the recovery period.
  • the reset button must be actuated subsequently to the recovery of the overload sensitive element in order to reclose the contacts. This feature prevents automatic recycling of the circuit breakers, which may cause damage to the protected circuit and also to the circuit breaker itself.
  • the hot wires are shown as round in cross section, but the invention is not so limited. It is only necessary to provide an elongated, electrically conductive member having a positive temperature co-efiicient of expansion, and the member may be of any desired cross-sectional shape. In fact, for circuit breakers intended for conducting relatively high currents it is prefered to use a hot wire of relatively flat, ribbon-like shape, particularly in the embodiment shown in Figs. 11 to 14-. In this embodiment, a certain degree of flexibility is needed in the wires in order to accommodate pivoting of the cross-bar lever 316. Such flexibility is more readily achieved in a flat, ribbon-like wire than in a round wire of comparable cross-sectional area and current carrying capacity.
  • a wire size as is practicable, that is, as large a wire as will be heated to' a temperae ture significantly higher than the highest expected ambient temperature by minimum overload current. This is desirable in order to avoid stretching of the wire, which tends to take place whenever the wire is heated, and which ecome's increasingly troublesome as the temperature increases.
  • the twowirecircuit breaker shown in Figs. 11 to 14 permits the achievement of sufficient Wire el0ngation for reliable operation with only a minimum heating of the wire.
  • the circuit breakers are tripped by current overload heating of the hot wires 300 and 3612 to only about 500* F.,.
  • circuit breaker according to this last described embodiment of the in vention' is substantially unaffected by ambient temperature variations, and will retain its initial calibration throughout a wide temperature range without additional adjustment.- This is an important advantage for many applications, particularly in aircraft wherein the circuit breakers are almost constantly subjected to relatively wide ambienttemperature changes.
  • circuit breakers according to this embodiment may be made surprisingly high, so
  • a hot wire which will expand upon the occurrence of a current overload condition in the circuit in which the circuit breaker is connected, is provided so as to substantially instantaneously break or interrupt the current fiow upon the occurrence of an overload current condition, and it will likewise be appreciated that the circuit breakers and/or switches of this invention can be readily adapted for carrying either extremely low currents, or relatively high currents.
  • the invention provides an improved circuit breaker, which is extremely efficient and durable in construction and relatively inexpensive to manufacture.
  • An electric circuit breaker having automatic overload current protection including a casing, terminals carried by said casing and adapted to be connected in an electric circuit, fixed contact means electrical-1y connected with one of said terminals, plunger means supported in said casing and movable between a first position and a second position, an pivotally supported on said plunger within said casing, contact means supported on; said arm and movable therewith between a positionin engagement with said fixed contact means and a position out of engagement with said fixed contact means, spring means connected with said arm and attempting to urge said arm and its contact means out of engagement with said fixed contact means, levermeans pivotally supported in said casingand .engageable with said contact arm to'notrrnallyretain said contact inengagement with said fixed contact :means when said plunger, is in its, first position; spring means attempting to urge said plunger means to its second position butnormally re-' strained by the engagement of said lever means with said arm and the engagementof said arm contact means with said fixed contact means, spring means attempting to
  • An electric switch including automatic over-load current protection, including a casing, terminals carried by said casing and connectable in an electric circuit, fixed contact means in said casing electrically connected with one of said terminals, plunger means supported in said casing for movement between a first position and a second position, arm means pivotally supported on said plunger in said casing, contact means carried by said arm means and engageable with said fixed contact means, resilient means connected with said arm means and attempting to urge said arm contact means to a position out of engage ment with said fixed contact means, lever means pivotal- 14 1y supported in said casing and engageable with said arm means to retain said arm contact means in engagement with said fixed contact means, spring means attempting to urge said lever means out of engagement with said arm means, a current carrying wire electrically connected with the other of said terminals and with said arm contact means, said wire having one end thereof anchored in said casing and the opposite end thereof operatively arranged with said lever means so that upon predetermined heating and expansion of said wire said lever means may be actuated by its spring means
  • a trip free electrical circuit breaker of compact construction comprising a casing, a first terminal fixed in said casing and extending exteriorly thereof for connection to an external circuit, a contact fixed within said casing and electrically connected to said first terminal, a movable contact positioned within said casing for travel into and out of pressure engagement with said fixed contact, a second terminal electrically connected to said movable contact, resilient means for urging said movable contact away from said fixed contact, a releasable latch for holding said movable contact in pressure engagement with said fixed contact against the urging of said resilient means and movable between a holding position and a release position, actuating means for moving said movable contact into engagement with said fixed contact when said latch'is in itsholding position, means disabling said actuating means from so moving said movable contact when said latch is in its release position, a.
  • a trip free electrical circuit breaker of compact construction comprising a casing, a first terminal fixed in said casing and extending exteriorly thereof for connection to an external circuit, a contact fixed Within said casing and electrically connected to said first terminal, a movable contact positioned within said casing for travel into and out of pressure engagement with said fixed contact, a second terminal electrically connected to said movable contact, resilient means for urging said movable contact away from said fixed contact, a releasable latch for holding said movable contact in pressure engagement with said fixed contactfagainst the urging of said resilient 'means andmovable between a holding position, anda estates release position, manually opcr'a'table actuating means for moving said movable contact into engagement with said fixed contact when said latch is in its holding position, said actuating means being disabled when said latch is in its release position, a wire having a plurality of juxtaposed portions connected electrically and mechanically in series and electrically connected in the circuit between said first and second terminals for conducting
  • a trip free electrical circuit breaker comprising a compact casing, 21 first terminal axes in said casing and extending exteriorly thereof for connection to an external circuit, a contact fixed within said casing and electrically connected to said first terminal, a movable contact positioned Within said casing for travel into and out of pressure engagement with said fixed contact, a second terminal electrically connected to said movable contact, resilient means for urging said i'nova-ble contact away from said fixed contact, a releasable latch for holding said movable contact in pressure engagement with said fixed con tact against the urging of said resilient means and mov able between a holding position and a release position, manually operatable actuating means for moving said movable contact into engagement with said fixed contact when said latch is in its holding position, means disabling said actuating means from so moving said movable con tact when said latch is in its release position, and overload responsive tripping means for moving said latch to its re lease position responsively to a current overload of pre* determined value including a wire electrically
  • a trip free electrical circuit breaker comprising a compact casing, a first terminal fixed in said casing and extending exteriorly thereof for connection to an external.- circuit, a contact fixed within said casing and electrically connected to said first terminal, a movable contact positioned within said casing for travel into and out of pressure engagement with said fixed contact, a second termis nal electrically connected to said movable contact, re silient means for urging said movable contact away from said fixed contact, a releasable latch for holdingsaid movable contact in pressure engagement with said fixed contact against the urging of said resilient means and movable between a holding position and a release position, manually operatable actuating means for moving said movable contact into engagement with said fixed contact when said latch is in its holding position, said actuating means being disabled from so moving said movable contact when said latch is in its release position, and overload responsive tripping means for moving said latch to its re,- lease position responsively to a current overload of predetermined value including a wire having
  • a trip free electrical circuit breaker comprising a compact casing, a first terminal hired in said casing and extending exteriorly thereof for connection to' an external circuit, a contact fixed within said casing and electrically connected to said first terminal, a movable contact positioned within said casing for travel into and out of pressure engagement with said fixed contact, a second terminal electrically connected to said movable contact, resilient means for urging said movable contact away from said fixed contact, a releasable latch for holding said movable contact in pressure engagement with said fixed contact against the urging'of said resilient means and movable between a holding position and a release position, manually operatabl'e actuating means for moving said movable contact into engagement with said fixed contact when 'said latch is in its holding position, said actuating means being disabled from so moving said movable contact when said latch is in its release position, and overload responsive tripping means for moving said latch to its release position responsively to a current overload of ma determined value including a wire electrically connected for conducting the thermal current
  • a trip free electrical circuit breaker of compact construction comprising a casing, a first terminal fixed on said casing and extending exteriorly thereof for connection to an external circuit, a contact fixed within said casing and electrically connected to said first terminal, a movable contact positioned withinsaid casingfor travel into and out of pressure engagement with said fixed contact, a second terminal electrically connected to said movable contact, resilient means for urging said movable contact away from said fixed contact, a'releasable latch for holding said' movable contact in pressure engagement with said fixed contact against the urging of said resilient means and movable between a holding position and a release position, manually operatable actuating means for moving said movable contact into engagement with said fixed contact when said latch is in its holding position, said actuating means being disabled from so moving said movable contact when said latch is in its release position, a wire having two juxtaposed portions, an electrically conductive lever centrally pivoted within said casing, adjacent ends of said wire portions being fixed to the opposite ends of said lever, the
  • a trip free electrical circuit breaker of compact construction comprising a casing, a first terminal fixed in said casing and extending exteriorly thereof for consection to an external circuit, a contact fixed within said casing and electrically connected to said first terminal, a movable contact positioned within said casing for travel into and out of pressure engagement with said fixed con tact, a second terminal electrically connected to said movable contact, resilient means for urging said movable contact.
  • a releasable latch for holding said movable contact in pressure engagement with said fixed Contact against the urging of said resilient means and movable between a holding position and a release positiomm'anually operatable actuating means for moving said movable contact into engagement with said fixed contact when said latch is in its holding position, said actuating means being disabled from so moving said movable contact when said latch is in its release position, a tensioned wire electrically series connected in the circuit between said first and second terminals, and means responsive to elongation of said wire for moving said latch toward its release position, a third terminal fixed in said casing and extending exteriorly thereof for connection to an external circuit, an auxiliary contact fixed within said casing and electrically connected to said third terminal, and contact means including a movable conductive member associated with said actuating means for electrically connecting said auxiliary contact to said first-named fixed contact during times when said movable contact is out of engagement therewith.
  • a trip free, multi-pole electrical circuit breaker of compact construction comprising a casing, a first terminal fixed in said casing and extending exteriorly thereof for connection to an external circuit, a first fixed contact mounted within said casing and electrically connected to said first terminal, a movable contact positioned within said casing for travel into and out of pressure engagement with said first contact, a second terminal electrically connected to said movable'contact, resilient means for urging said movable contact away from said fixed cont-act, a releasable latch for holding said movable contact in pressure engagement with said fixed contact against the urging of said resilient means and movable between a holding position and a release position, actuating means for moving said movable-contact into engagement with said fixed contact when said latch is in its holding position, said actuating meansincluding a manually operatable plunger slidably mounted in said casing and movable therein between an actuated position and a fnon-actuatedposition, said actuating means further being disabled from so moving said movable
  • a trip free electrical circuit-breaker comprising a compact casing, a first terminal fixed in said casing and extending exteriorly thereof for connection to an external circuit, a contact fixed within said casing-and electrically connected 'to said first terminal, 'a movablecontact positioned within said casing for travel into and out of pressure engagement with said fixed contact, a second terminal electrically connected to said movable contact, resilient means for urging said movable contact away from said fixed contact, a releasable latch for holding said movable contact in pressure engagement with said fixed contact against the urging of said resilient means and movable between a holding position and a release position, manually operatable actuating means for moving said movable contact into engagement with said fixed contact when said latch is in its holding position, said actuating means being disabled from so 'moving said movable contact when said latch is in its release position, overload responsive tripping means for moving the latch to its release position responsively to a current overload of predetermined value including a wire electrically connected in the circuit breaker for conducting
  • a trip free electrical circuit breaker of compact construction comprising a casing, a first terminal fixed, in said casing and extending exteriorly thereof for connection to an external circuit, a contact fixed within said casing and electrically connected to said first terminal, a movable contact positioned within said casing for travel into and out of pressure engagement with said fixed contact, a second terminal electrically connected to said movable contact, resilient means for urging said movable contact away from said fixed contact, a releasable latch for holding said movable contact in pressure engagement with said fixed contact against the urging of said resilient, means and movable between a holding position and'a release position, said latch including a bellcrank having arms of unequal length, a resilient biasing member disposed near the outer end of the longer one of said arms for urging said bellcrank toward the'holding position, actuating means for moving said movablecontact into engagement with said fixed contact when said latch is in its holding position, said actuating means being disabled when said latch is in its release position, a wire electrically connected
  • a trip free electrical circuit breaker comprising acompact casing, a first terminal fixed in said casing and extending exteriorly thereof for connection to an external circuit, a contact fixed within said casing and electrically connected to said first terminal, a movable contact positioned within said casing for travel into and out of pressure engagement with said fixed contact, a second terminal electrically connected to said movable contact, resilient means for urging said movable contact away from said fixed contact, a releasable latch for holding said movable contact in pressure engagement with said fixed contact against the urging of said resilient means and movable between a holding position and a release position, manually operatable actuating means for moving said movable contact into engagement with said fixed contaot when said latch is in its holding position, and an overload responsive tripping mechanism for mov-; ing the latch to its release position responsively to-a cur-' rent overload of predetermined value, said mechanism being contained within a compact subassembly which is separately removable from said casing and which includes a mounting block,
  • a trip free electrical circuit breaker comprising a compactcasing, a first terminal fixed in said casing and extending exteriorly thereof for connection to an external circuit, a contact fixed within said casing and electrically connected to said first terminal, a movable contact positioned within said casing for travel into and out of pressure engagement with said fixed contact, a second terminal electrically connected to said movable contact, resilient means for urging said movable contact away from said fixed contact, a releasable latch for holding said movable contact in pressure engagement with said fixed contact against the urging of said resilient means and movable between a holding position and a release position, manually operatable actuating means for moving said movable contact into engagement with said fixed contact when said latch is in its holding position, and an overload responsive tripping mechanism for moving the latch to itsrelease position responsively to a current overload of predetermined value, said mechanism being contained within a compact subassembly which is separately removable from said casing and which includes a mounting block, a pair of heat insulating tubes secured to and
  • Electrical current overloadresponsive mechanism for use in an electrical circuit breaker of the type having a movable trip lever, said mechanism comprising a mounting block, first and second heat insulating tubes fixed to. and extending side by side through said block, a first electrically conductive wire portion disposed within and extending generally axially along said first tube, a second electrically conductive wire portion disposed within and extending generally axially along said sec ond tube, a centrally pivoted electrically conductive lever mounted adjacent to one end of said tubes and having its opposite ends connected to said first and second wire portions, respectively, a securing member fixed to the end of said first wire portion opposite from said lever and arranged to engage said first tube for holding said first wire portion against axial tension, a movable securing member fixed to the end of said second wire portion opposite from said lever and guidingly received in said second tube, a coil spring fitted externally around said second tube and being thereby insulated from heat emitted by said second wire portion, said spring being held in compression between said block and said movable mov
  • Electrical current overload responsive mechanism for use in an electrical circuit breaker of the type having a movable trip lever, said mechanism comprising a mounting block, first and second tubes fixed to and extending side by side through said'block, an electrical conductive wire having adjacent juxtaposed portions extending axially in said tubes and connected electrically and mechanically in series, a member fixed to one end of said wire and retaining said wire end against movement relative. to one of said tubes, an electrical conductor member secured to the other end of said wire and movable relative to said other tube, spring means resiliently tensioning said wire and resiliently urging said movement of said conductor member so as to cause said conductor member to move axially of said other tube in response to expansion of said wire portions.

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  • Breakers (AREA)
  • Thermally Actuated Switches (AREA)
US741207A 1958-06-09 1958-06-09 Electric switch incorporating an automatic circuit breaker Expired - Lifetime US2943172A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US741207A US2943172A (en) 1958-06-09 1958-06-09 Electric switch incorporating an automatic circuit breaker
NL238421A NL100555C (xx) 1958-06-09 1959-04-22
GB16279/59A GB862259A (en) 1958-06-09 1959-05-12 Improvements in and relating to electric circuit breakers
DEM41763A DE1126975B (de) 1958-06-09 1959-06-08 UEberstromschutzschalter mit thermischer Ausloesung
FR796893A FR1226392A (fr) 1958-06-09 1959-06-08 Perfectionnements apportés aux disjoncteurs électriques

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US741207A US2943172A (en) 1958-06-09 1958-06-09 Electric switch incorporating an automatic circuit breaker

Publications (1)

Publication Number Publication Date
US2943172A true US2943172A (en) 1960-06-28

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US741207A Expired - Lifetime US2943172A (en) 1958-06-09 1958-06-09 Electric switch incorporating an automatic circuit breaker

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US (1) US2943172A (xx)
DE (1) DE1126975B (xx)
FR (1) FR1226392A (xx)
GB (1) GB862259A (xx)
NL (1) NL100555C (xx)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3021404A (en) * 1959-10-09 1962-02-13 Wood Electric Corp Heat responsive wire controlled overload circuit breaker
US3134873A (en) * 1960-10-07 1964-05-26 Mechanical Products Inc Thermo-responsive trip free circuit breaker
US3142737A (en) * 1960-09-09 1964-07-28 Wood Electric Corp Heat responsive wire circuit breaker
US3169180A (en) * 1960-09-13 1965-02-09 Ass Elect Ind Hot wire thermal trip overload electric device
US3242289A (en) * 1963-08-26 1966-03-22 Mechanical Products Inc Trip device for circuit breaker
US3256405A (en) * 1961-05-15 1966-06-14 Texas Instruments Inc Rapid response electrical switch and the like
US3261949A (en) * 1963-11-18 1966-07-19 Mechanical Products Inc Circuit breaker
US4054857A (en) * 1976-08-02 1977-10-18 General Electric Company Time delay disconnect switch

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3232466A1 (de) * 1982-09-01 1984-03-01 Bayerische Motoren Werke AG, 8000 München Schaltanordnung in kraftfahrzeugen

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US554557A (en) * 1896-02-11 Electric switch
US1046499A (en) * 1911-03-06 1912-12-10 George J Schneider Automatic controlling-switch for electric circuits.
CH91711A (fr) * 1921-06-13 1922-04-01 Marcel Kuenzer Coupe-circuit.
DE383105C (de) * 1922-05-21 1923-10-10 Otto Stolz Durch Hitzdraht gesteuerter elektrischer Sicherungsschalter in Schraubstoepselform
DE394057C (de) * 1924-04-12 Tutrix Akt Ges Elektrische Stromueberlastungssicherung
US1627029A (en) * 1925-05-08 1927-05-03 Milton E Greenway Automatic circuit breaker
DE443870C (de) * 1924-09-02 1927-05-12 Allg Elektro Ind Heinrich Wink Selbsttaetiger Druckknopf-UEberstromschalter in Stoepselform mit Hitzdrahtausloesungund achsial verschiebbarem Schaltglied
US1990122A (en) * 1933-03-30 1935-02-05 Hauser Michael Electrical overload circuit breaker
AT147220B (de) * 1936-01-02 1936-10-10 Hedwig Gottschlich Überstromselbstschalter.

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE392296C (de) * 1921-12-11 1924-03-18 Tutrix Akt Ges Elektrische Sicherung, insbesondere in Schraubstoepselform, mit einem Hitzdraht und einem Elektromagneten zur Unterbrechung des Stromkreises

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US554557A (en) * 1896-02-11 Electric switch
DE394057C (de) * 1924-04-12 Tutrix Akt Ges Elektrische Stromueberlastungssicherung
US1046499A (en) * 1911-03-06 1912-12-10 George J Schneider Automatic controlling-switch for electric circuits.
CH91711A (fr) * 1921-06-13 1922-04-01 Marcel Kuenzer Coupe-circuit.
DE383105C (de) * 1922-05-21 1923-10-10 Otto Stolz Durch Hitzdraht gesteuerter elektrischer Sicherungsschalter in Schraubstoepselform
DE443870C (de) * 1924-09-02 1927-05-12 Allg Elektro Ind Heinrich Wink Selbsttaetiger Druckknopf-UEberstromschalter in Stoepselform mit Hitzdrahtausloesungund achsial verschiebbarem Schaltglied
US1627029A (en) * 1925-05-08 1927-05-03 Milton E Greenway Automatic circuit breaker
US1990122A (en) * 1933-03-30 1935-02-05 Hauser Michael Electrical overload circuit breaker
AT147220B (de) * 1936-01-02 1936-10-10 Hedwig Gottschlich Überstromselbstschalter.

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3021404A (en) * 1959-10-09 1962-02-13 Wood Electric Corp Heat responsive wire controlled overload circuit breaker
US3142737A (en) * 1960-09-09 1964-07-28 Wood Electric Corp Heat responsive wire circuit breaker
US3169180A (en) * 1960-09-13 1965-02-09 Ass Elect Ind Hot wire thermal trip overload electric device
US3134873A (en) * 1960-10-07 1964-05-26 Mechanical Products Inc Thermo-responsive trip free circuit breaker
US3256405A (en) * 1961-05-15 1966-06-14 Texas Instruments Inc Rapid response electrical switch and the like
US3242289A (en) * 1963-08-26 1966-03-22 Mechanical Products Inc Trip device for circuit breaker
US3261949A (en) * 1963-11-18 1966-07-19 Mechanical Products Inc Circuit breaker
US4054857A (en) * 1976-08-02 1977-10-18 General Electric Company Time delay disconnect switch

Also Published As

Publication number Publication date
GB862259A (en) 1961-03-08
FR1226392A (fr) 1960-07-11
DE1126975B (de) 1962-04-05
NL238421A (xx) 1961-09-15
NL100555C (xx) 1962-02-15

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