US3356816A

US3356816A - Automatic trip manual reset circuit breaker and latch mechanism therefor

Info

Publication number: US3356816A
Application number: US530948A
Authority: US
Inventors: David E Clarke
Original assignee: Texas Instruments Inc
Current assignee: Texas Instruments Inc
Priority date: 1966-03-01
Filing date: 1966-03-01
Publication date: 1967-12-05
Anticipated expiration: 1984-12-05

Description

1967 D. E. CLARKE 3,356,816

7 AUTOMATIC TRIP MANUAL RESET CIRCUIT BREAKER AND LATCH MECHANISM THEREFOR Filed March 1, 1966 l3 Sheets-Sheet 1 'INVENTOR. DAVIDE. CLARKE Z MWA 1967 D. E. CLARKE 3,35

AUTOMATIC TRIP MANUAL RESET CIRCUIT BREAKER AND LATCH MECHANISM THEREFOR Filed March 1, 1966 l3 Sheets-Sheet 2 INVENTOR.

DAVID E. CLARKE BY A fim/

Dec. 5, 1967 E CLARKE 3,356,816

AUTOMATIC TRIP MANUAL RESET CIRCUIT BREAKER AND LATCH MECHANISM THEREFOR. Filed March 1, 1966 1.3 Sheets-Sheet 5 INVENTOR. DAVID E. CLARKE Dec. 5, 1967 D. E. CLARKE 3,356,816

AUTOMATIC TRIP MANUAL- RRSET CIRCUIT BREAKER AND LATCH MECHANlSM THEREFOR Filed March 1, 1966 15 Sheets-Sheet 4- INVENTOR. DAVID E. CLARKE BY J 511M439 Q Dec. 5, 1967 Filed March 1, 1966 D. E. CLARKE AUTOMATIC TRIP MANUAL RESET CIRCUIT BREAKER AND LATCH MECHANISM THEREFOR.

1 5 Sheets-Sheet 5 INVENTOR. DAVID E. CLARKE D. E. CLARKE 3,356,816 AUTOMATIC TRIP MANUAL RESET CIRCUIT BREAKER Dec. 5, 1967 AND LATCH MECHANISM THEREFOR 1T5 Sheets-Sheet 6 Filed March 1, 1966 D. E. CLARKE 3,356,816 AUTOMATIC TRIP MANUAL RESET CIRCUIT BREAKER Dec. 5, 1967 AND LATCH MECHANISM THEREFOR Filed March 1., 1966 l3 Sheets-Sheet 7 m N E V m DAVID E. CLARKE Dec. 5, 1967 D. E. CLARKE 3,356,816

' AUTOMATIC TRIP MANUAL RESET CIRCUIT BREAKER AND LATCH MECHANISM THEREFOR Filed March 1, 1966 13 Sheets-Sheet 8 /5? 254 zaz /66 O //58 FIG. 8

INVENTOR.

DAVID Ev CLARKE Dec. 5, 1967 D. E. CLARKE 3,356,816

AUTOMATIC TRIP MANUAL RESET CIRCUIT BREAKER AND LATCH MECHANISM THEREFOR Filed March 1, 1966 13 Sheets-Sheet 11 FIG. 13

we I F 206 76 /66/ /fiflfi xp'a \ INVENTOR.

DAVID E. CLARKE Dec. 5, 1967 CLARKE 3,356,816

AUTOMATIC TRIP MANUAL RESET cmcun' BREAKER AND LATCH MECHANISM THEREFOR Filed March 1, 1966 13 Sheets-Sheet 1s INVENTOR. DAVID E. CLARKE United States Patent 3,356,816 AUTOMATIC TRIP MANUAL RESET CIRCUIT BglEzAKER AND LATCH MECHANISM THERE- F David E. Clarke, Attleboro, Mass., assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Filed Mar. 1, 1966, Ser. No. 530,948 9 Claims. (Cl. 200-116) ABSTRACT OF THE DISCLOSURE A circuit breaker characterized by ease of manual operation and by its capability of repeated manual operation without upsetting its calibration for automatic operation in response to overload current conditions is shown to have fixed contacts on a base and other contacts movable between a closed circuit position engaging the fixed contacts and an open circuit position spaced from the fixed contacts. The circuit breaker has a latch mechanism which includes a latching shoulder fixed to the circuit breaker base, a latch carrier movable relative to the latching shoulder, and means biasing the movable contact means and latch carrier to open circuit position. The latch carrier carries a ball which can engage the latching shoulder for holding the movable contacts and latch carrier in closed circuit position. In addition, the circuit breaker has an operating means which has a surface tangentially, engaging the ball for normally holding the ball in engagement with the latching shoulder, the operating means also having two recesses which when aligned with the ball, receive the ball and release the ball from its shoulder engagement so that the movable contact means and latch carrier move to open circuit position. The operating means is resiliently mounted on the latch carrier for manual movement to align one of these recesses with the latching ball. The operating means is also biased for movement relative to the latch carrier to align the other of these recesses with the ball. The circuit breaker includes current-responsive means which normally restrain the operating means against movement in response to this operating means bias, this currentresponsive means being adopted to release the operating means for movement in response to its bias when overload current conditions exist in the circuit breaker. The operating means moves to open circuit position with the latch carrier when the latching ball is received in either of the operating means recesses, and, by the position of the operating means relative to the latch carrier, indicates whether the circuit breaker has been opened manually or in response to overload current conditions in the circuit breaker.

This invention relates to condition responsive devices, and in particular to such devices in which a control element is automatically tripped to move to a second position upon the occurrence of a predetermined condition, the control element being resettable.

By way of example only, a condition responsive device of the above general class may be a manually operable circuit breaker which may be tripped automatically, by means of thermal element or electromagnet, to open the contacts of the circuit breaker upon the occurrence of an overload current through the device, and which way also be used as a manually operated switch to turn a circuit on or ofif, the device being trip-free. Another such device, by way of example only, may be a gas valve in which it is desired to have the valve either close or open upon the happening of a predetermined condition, and yet in which the valve may be manually actuated. In order to illustrate the principles of this invention, ref- 3,356,816 Patented Dec. 5, 1967 erence will be had in the description to a circuit breaker.

Among the problems present in the devices with which this invention is concerned, are those of indicating the condition of the device, that is, whether it is in a closed position, or whether it has responded to the occurrence of a predetermined condition, or whether it is in an open position because of having been manually actuated.

Another problem is that such devices, in todays technologies and markets, must be economical, fool-proof in operation, and of long life. If the device is to be operated often as a manually actuated device, then repeated manual operations should not destroy the calibration of the device. In manufacture, it is advantageous to have a device in which calibration can be readily made, and as indicated above, such a device preferably is trip-free. Further, means should be provided to indicate whether an operation of the device occurred because of an automatic trip, or because of a manual actuation. There are presently available on the market devices which, in whole or in part, answer the above problems and provide the desired features. However, these present devices do not do so as simply and economically as this invention.

It is the general purpose of this invention to provide an improved condition-responsive device which satisfies the above requirements, and therefore among the several objects and advantages of invention may be noted the following: the provision of a condition responsive device having means to indicate whether the device has operated automatically or has been operated manually; the provision of a device of the above class in which the means used to trip the device automatically does not have its calibration harmed by repeated manual operation of the device; the provision of a device in which calibration is facilitated; the provision of a device of any of the above classes which can be used repeatedly as a manually operated device for manual control of a control function; the provision of a device of the above classes which contains relatively few moving parts and in which such parts are long-wearing; the provision of a device of the above classes which is economical to make and adapted to mass production; the provision of an automatically tripping, manually operable, and manually resettable circuit breaker having all of the above provisions, and in which good electrical contact pressures are maintained up to the point in which the electrical contacts separate to open a circuit; and the provision of a device of the above classes in which the control function occurs with a snap action. Other objects and advantages will be in part apparent and in part pointed out hereinafter.

Theinvention accordingly comprises the elements and combinations of elements, features of construction, and arrangement of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the appended claims.

In the accompanying drawings, in which two embodiments of the invention are shown,

FIG. 1 is an elevation, in section, of one embodiment of the invention showing the parts in a closed position;

FIG. 2 is an elevation shovw'ng a side view, in section, taken in the direction of sight lines 2-2 on FIG. 1; FIG. 3 is an elevation of the FIG. 1 embodiment, in section, showing the contacts thereof in full open position as a result of the device having tripped automatically;

FIG. 4 is an elevation, in section, showing the parts in the position they occupy when the device is opened manually;

FIG. 5 is an elevation, in section, showing the position of the parts when the device has tripped automatically, but the manual reset button has been held in the contactscl-osed position;

FIG. 6 is an elevation of the FIG. 1 embodiment, showing an intermediate position of the parts after the device has tripped thermally;

FIG. 7 is an exploded view, partly in section, or to show more clearly the relationship and construction of certain parts of the device;

FIG. 8 is an elevation of a second embodiment of the invention, with a portion of the casing removed (and certain other parts broken away) to show the arrangement of parts with the contacts closed;

FIG. 9 is a side elevation, partly in section, taken in the direction of sight lines 99 on FIG. 8;

FIG. 10 is a sectional view, taken in the direction of sight lines 1010 on FIG. 8;

FIG. 11 is a view similar to that of FIG. 8, but showing the device with its contacts opened by a thermal tripping action;

FIG. 12 is a view similar to FIG. 8 but showing the device with its contacts opened by a manual tripping action;

FIG. 13 is a view similar to FIG. 8 but showing the parts in an intermediate position after a thermal tripping action;

FIG. 14 is a view similar to FIG. 8, but showing the position of the parts of the device after it has tripped automatically but with the operating handle being held in the contacts-closed position;

FIG. 15 is a pictorial view of the operating handle of the FIG. 8 embodiment;

FIG. 16 is a pictorial view, with a portion broken away, of an operating member of the FIG. 8 embodiment;

FIG. 17 is a pictorial view of a ball carrier member of the FIG. 8 embodiment;

FIG. 18 is a pictorial view, exploded, of an assembly of a ball-raceway and cover plates used in the FIG. 8 embodiment;

FIG. 19 is a pictorial view of a latch arm of the FIG. 8 embodiment;

FIG. 20 is a pictorial view of a contact arm assembly used in the FIG. 8 embodiment; and

FIG. 21 is a pictorial view of stationary contacts used in the FIG. 8 embodiment, given to show the configuration of these contacts and their spatial relationship in the device.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

Dimensions of certain of the parts as shown in the drawings may have been modified and/or exaggerated for the purpose of clarity of illustration.

Referring to FIG. 1, there is shown a sectional elevation of an exemplary circuit breaker of this invention. In general, and for the purpose of further explanation, the device consists of a casing indicated generally by numeral 2 and an elongated neck portion or extension indicated generally by numeral 4. Within the casing 2, are enclosed cooperating electrical contacts and a thermally trippable latch mechanism, and within the extension 4 are located a mechanical latch structure and the means for operating the device manually as an on-oif switch or of resetting the device to a contacts-closed position if the device has tripped automatically to open its contacts. I

The extension 4 is preferably cylindrical in shape, but if desired could be made in a square or rectangular cross section. It is made of metal, and preferably of hardened steel or stainless steel. Cylinder 4 comprises an outer wall 6 and, concentric therewith, an inner wall or skirt 8. A recess 10 is provided between outer wall 6 and wall 8. Neck 4 is provided with a series of

shoulders

12 and 14 which engage the top surface 16 and mating shoulders on the top of the casing to hold neck 4 onto the casing.

Neck 4 is also provided with

co-axial bores

18 and 20, bore 20 being larger in diameter than bore 18. Where bore 20 meets bore 18, an inwardly directed peripheral shoulder 22 is provided for latching purposes, as will be described later.

A manually-operable push button or knob 24 is provided having a series of

internal bores

26, 28, 30 and 32. A skirt 34 terminates the inner end of push button 24, and mounted on skirt 34 are the indicating

bands

36 and 38.

Bands

36 and 38 are of different colors, one (36) being white for example, and band 38 being red. Push button 24 may be made of a molded synthetic resin such as a phenolic resin or nylon. The

bands

36 and 38 may be likewise made of a synthetic durable resin or plastic, and are secured to the outer periphery of skirt 34 by conventional means, such as a suitable adhesive. The diameter of the push button 24 with its

bands

36 and 38 is such that the skirt 34 and bands are slidably received in the recess 10 adjacent the inner wall 40 of the skirt or wall 6. The thickness of the combined skirt 34 and

bands

36 and 38 is such that a space is left in recess 10 for the compression spring 42.

A closure element or cap 44 of a size to be snugly received in the bore 26 is provided, and may be held in place by suitable adhesives. It serves not only as a closure element, but also provides a surface on which the rating of the circuit breaker may be marked.

Slidably received in the internal bore 18 is a ball latch carrier 46 made of metal such as steel. Carrier 46 is provided with a radially extending flange 48 at one end, which is slidably received within the internal cavity provided by the skirt 34. Flange 48, it will be noticed, is of surficient diameter so that it is engaged by one end of the spring 42. The other end of spring 42 is seated at the bottom of the recess 10.

Ball latch carrier 46 is an elongated cylindrical member having an internal bore 50, and at its inner end is provided with a portion of reduced diameter in order to provide the shoulder 52. Between the ends of ball carrier 48, it is pierced by diametrically

opposite holes

54 and 56. In this embodiment, only two such holes are provided, but more could be used, if desired.

Slidably received in

holes

54 and 56 are the

balls

58 and 60 which serve as latch members. The diameter of

balls

58 and 60 is such that they are received in the

holes

54 and 56 with a smooth sliding fit and preferably with a minimum of play lengthwise of the carrier. The diameter of the balls 58 and 60 (and thus also the holes 54 and 56) is also such that preferably it is equal to the radial distance from the wall of bore 50 to the wall of bore 20.

As shown in FIG. 1, when the

balls

58 and 60 are in their outward (radially) position they engage the peripheral shoulder 22, and while so engaging this shoulder, they look the ball carrier 46 against upward (as drawn) mo tion, spring 42 urging the ball carrier 46 in said direc tion. Because the shoulder 22 engages the

balls

58 and 60 on a curved outer portion of the periphery of each ball, there is a camming action (due to the bias of spring 42 on carrier 46) tending to move the

balls

58 and 60 radially inward toward each other.

Means will now be described for preventing the above radial inward motion of the balls from taking place except under predetermined conditions, as follows: Slidably received in the bore 50 of the ball carrier is an operable member or plunger 62 of metal such as steel. Operable member 62 is a latch release member, and is provided with a neck 64 which is slidably received in bore 32 of the push button 24. At the upper end (as drawn) of neck 64, a conventional reduced end portion is provided over which is fitted the washer 66. Washer 66 is held in place on the end of the neck by conventional means, such as by upsetting the end of the reduced portion. Washer 66 provides a thrust shoulder for the end of the compression spring 68, the other end of this spring seating against the shoulder formed at the junction of

bores

30 and 32.

Between the ends of the member 62 is provided the

peripheral grooves

70 and 72, these grooves bein separated by a ring portion 74 and forming pockets into which

balls

58 and 60 can move under predetermined conditions. The depth of each of

grooves

70 and 72 is such that if the member 62 is moved to position either one of these grooves opposite the

balls

58 and 60, the balls can move inwardly (radially) far enough so that the outer periphery of each ball just clears the peripheral shoulder 22. One function of the ring 74 is to prevent such inward motion of the balls, when the member 62 is positioned as shown in FIGURE 1. It will also be noted, in respect to ring 74, that its outer periphery is provided with a reentrant or concave surface which has approximately the same radius as that of each of the

balls

58 and 60. The reason for providing this surface is to provide a measure of restraint on the motion of the plunger 62 in either direction past the balls. The rims of the ring 74 are preferably the same diameter as the body of member 62, thus permitting these rims to slide past the balls (urging the balls outwardly as they do so) upon motion of the member 62.

At the inner end of member 62 there is provided an outwardly extending sloped shoulder or flange 76, as shown, the sloping shoulder being provided for the purpose of assisting in centering latch plate 78 on the operable member 62.

Latch plate 78 is made of metal, preferably hardened steel or stainless steel, is circular in shape, and is provided with the peripheral shoulder 80 and a hole 82 therethrough. A bore 84 is provided, which meets the hole 82 to form the shoulder 86. The diameter of hole 82 is greater than the diameter of the operable member 62, so that the latch plate 78 is a loose fit thereon. The diameter of bore 84 is preferably large enough to receive loosely the full diameter of the shoulder 76, and the diameters of hole 82 and shoulder 76 are such that the shoulder 86 will meet or strike the sloped shoulder 76 when the plate 78 is pulled against the shoulder. With this construction, when this latter engagement takes place, the latch plate 78 will be automatically centered on the operable member 62, but is still free to move loosely on the member 62 prior to such engagement. The purpose of providing first the loose engagement and secondly the centering is to assist in a relatching operation of a thermally responsive catch member now to be described, and also to permit tilting of the latch plate in the event one side of the thermally responsive catch should free itself first from plate 78. Latch plate 78 is larger in diameter than bore 20.

- A compression spring 87 is positioned between latch plate 78 and shoulder 52 to bias the plate 78 downwardly (as drawn).

As described in United States Patent No. 3,042,776, a thermally responsive combined contact member and catch, indicated generally by numeral 88, is provided. Referring particularly to FIG. 7 herein, the exemplary thermally responsive unit illustrated comprises an element formed of a section of composite thermoflexing material. The high expansion component of the composite material is indicated by numeral 90, and the low expansion component is indicated by numeral 92. There is provided a longitudinally extending slot 94 in element 88, and also a longitudinally extending bridging portion 96 at each end of the element, each of which carries a

movable contact

98 and 100, respectively, which are electrically connected to the low expansion side 92. Thermally responsive unit 88 is further provided with and carries a pair of opposed, spaced slotted

arms

102 and 104.

With this construction, thermally responsive catch 88 provides an electrically conductive path leading from contact 98 to contact 100 through the bridging portion 96,

arms

102 and 104 and the other bridging portion 96. As explained in said patent, heating of element 88, by passing electrical current therethrough, will cause

arms

102 and 104 to flex or warp away from each other. The upper ends (as drawn) of the

arms

102 and 104 are engageable with the shoulder 80 provided by the latch plate 78, and in their normal unheated condition, these arms prevent downward motion of the latch plate 78 when when the movable contacts 98 and are closed against their respective mating contacts.

It has been indicated above that the latch plate 78 is made of metal. The reason that this can be done in conjunction with the thermally responsive unit 88 is that no potential exists across the distal ends of the

arms

102 and 104, since each arm is traversed by the same current and, due to the symmetry of element 88, each side thereof presents the same resistance to the flow of current, On the other hand, if the

arms

102 and 104 were to be mounted transversely in respect to the length of the thermal unit, then a potential difference would exist across the distal ends of the arms upon the passage of current. Such a construction can be used, but in that case the latch plate would need to be insulated from the arms. This can be done by making the latch plate of insulating material but further providing hardened steel non-connected hearing plates under the shoulder 80 at the places where the distal ends of the thermally responsive arms would engage the shoulder.

An insulating bushing 106 is provided, and is inserted in the thermal catch 88 against the bottom surface thereof (as drawn). Bushing 106 is made of a molded plastic, for example, a phenolic resin, is circular in shape, and has provided on its top surface the

upstanding ribs

108 and 110 to center the bushing on the catch. Rib 110 snugly fits into the longitudinal slot 94 in the catch 88, and rib 108 fits into the transverse slot 95 of the catch. On the bottom of bushing 106 is provided a circular boss 112 of smaller diameter than the top portion of the bushing, thus providing means for centering the top end of compression spring 146 as well as providing an insulating shoulder 114 to insulate the spring 146 from the catch 88.

The housing or casing 2 is made in the form of two clamshells which are alike, these clamshells being molded from a synthetic resin, such as a phenolic, capable of withstanding any arc discharge between the contacts of the device when the device opens. Each clam-shell has the top 16, the side walls 120, the bottom 122, and the back or face 124.

Molded as an integral part of each clam-shell are the partitions 126 which have two functions. It will be noted, by reference to FIGS. 1 and 2, that the partitions extend downwardly so that their bottom ends (as drawn in FIG. 1) extend just below the thermally responsive element 88 when the electrical contacts of the device are engaged. A stepped portion 128 in each partition is provided, so that when the clam shells are put together, an opening 129 is provided in each portion to guide thermal unit 88 against rotational movement within the casing. The meetings of the unstepped portions of the partitions constitute stops 130 for thermally responsive unit 88 in its passage or movement upwardly (as drawn) when the contacts open.

Snugly received in suitably provided grooves 132 in the bottom 122 of each clam shell are the

terminals

134 and 136. Mounted on the inner end of each of these terminals are the

electrical contacts

138 and 140, the mounting being done by conventional means such as welding or soldering. When the thermally responsive element 88 is in the contacts-closed position, contact 98 engages contact 138, and contact 100 engages contact 140. With this construction, therefore, there is provided an interior path for the flow of electrical current from terminal 134 through contact 138, contact 98, thermal catch 88, contact 100, contact 140 and terminal 136.

Molded as an integral part of the bottom 122 of the casing is an upstanding boss 142, and surrounding this boss is the upstanding skirt 144. Skirt 144 is spaced from boss 142 in order to provide a space in which is seated one end of a spring 146. The other end of spring 146 seats against the insert 106 which has been described above, and thus is insulated from catch member 88.

The assembly of the device is as follows: The latch plate 78, operable member 62, ball carrier 46, and push button 24 are assembled by first placing the latch plate on the operable member. Spring 87 is next put on member 62, then the ball carrier 46 is placed on the member 62. This assembly is inserted upwardly (as drawn in FIG. 1) into bore 18. Spring 42 is placed in recess 10, the

balls

58 and 60 are placed in the ball carrier 46, and ball carrier and balls are slid over operable member 62 and into bore 18. Push button 24 is placed upon neck 64, spring 68 is then located in position, washer 66 is then put in place, and an upsetting operation (for example) is performed to fasten the washer 66 to the end of the operable member '62. It will be thus noted that as thus assembled, the mechanical and thermal latches of the device comprise a unitary assembly with the extension 4.

Terminals

134 and 136 are inserted in their grooves in the bottom of one of the clam-shells, spring 146 is put in position over the boss 142, and thermally responsive catch 88 is then put in position. The unitary assembly of the extension 4 and its contained parts is then placed in position at the top of the clamshell, and the other clam-shell is fitted in place to hold the parts together. After these parts have been thus assembled, suitable fastening means (not shown but conventional) can be used to hold the clam-shells together. I

In order to calibrate the device, it Will be noted that the thermally responsive unit and the unitary assembly of the neck 4 with its moving parts can be placed in a calibrating jig outside the casing 2, and the combination can be calibrated by, for example, bending the

arms

102 and 104 until the proper tripping current is arrived at. Once this calibration has been done, then the unitary assembly and thermal catch can be removed from the calibrating jig and placed in the casing, as described above.

In the device, as thus described, spring 87 is stronger in compressive force than is spring 68. The function of spring 68 is to exert enough force to maintain the push button 24 in engagement with the ball carrier when the device is tripped automatically, but to permit the disengagement of these parts when the device is tripped manually. Spring 146 is of such strength as to provide a lifting force on the thermal 88 sufiicient to carry it to the top portions 130 of the partitions 126, and is less in strength than spring 87.

Operation of the device will now be described, first for an automatic tripping of the circuit breaker, and secondly on manual use of the circuit breaker as a switch. A third description will be also given as to the operation of the moving parts when the reset push button 24 is held in the contacts-closed position.

Referring particularly to FIGS. 1, 2, 3 and 6, in FIG. 1 the device is shown with the contacts closed; the

thermal catch arms

102 and 184 are engaging the latch plate 78 to hold the latch plate away from shoulder 76; the

balls

58 and 60 are engaging the peripheral catch shoulder 22 with the ball carrier positioned inwardly as far as it goes but under the outward bias of spring 42; and push :button 24 is seated inwardly against the outer end of the ball carrier 46 under the bias of spring 68 and engagement of ring 74 with

balls

58 and 60. If an overload current is now passed through the circuit breaker, it heats thermally responsive catch 88, causing the

arms

102 and 104 to flex outwardly away from each other as described above. This action releases the latch plate 78 which moves downwardly under the influence of the biasing spring 87 until it contacts the shoulder 76. Spring 87 continues to move plate 78 further downward, with the result that plate 78 pulls the operable member 62 down with it. Upon motion downwardly of member 62, the engagement of the curved surfaces of ring 74 with the balls is interrupted (this engagement being relatively weak), and the member 62 continues to move downwardly until the lower rim of groove 70 (which is the upper rim of ring 74) passes the center line of the balls. At this point, because of the camming action being exerted by the shoulder 22 on the balls, the

balls

58 and 60 begin to move inwardly, and this inward movement further enhances and increases the speed with which the operable member 62 moves downwardly, because of the camming action of the balls on said lower rim, so the final stages of that movement are substantially a snap action. With groove 70 now

opposite balls

58 and 60, the balls complete their inward motion until they clear shoulder 22, thus unlocking the ball carrier 46. The latter moves upwardly carrying member 62 and thus latch plate 78 with it until the latch plate engages the underneath surface of the top 16 of the casing. This final open position is shown in FIG. 3; and an intermediate position is shown in FIG. 6, at which intermediate position the balls have just cleared the catch shoulder 22 and have started their upward motion.

Referring to FIG. 3, it will be noted that when the latch plate has stopped the upward motion of the operable member 62, push button 24 has extended far enough out from the recess 10 to expose both the white band 36 and the red band 38. The visibility of both bands indicates that the circuit breaker has undergone a thermal trip-out.

To reclose the device, all'that is necessary is to push button 24 inwardly, which will move the ball carrier 46 and operable member 62 inwardly until the balls engage the peripheral shoulder 22, locking the ball carrier again in position. When the operable member 62 is thus moved inwardly, the latch plate 78 will come in contact with the distal ends of the

bimetal arms

102 and 104,

since the latter have cooled to their normal unheated position and thus are positioned to engage shoulder 80;

and under the bias of spring 87 will move the element 88 to the contacts-closed position. Operable member 62 also moves inwardly until ring 74 locks in position between the walls, thus locking the whole mechanical latch mechanism in the FIG. 1 position.

The operation of the device on a manually actuated opening is as follows: Referring to FIGS. 1 and 4, and starting with the FIG. 1 position, the knob 24 is pulled outwardly. The result of this is to compress the spring 68 until the washer 66 engages the shoulder provided by the junction ofbores 28 and 30'. Further outward,

motion of the button '24 will now move the element 62 outwardly sufliciently to bring pocket or groove'72 opposite the balls 58 and 60 (as contrasted to a thermal trip, where it is groove 70 that moves opposite the balls). As before, this permits the balls to move radially inward to clear the catch shoulder 22, thus unlocking the ball carrier '46. Having unlocked the ball carrier, the push button, ball carrier and member 62 will now continue to move outwardly until the latch plate 78 again comes to a stop against the inner underneath surface of the top 16 of the casing. At this point, it Will be noticed that since the latch plate provides a fixed stop for the outward motion of the element 62, and since the balls are now in pocket 72, the ball carrier comes to rest lengthwise of the neck 4 more inwardly than in the case of the thermal tripping action. Since the ball carrier has not moved out as far, the spring 68 is now effective to expand to position push button 24 inwardly of the neck 4, to the point that only band 36 shows, thus indicating a manual opening of the contacts. This position is shown in FIG. 4.

In this manual operation, the thermal arms have not become overheated to the point of releasing the latch plate 78, and thus the thermally responsive unit 88 simply follows the latch plate upward with the arms still in engagement with the plate until unit 88 engages stops 130.

In view of the fact that the final position of push button 24 on manual opening of the device is determined by spring 68 (once member 62 has come to a stop) it is obvious that spring '68 must be made the correct length to provide the final position of button 24. On the con- 9 trary, in the thermal tripping operation, the ball carrier 46 pushes the push knob outwardly to the full extent, overcoming as it does the compressive strength of the spring 68.

The description of a trip-free operation will now be described, that is, an operation in which the push button is maintained in its most inward position but the devices opens on a thermal trip. Reference to FIG. will show that in this instance, holding the push button in its innermost position will also hold the ball carrier 46 in its innermost position, thus maintaining the balls in engagement with the peripheral catch shoulder 22. The contacts are closed, and when the device is now subjected to an overload current, the thermally

responsive arms

102 and 104 expand outwardly, as described above for the FIG. 1 operation. Because of the spreading apart of the

arms

102 and 104, the thermally responsive unit 88 is enabled to move upwardly under the influence of spring 146 to the position shown in FIG. 5, thus open ing the contacts. At the same time, latch plate 78 is released and moves downwardly, carrying the operable member 62 with it to bring the upper pocket 70 opposite the

balls

58 and 60.

If, now, starting with the position of the parts shown in FIG. 5, the push button is released, then the succeeding motions of the several parts are those described for the thermal trip opening, in that the

balls

58 and 60 will move inwardly into the pockets 78 under the camming action of the peripheral catch shoulder 22, and the parts move outwardly to the full open position of a thermal trip as shown in FIG. 3. Resetting to close the contacts then follows as described above for the thermal trip operation.

Turning now to FIGS. 8-21, there is shown a second embodiment of the invention using the same principles as found in the FIGS. l-7 embodiment described above. In this instance, the device is operable by a rotary motion, rather than a straight-line motion as in FIG. 1. Again, as in the FIG. 1 embodiment, these parts move on a common axis.

Referring to FIGS. 8-10, again there is shown a casing comprising the clam-

shells

152 and 154, one of the clamshells (152) being shown in elevation in FIG. 8. Each clam-shell is provided with a top 156, sides 158, and bottom 160. Clam-shell 152 is provided with the recess 162 to accommodate certain moving parts as will be described below (see FIG. and clam-shell 154 is provided with the recessed portion 164 for like purposes. The bottoms of each clam-shell are provided with mating slots in conventional manner for the mounting of a pair of stationary terminals and contact structures, one of these terminals and its associated contact structure being shown in FIGS. 8 and 21. A stationary contact 168 is mounted on the inner end of terminal piece 166 in conventional manner, such as by welding or riveting. The associated terminal proper 170 is mounted at the other end of the case, being held therein by the aforesaid mating slots in the bottoms of clam shells. A connecting strap 172 of conductive material (such as copper) connects terminal 170 with the stationary contact structure or terminal piece 166. The other terminal structure comprising a stationary contact arm and terminal 176 (see FIG. 21) on which is mounted in conventional manner the other stationary contact 176. Terminal 174 is held in the housing by means of suitably provided slots and supporting casing structure in conventional manner.

Contacts

168 and 176 have their contact faces substantially in alignment.

An arcuate ball race-way 180 is provided, and is more fully illustrated in FIG. 18. It is preferably made of metal, but may be made of a tough synthetic moldable plastic, if desired. It is approximately semi-circular in configuration, and may have an approximately rectangular cross-section. A ball catch pocket 184 is provided in the inner surface of the race-way. Mounting studs 186 are provided, one at each end of the race-way and projecting laterally therefrom, for fastening the race-way in the casing, these mounting studs preferably being steel pins traversing the race-way and projecting therefrom on each side, or they may be integrally molded as a part of the race-way if the latter is molded. As can be seen in FIG. 10; mounting studs 186 engage in suitably provided sockets in opposing portions of the inner faces of the clam-shells, this engagement serving to mount the race-way within the housing. The race-way is preferably mounted so that its ends are flush with the inside surfaces of the tops 156 of the clam-shells.

The tops 156 of the clam-shells are provided with the mating reliefs 188, these reliefs providing (when the clamshells are adjoined) an opening adapted to receive therein the manually operable member 190.

Member 190 comprises a circular rotatable disk-like portion 192, an operating handle 194, a radial lever-extension 126, and a second radial lever-extension 198. The entire structure 190 is preferably molded of a durable plastic such as a phenolic resin, or nylon. Around a portion of the periphery of the disk 192 is mounted by conventional means (for example, a suitable adhesive) the indicating

bands

200 and 202. These bands are of different colors, band 200 being for example white, and band 202 being for example red. Manually operable member 190 is rotatably mounted within the housing formed by the clam-shells by means of an arbor 284, the latter being preferably a steel pin passing through a suitably provided bore 296 in disk 15 2, the ends of the arbor being positioned in suitably provided sockets 208 molded in the opposing inner faces of the clam-shells. Arbor 204 is positioned, in respect to the inner surface of the race-way 180, to be at the center of curvature of the latter. The length of the lever 198 is such that it slidably engages said inner (or upper, as drawn) surface of race-way 180.

Slidably mounted on the inner surface of race-way is the ball carrier 216. Ball carrier 210 (see FIG. 17) is an arcuate slide member having a center of curvature on the axis of arbor 204, and may be molded of a tough plastic such as a phenolic resin or nylon, or preferably may be made of steel. The ball carrier is rectangular in cross section and is provided with the pocket 212 for receiving the ball 213. The thickness of ball carrier 210 is preferably the same as the thickness of the race-way.

It has been indicated, the ball carrier 210 may be molded of tough plastic, or preferably is made of steel such as stainless steel. In the latter instance, the ballreceiving pocket 212 may be broached in a solid steel member, or the ball carrier may be made in composite form comprising the two end pieces 214 and the cover plates 216, the assembly being held together by the conventional means such as riveting or welding.

In Width ball carrier 210 is sized and curved to fit between the said inner surface of ball race 180 and the end of lever extension 196, the end of lever 196 being a sliding fit against the inner surface of the ball carrier.

An operable member or operator 218 is provided which serves the same function as operable member or operator 62 in the FIG. 1 embodiment. Operable member 218 is arcuate in shape (see FIG. 16), and is provided with the ball-receiving

pockets

220 and 222.

Pockets

220 and 222 are separated by a partition member 224 the outer face of which is provided with a cylindrical surface having approximately the same radius of curvature as the ball 213. Member 218 is preferably made of steel, but may be molded of a durable synthetic resin such as a phenolic condensate. If made of steel, it may be made composite as described for the ball carrier itself, that is, it may have the separate end pieces 226, partition 224, and the cover plates 228. The parts may then be fastened by conventional means such as riveting or welding.

The depth of each of

pockets

220 and 222 is such that when the ball 213 is in the pocket of the ball carrier 210 and is also in either pocket of the operable mem- 1 1 her 218 the ball will just clear the inner surface of the race-way member.

Operable member 218 has approximately the same thickness as the ball carrier 210, and in width is dimensioned to fit with a smooth sliding fit between the outer periphery of the disk 192 and the inner surface of the ball carrier 210.

With this construction, it will be observed that the manually operating member may be rotated about arbor 204 with respect to the casing, and the ball carrier and operable member may also be rotated about said arbor with respect to the casing, with respect to the manually operable member, and with respect to each other.

In order to prevent transverse motion of the ball carrier and operable member,

retainer plates

230 and 232 are provided (see FIG. 18). Retainer plate 230 is semi-circular in configuration, is provided with a clearance notch 234 (with respect to said arbor) at the upper surface thereof, and is provided with the mounting holes 236 at its corners. Holes 236 are adapted to receive the mounting studs 186 of the race-Way 180 so that when the plate is mounted on the studs, its top edge is flush with the inner surface of the top 156 of one of the clam-shells. The periphery of the plate 230 is radially dimensioned to lie adjacent the bottom or outer periphery of the raceway. Plate 230 thus provides a wall to retain the ball carrier and the operable member along the back sides thereof (as drawn). Plate 232 is likewise made semicircular in configuration, with the exception that an arcuate slot 238 is provided to accommodate the motion of certain thrust pins described below. Mounting holes 240 are provided which are adapted to receive the mounting studs 186 of the race-way. A notch 242 is also provided in the plate 232 to clear the arbor 204. Clearance holes 243 and 245 are provided to fit over spring-retaining pin 250 and stop pin 252 described below. The upper periphery 247 (as drawn in FIG. 18) of slot 238 is radially dimensioned to extend below the upper periphery or surface of the operable member 218 and thus, in conjunction with back plate 230, holds the operable member in place on the ball carrier. In similar manner, the lower periphery 249 of slot 238 is radially dimensioned so that it projects above the inner or upper (as drawn) surface of the race-way 180, thus holding the ball carrier 210 on the race-way in conjunction with the back plate 230.

For the purpose of actuating the ball carrier, the operable member, and other parts, certain thrust and stop pins are provided, as follows: Mounted on operable member 218 is the thrust pin 244, which may be of steel or other rigid material. Similarly mounted on the ball carrier 210 are the thrust pins 246 and 248, and in like manner are mounted on the race-way 180 the thrust pin 250 and the stop pin 252. In view of the fact that the operable member 218 must slide relatively to the retainer plate 232, pin 244 is positioned so as to clear periphery 247 of slot 238; and in like manner, since the ball carrier 210 must move relatively to the race-way 180, the

pins

246 and 248 are positioned on the ball carrier to clear the periphery 249 of slot 238.

A movable contact and contact arm structure therefor are provided and are illustrated in detail in FIG. 20. The contact arm 254 swings from one end thereof which is pivoted by means of bearing sleeve 255 on arbor 204 and extends below the race-way 180. On a portion of arm 254 below the race-way there are provided two movable contact structures indicated generally by

numerals

256 and 258. Structure 256 comprises a bracket 260 which is rigidly fastened to the arm 256 in a manner electrically to insulate the bracket from the contact arm. (Such an electrically insulating attachment is conventional in the art and will not be described further.) At the upper end of bracket 260 there is mounted by conventional means such as riveting or welding, the movable electrical contact 262. Contact assembly 258 likewise comprises a bracket 264 which is rigidly fastened to the movable arm 254 in conventional manner but is electrically insulated therefrom, this bracket being separated from bracket 260 by a gap 265. A movable contact 266' is likewise fastened to the face of bracket 264 in conventional manner, such as by riveting or by welding.

Contacts

262 and 266* are so positioned on the arm 254 that when the arm swings to the left, as shown in FIG. 8, contact 262 makes electrical engagement with stationary contact 178, and contact 266 makes electrical engagement with stationary contact 168. Arm 254 is extended further downwardly, so that when the arm swings to the full contacts-open position (see FIG. 11), this extended end portion of the arm 254 engages the stop pin $268, which extends transversely across the interior opening of the switch enclosu-re, the ends of the pin engaging suitable sockets molded in the inner faces of the clam-shells in conventional manner. As seen in FIGS. 9 and 10, contact arm 254 is mounted on the arbor 204 and swings in the aforementioned recess 162 adjacent the retainer plate 230.

Attached to the

brackets

260 and 264 is a U-shaped bimetal catch 270 comprising the

legs

272 and 274 joined at their outer end by the cross member 276. The ends of

legs

272 and 274 are attached to and electrically connected with the

brackets

260 and 264 by conventional means and as illustrated there is shown one way, viz, by bending the ends of the legs and then welding the up wardly bent ends to the brackets. As so mounted, the high expansion side of the thermostat metal is on the top (as drawn) and the low expansion side is on the bottom.

In order to bias the contact arm 254 counterclockwise, that is, into a contact-open position, a spring 278 is provided of hairpin type, the bight of which surrounds the arbor 204 and sleeve 255 and the ends of which extend downwardly (as drawn) in the recess 162. One end is connected to the movable contact arm 254 in conventional manner (for example, by being hooked and engaging the side of the arm), and the other of the spring is engaged in a recess or socket 280 provided in the wall of the clam-shell housing.

A rotatable latch arm 282 is provided (see FIG. 19), and is pivoted on the arbor 204 by means of a bushing 283 attached to the upper end of the latch arm. The latch arm is provided with an offset end 284 with a detent shoulder 285 on the extremity thereof which serves as a latching catch for the thermostat metal catch 270. A thrust pin 286 is provided on latch arm 282, and is engaged by one end of hairpin spring 288, the bight of which surrounds the bushing 283. The other end of this spring is attached to or bears against the thrust pin 248 as shown in order to bias the latch arm 282 clockwise about arbor 204. Thus, with the latch arm 282 held by the bimetal catch 278 in the FIG. 8 position, spring 288 urges the ball carrier 210 counterclockwise about arbor 204. When the bimetal catch releases the latch arm (with the ball carrier locked in the FIG. 8 position), spring 288 biases the latch arm against the thrust pin 244 on operable member 218 to move the latter to unlocking position.

Also mounted on the arbor 204 is the hairpin spring 290. One end of spring 290 engages the fixed thrust pin 250, and the other end engages the thrust pin 246 on the movable ball carrier 210. The spring is so constructed and mounted that it biases the ball carrier counterclockwise about arbor 204.

A slot 292 is provided in disk 192 (see FIG. 9) extending beyond the arbor hole or bore 206 therein. A hairpin spring 296 is mounted in slot 292, the bight of said spring encircling the arbor. One end of spring 296 bears against the disk 192, and the other end of this spring rests against the left end (as drawn in FIG. 8) of the operable member 218, preferably in a slot 298 in the end thereof (see FIG. 16). The bias of spring 296 is such as to urge the operable member 218 counterclockwise about the arbor 204.

The operation of this embodiment is as follows:

As in the FIG. 1 embodiment, use is made of a latching member which can be unlocked from its latched position by positioning a pocket of a plurality of pockets in the operable member opposite the pocket or opening in the ball carrier. If one of these pockets is so oppositely positioned to unlock the latch for contact-opening, the device will indicate a thermal trip-out. If another pocket is so positioned instead, then there will be indicated a manual opening of the contacts. Referring first to the thermal trip-out, and particularly referring to FIGS. 8 and 11, in FIG. 8 the parts are shown with the contacts closed. The latch arm 282 is shown in engagement with the thermally responsive latch or catch 270* under the bias of spring 288 and maintains the contacts closed, this bias being greater than the bias of spring 278 which is urging the contacts open. The partition member 224 is opposed to ball 213 and maintains the ball in pocket 184 in the race-way. It will be noticed that since the latch arm 282 is maintained by the thermostat metal catch 270 in fixed position, the spring 288 is biasing the ball carrier (and thus the ball .213) in a counterclockwise direction above the arbor 204, motion being restrained by the engagement of the ball against the shoulder provided by the pocket 184 and the surface of the race-way. Because of the engagement of said shoulder on the ofl-center peripheral portion of the ball, there will be a force tending to move the ball radially upward (as drawn) which force is resisted by the aforesaid center partition 224.

If now, an overload current is passed through the circuit breaker it traverses terminal 174, stationary contact 176, movable contact 262, thermostat metal catch 270, electrical movable contact 266, stationary contact 168, arm 166, connecting strap 172, and terminal 170. Thermostat metal arm 270 heats, and because the high expansion side is on the top (as drawn) the catch bends downwardly to release the shoulder 285 of the latch arm 282, thus freeing the latch arm so that under the influence of spring 288 it will move clockwise to strike thrust pin 244. The force thus brought to bear by spring 288 against the thrust pin 244 will move the operable member 218 clockwise, disengaging center partition 224 from the ball and positioning pocket 222 opposite pocket 212 in the ball carrier. Under the aforesaid force striving to move the ball radially toward the arbor 204, the ball will now move into pocket 222 and in so doing the ball is released from the aforesaid shoulder and thus ball carrier 210 can traverse the raceway 180. With ball 213 now being in both

pockets

222 and 212, the operable member 218 and the ball carrier 210 are locked together, and both move as a unit under the influence of spring 290 counterclockwise, thus moving the extension lever arm 198 and disk 192 and handle 194 about the arbor 204. Because it is pocket 222 that is thus locked in position With the ball carrier, disk 192 willrotate counterclockwise until both of

bands

282 and 264 are exposed to view, thus showing that, a thermal trip-out has occurred. In the meantime, because the thermostat metal latch has earlier become disengaged from the latch arm 282, the movable contact arm is free to rotate under the bias of spring 278 in a counterclockwise direction about the arbor 204 to the fully open contact position, at which point the movable contact arm'254 engages the stop pin 268 and comes to rest.

Upon the opening of the contacts, current ceases to flow in the thermostat metal catch and the latter cools and returns to its original configuration, thus coming into position to be engaged by the shoulder 285. If, now, the disk 192 is rotated in a clockwise direction by means of the handle 194, the extension lever 198 engages the ball carrier 210 to move it and operable member 218 until ball 213 becomes positioned over pocket 184. At this point the off-center engagement of the shoulder of pocket 222 with the ball cams the latter down into pocket 184. It is to be noted that ordinarily the ball will be free to move downwardly under the influence of gravity into the pocket 184, but if the device should be in an upside down position, the above camming action will force the ball into the latching race-way pocket 184, thus leading to a position-free latching function. This return of ball 213 into pocket 184 is also aided by the camming action of the right-hand shoulder (as drawn) formed by the center partition 224, this resolved force assisting in moving the ball into pocket 184. As the ball moves into the pocket, the center partition overrides the ball and comes into opposition as shown in FIG. 1, thus latching the ball in pocket 184.

As pointed out above, indication of a thermal trip-out is that both of

bands

200 and 202 appear. That these bands both show is explained as follows: it will be observed that the position of operable member 218 is determined (when the contacts are open) by the latch arm 282, which in turn is positioned by the stop pin 252. The operable member 218 in turn, depending on which of the two pockets the ball is placed in on a release of contacts, determines the position of the ball carrier 210. When the ball is in pocket 222 of the operable member, the ball carrier is thus eventually stopped in its furthest posi tion around arbor 204, and in so doing it moves extension lever 198 to its fullest counterclockwise position, that is, until it approximates the inner surface of the housing tops 156. In this position, both the white and red band show to indicate the thermal opening.

On the other hand, had the ball 213 been in the pocket 220 (which occurs on a manual opening), then the ball carrier would not have been positioned as far around by the operable member, and disk 192 would not have moved around far enough to show the red band. Thus, in a manual opening operation, starting with the contacts in the FIG. 8 position, when the manually operable member is rotated counter-clockwise by manipulation of the handle 194, lever extension 196 engages the end of the operable member 218 and moves the latter until pocket 228 of the operable member is opposite the pocket 184 in the raceway. Under the influence of aforesaid camming force on the ball exerted by the shoulder of pocket 184 and the ball carrier, the ball will move upwardly and again unlatch both the operable member and the ball carrier from pocket 184. Under the influence of their respective biasing springs, both these members will now move in a counterclockwise direction along the race-way until the FIG. 12 position is arrived at. As they move, latch arm 182 moves counterclockwise, thus permitting spring 278 to open the contacts.

Attention is directed to the remarks given above in that with the ball carrier positioned by the respective thrust pin, latch arm and stop pin, the ball carrier finally occupies on manual opening a position different from that found in an opening of the contacts due to a thermal tripping. The result is that the manually operable member has not been rotated far enough around counter clockwise to expose the red band 202. In this operation, the final position of the manually operable member is determined by the operable member 218 and not by the ball carrier 210. Member 218 is stopped in motion by the latch arm 282 coming to rest against pin 252, with the result that since the ball carrier 210 is further within the race-way 180 (clockwise) than in the final thermal tripout position, it does not contact the lever extension 198. This leaves the operable member as the element which determines the extent of rotation of the manually operable member.

'The device is trip free, and a reference to FIG. 14 will show the operation in that instance. Assuming that the manually operable member 190 is held in the normal contacts closed position, heating of latch 270 will free it and the movable contacts from the restraint of latch arm 282.

The movable contacts will now swing counterclockwise to a contacts-open position. On the other hand, had a force been applied to the manually operable member to

Claims

1. A CIRCUIT BREAKER COMPRISING A CASING: A FIRST ELECTRICAL CONTACT MOUNTED ON SAID CASING; A CONTACT ARM MOVABLY MOUNTED IN SAID CASING; A SECOND CONTACT CARRIED BY SAID CONTACT ARM AND ADAPTED TO COOPERATE WITH THE FIRST CONTACT TO MAKE AND BREAK AN ELECTRICAL CIRCUIT; SPRING MEANS IN SAID CASING BIASING SAID CONTACT ARM IN A CONTACTOPENING DIRECTION; A THERMALLY RESPONSIVE MEMBER CARRIED BY SAID CONTACT ARM; A MANUALLY OPERABLE MEMBER MOVABLY MOUNTED ON SAID CASING; SPRING MEANS IN SAID CASING FOR BIASING SAID MANUALLY OPERABLE MEMBER IN A CONTACTOPENING DIRECTION; A FIRST LATCH MEMBER MOVABLY MOUNTED IN SAID CASING; SPRING MEANS IN SAID CASING FOR BIASING SAID FIRST LATCH MEMBER IN A CONTAT-OPENING DIRECTION; AN OPERATOR MOVABLY MOUNTED IN SAID CASING AND MOVABLY RELATIVE TO SAID MANUALLY OPERABLE MEMBER, SAID OPERATOR INCLUDING RELEASE MEANS FOR SAID FIRST LATCH MEMBER; SPRING