US2961509A

US2961509A - Operating mechanism for an electric circuit interrupter

Info

Publication number: US2961509A
Application number: US791076A
Authority: US
Inventors: Leslie L Baird; Ralph J Baskerville
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1959-02-04
Filing date: 1959-02-04
Publication date: 1960-11-22
Anticipated expiration: 1977-11-22

Description

a i Ah.

Nov. 22, 1960 L. L. BAIRD ETAL 2,961,509

OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT INTERRUPTER Filed Feb. 4, 1959 5 Sheets-Sheet l CLO-SEO Inventors: Leslie L... Baird, -J'Ralph J. Baskerville be; I WMAMW/ weir Attorneg.

Nov. 22, 1960 L. BAIRD ETAL 2,961,509

OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT INTERRUPTER Filed Feb. 4. 1959 5 Sheets-Sheet 2 Fig.2.

TR/PPED OPE/V CLO'S/NG I a l i Q Invent rs: III'I'II, L, e S I e T d 7 1 h J. Bask mej 5 a p heif'Attorneg.

Nov. 22, 1960 L. L. BAIRD ETAL OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT INTERRUPTER Filed Feb. 4, 1959 5 Sheets-Sheet 3 Inventors:

Leslie J... Baird, Ralph J. Baskerville,

Their Attorney.

Nov. 22, 1960 L. L. BAIRD ETAL 2,961,509

OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT INTERRUPTER Filed Feb. 4, 1959 5 Sheets-Sheet 4 CLOSED Inventor-s: Leslie L.. Baird,

alph J. Baskerville,

by h

heir Attorneg Nov. 22, 1960 1.. L. BAIRD ETAL 2,961,509

/ OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT INTERRUPTER Filed Feb. 4, 1959 s Sheets-Sheet 5 OPEN-RESET CLOSING Inventors: Leslie J... Baird, jRalph J. Basker-ville United States Patent OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT INTERRUPTER Leslie L. Baird, Swarthmore, and Ralph J. Baskerville,

Drexel Hill, Pa., assignors to General Electric Company, a corporation of New York Filed Feb. 4, 1959, Ser. No. 791,076

41 Claims. (Cl. 200106) This invention relates to an electric circuit interrupter or breaker, and more particularly it relates to a circuit breaker operating mechanism wherein a spring is arranged to release stored energy to the mechanism for obtaining a quick-action circuit closing or making operation.

Such stored energy mechanisms are commonly used in low-voltage air circuit breakers for driving a movable switch member between open and closed circuit positions. Mechanical energy is first accumulated in the spring by the controlled action of a pivotally movable operating member connected thereto. By moving the operating member from a reset position to an operated position with the mechanism in a releasably latched condition, the spring is stressed and accumulates energy the release of which imp-arts quick and positive switch closing movement to the mechanism. It is a general object of the present invention to provide an improved circuit breaker operating mechanism of this type.

A more specific object of the invention is to provide an operating mechanism of this type wherein the spring must be substantially fully stressed or charged and will always release a predetermined constant amount of stored energy for imparting switch closing movement to the mechanism regardless of liberal manufacturing tolerances, variations in the rate at which the operating member is moved to its operated position, and changes in the frictional forces of the mechanism due to wear.

Another object of this invention is the provision of an improved operating mechanism wherein the operating member cannot be returned from its operated to its reset position while the switch member is in its closed circuit position, whereby the mechanism must be unlatched in order to obtain switch opening movement thereof.

Still another object is the provision of an improved operating mechanism utilizing electromagnetic means for moving the operating member from its reset to its operated positions, said movement of the operating member controlling the accumulation of energy in the spring and efiecting release of energy thus accumulated for producing switch closing movement of the mechanism.

It is still another object of the invention to provide electromagnetic means comprising a solenoid and a rigid armature which is adapted to be directly and positively connected to the pivotally movable operating member of the circuit breaker operating mechanism for moving the operating member between different angular positions.

A further object is the provision of electromagnetic means, comprising a solenoid, a magnetizable yoke and a movable plunger, for stressing or charging a spring wherein the magnetic force acting on the plunger increases relatively linearly throughout the charging operation.

A specific object of the present invention is to provide improved electromagnetic apparatus comprising an electric coil wound on a spool of insulating material, a magnetizable yoke supporting the spool and a plunger disposed for movement within the spool, the electromagnetic apparatus being extremely simple and inexpensive to manufacture and assemble.

in carrying out our invention in one form, we provide a circuit interrupter including a movable switch member, a releasably latched operating mechanism connected to the switch member, and an operating member disposed for pivotal movement between reset and operated positions. The operating mechanism includes a spring connected to the operating member, the spring being charged and exerting a switch closing force on the mechanism during movement of the operating member toward its operated position. We provide means for restraining the switch member in an open circuit position until the operating member reaches a predetermined point near its operated position whereupon the switch member is released and the operating mechanism undergoes quick-action switch closing movement in accordance with the force being exerted by the spring. In addition, the mechanism is arranged so that the operating member is blocked in its operated position in response to circuit closing movement of the switch member, whereby the operating mechanism has to be unlatched in order to obtain a circuit opening operation and permit return of the operating member to its reset position.

In one aspect of our invention, the operating member is moved from its reset to its operated position by electromagnetic means comprising a solenoid and a cooperating rigid armature. The armature, which is moved longitudinally by the force of magnetic attraction upon energization of the solenoid, is connected to the operating member at a point defining an arcuate path while the operating member is being moved toward its operated position. We provide means for guiding the rigid armature with leeway for lateral deviation during its longitudinal movement, and preferably this means comprises the insulating spool of the solenoid in which the armature is relatively loosely disposed. A magnetizable yoke is also provided for the solenoid, the yoke and the armature being configured and arranged so as to reduce the nonlinearity of the rate of increase of magnetic force experienced by the armature while moving the operating member. The yoke preferably comprises two parts assembled in cooperation with specially constructed grooved flanges of the aforesaid spool for supporting the solenoid.

The invention will be better understood and its various objects and advantages will be more fully appreciated from the following description taken in conjunction with the accompanying drawings in which:

Fig. l is a side elevation of a circuit interrupter having an operating mechanism constructed in accordance with one embodiment of the invention, the circuit interrupter being shown in its closed circuit position;

Fig. 2 is a simplified side elevation of the circuit interrupter of Fig. l with the operating mechanism and the switch member of the interrupter being shown in tripped-open positions;

Fig. 3 is a partial side elevation of the circuit interrupter of Fig. 1 showing the operating mechanism in its open-reset position;

Fig. 4 is a side elevation of the operating mechanism shown intermediate its open-reset and closed positions just prior to snap-action switch closing movement thereof;

Fig. 5 is a section taken along lines 5-5 of Fig. 1;

Fig. 6 is a section taken along lines 66 of Fig. 5;

Fig. 7 is a view similar to that of Fig. 1 but illustrating a manually operable operating mechanism constructed in accordance with another embodiment of our invention;

Fig. 8 is a partial side elevation of the operating mechanism of Fig. 7 with the mechanism moved to its open-reset position; and

Fig. 9 is a partial side elevation of the operating mechanism of Fig. 7, the mechanism being shown intermediate its open-reset and closed positions just prior to snap-action switch closing movement thereof.

Referring now to Fig. l, we have shown an electric circuit breaker or interrupter comprising a frame member 11 supporting a base member 12 of electric insulating material, a relatively stationary contact or switch member 13 mounted on the base, a bracket 14 mounted on the base in spaced relation to the stationary contact member, a movable contact or switch member 15 pivotally supportedby bracket 14 and disposed in cooperative relationship with the stationary switch member 13, and actuating means such as a crossbar 16 coupled to the movable switch member 15 for moving this member into and out of circuit-making engagement with the stationary switch member 13. Movement of the switch member 15 into and out of engagement with the member 13 closes and opens, respectively, an electric circuit represented by'conductors 17 and 18. The

components

13, 14 and 15 comprise thecontact structure of one pole unitrof an'alternating or direct current circuit interrupter, and other pole units substantially identical to that shown could be mounted on the frame member 11 for gang operation by the common crossbar 16. The particular contact structure that has been shown in the drawings" for the purpose of illustrating the present invention is the subject matter of the copending patent application of Leslie'L. Baird, S.N. 764,642 filed on October 1, 1958, and assigned to the assignee of the present invention.

Movement of the switch member15 between its closed circuit position (Fig. 1) and its open circuit position (Fig. 2) is controlled by an operating mechanism which is connected to the switch member by means of an elongated connecting member 19 pinned to a link 20 which in turn is firmly affixed to the crossbar 16. The operating mechanism comprises a plurality of interconnected movable members one of which is a guide member 21 pivotally mounted on the frame member 11 by means of a rod 22 fixedly supported thereby. The remaining members constitute a force-transmitting linkage mechanism 23 pivotally fastened by a pin 24 to theconnecting member 19 and hence to the movable switch member 15. The pin 24- is supported for movement along a predetermined arcuate path by an output crank 25 of the. mechanism' which is pivotally mounted on the frame member 11 at 26. The various illustrated parts of the operatmg mechanism, with the exception of the guide member 21, preferably are provided in identical pairs so that the entire mechanism is symmetrical with respect to a vertical plane parallel to the plane of the drawings, with the guide member 211 being disposed in the plane of symmetry. The output crank 25 actually is a U-shaped member, the two identical, spaced-apart upstanding parts of which are rigidly interconnected by a transverse part 25a.

The operating mechanism also includes at least one helical tension spring 27 arranged to release stored energy to the mechanism for imparting quick-action switch closing and opening movement thereto. Accumulation of energy in the spring 27 is controlled by a movable ope-rating member 28 which is pivotally mounted on the frame member 11 by means of the rod 22 afiixed thereto. The operating member 23 preferably comprises two identical upstanding parts, only the far one being shown, rigldly interconnected by a pair of transverse sections 28a and 28b. The spring 27 interconnects the operating mechanism and a laterally extending pin 29 carried by the operating member 23.

The operating member 28 is disposed for pivotal movement between two difierent angular positions at opposite ends of its normal range of movement: a first or reset position shown in Fig. 3, and a second or operated position shown in Fig. 1. While moving to its second or operated position with the operating mechanism in a releasably latched condition (the latching means is described in detail hereinafter), the operating member will stress or charge the spring 27 and will effect release of energy thus stored in the spring for producing switch closing movement of the mechanism. In order to obtain this movement of the operating member 28, suitable electroresponsive means such as the solenoid 30 and co operating armature 31 shown in Figs. 1 and 3 may be employed, or the operating member may be coupled to a suitably disposed manually operable handle 32 such as is illustrated in Figs. 79.

In the illustrated embodiments of the invention, the operating mechanism includes a toggle comprising two

links

33 and 34 pivotally joined by a pin 35 which forms the knee of the toggle. (Actually, as has been pointed out hereinbefore, the links 33" and 34 are provided in identical pairs, and the near one of'the links 34 is omitted in the drawings for the sake of clarity.) The spring 27 functions as an overcenter spring, and one end of the spring is connected to the pin or toggle knee 35. One end of the toggle, specifically the right-hand end of the link 34 as viewed in the drawings is connected to the pin 24 and hence to-the switch member 15' for moving the switch member between its open and closed circuit positions. The other end of the toggle, specifically the left-hand end oflink 33; is supported by a pin 36 for'movement between two'dilferent positions.

The pin 36 is connected to the guide member 21. As the guide member moves pivotally between predetermined latched and unlatched positions, the pin 36 is carried along a predetermined arcuate path 35p (Fig. 1) with respect to the axis of the supporting rod 22. In Figs. 1 and 3-the guide member'or lever 21 is shown in its latched position where it is releasably restrained by a latch indentified generally by the reference number 37.

In order to close the circuit interrupter, the'operating mechanism is arranged to move the switch member 15 from its open circuit positionito its closed position with quick and positive action. This is accomplished by moving the operating member'ZS from its first or reset position (Fig. 3) toward its second or operated position (Fig. 1) in response to which the overcenter spring 27 is stretched or charged and moves over center with respect to the toggle link 33. The spring force being exerted on the toggle knee 35 willnow produce in toggle link 33' a counter clockwise torque tending to straighten the toggle from its initially collapsed condition shown in Fig. 3. Upon release of energy stored in the spring, the'toggle knee is pulled upward and the toggle undergoes snap-action switch closing movement which rotates the output crank' 25 clockwise and drives the switch member 15 to its closed position.

The closed position of the operating mechanism, as can be seen in Fig. 1, is determined by the engagement of a pin 38 protruding laterally from toggle link 33 with an interfering stop surface 39 of the guide member 21, the guide member at this time being firmly held in its latched position by the latch 37. Suitable stop and blocking means, to be described hereinafter, are respectively provided for definitely determiningthe second position of the operating member 28 and for preventing the return of the operating member to its first position as long asv the switch member 15' is closed. As is evident in Fig. l, the second position of the operating member 28 is so located in relation to the toggle after undergoing switch closing movement thereof that the line of action of the overcenter spring force intersects the path 36;; to. be followed by the pin 36 during subsequent movement of the guide member 21' to its unlatched position. In the closed position of the operatingvmechanism there is still a substantial amount of energy remaining in the overcenter spring 27, since not all of the stored energy was given up by this spring while effecting the abovedescribed closing operation.

As is clearly shown in Fig. l, the. overcenter spring 27 exerts a force on the guide member 21, by way of toggle link 33 and the

pins

36 and 38,.tending to drive this member in a clockwise direction from its latched position. It is the function of the latch 37 to prevent such movement by the guide member until a circuit opening operation of the interrupter is desired. The latch comprises a transversely extending trip shaft 40 supported by the frame member 11 for rotary movement between a normal position shown in Figs. 1 and 3 and a trip position shown in Fig. 2. A radially protruding portion or prop 41 of the trip shaft 40 cooperates with an intermediate latch member or catch 42 for releasably restraining the guide member 21 in its latched position with the trip shaft in its normal position.

The latch member 42 is pivotally mounted intermediate its ends on a transverse rod 43 which is supported by the frame 11. On one side of the rod 43 this member is provided with a stud 44 disposed in self-releasing engagement with the heel of an integral leg 45 of the guide member 21. With the trip shaft 40 in its normal position, the stud 44 of the intermediate latch member 42 is firmly held in engagement with leg 45 of the guide member, thereby maintaining the guide member in its latched position, by the prop 41 which abuts a roller 46 carried by the latch member on the other side of rod 43. The latch member 42 preferably comprises two similar parts (only the near one being shown) that are firmly joined by the stud 44 and the axle of the roller 46. A tension spring 47 is provided for biasing the trip shaft 40 in a clockwise direction to its normal position and for biasing the intermediate latch member or catch 42 in a clockwise direction into self-releasing engagement with the guide member 21.

The intermediate latch member 42 with its roller 46 and the prop 41 are constructed and arranged so that the resultant force of action and reaction therebetween is directed normal to the axis of rotation of the trip shaft 40. To accomplish this result in the illustrated embodiments of the invention, the prop surface 41a abutting the roller 46 is conformed to a circumferential section of a right cylinder whose axis is the axis of shaft 40. Consequently, the line of action of the resultant force transmitted by the prop 41 to the trip shaft, in order to restain the guide member 21 in its latched position against the force of overcenter spring 27, intersects the axis of the trip shaft 40 and has no moment arm with respect thereto. This arrangement helps to eliminate accidental unlatching operation by the latch 37 upon the occurrence of any relatively sudden and severe mechanical shock to the circuit interrupter. The prop 41 is in compression and free of bending stresses, whereby any tendency to distort adversely the circumferential surface 41a is relieved.

In order to open the circuit interrupter, the operating mechanism is arranged to move the switch member 15 from its closed circuit position to its opened circuit position with quick and positive action in response to toggle releasing operation of the latching means. The opening operation is initiated by rotating the trip device 40 in a counterclockwise direction from its normal position (Fig. 1) to its tripped position (Fig. 2). For this purpose any suitable means may be used, such as, for example the schematically illustrated manually operable trip bar 48. Longitudinal movement of the trip bar 48 to the right, as viewed in Fig. 1, causes an adjustablelength terminal portion 49 of this bar to strike and tilt a paddle member 54 which is rigidly aifixed to the trip shaft 40. As a result, the trip shaft is rotated counterclockwise and the prop 41 is pivoted away from the roller 46 of intermediate latch member 42. The force necessary to accomplish this result is significantly less than the force being exerted at this time by the overcenter spring 27 because of the favorable force amplifying leverage system formed by the interengaging pivotally supported

members

50, 41, 42 and 21 of the latching means.

The removal of prop 41 from abutting relationship with roller 46 enables the intermediate latch member 42 to move counterclockwise about rod 43 in accordance with the force applied at its stud 44 by the leg 45 of guide member 21, whereupon the guide member is no longer restrained in its latched position. The overcenter spring 27 is effective in response to this guide releasing operation of the latch 37 to drive the guide member to its unlatched position (Fig. 2) thereby enabling the operating mechanism to undergo switch opening movement. As the spring releases energy during the opening operation, the toggle knee 35 is pulled to the left (as viewed in Fig. 1) and the pin 36 carried by the guide member moves upward along its arcuate path 36p. When the pin 36 has passed through the line of action of the overcenter spring 27, the toggle collapses and undergoes snap-action switch opening movement. During this action the output crank 25 is rotated counterclockwise and the movable switch member 15 is driven to its open circuit position.

The operating mechanism is shown in a collapsed, tripped-open condition in Fig. 2. As can be seen in this figure, the open position of the switch member 15 and the corresponding position of the mechanism output crank 25 are determined by the engagement of a bushing 52 located on pin 24 with a concave stop surface 53 of the frame member 11. The guide member 21 is here in its unlatched position which is determined by the engagement of a shoulder 54 of the guide mem her with suitable stop means such as the illustrated rod 55. The rod 55 is rigidly afiixed to the frame 11 and blocks further clockwise movement of the guide member 21 about its pivot 22. Since one end of the toggle is connected to the pin 24 and the opposite end is connected through pin 36 to the guide member 21, the position of the toggle knee 35 at this time is necessarily fixed. For the reasons which will be explained hereinafter, the operating mechanism is only momentarily in the position in which it is shown in Fig. 2.

During the above-described opening operation, the toggle knee 35 is forced to follow a relatively linear path from its position shown in Fig. 1 to its position shown in Fig. 2. This is accomplished by providing suitable camming means controlled by movement of the guide member 21 and disposed in cooperation with the toggle. Preferably the camming means comprises a concave camming surface 56 of the guide member 21 which engages a roller 57 connected to the toggle link 34 while the guide member is moving toward its unlatched position. As a result, the movement of the toggle is controlled in a manner to obtain a substantially uniform rate of energy release by the overcenter spring 27 throughout the opening operation, and the spring will manifest a relatively high force gradient in resisting rebound of the movable switch member 15 from its open circuit position.

The circuit interrupter operating mechanism, in the rst embodiment of the invention, is automatically moved by the overcenter tension spring 27 from its trippedopen position of Fig. 2 to its open-reset position shown in Fig. 3. This is accomplished by arranging the mechanism in accordance with the principle fully explained and claimed in United States Patent 2,866,872 issued to W. Turner on December 30, 1958. If automatic reset is not desired, as in the case of a manually operable circuit interrupter such as that illustrated in Figs. 7-9, the operating mechanism can be arranged differently so that movement of the operating handle 32 is required to accomplish the resetting operation. Regardless of whether it is eifected automatically by the spring 27 or manually by other means, the resetting operation is basically the same: the operating member 28 is returned to its first or reset position, the guide member 21 is simultaneously driven to its latched position, and the toggle is moved in its collapsed condition to the position in which it is shown in Fig. 3.

With the operating mechanism in its tripped-open position, as can be seen in Fig. 2, the overcenter spring" 27 is exerting a forceon the operating member 28 tending to move this pivotally mounted member in a counterclockwise'direction toward its first or reset position. Counterclockwise movement of the operating member carries pin 29 along a predetermined arcuate path 29p shown in Fig. 3; An arm 65 of the guide member 21 is disposed, with the guide member in its unlatched position, immediately below the laterally extending pin 29. While the operating member is being moved from its first to its second positions, the pin 29 engages the upper surface of arm 65 and drives the guide member 21 in a counterclockwise direction about its pivot 22to its latched position. While moving toward its latched position, the guide member, being pinned at 36 to the toggle link 33, impels the toggle to-its open-reset position shown in Fig. 3. In attaining this position, the toggle knee 35 has followed a path 351' which progressively converges with the arcuate path 29p of pin 29. Therefore the overcenter tension spring 27, which is connected between pin 29 and toggle knee 35; progressively shortens during the resetting operation and releases energy for returning the operating member 28 to its first position and for driving the guide member 21 to its latched position.

During the resetting operation of the mechanism, the latch 37 is also reset thereby releasably restraining the guide member 21 in its latched position. Vfnen the guide member is in its unlatched position (Fig. 2), and during the initial movement of this member toward'its' latched position, the intermediate latch member 42 is held in a tilted position against the force of its bias spring 47 by the guide member leg 45 whose lower surface slidably engages a cooperating extension 66 of the member 42. The leg 45 slides across the top of stud 44 as the guide member approaches its latched position and finally passes beyond this stud, whereupon the intermediate member 42 is free to pivot clockwise on rod 43 in accordance with its bias and the stud 4 moves into self-releasing engagement with the heel of leg 45. This enables the trip shaft 40 to return to its normal position, and the prop 41 moves into its abutting disposition with respect to the roller 46 of latch member 42. See Fig. 3. When the operating member 28 is subsequently moved toward its second or operated position, member 42 will tilt slightly into engagement with prop 41 and the latch 37 is again effective to restrain the guide member 21 in its latched position.

The above-described resetting operations cannot take place until the movable switch member of the circuit interrupter has moved from its closed circuit position to its open circuit position. This is due to the provision of blocking means for positively preventing movement of the operating member 28 from its second or operated position to its first or reset position whenever the switch member is closed. Since the operating member is blocked in its second position with the switch member closed, the only way the circuit interrupter can be opened is by actuating the latching means in consequence of which the operating member is permitted to return to its first position.

The blocking means preferably comprises a pair of cooperating blocking elements 67 and 63 associated with the operating member 28 and the mechanism output crank 25, respectively. As can be seen in Fig. 1, the blocking element 67 is an integral limb of the operating member having a blunt end and generally curved edges disposed for movement along a predetermined arcuate path in accordance with the pivotal movement of the operating member 28 between its first and second positions. The cooperating element 68 comprises a lug extending transversely from a projection of the output crank for movement about pivot 26 in response to circuit opening and closing movement of the switch member 15. In other words, the blocking element 68 is actuated by move- 8 ment of pin 24 which physically interconnects the output end of the toggle and themovable switch member 15'.

By moving the operating member 28 from its first position shown in Fig. 3 to its second position shown in Fig. 1, a'snap-action switch closing operation of the mechanism is effected. The blocking element 68 is accordingly moved into the predetermined path of movement of the blocking element 67 where, as best seen in Fig. 1, it interferes with the blunt end of element 67 and positively blocks the operating member 28 in its second position. When later the latching means is operated to release the toggle, the mechanism undergoes switch opening movement during which the element 68 is moved out of the aforesaid predetermined path to unblock the operating member 23, as shown in Fig. 2; Only now can a resetting operation be undertaken and the operating member moved to its first position (Fig. 3).

Thus, the blocking means which became effective during the closing operation to releasably restrain the operat ing member 28 in its second position, is moved'only in response to a subsequent opening operation to free the operating member for return to its first position. The blocking means is arranged so that movement ofthe operating member 28 toward its first'position is permitted only after the snap-action switch opening movement of the toggle has been initiated and the movable switch member 1515 substantially fully opened, whereby in the first embodim'entof the invention the automatic resetting operation cannot begin untilafter the opening operation is practically completed.

With the operating mechanism in its open-reset position, the circuit interrupter can be closed by energizing the illustrated electromagnetic means which will move theoperating member 28 from its first to its second position. The energizing circuit for the electromagnetic means includes, for example, a suitable control switch (not shown), a pair of separable electric contacts 70 and 71 of a cutofi switch '72, and the coil of solenoid 34) all connected in series circuit relationship to a suitable source of control power (not shown). Closing the control switch enables current to fiow through the solenoid coil, and the resulting force of magnetic attraction causes the armature or plunger 31 to move upwardly from the position in' which it is shown in Fig. 3. This drives the operating member 23 toward its second position inresponse to which energy is accumulated in the overcenter spring 27 and a switch closing force is exerted on the toggle.

The actual snap-action switch closing movement of the toggle cannot take place before the operating member 23' reaches a predetermined point near its second position such as is shown in Fig. 4. This is due to the provision of blocking means for releasably restraining the movable switch member 15 in its open circuit position until the operating member is moved past the aforesaid predetermined point, whereupon the switch member is released and the toggle is able to undergo switch closing movement in accordance with the force being exerted by the overcenter spring.

The predetermined point at which the blocking means becomes ineffective and energy stored in the spring is first released for imparting switch closing movement to the mechanism is selected in the preferred embodiment of our invention, for example, so that the operating member must be moved through approximately 97 percent of its total range of movement in order to reach this point. This ensures that'the overcenter spring 27 will be substantially fully charged with the maximum amount of energy being stored therein before any of its energy is released. Thus the closing and subsequent opening and resetting operations of the circuit interrupter will be unaffected in the event control power should fail while the movable switch member is closing. By providing a definite, fixed release point, the blocking means also ensures that a substantially constant amount of closing energy is always available each. time the circuit interrupter is closed and regardless of the speed with which the operating member 28 is moved to its second position.

The blocking means preferably comprises the same pair of cooperating blocking

elements

67 and 68 described her'einbefore. The blocking element 68, which is associated with the output end of the toggle, is disposed for movement along a predetermined arcuate path about pivot 26 during closing movement of the switch member 15. With the operating member 28 in its first angular position and during most of the movement of this member toward its second position, as clearly indicated in Figs. 3 and 4, the blocking element 67 is disposed in this predetermined path and the element 68 is positively blocked by the lower edge thereof, whereby appreciable switch closing movement of the toggle is prevented.

When the operating member approaches its second position, it passes through the position in which it is shown in Fig. 4 (line 29p in Fig. 4 representing the path being followed by the laterally extending pin 29 carried by the operating member), and it will be observed that the tension spring 27 has moved overcenter with respect to the toggle link 33 at this point. As the operating member proceeds beyond this point, it causes the blunt end of element 67 to move beyond element 68 which will now be able to travel freely along its predetermined path. In this manner the blocking means consistently operates near the end of the movement of the operating member toward its second position to free the toggle and to effect release of energy stored in the spring 27 for producing switch closing movement of the operating mechanism, whereupon the closing operation is completed.

As the circuit interrupter operating mechanism is undergoing switch closing movement, the element 68 moves into its blocking position (Fig. 1) wherein it releasably restrains the operating member 28 in its second position. It is important that the electromagnetic means which has moved the operating member to its second position remain energized until this blocking action has taken effect, thereby maintaining the operating member in its second position while the switch closing movement of the mechanism is getting underway. In order to accomplish this result, the cutoff switch 72, which controls the energization of the solenoid 30, is arranged to be actuated in response to the switch closing movement of the mechanism. This will ensure that the operating member 28 is blocked in its second position and that the spring energy has been released for imparting irreversible switch closing movement to the operating mechanism before the solenoid is de-energized.

The cutoif switch 72, as is shown in Figs. 1-3, comprises a resilient switch arm 74 supporting the electric contact 70 at one end and pivotally connected at its other end to a transverse shaft 75. The shaft 75 is suspended between two spaced-apart supporting elements 76 (only the near one being shown) fastened to a base member 77, and the cooperating electric contact 71 is mounted on a bracket 78 also fastened to the base member 77. The base member 77 is located above the operating mechanism of the circuit interrupter where it is aflixed to the frame 11. A broad cantilever control arm 97 is yieldably coupled to the switch arm 74 and depends from the cutoff switch in cooperation with the operating mechanism for actuating the separable contacts 70 and 71. Suitable spring means is provided for biasing the interconnected switch and control

arms

74 and 79 in a counterclockwise direction about the shaft 75 to predetermined normal positions wherein the contact 70 is maintained in an engaged position with respect to contact 71, as can be seen in Fig. 3.

The control arm 79 of the cutoff switch 72 is disposed for engagement by an upwardly extending appendage 33a of the toggle link 33 in response to switch closing movement of the operating mechanism. The final stage of a closing operation involves the straightenng of the toggle with snap-action, and the toggle link 33 is abruptly pivoted counterclockwise on pin 36 from the position shown in Fig. 4 to the position shown in Fig. 1. As a result, appendage 33a of link 33 engages the control arm 79 and tilts this arm in a clockwise direction about shaft 75 to an actuated position, thereby causing separation of the cooperating contacts 71) and 71. See Fig. 1. The contact 79 has been moved to a disengaged position thereby opening the energizing circuit for the solenoid 30 and deenergizing the electromagnetic means. The operating member 28, which was being upheld in its second position by the armature 31, is now releasably restrained in this position by the

abutting blocking elements

67 and 68, and the armature 31 cannot return to its original position shown in Fig. 3.

As long as the circuit interrupter is closed, the control arm 79 of the cutoff switch is held in its actuated position, thereby preventing reenergization of the electromagnetic means, by the operating mechanism acting through link 33. The control arm is also disposed for engagement by a protrusion 80 of the guide member 21 in response to switch opening movement of the operating mechanism, whereby control arm 79 is maintained in its actuated position, and energization of the solenoid 30 is prevented, with the mechanism in its trippedopen position (Fig. 2). Upon operation of the latch 37 with the circuit interrupter closed, the guide member 21 is driven in a clockwfse direction about pivot 22 to its unlatched position and protrusion 81) moves into engagement with control arm 79. At the same time the toggle is collapsing and appendage 33a of toggle link 33 rides along the curved underside arm 79 while holding this arm in its actuated position. The operating mechanism is arranged so that during the initial portion of its switch opening movement the appendage 33a of link 33 is maintaining the control arm '79 in its actuated position, while during the remaining portion of this movement the protrusion 88 of guide member 21 will prevent the control arm from returning to its normal position, whereby the cooperating electric contacts 70 and 71 are caused to be separated throughout the opening operat on.

The cutoff switch 72 will not reset to permit subsequent energization of the solenoid 30 until a resetting operation of the mechanism is underway, as indicated by counterclockwise movement of the guide member 21 toward its latched position. Th s ensures that before the solenoid can again be energized the movable switch member 15 is fully open and the condition of the operating mechanism and the armature 31 will be proper for a normal closing operation. During the resetting operation, the protrusion 80 of the gu'de member 21 drops away from the control arm 79 thereby enabling the control and switch

arms

79 and 74 to move to their normal positions in accordance with their bias, whereupon contact 70 engages contact 71 to set up the energizing circuit for the solenoid 30 (Fig. 3).

When energized, the solenoid 30 wll produce a magnetic field. A magnetizable yoke 94 provides physical support for the solenoid and forms a part of the magnetic circuit for its field. The yoke 94 comprises a plurality of iron laminations stacked between a set of hangers 95, and the hangers 95, as can be seen in Figs. 1 and 3, are provided w'th mounting feet securely fastened by rivets or the like to the underside of a horizontal channel element 11a of the circuit interrupter frame member 11. Preferably the yoke is made in two separate parts, the bottom part including supporting elements 96 which are respectively fastened to the hangers by bolts 97. This enables the hollow spool 98 on which the solenoid coil 99 is wound to be conveniently clamped between the two parts of the yoke 94, as indicated in the drawings.

The configuration of the yoke 94 is best seen in Fig. 5. Clearly shown in this sectional view are a plurality of rivets 100 by means of which the set of hangers 95 and supporting elements 96 are respectively attached to edges of the flanges.

the iron laminae comprising the two parts of the yoke 94. The axially outward facing surfaces of the flanges located at opposite ends of the spool 98 are provided with grooves 191 for receiving the transverse portions of the yoke 94. The width of each groove 101 is substantially the same as the width of the transverse portions of the yoke, whereby these portions nest snugly between the sidewalls defining the grooves. The depth of each groove, however, is tapered and is deepest at the outer Therefore the yoke 9 iwill rest against the bottom'of the grooves 101 only in the vicinity of the sp'ools hollow body portion 98a, as is seen in Fig. 5. As a result, when the spool 98 is clamped between the two parts of the yoke 94, its body @ila is axially compressed while its flanges are relieved of bend'ng stresses. Since the compression strength of' electric insulating material, of which the spool is made, is greater than the tensile or bending strength of such material, this feature of'ourinvention materially improves the ability of the spool to successfully withstand the mechanical shock to which it is subjected during operation of the circuit interrupter.

The loke 94 includes a pole piece 192 which extends into the solenoid spool 98 at its upper end. The transverse dimension of the pole piece 162 is substantially the same as the transverse distance between the inner surfaces of the sidewalls of the spool body 98a so that there is a snug fit therebetween, as is shown in Fig. 5. n the other hand, the width of the pole piece is less than the corresponding distance between the spool sidewalls, whereby ample passageways are provided on opposite sides of the pole piece, respectively, for a pair of generally longitudinally movable, spaced-apart elongated metallic strips 103 and res. The strips 163 and 164 comprise part of the armature or plunger 3?. which is disposed in the solenoid 3% for longitudinal movement under the influence of the force of magnetic attraction.

A laminated, magnetizable core piece 195 of the plunger 31 is sandwiched between the

parallel strips

103 and 104, near their lower ends, where it is securely attached by means of recessed-head rivets MP6 or the like. The core piece 1 comprises another portion of the magnetic circuit for the magnetic field'produced by the solenoid 30 when energized, and, in cooperation with the yoke 94, it is disposed for movement into the lower end of the solenoid spool 93 in accordance with the magnetic force exerted by the field. For this purpose the laminae comprising the bottom part of the yoke 94 are discontinued immediately beneath the opening through the spool 98, and the supporting elements 96' are appropriately bowed at 95a. The

strips

103 and 104 of the plunger 31 extend upwardly through the solenoid spo'ol, passing on opposite sides of the core piece 192, and are rigidly joined at their upper ends to an armature extension it which in turn is positively connected by means of the pin 29 to the operating member 28 of the circuit interrupter operating mechanism.

The rigid junction between the metallic strips M3 and 104 and armature extension Hi7, best seen in Figs. 5 and 6, is designed for convenient connection and disconnection. This will enable the plunger 31 to be readily assembled in, and removed from, the solenoid Edwith the supporting yoke 94 mounted on the framernember i1 and the armature extension 1W pinned to the operating member 28 of the mechanism. The lower end of the armature extension is centrally disposed intermediate the upper ends of strips 163 and Edd, with the width of N7 corresponding to the Width of the core piece 1&5. As is shown in Figs. 5 and 6, the metallic armature extension is provided with a set of laterally protruding lugs or ears 1% which are releasably keyed into cooperating slots in the strips 163 and 1%. A fiat-head screw 1tl"inserted through a tapered hole 11b inthe upper end of strip 103 is threaded into a tapped hole 11 in strip 134 in order to interconnect these corresponding ends of the strips and keep them from being spread apart. In this maner a rigid and strong junction is provided.

7 For the purpose of connecting and disconnecting the armature extension Hi7 and the metallic strips, a tapped hole 112 is provided in strip 1&3 abovethe' hole 110. The screw 1'fi9 when removed from its interconnecting disposition and turned into the hole 112, as is shown at 109 in Fig. 6', will abut a solid portion of the strip 104 and force this strip apart from strip 1'93 to a relative position such as that indicated at lit i, whereby the lugs 108 of the armature extension are released from the cooperating slots in the strips and the armature extension 107 can be easily removed.

pon" energization of the solenoid coil 9?, the core pieceliiS of armature 31 is moved by the force of magnetic attraction in a generally longitudinal direction from a lower or normal position shown in Fig. 3 to an attracted position at the upper limit of its longitudinal movement, shown in'Fig. l. The magnetic force is transmitted by way of the armature extension 107 to the operating mechanism whose member 23 is thereby driven from its first or reset position to its second or operated position, and as a result the circuit interrupter is closed. The operating member 23 is stopped in its second position, beyond which it cannot be moved, by the abrupt interengagement withinthe sloenoid 39 of the core piece of armature 31 and the pole piece of yoke 94 occurring when the armature attains its attracted position. See Fig. 5. This is the stop means for the operating member referred to hereinbefore. The force of gravity assists in returning the armature 31 to its normal position during the previously described resetting operation of the mechanism, and the normal. position of the armature is determined by the interengagement of the bottom edge liiia of the armature 137 withthe top of yoke 94.

The upper end of the armature extension 197, being positiveiy'pinned to the pivotally mounted operating member 22' of the mechanism, follows an ar uate path (29p in Fig; 3) as the operating member is moving between its first and second angular positions. In accordance with our invention, the elongated armature or plunger 31 of the electromagnetic means is guided in a manner to permit lateral deviation thereof while its upper end is moving along this arcuate path, whereby no additional pivotally connected link or joint is needed for connecting the plunger to the operating'member. As is clearly shown in Pig. 3, the width of the opening between the sidewalls of the'body 93a of thesolenoidspool is made slightly greater than the corresponding dimension of the plunger fiityan'd consequently the plunger fits sloppily or loosely in the spool; Thus the plunger is guided with leeway for a relatively small amount oflateral or sidewise deviation during its generally longitudinal movement in the solenoid. In other words, the plunger is able to deviate from-straight-line motion while'driving the pivotal-lymovable operating member 2% toward its second position upon energization of the solenoid, such lateral deviation by the plunger being the result of its upper end following an arcuate path. This deviation is minimized by supportingthe solenoid and plunger in tlited disposition as shown.

By using the-spool 98 itself for supporting and guiding" the plunger 31 in accordance with the preferred construction and arrangement shown in Figs. 3'and 5, frictional forces and Wear on the relatively movable parts'are materially reduced. The spool 98 is made of molded electricinsulating material which provides a good wear-resistant surface for the sliding motion of the plunger, and the plunger does not bear against any'metallic parts. This arrangement is relatively simple and inexensive to fabricate and asemble, and no separate guides are required.

As the plunger 31 moves toward its attracted position and consequently drives the operating member 28 toward its second position, theoverc'enter tension spring-27 of the mechanism is stretched or charged. The force required to stress the spring 28, which has a conventional spring constant, increases linearly with its displacement. The magnetic force exerted on a moving plunger in the field of a solenoid will conventionally increase nonlinearly with its displacement. Preferably the force-displacement characteristic of the plunger 31 should approximately match that of the spring 27 being charged thereby, and toward this desired end we have designed the electromagnetic means so as to reduce the non-linearity of the rate of increase of the magnetic force experienced by the plunger 31 while moving toward its attracted position.

In the embodiment of our invention illustrated in Fig. 5, the face of the pole piece 102 is recessed and the cooperating face of the core piece 105 is tapered. The tapered face of 105 is received in the recessed face of 102 when the plunger 31 is in its attracted position as shown. The purpose of this particular configuration and arrangement of the cooperating pole and core pieces is to produce an accelerated rate of decrease of the reluctance of the magnetic circuit, by accelerating the reduction of the effective air gap between the pole and core faces, as the plunger 31 is travelling through the intermediate phase of its longitudinal movement toward its attracted position, whereby the plunger experiences an increasing force of attraction throughout this phase of its movement. As a result, the magnetic force impelling the plunger 31 from its normal to its attracted position will increase at a relatively linear rate, i.e., the magnetic force bears a generally linear relationship to the distance moved by the plunger under the influence of this force. Without this feature of our invention, the magnetic force exerted on the plunger would be substantially constant during a significant portion of its longitudinal movement.

Having described in detail the circuit interrupter structure illustrated in Figs. 1-6, its mode of operation will now be summarized. With the circuit interrupter switch member 15 in an open circuit position and the operating mechanism in its reset condition, as is shown in Fig. 3, the contacts 70 and 71 of the cutoff switch 72 are in engagement and a closing operation may be initiated by operating a suitable external control switch to energize the solenoid 30. The plunger 31 is raised from its normal position by the resulting force of magnetic attraction, and the operating member 28 is driven in a clockwise direction about its pivot 22 toward its operated position. This stretches the tension spring 27 which consequently accumulates closing, tripping and resetting energy. The spring is carried overcenter with respect to the toggle link 33 of the mechanism, and a closing force is exerted on the toggle.

During this portion of the closing operation the toggle is substantially immovable, and consequently the switch member 15 cannot be moved to its closed circuit position, because the toggle link 33 is being held stationary by the guide member 21 which is releasably restrained in its latched position by the latch 37, and the toggle link 34 is being held stationary by the blocking action of

elements

67 and 68 which prevent appreciable clockwise movement of the output crank 25 to which the link 34 is pinned. As the operating member 28 approaches its operated position, it reaches a point just beyond the position in which it is shown in Fig. 4 and the blocking element 67 is moved out of engagement with the element 68. The output crank 25 is now free to move clockwise about its pivot 26, and the spring 27 immediately releases stored energy as snap-action switch closing movement is imparted to the operating mechanism.

Early during this switch closing movement of the mechanism, the blocking means 67, 68 becomes effective to prevent the return of the operating member 28 toward its reset position. The solenoid 30 will remain energized, thereby upholding the operating member in its operated position, until the separable contacts 70 and 71 of the cutoff switch are actuated by the control arm 79 upon engagement thereof by appendage 33a of the operating mechanism during the final stage of its switch closing movement. See Fig. 1.

To initiate an opening operation, the trip shaft 40 is rotated counterclockwise from its normal position thereby removing the prop 41 from roller 46. As a result, the latch 37 releases the guide member 21 which is forthwith driven in a clockwise direction about its pivot 22 by the action of the tension spring 27. This enables the spring to release opening energy, and the mechanism undergoes switch opening movement thereby pulling the switch member 15 to its open circuit position shown in Fig. 2. As the guide member is moving to its unlatched position, the toggle link 33 moves through the centerline of the spring 27 at which point snap-action collapse of the toggle takes place.

During the course of the switch opening movement of the operating mechanism, the concave camming surface 56 of the guide member 21 engages roller 57 of the toggle and controls the movement thereof, whereby a substantially uniform rate of energy release by the spring 27 is obtained throughout the opening operation. At the conclusion of the opening operation, the blocking element 68 has moved out of engagement with the cooperating element 67, thereby releasing the operating member 28 for return to its reset position, and the cutoff switch 72 remains actuated due to the engagement of its control arm 79 by protrusion 80 of the guide member 21 when in its unlatched position. See Fig. 2.

The operating mechanism, in this embodiment of the invention, automatically undergoes a resetting operation immediately following the above-described opening operation. The force of spring 27 applied to the operating member 28 tends to move this member in a counterclockwise direction toward its reset position, and by means of pin 29 acting on the guide member arm 65, the guide member 21 is simultaneously propelled in a counterclockwise direction toward its latched position. This causes the toggle knee 35 to follow a path which progressively converges with the path 29 of pin 29, thereby enabling the spring 27 to give up still more energy for effecting the resetting operation.

When the guide member 21 reaches its latched position, the latch 37 is automatically reset by the action of its biasing spring 47 which tilts the intermediate latch member 42 clockwise so that its stud 44 engages the heel of the guide member leg 45, whereupon the trip shaft 40 returns to its normal position. See Fig. 3. The cutoff switch 72 is now reset, the operating member 28 is in its reset position, and the plunger 31 has returned to its normal position in readiness for another closing operation.

Referring now to Figs. 79, a manually operable embodiment of the invention has been illustrated and will now be described. This embodiment is essentially the same as that described hcreinbefore, and the same reference characters have been used in these three figures to identify the various parts thereof that are identical to the parts shown in Figs. 1, 3 and 4, respectively.

The operating member of the manually operable mechanism, as can be seen in Fig. 7, is pivotally pinned at 116 to the circuit interrupter frame member 11, instead of being mounted on the rod 22 as was the case with the operating member 28 previously described. The operating member 115, which preferably is a generally U-shaped member comprising two upstanding parts (only thesfar one being shown) rigidly interconnected by a single transverse part 115a, is pivotally movable from a first or reset position shown in Fig. 8 to a second or operated position shown in Fig. 7, and it carries the laterally extending pin 29 along a predetermined arcuate path 29r.

With the circuit interrupter closed, as is shown in Fig. 7, the operating member 115 is positively blocked in its second position by means including, in this embodiment of the invention, a blocking member 117 pivotally supported on the rod 22. The blocking member 117 preferably comprises two identical upstanding parts, only the far one being shown, rigidly interconnected by a transverse part 117a, and this member is disposed for engagement by and movement with the operating member 115. Counterclockwise movement of the operating member 115 about its pivot 116 from its second to its first position must be accompanied by counterclockwise movement of the blocking member 117 about its pivot 22, due to the abutting engagement 'of a tail 118 of the operating member with a cooperating surface 119 of the blocking member. Counterclockwise movement of the blocking member 117, however, is prevented whenever the switch member of the circuit interrupter is closed due to the blocking element or lug 68' of the output crank 25 being disposed in interfering relationship with the blunt end of a cooperating element 120 protruding integrally from member 117. See Fig. 7.

The only way in which the circuit interrupter can be opened is by operating the latch 37 to release the guide member 21, whereupon the' overcenter spring 27 effects switch opening movement of the operating mechanlsm. During the opening operation, the output crank 25 is pivoted counterclockwise to the position shown in Fig. 8 and the blocking element 68 is moved out of its blocking disposition in relation to the element 120. This releases the blocking member 117 which is now free to move pivotally in a counterclockwise direction. Consequently the operating member 115 is no longer restrained in Its second position and can be returned at any time to its first position, thereby resetting the operating mechanism and the latch in the manner described hereinbefore in connection with Figs. 1-3. However, in the manually operable embodiment of the invention, the resetting operation is effected manually.

In order to move the operating member 115 between its first and second predetermined positions, a manually operable handle mechanism is provided. This mechanism includes a shaft 121 which is journaled in a stationary escutcheon plate 122 affixed to the frame 11, and the pistol-grip operating handle 32 is attached to the outer end of the shaft 121 for effecting limited rotatron thereof. Anchored to the inner end of the shaft 131 is a crank 123 having an axially extending crankpin 124. A tie bar 125 positively couples the crankpin 124 to the pin 29 carried by the operating member 115. A tension spring 126 is eccentrically connected to the crank 1 23 in a manner to bias the handle 32 in a clockwise dlrection, as viewed from the front of the circuit interrupter, to' a substantially vertical position in which it is shown in Fig. 7.

With the circuit interrupter open, the operating handle 32 can be manually rotated in a counterclockwise direction to the position shown in Fig. 8. This impels the tie bar 125 downwardly and moves the operating member 115 in a counterclockwise direction to its first position thereby resetting the mechanism and partially stressing or charging the overcenter spring 27. The blocking member 117 is simultaneously pivoted in a counterclockwise direction to the position shown in Fig. 8, and the lower edge of its protrusion 120is now disposed in V blocking relationship with the element 680i the output crank 25. Thus the output crank 25 is prevented from undergoing appreciable clockwise pivotal movement, and as a result both the operating mechanism and the movable switch member of the circuit interrupter are positively restrained in their open positions.

Subsequent clockwise rotation of the handle 32 drives the operating member 115 in a clockwise direction about its pivot 116 from its first position (shown in Fig. 8) toward its second position. This action further charges the'spring' 27 which moves overcenter with respect to the toggle link 33 and exerts. a switch closing force on the toggle. Due to the abutting engagement between a finger 127 of the blocking member 117 and a cooperating edge 128 of the operating member 115, clockwise movement of the operating member to its second position necessarily actuates the blocking member in a clockwise direction about its pivot 22.

As the operating member approaches its second position and the spring 27 is substantially fully charged, the pin 29 of member 115 passes through the point at which it is shown in Fig. 9, whereupon the element of the blocking member 117 is moved out of its blocking disposition in relation to the cooperating element 68 and the output crank 25 is freed for clockwise movement. In this manner the blocking means is rendered ineffective, and the operating mechanism is now able to undergo snap-action switch closing movement in accordance with the force being exerted by the spring 27, thereby closing the circuit interrupter. By providing a predetermined release point near the end of the clockwise movement of the operating member 115, the blocking means ensures that the same amount of closing energy will be given up by the overcenter spring 27 every time the interrupter is closed regardless of the speed with which the handle 32 is operated,

The second position of the operating member 115 is determined by the interengagement between the transverse part 115a of this member and the rod 55 which is rigidly affixed to the frame 11, as is shown in Fig. 7. This stops further clockwise movement of the operating member about its pivot 116. With the circuit interrupter closed, counterclockwise movement of the operating member is prevented by the blocking means 117-20 and 68 described above.

The operation of the manually operable mechanism illustrated in Figs. 79, except for the particulars pointed out above, is the same as that of the electrically operable mechanism already described.

While we have shown and described preferred forms of our invention by way of illustration, many modifications will occur to those skilled in the art. We therefore contemplate by the claims which conclude this specification to cover all such modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letter Patent of the United States is:

1. A circuit interrupter comprising: a frame member; a movable switch member pivotally supported by the frame member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member mounted on said frame for pivotal movement; means for moving the operating member from first to second predetermined positions; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from its first to its second position to produce snap-action switch closing movement of the toggle; means eifective during closing operation and subsequent thereto for positively preventing movement of the operating member from its second to its first position; and means responsive to toggle releasing operation of the latching means for effecting switch opening movement of the toggle; said means for preventing movement of the operating member being disposed .to permit movement of the operating member to its first the operating member from its first to its second position to produce snap-action switch closing movement of the toggle; and blocking means disposed to releasably restrain the operating member in its second position with the switch member closed; said overcenter spring being effective in response to toggle releasing operation of the latching means to produce switch opening movement of the toggle and said blocking means being arranged to free the operating member for return to its first position in response to the opening operation.

3. In a circuit interrupter: a movable switch member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; a movable operating member; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from a first position to a second position to produce snap-action switch closing movement of the toggle; and blocking means disposed for movement in accordance with the movement of said one end of the toggle for releasably restraining the operating member in said second position; said overcenter spring being effective in response to toggle releasing operation of the latching means to produce switch opening movement of the toggle as a consequence of which said blocking means is moved to free the operating member for return to said first position.

4. In a circuit interrupter: a switch member movable between open and closed circuit positions; a toggle hav ing one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member supported for pivotal movement between first and second positions; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from its first to its second position to produce snap-action switch closing movement of the toggle, whereby the switch member is moved to its closed circuit position; and means actuated in response to movement of the switch member to its closed circuit position for blocking the operating member in its second position until the switch member returns to its open circuit position.

5. A circuit interrupter comprising: a frame member; a switch member supported by the frame member for movement between closed and open circuit positions; a toggle having one end connected to the switch member; a guide member connected to the other end of the toggle and supported by the frame for movement between latched and unlatched positions; a latch disposed releasably to restrain said guide in its latched position; an operating member pivotally mounted on the frame; means for moving the operating member from a first position to a second position; an overcenter tension spring interconnecting the operating member and the toggle and efiective in response to movement of the operating member from its first to its second position to produce snapaction switch closing movement of the toggle; a first blocking element integrally associated with the operating member and movable along a predetermined path in accordance with movement of the operating member between its first and second positions and a second blocking element, responsive to movement of the switch member, disposed for movement into the predetermined path of movement of the first blocking element during closing operation thereby to block the operating member in its second position; said overcenter spring being effective in response to guide releasing operation of the latch to drive the guide to its unlatched position and produce switch opening movement of the toggle; said second blocking element being disposed for movement out of said predetermined path during opening operation thereby unblocking the operating member and permitting its return to its first position.

6. An electric circuit interrupter comprising: a frame member; a movable switch member pivotally supported by the frame member in cooperation with a relatively stationary switch member for closing and opening the electric circuit; a toggle having one end connected to the movable switch member; latching means for releasably restraining the other end of the toggle in a latched posi tion; an operating member pivotally mounted on the frame for movement between first and second positions; an overcenter tension spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from its first to its second position to produce snap-action switch closing movement of the toggle; a blocking member pivotally supported by the frame for engagement by and movement with the operating member; and means for preventing movement of the blocking member whenever the circuit interrupter is closed thereby blocking the operating member in its second position; said overcenter spring being effective in response to toggle releasing operation of the latching means to produce switch opening movement of the toggle; said blocking member being released for movement whenever the circuit interrupter is opened.

7. In a circuit interrupter: a frame member; a movaole switch member pivotally supported by the frame member; a toggle having one end connected to the switch member; latching means comprising a guide member connected to the other end of the toggle and mounted on said frame for pivotal movement between latched and unlatched positions, a trip shaft supported by said frame for rotation between normal and tripped positions, and a latch member pivotally mounted on said frame and disposed intermediate the guide member and a radially protruding portion of the trip shaft for releasably restraining the guide member in its latched position with the trip shaft in its normal position, said intermediate latch member and said protruding portion being constructed and arranged so that the resultant force of action and reaction therebetween is directed normal to the axis of rotation of the trip shaft; an operating member mounted on said frame for pivotal movement between first and second positions; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from its first to its second position to produce snap-action switch closing movement of the toggle; and blocking means effective during closing operation and subsequent thereto for positively preventing movement of the operating member from its second to its first position; said overcenter spring being effective in response to movement of the trip shaft to its tripped position and the resulting release of the guide member to drive the guide member to its unlatched position and produce switch opening movement of the toggle; said blocking means being disposed to permit movement of the operating member to its first position in response to opening operation.

8. A circuit interrupter comprising: a movable switch member; a toggle having one end connected to the switch member; a guide member supported for movement between latched and unlatched positions connected to the other end of the toggle; a latch disposed releasably to restrain the guide member in its latched position; a movable operating member; means for moving the operating member from first to second predetermined positions; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from its first to its second position to produce snap-action switch closing movement of the toggle; means effective during closing operation and subsequent thereto for positively preventing movement of the operating member from its second to its first position; said overcenter spring being effective in response to guide releasing operation of the latch to drive the guide member to its unlatched position and produce snap-action switch opening movement of the toggle; and means disposed in cooperation with the toggle and effective while the guide member is moving toward its unlatched position to control the resulting movement of the toggle in a manner to obtain a substantially uniform rate of energy release by the overcenter spring throughout the opening operation; said means for preventing movement of the operating member being disposed to permit movement of the operating'membe'r to its first position only after said snap-action switch opening movement of the toggle has been initiated.

9. in a circuit interrupter: a switch member movable between open and closed circuit positions; a toggle having one end connected to the switch member; latching means comprising a guide member movable between latched and unlatched positions connected to the other end of the toggle; a pivotally mounted latch member biased into self-releasing engagement with the guide member when in its latched position, and a trip member abutting the latch member for holding the latch member in engagement with the guide member thereby to maintain the guide member in its latched position, said trip member being mounted for pivotal movement with respect to an axis of rotation and being disposed in relation to said latch member so that the line of action of the resultant force at the abutting surfaces of these two members intersects said axis; an operating member movable between first and second positions; an overcenter spring interconnecting the operating member and the toggle for exerting a switch closing force on the toggle as the operating member moves toward its second position; and blocking means disposed in cooperation with the operating and switch members to prevent movement of the switch member to its closed position until the operating member approaches its second position, whereupon the blocking means is rendered ineffective to prevent movement of the switch member and the toggle undergoes snap-action switch closing movement in accordance with the force exerted by the overcenter spring, and to prevent movement of the operating member from its second to its first position whenever the switch member is in its closed position; said overcenter spring being effective, upon pivotal movement of said trip member to release said guide member, to drive the guide member to its unlatched position and produce switch opening movement of the toggle; said blocking means being disposed to permit movement of the operating member to its first position whenever the switch member is in its open position.

10. In a circuit interrupter: a switch member movable between open and closed circuit positions; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member movable between first and second predetermined positions; an overcenter spring interconnecting the operating member and the toggle for exerting a switch closing force at the toggle during movement of the operating member toward its second position; and blocking means disposed in cooperation with the operating and switch members to prevent movement of the switch member to its closed position until the operating member reaches a predetermined point near its second position, whereupon the blocking means is rendered inefiective to prevent movement by the switch member and the toggle is able to undergo snap-action switch closing movement in accordance with the force being exerted by the overcenter spring, and to prevent movement of the operating member from its second to its first position until the switch member returns to its open position upon subsequent toggle releasing operation of the latching means.

11. In a circuit interrupter: a switch member movable between open and closed circuit positions; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member movable between first and second positions at opposite ends of its normal range of movement; an overcenter spring interconnecting the operating member and the toggle to exert a switch closing force on said toggle during movement of the operating member from its first position toward its second position; and blocking means effective during said operating member movement to prevent movement of the switch member to its closed position until the operating member reaches a point near its secend position, whereupon the blocking means is rendered ineffective to prevent movement by the switch member and the toggle is able to undergo snap-action switch closing movement in accordance with the force exerted by the overcenter spring.

12. In a circuit interrupter: a frame member; a movable switch member pivot'ally supported by the irame member; a togge having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member mounted on the name for pivotal movement; means for moving the operating member from first to second predetermined positions; an overcenter spring interconnecting the operating member and the toggle and efiective in response to movement of the operating member toward its second position to exert a switch closing force on the toggle; and blocking means disposed in cooperation with the operating member for releasably restraining the switch member in an open circuit position while the operating member is moving toward its second position, said blocking means being operable as the operating member approaches its second position to release the switch member and permit snap action switch closing movement of the toggle in accordance with the force exerted by the overcenter spring.

'13. A circuit interrupter comprising: a switch member disposed for movement between open and closed circuit positions; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member disposed for movement between first and second positions; an overcenter spring interconnecting the ope-rating member and the toggle and effective during movement of the operating member from its first position toward its second position to exert a switch closing force on the toggle; and blocking means disposed for movement in accordance with the movement of the operating member for preventing appreciable movement or the switch member toward its closed position until the operating member reaches a predetermined point near its second position, whereupon said biocking means is moved to a position wherein it is ineffective to prevent movement of the switch member and the toggle is able to undergo snap-action switch closing movement in accordance with the force exerted by the overcenter spring.

14. In a circuit interrupter: a switch member mov able between open and closed circuit positions; a toggle having one end connected to the switch member; a guide member, connected to the other end of the toggle, movable between latched and unlatched positions; a latch disposed releasably to restrain -said guide in its latched position; a movable operating member; means for moving the operating member between first and second positions; an overcenter spring interconnecting the operating member and the toggle for exerting a switch closing force on the toggle as the operating member is moved toward its second position; and means actuated in response to said operating member movement to block switch closing movement of the toggle until the operating member approaching its second position, whereupon the toggte is freed for snap-action switch closing movement in accordance with the force exerted by the overcenter spring; said overcenter spring being effective in response to guide releasing operation of the latch to drive 'the guide to its 21 unlatched position and produce switch opening movement of the toggle.

15. A circuit interrupter comprising: a frame member; a switch member movably supported by the frame member; a toggle having one end connected to the switch member for moving the switch member between closed and open circuit positions; a first blocking element associated with said one end of the toggle and movable along a predetermined path in accordance with the movement of said one end; latching means for releasably restraining the other end of the toggle in a latched position; an operating member pivotally mounted on the frame; means for moving the operating member from a first position to a second position; an overcenter tension spring interconnecting the operating member and the toggle for exerting a switch closing force on the toggle as the operating member is moved toward its second position; and a second blocking element disposed in the predetermined path of movement of the first blocking element for preventing appreciable movement of said one end of the toggle, whereby the toggle is unable to move the switch member to its closed circuit position, said second blocking element being moved out of said predetermined path in response to the operating member approaching its second position thereby unblocking said one end and releasing the toggle for snap-action switch closing movement in accordance with the force exerted by the overcenter spring.

16. An electric circuit interrupter comprising: a frame member; a movable switch member pivotally supported by the frame member in cooperation with a relatively stationary switch member for closing and opening the electric circuit; a toggle having one end connected to the movable switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member pivotally mounted on the frame for movement between first and second positions; an overcenter tension spring interconnecting the operating member and the toggle and eifective during move ment of the operating member toward its second position to exert a switch closing force on the toggle; and a blocking member pivotally supported by the frame for engagement by and movement with the operating member, said blocking member being disposed to restrain movement of the toggle thereby to prevent closing of the circuit interrupter until the operating member has been moved to a predetermined point near its second position at which point the blocking member releases the toggle for snap-action switch closing movement in accordance with the force being exerted by the overcenter spring.

17. A circuit interrupter comprising: a frame member; a movable switch member pivotally supported by the frame member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member mounted on said frame for pivotal movement; electromagnetic means for moving the operating member from first to second predetermined positions, said electromagnetic means including a solenoid for producing a magnetic field when energized, means disposed to support the solenoid, and a rigid, elongated magnetizable armature, comprising a portion of the magnetic circuit for said field, disposed for longitudinal movement in accordance with magnetic force exerted by said field, said armature being connected to the operating member and being guided in a manner permitting lateral deviation thereof while moving the operating member toward its second position upon energization of the solenoid; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from its first to its second position to produce snap-action switch closing movement of the toggle; means effective during closing operation and subsequent thereto for preventing movement of the operating member from its second to its first position; and means 22 responsive to toggle releasing operation of the latching means for effecting switch opening movement of the toggle; said means for preventing movement of the operating member being disposed to permit movement of the operating member to its first position in response to opening operation.

18. In a circuit interrupter: a frame member; a movable switch member pivotally supported by the frame member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member mounted on the frame for pivotal movement; electromagnetic means for moving the operating member from first to second predetermined positions, said electromagnetic means including a solenoid for producing a magnetic field when energized, a magnetizable yoke comprising a portion of the magnetic circuit for said field, and a rigid, elongated magnetizable armature, comprising another portion of the magnetic circuit, disposed for longitudinal movement in accordance with magnetic force exerted by said field, said armature being connected to the operating member and being guided in a manner enabling the armature to deviate laterally while moving the operating member toward its second position upon energization of the solenoid; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member toward its second position to exert a switch closing force on the toggle; and blocking means disposed in cooperation with the operating member for releasably restraining the switch member in an open circuit position while the operating member is moving toward its second position, said blocking means being operable as the operating member approaches its second position to release the switch member and permit snap-action switch closing movement of the toggle in accordance with the force exerted by the overcenter spring.

19. In a circuit interrupter: a movable switch member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member disposed for pivotal movement from a first angular position to a second angular position; electromagnetic means for moving the operating member comprising a solenoid for producing a magnetic field when energized, a magnetizable yoke comprising a portion of the magnetic circuit for said field, and a rigid magnetizable armature, comprising another portion of the magnetic circuit, disposed for movement in accordance with magnetic force exerted by said field, said armature being connected to the operating member and being guided in a manner enabling the armature to deviate laterally while moving the operating member toward its second angular position upon energization of the solenoid; and an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member to its second angular position to produce snap-action switch closing movement of the toggle.

20. A circuit interrupter comprising: a frame member; a movable switch member pivotally supported by the frame member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member mounted on said frame for pivotal movement; electromagnetic means for moving the operating member from first to second predetermined positions, said electromagnetic means including a solenoid for producing a magnetic field when energized, a magnetizable yoke mounted on said frame and disposed to support the solenoid, a rigid magnetizable plunger disposed for longitudinal movement within the solenoid in accordance with the magnetic force of said field, one end of the plunger being connected to the operating member at a point which follows an arcuate path as the operating member is moved pivotally toward its second position upon energization of the solenoid, and means guiding the plunger with leeway for lateral deviation thereof as said one end moves along said arcuate path; an overcenter spring interconnecting the operating memher and the toggle and eifective in response to movement of the operating member from its first to its second position to produce snap-action switch closing movement of the toggle; means effective during closing operation and subsequent thereto for positively preventing movement of the operating member from its second to its first position; and means responsive to toggle releasing operation of the latching means for effecting switch opening movement of the toggle; said means for preventing movement of the operating member being disposed to permit movement of the operating member to its first position in response to opening operation.

21. In a circuit interrupter: a frame member; a movable switch member pivotally supported by the frame member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member mounted on the frame for pivotal movement; electromagnetic means for moving the operating member from first to second predetermined positions, said electromagnetic means including a solenoid for producing a magnetic field when energized, a magnetizable yoke mounted on the frame and disposed to support the solenoid, a rigid magnetizable plunger disposed for longitudinal movement within the solenoid in accordance with the magnetic force of said field, one end of the plunger being connected to the operating member at a point which follows an arcuate path as the operating member is moved pivotally toward its second position upon energization of the solenoid, and means for relatively loosely guiding the plunger thereby permitting lateral deviation thereof as said one end moves along said arcuate path; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member toward its second position to exert a switch closing force on the toggle; and blocking means disposed in cooperation with the operating member for releasably restraining the switch member in an open circuit position while the operating member is moving toward its second position, said blocking means being operable as the operating member approaches its second position to release the switch member and permit snapaction switch closing movement of the toggle in accordance with the force exerted by the overcenter spring.

22. In a circuit interrupter: a movable switch member; a releasably latched operating mechanism connected to the switch member, said mechanism including a spring arranged to release stored energy for imparting switch closing movement to the mechanism; a movable operating member connected to the spring and disposed for pivotal movement from a first angular position to a second angular position to control the accumulation of energy by the spring; and electromagnetic means for moving the operating member comprising an electric coil wound on a spool of electric insulating material for producing a magnetic field when energized, means disposed to support the spool, and a magnetizable plunger disposed for movement within the spool in a generally longitudinal direction under the influence of the force of magnetic attraction, said plunger being connected to the operating member for moving the operating member to its second angular position upon energization of said coil and being guided by the spool with leeway for lateral deviation while moving the operating member toward said second position.

23. In a circuit interrupter: a movable switch mem her; a releasably latched mechanism connecting to the switch member for controlling the movement thereof; a pivotally movable operating member coupled to the mechanism and movable from first to second predetermined positions to cause switch closing movement of the mechanism; and electromagnetic means for moving the operating member to its second position comprising a solenoid for producing a magnetic field 'when energized, means disposed to support the solenoid, a rigid, elongated magnetizable armature, providing a portion of the magnetic circuit for said field, positively'connected tothe operating member and disposed for longitudinal movement in accordance with magnetic force exerted by said field, and means guiding the armature with leeway for lateral deviation thereof While moving the operating member toward its second position upon energization of the solenoid.

24. In electromagnetic apparatus for moving a pivotally mounted operating member'from a'first angular :position to'asecond angular position; a solenoid comprising an electric coil wound on a spool of electric insulating material for producing a magnetic field when energized; a magnetizable yoke disposed to support the spool; and a rigid magnetizable plunger disposed within the spool and guided thereby with leeway fora relatively small amount of lateral deviation as the plunger is moved in a generally longitudinal direction by the force of magnetic attraction, one end of the plunger being connected 'to the operating member at a point which follows an arcuate path while the plunger is moving the operating member toward its second angular position upon energization of the coil.

25. In electromagnetic apparatus for moving a pivotally mounted operating member from a first angular position to a second angular position: a solenoid comprising an electric coil wound on a spool of electric insulating material for producing a magnetic field when energized; a magnetizable yoke arranged to support the spool; and a rigid magnetizable plunger disposed within the spool for longitudinal movement in accordance with the force of magnetic attraction; said plunger being connected to the operating member for movement thereof upon energization of the solenoid and said spool being constructed and arranged for relatively loosely guiding the plunger thereby enabling the plunger to deviate laterally while moving the operating member toward its second angular position.

26. In electromagnetic apparatus for moving a'pivotally movable operating member from a first position to a second position: a solenoid for producing a magnetic field when energized; means disposed to support the solenoid; a rigid, elongated magnetizable Jarmature, comprising a portion of the magnetic circuit for 'said field, positively coupled to the operating member and disposed for longitudinal movement in accordance with 'magnetic force exerted by said field; and means guiding the armature with leeway for lateral deviation thereof while moving the operating member toward its second position upon energization of the solenoid.

27. A circuit interrupter comprising: a frame member; a movable switch member pivotally supported by the frame member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member mounted on said frame for pivotal movement; electromagnetic means for moving the operating member from first to second predetermined positicns, said electromagnetic means comprising a solenoid for producing a magnetic field when energized, a magnetizable yoke for the solenoid having a pole piece extending into one end thereof, and a magnetizable plunger disposed for longitudinal movement within the solenoid in accordance with magnetic force exerted bysaid field, said plunger being connected to the operating member and including a core piece disposed to engage said pole piece at the limit of said longitudinal movement, said pole and core pieces being configured and arranged so that the plunger experiences substantially linearly increasing mag: netic force while moving the operating member toward its 25 second position upon energization of the solenoid; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from its first to its second position to produce snap-action switch closing movement of the toggle; means effective during closing operation and subsequent thereto for positively preventing movement of the operating member from its second to its first position; and means responsive to toggle releasing operation of the latching means for effecting switch opening movement of the toggle; said means for preventing movement of the operating member being disposed to permit movement of the operating member to its first position in response to opening operation.

28. In a circuit interrupter: a frame member; a movable switch member pivotally supported by the frame member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member mounted on the frame for pivotal movement; electromagnetic means for moving the operating member from first to second predetermined positions, said electromagnetic means comprising a solenoid for producing a magnetic field when energized, a magnetizable yoke disposed to provide a portion of the magnetic circuit for said field and provided with a pole piece extending into one end of the solenoid, and a magnetizable plunger disposed for longitudinal movement within the solenoid in accordance with magnetic force exerted by said field, said plunger being connected to the operating member and including a core piece disposed to engage said pole piece at the limit of said longitudinal movement, said pole and core pieces being configured and arranged to reduce the non-linearity of the increasing magnetic force experienced by the plunger while moving the operating member toward its second position upon energization of the solenoid; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member toward its second position to exert a switch closing force on the toggle; and blocking means disposed in cooperation with the operating member for releasably restraining the switch member in an open circuit position while the operating member is moving toward its second position, said blocking means being operable as the operating member approaches its second position to release the switch memher and permit snap-action switch closing movement of the toggle in accordance with the force exerted by the overcenter spring.

29. In a circuit interrupter: a movable switch member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member disposed for movement between first and second predetermined positions; electroresponsive means for moving the operating member to its second position comprising a solenoid for producing a magnetic field when energized, a magnetizable yoke providing a portion of the magnetic circuit for said field and including a pole piece extending into one end of the solenoid, and a magnetizable plunger, providing another portion of the magnetic circuit, disposed for movement into the other end of the solenoid in accordance with magnetic force exerted by said field, said plunger being connected to the operating member and including a core piece disposed in cooperating relationship with said pole piece, said pole piece and core pieces being configured and arranged to reduce the non-linearity of the rate of increase of the magnetic force experienced by the plunger while moving the operating member toward its second position upon energization of the solenoid; and an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member to its second position to produce snap-action switch closing movement of the toggle.

30. A circuit interrupter comprising: a frame mem her; a movable switch member pivotally supported by the frame member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; a movable operating member mounted on said frame; electromagnetic means for moving the operating member from first to second predetermined positions, said electromagnetic means comprising a solenoid for producing a magnetic field when energized, a magnetizable yoke mounted on said frame and disposed to support the solenoid, said yoke including a pole piece extending into one end of the solenoid, and a magnetizable plunger including a core piece disposed for longitudinal movement within the solenoid in accordance with the magnetic force of said field, said plunger being connected to the operating member for movement thereof upon energization of the solenoid, said pole and core pieces having cooperating faces one of which is formed with a generally U-shaped recess for receiving the other with the plunger at the limit of said longitudinal movement; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from its first to its second position to produce snapaction switch closing movement of the toggle; means effective during closing operation and subsequent thereto for positively preventing movement of the operating member from its second to its first position; and means responsive to toggle releasing operation of the latching means for effecting switch opening movement of the toggle; said means for preventing movement of the operating member being disposed to permit movement of the operating member to its first position in response to opening operation.

31. In a circuit interrupter: a frame member; a movable switch member pivotally supported by the frame member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member mounted on the frame for movement between first and second predetermined positions; electromagnetic means for moving the operating member comprising a solenoid for producing a magnetic field when energized, a magnetizable yoke mounted on the frame and disposed to support the solenoid, said yoke including a pole piece extending into one end of the solenoid, a magnetizable plunger including a core piece disposed for movement into the solenoid at the other end thereof in accordance with the magnetic force of said field, said plunger being connected to the operating member for moving the operating member to its second position upon energization of the solenoid, said pole and core pieces having cooperating faces one of which is recessed for receiving the other thereby to reduce the non-linearity of the rate of increase of magnetic force experienced by the plunger while moving the operating member toward its second position; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member toward its second position to exert a switch closing force on the toggle; and blocking means disposed in cooperation with the operating member for releasably restraining the switch member in an open circuit position while the operating member is moving toward its second position, said blocking means being operable as the operating member approaches its second position to release the switch member and permit snap-action switch closing movement of the toggle in accordance with the force being exerted by the overcenter spring.

32. In a circuit interrupter: a movable switch member; a releasably latched operating mechanism connected to the switch member, said mechanism including a spring arranged to release stored energy for imparting switch closing movement to the mechanism; a movable operating member connected to the spring and disposed for movement from first to second predetermined positions to control the accumulation of energy by the spring; and electromagnetic means for moving the operating member comprising a solenoid for producing 'a 'magnetic field when energized, a magnetizable yoke for the solenoid including a pole piece extending into one end thereof, and a magnetizable plunger connected to the operating member and including a core piece disposed for movement into the other end of the solenoid under the influence of the force of magnetic attraction, said pole and core pieces having cooperating faces one of which is recessed for receiving the other thereby to reduce the non-linearity of the rate of increase of force of magnetic attraction experienced by the plunger while moving the operating member toward its second position upon energizationof the solenoid.

33. In a circuit interrupter: a switch member disposed for movement between open and closed circuit positions; an operating member movable between first'and second predetermined positions; a releasably latched operating mechanism connected to the switch member, said mechanism including a spring connected to the operating member and responsive to movement of the operating member to its second position for first accumulating mechanical energy and then releasing stored energy to the mechanism for producing switch closing movement thereof, whereby the switch member is moved to its closed circuit position; and means actuated in response to movement of the switch member to its closed circuit position for blocking the operating member in its second position until the switch member returns to its open circuit position.

34: In a circuit interrupter: a switch member disposed for movement between open and closed circuit positions; an operating member movable between first and second predetermined positions; a releasably latched operating mechanism connected to the switch member and including a spring connected to the operating member, said spring being effective in response to movement of the operating member from its first position toward its second position to accumulate mechanical energy and to exert a switch closing force on the mechanism; blocking means disposed for movement in accordance with the movement of the operating member for preventing appreciable movement of the switch member toward its closed position until the operating member reaches a predetermined point near its second position, whereupon said blocking member moves to a position wherein it is ineffective to prevent movement of the switch member and the operating mechanism is able to undergo switch closing movement in accordance with the force being exerted by the spring; and means actuated in response to movement of the switch member to its closed circuit position for blocking the operating member in its second position until the switch member returns to its open circuit position.

35. In an electromagnetic device: a solenoid comprising an electric coil wound on the body of a spool of electric insulating material for producing a magnetic field when energized, said spool having, at opposite ends of its body, respectively, flanges in which transverse grooves are formed; and a magnetizable yoke arranged to support the spool and provide a portion of the magnetic circuit for said field, said yoke comprising two separable parts between which the spool is clamped withcooperating transverse portions of the two parts being disposed in the transverse grooves of the spool flanges; said grooves being deeper at the outer edges of the flanges than in the vicinity of the spool body whereby the flanges are relieved of bending stresses when the spool is clamped between the two parts of the yoke.

36. In electromagnetic apparatus for accumulating energy in a spring having a predetermined spring constant: a pivotally movable operating member connected to the spring and disposed to stress the spring upon movement from a first angular position to a second angular position; a solenoid for producing a magnetic field when energized; a magnetizable yoke disposed to support the solenoid and including a pole piece extending into one end thereof; a magnetizable plunger positively coupled to the operating member and including a core piece disposed for movement into the other end of the solenoid in accordance with magnetic force exerted by said field thereby to move the operating member to its second angular position upon energization of the solenoid; and means guiding the plunger with leeway for lateral deviation thereof while moving the operating member toward its second angular position, said pole and core pieces having cooperating faces configured and arranged to reduce the non-linearity of the increasing magnetic force experienced by the plunger while moving the operating member toward said second position.

37. In a circuit interrupter: a movable switch member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member disposed for movement between first and second predetermined positions; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from its first to its second position to produce snap-action switch closing movement of the toggle; and electromagnetic means for moving the operating member to its second position comprising a solenoid for producing a magnetic field when energized, means for supporting the solenoid, and a magnetizable armature, providing a portion of the magnetic circuit for said field, coupled to the operating member and disposed for movement in accordance with magnetic force exerted by said field upon energization of the solenoid thereby to move the operating member to its second position.

38. In a circuit interrupter: a movable switch member; a releasably latched operating mechanism connected to the switch member and including a spring arranged to release stored energy for imparting switch closing movement to the mechanism; a movable operating member connected to the spring and disposed for movement from first to second predetermined positions to stress the spring, thereby controlling the accumulation of energy therein, and to effect said release of stored energy by the spring; and electromagnetic means for moving the operating member including a solenoid for producing a magnetic field when energized, means supporting the solenoid, and a magnetizable armature, comprising a portion of the magnetic circuit for said field, coupled to the operating member and disposed for movement in accordance with the force of magnetic attraction upon energization of the solenoid thereby to move the operating member to its second position.

39. In a circuit interrupter: a frame member; a switch member mounted on the frame member for movement between open and closed circuit positions; a toggle having one end connected to the switch member;-latching means for releasably restraining the other end of the toggle in a latched position; an operating member mounted on the frame member for movement between first and second predetermined positions; electromagnetic means for moving the operating member toward its second position comprising a solenoid for producing a magnetic field when energized, said solenoid being supported by the frame member, and a magnetizable plunger disposed in the solenoid for longitudinal movement in' accordance with the force of magnetic attraction, said plunger including a pair of spaced-apart metallic strips extending from the solenoid in generally parallel relationship, an elongated metallic extension having one end disposed intermediate the strips where it is releasably keyed and having its other end positively coupled to said operating member, and removable means interconnecting said strips to prevent their spreading apart with said extension keyed therebetween; an over-center spring interconnecting the operating member and the toggle for exerting a switch closing force at the toggle during movement of the operating member toward its second position; and blocking means disposed in cooperation with the operating and switch members to prevent movement of the switch member to its closed position until the opcrating member reaches a predetermined point near its second position, whereupon the blocking means is rendered ineifective to prevent movement of the switch member and the toggle is able to undergo snap-action switch closing movement in accordance with the force being exerted by the over-center spring, and to prevent movement of the operating member from its second to its first position until the switch member returns to its open position upon subsequent toggle releasing operation of the latching means.

40. In a electromagnetic apparatus for actuating a movable member: a solenoid for producing a magnetic field when energized; means disposed to support the solenoid; a magnetizable plunger disposed in the solenoid for longituduinal movement in accordance with magnetic force exerted by said field, said plunger including a pair of spaced-apart metallic strips extending from the solenoid in generally parallel relationship and an elongated metallic extension joined at one end to the strips and adapted to be positively coupled at its other end to said movable member, said one end of the extension being disposed intermediate said strips and being releasably keyed thereto; and removable means interconnecting said strips to prevent their spreading apart with said extension keyed therebetween, whereby a rigid junction is maintained between the extension and the strips.

41. The electromagnetic apparatus of claim in which one of the spaced-apart metallic strips is provided with a tapped hole disposed in alignment with a solid portion of the other strip whereby the strips can be forced apart and the elongated metallic extension released by turning a screw into said tapped hole with the interconnecting means removed.

References Cited in the file of this patent UNITED STATES PATENTS 2,539,547 Mossman et al Jan. 30, 1951 2,821,600 Ridgley Jan. 28, 1958 2,844,682 Furnas July 22, 1958