US2435432A - Electric switch - Google Patents

Description

J. A. FAVRE ELECTRIC SWITCH Feb. 3, 1948.

filed May 21, 1946 2 Sheets-Sheet 1 Inventor John AJFavre,

His Att orney.

Feb. 3, 1948. J. A. FAVRE ELECTRIC SWITCH Filed lay 21, 1946 2 Sheets-Sheet 2 Inventor:

John A.Favre,'

H is Attor-n ey.

Patented Feb. 3, 1948 ELECTRIC SWITCH John A. Fayre, Drexel Hill, Pa., assignor to General Electric Company, a corporation of New York Application May 21, 1946, Serial No. 671,185 9 Claims. (01.200-116) My invention relates to improvements in electric switches and more particularly circuit breakers and especially automatic trip-free circuit breakers which are provided with thermally responsive tripping devices.

Electromagnetic tripping devices for circuit breakers are usually so constructed that, even when p ng with a time delayed action, the

final stage of movement of the armature to the attracted position is sudden and unobstructed until the armature hits the trip latch. This sudden movement produces such a firm blow or impact that friction between the parts of the latching mechanism or variations in such friction do not materially affect the certainty of release. Also, because of the final free and unrestrained movement of the armature, its tripping response or calibration is not dependent on the friction load which has to be overcome to cause tripping.

is no sudden blow or movement. Instead, the

thermal element gradually moves into engagement with the trip latch and urges it to the releasing position. Consequently, the trip latch load must be light or the thermal device so large as to be unwieldy and cumbersome, especially in small circuit breakers. In other words, the latchlng mechanism must be sensitive in action and should not release under such shocks as are normally to be expected. Moreover, if the tripping friction load of the mechanism varies materially, the accuracy of the tripping response will be ailected and tripping may occur unnecessarily or actually fail to occur when it should.

An object of my invention is to provide for the movable circuit controlling member of an elsetrio switch such an improved releasable mechanism for operating the circuit controlling member to and maintaining it in a predetermined circuit controlling position that the latch pressure on the tripping member for normally holding the mechanism in the maintaining position is reduced to a minimum in order to improve sensitivity and insure consistent action. Another object of my invention is to provide for automatic trip-free circuit breakers an improved operating mechanism for obtaining the maximum accuracy of tripping response possible with tripping based on the use of bimetallic thermal elements. These and other objects of my invention will appear in more detail hereinafter.

In accordance with my invention, Iprovide for an electric switch, having a. movable circuit controlling member, means for moving the member to and maintaining itin a predetermined circuit controlling position comprising a movable resetting element and a toggle interconnecting this element and the circuit controlling member and movable over center against a stop to e ect movement of the member to the predetermined circuit controlling position when the resetting element is in a. given position. Further, in accordance with my invention, I provide a collapsible mechanism which is operable in a rigid condition to hold the resetting element in said given position. For operating the switch, I further provide a movable operating lever movement of which, in one direction, is limited and yielding means which interconnects the operating lever and the toggle of the switch and which is arranged upon movement of the operating lever in said one direction while the collapsible mechanism is in the rigid condition to effect movement of the toggle over center against its stop. Also in accordance with my invention, I provide means for setting the collapsible mechanism in its rigid condition upon movement of the operating lever in the reverse direction comprising a projection on the resetting element which is engageable with the operating lever when the circuit controlling member is in another circuit controlling position.

My invention will be better understood from the following description when considered in connection with the accompanying two sheets of drawings, and its scope will be pointed out in the appended claims.

J 'In the accompanying two sheets of drawings, Fig. 1 is a sectional elevation on the line l-l of Fig. 2 of an automatic trip-tree circuit breaker embodying my invention; Fig. 2 is a plan view of the circuit breaker shown in Fig. 1; Fig. 3 is an exploded perspective of the circuit breaker shown ,in Fig. 1; and Figs. 4, 5, and 6 are elementary mechanical diagrams illustrating the tripped, reset but open, and closed positions, respectively, of the circuit breaker mechanism shown in Figs. 1, 2, and 3. l I

For the purpose of illustrating my invention. I have shown an embodiment thereof as applied to a two-pole automatic trip-free circuit breaker, the parts of which are mounted on a base I of suitable molded insulating material. Each pole comprises a movable circuit controlling member 2 which is pivotally supported on a pin 3 mounted in the base I. As shown, the circuit controlling members 2 01' the two poles are of suitable molded insulating material having a rigid transverse connecting portion 4 so that both circuit controlling members move to gether. For simplicity, they will hereinafter be designated as the circuit controlling member 2. At the ends of the transverse connecting portion 4, suitable resiliently supported contacts 5 are mounted. Each of these is arranged to engage a cooperating stationary contact 6 upon a predetermined counterclockwise movement, as viewed in Fig. 1, of the circuit controlling member 2. Clockwise movement of the circuit controlling member 2 to the open circuit position is limited by a pin 1 which is mounted in the base I and against which the circuit'controlling member 2 abuts as a stop, as shown more clearly in Fig. 3. In the elementary mechanical diagrams of Figs. 4, 5, and 6, the stop is indicated as 1', which by virtue of the width of the parts of the circuit controlling member 2 has to be spaced from the pin 1.

In accordance with my invention, I provide means for moving the circuit controlling member 2 to and maintaining it in one circuit controlling position, the closed circuit position shown schematically in Fig. 6. As illustrated, this means comprises a movable resetting element 3 which is mounted on the pin 1. For cooperating with this resetting element 8, I provide a collapsible mech 'anism which is operable to a rigid or thrust transmitting condition, shown schematically in Figs. 5 and 6, upon movement of the resetting element i.i one direction, clockwise as viewed in Figs. 1, 3, and explanatory Figs. 4, 5, and 6, to hold the resetting element in a given position. As shown, this collapsible mechanism comprises a movable rocking lever 3 mounted on the pin 3 for convenience and simplicity, a latch I pivotally connected to the rocking lever 9 at an intermediate point H thereof, two links 12 and i3 pivotally connected to the resetting element 8 at Hand respectively to the rocking lever B at I and to the latch ID at l6. In eiIect, the resettin element 8 comprises three rigidly connected arms II, l8. and i9, the arms I8 and I9 each comprising two portions suitably inclined to each other for reasons hereinafter to appear. Also, as shown, the rocking lever 9 comprises two arms 26 and 2| suitably inclined to each other, In the mechanical diagrams of Figs. 4, 5, and 6, multiple armed linkage elements such as the rocking lever 9 and the resetting element 8 are shown as having some width in order more clearly to differentiate them from single armed levers and links such as the circuit controlling member 2, the latch l0 and the links I2 and I3.

For holding the collapsible mechanism in the rigid condition, there is provided a releasable abutment which, as shown, takes the form of a transverse member or bar 22 of insulating material. This bar is pivoted on a pin 23 mounted in the base I and is biased for counterclockwise movement to the holding position abutting shoulders 24 on the base I, as shown in Fig. 1. As shown more clearly in Fig. 1, the biasing means is a relatively light spring 25. For direct engagement with the latch, the bar 22 is provided with a latch or bearing plate 26 having a suitably hardened bearing surface 21. In order to have a. micrometric adjustment of the amount of engagement between the plate 26 and the latch Hi, the underside of the plate is provided with two parallel grooves which register with. two parallel ribs 23 on the bar 22. The angle between the ribs 28 and the axis of the pin 23 about which the bar 22 turns is relatively small so that by means of a slot 23 in the plate 26 and a holding screw 30 extending therethrough into the bar 22, it is possible to obtain a very fine adjustment oi the amount of the plate in engagement with the latch when the collapsible mechanism is in. the rigid condition. Also the edge of the bearing surface 27 is parallel to the axis of the pin 23. This latching device constitutes the subject matter of the copending application of Claude D. Hayward, Serial No. 695,515, filed September '7, 1946, and assigned to the assignee of this application,

For. actuating the circuit controlling member 2 to the circuit closed position after the collapsible mechanism is set and latched and also for opening the circuit breaker, I provide an over-center operating means for eifecting a snap action in the opening and closing movements of the circuit controlling member. As shown, this operating means comprises a toggle 3l32 interconnecting the circuit controlling member 2 and the resetting element 8. The tog le link 3| is pivotally connected to the circuit controlling member 2 at 33 and to the toggle link 32 at 34, while the toggle link 32 is pivotally connected to the resetting element 8 at 35. In the closed circuit position of the circuit controlling member 2, schematically shown in Fig. 6, the toggle 3l-32 is overset against a stop 36 mounted on the pin 1. Because of the width of the parts. it is necessary to show the stop 36 in the mechanical diagrams of Figs. 4, 5. and 6 as materially spaced from the pin 1.

For actuating the toggle 3l32 over center to the holding position when the collapsible mechanism is latched in the rigid condition, I provide an operating member 31 which is mounted for movement about a stationary axis 33. As shown, the operating member 31 is U-shaped and has two parallel spaced legs 39. the ends of which set in V-shaped pockets 40 in the base I, as shown more clearly in Figs. 2 and 3. In the closed position of the circuit breaker, the legs 39 of the operating member come to rest against one edge of the V-shaped notches 40 formed in the base. In Figs. 4, 5, and 6, this stop feature is indicated at 4|.

For providing the r'.sired over-center snap action, I connect suitable resilient means such as one or more $1111.25 42 between the knee pin 34 of the toggle and a suitable point on the operating member 31 such as the transverse portion 43 thereof, as shown more clearly in Figs. 1, 2, and 3. In order to accomplish the resetting action and the opening and closing of the circuit breaker by operation of the operating menjuer alone, the arm 19 of the resetting element 3 has an angularly displaced portion 44 which abutsthe transverse portion 43 of the operating member 31 when the circuit breaker is in the circuit open position, as shown more clearly in Figs. 1 and 3 and also 4 and 5. In order that a circuit breaker mounted inside a transformer tank, for example, can be readily operated from the outside of the tank, each of the legs 39 of the operating member is provided with a'wing extension 45 to which an operating rod or the like can readily be connected by a pin, for example, passing through openings 46 in the wing extension.

For actuating the tripping bar 22 to effect an automatic opening of the circuit breaker, thermal electroresponsive means are provided and, as shown, similar means i provided for each pole. Thus, each thermal electrcresponsive means comprises two substantially parallel spaced bars 41 and 43 of suitable bimetallic material concluctively joined at their free ends by an opera screw 60.

atlng bar 48 of suitable material but not blmetallic. Each of the bimetallic bars 41 and 48 is firmly secured to the base i by suitable means such as rivets 58 and the stationary contact 6 is in conductive relation with the fixed end of the bimetallic bar 48 while the fixed end of the bar 41 is provided with a terminal 5|. The path of current flow through a pole of the circuit breaker is thus from terminal 5| through bimetallic bar 41 across through the operating bar 49 to the bimetallic bar 48, thence to the stationary contact 6, the movable contact 5 and out through a flexible lead 52 which is firmly secured in a pocket in the base I under a locking member such a a washer 53 riveted to the base.

Preferably the contact 5 is resiliently mounted on the circuit controlling member 2. Thus, as shown, the contact 5 is secured to a stirrup 54 set in an opening in the transverse portion 4 of the circuit controlling member 2 and the lead 52 is secured to the stirrup as shown in Fig. 3. This stirrup is biased downwardly as viewed in Fig. 1 by suitable means such as a spring 55, the upper end of which is held in place by a locking plate 56 secured under parallel shoulders 51 formed in the opening in the circuit controlling member. The operating bar 49 has a downward extension 58 to which is secured a suitable type of lock nut 59 in which is adjustably positioned Rigidly secured to the upper end of this screw is a projection 6| s positioned below th. tripping bar 22 that upon suiiicient heating of the bimetallic thermal elements 41 and 48 the projection engages the tripping bar and moves it clockwise to release the plate 26 from the latch 10 whereby to effect the opening of the circuit breaker.

Assuming the circuit breaker closed with the parts ositioned as shown in the schematic diagram of Fig. 6, then the collapsible mechanism is held in a rigid condition by the latch in bearing against the plate 26 on the tripping bar 22 which in turn is held by the stop 24. In this position, the toggle 3I-32 is overset with its knee pin 34 against the stop 36 and the overcenter spring 42 provides the necessary pressure to hold the contacts 5 and 6 in the circuit closed position. If new there is suiflcient current flow in either pole of the circuit breaker to cause such a deflection of the bimetallic elements 41 and 48 that the projection 6| engages the tripping bar 22 firmly enough to effect clockwise movement thereof, then the latch plate 26 will no longer sustain the latch l8 and the collapsible mechanism will move to the tripped or circuit open position shown in Fig. 4. In this position, an extension 62 on the arm I8 of the resetting element comes to rest against the pin l5 on the arm 2| of the rocking lever 9. The extension 44 on the arm [9 of the restting element comes to rest against the transverse portion 43 of the operating lever as the toggle 3l-32 is moved over center away from its stop 36 by the over-center spring 42. Also, the circuit controlling member 2 comes to rest against the pin 1, which is indicated as the stop 1 in Figs. 4, 5, and 6.

In order to close the circuit breaker, the collapsibie mechanism must first be reset and latched. For this purpose, the operating lever 31 is moved clockwise about its pivot 38 to effect clockwise movement of the resetting lever about its pivot 1. controlling member 2 is maintained against its stop 1 by the action of the spring 42. At the end of the resetting movement of the operating During this movement, the circuitlever 31, the collapsible mechanism is reset and locked with the latch ID in engagement with the plate 26 on the tripping bar 22 and the parts are positioned as shown in Fig. 5. To close the circuit breaker, the operating lever 31 is moved coun.. terclockwise about its pivot 38 until it engages the stop Al. During this movement, spring 42 is moved over center to actuate the toggle I i-32 into the overset position whereby to move the circuit controlling member 2 into the closed circuit position. The parts are then positioned as shown in Fig. 6.

While I have shown and described my invention in considerable detail, I do not desire to be limited to the exact arrangements shown, but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my invention.

What I claimas new and desire to secure by Letters Patent of the United States, is:

1. An electric switch comprising a movable circuit controlling member and means for m0ving said member to and maintaining it in one circuit controlling position comprising a movable resetting element, a stop, a toggle interconnecting said member and said element movable over center against said stop to effect movement of the member to said circuit controlling position when the element is in a given position, a collapsible mechanism operable in a rigid condition to hold said element in said given position, a movable operating lever, means for limiting movement of said operating lever in one direction, and yielding means interconnecting said operating lever and said toggle and arranged upon movement of the operating lever in said one direction while the collapsible mechanism is in the rigid condition to effect movement of said toggle over center against its stop.

2. An electric switch comprising a pivoted circuit controlling member and means for moving said member to and maintaining it in the closed circuit position comprising a pivoted restting element, a stop, a toggle interconnecting said mem-- her and said element movable over center against said stop to eifect movement of the member to said closed circuit position when the element is in a given position, a trip-free collapsible mechanism operable in a rigid condition to hold said element in said given position, a pivoted operating lever, a stop for limiting movement of said operating lever in one direction, and resilient means interconnecting said operating lever and said toggle and arranged upon movement of the operating lever in said one direction while the collapsible mechanism is in the rigid condition to effect movement of the toggle over center against it stop.

3. An electric switch comprising a movable circuit controlling member and means for moving said member to and maintaining it in one circuit controlling position comprising a movable resetting element, a stop,-a toggle interconnecting said member and said element movable over center against said stop to eifect movement of the member to said circuit controlling position when the element is in a given position, a latch, a collapsible mechanism interconnecting said latch and said resetting lever operable in a rigid condition to hold said element in said given posi tion, releasable means for holding said latch to maintain said collapsible mechanism in the rigid condition, a movable operating lever, means for limiting movement of said operating lever in one direction, and yielding means interconnzcting said operating lever and said toggle and ar ranged upon movement of the operating lever in said one direction while the collapsible mech anism is in the rigid condition to eifect movement of said toggle over center against its stop.

4. An electric switch comprising a movable circuit controlling member and means for moving said member to and maintaining it in one circuit controlling position comprising a movable resetting element, a stop, a toggle interconnecting said member and said element movable over center against said stop to effect movement of the member'to said circuit controlling position when the element is in a given position, a collapsible mechanism operable in a rigid condition to hold said element in said given position, a movable operating lever, means for limting movement of said operating lever in one direction, yielding means interconnecting said operating lever and said toggle and arranged upon movement of the operating lever in said one direction while the collapsible mechanism is in the rigid condition to effect movement of said toggle over center against its stop, and means for setting the collpasible mechanism in its rigid condition upon movement of the operating lever in the reverse direction comprising a projection on the resetting element engageable with the operating lever when the circuit controlling member is in another circuit controlling position.

5. An electric switch comprising a pivoted circuit controlling member and means for moving said member to and maintaining it in the closed circuit position comprising a pivoted resetting element, a, stop, a toggle interconnecting said member and said element movable over center against said stop to effect movement of the member to said closed circuit position when the element is in a given position, a collapsible mechanism operable in a rigid condition to hold said element in said given position comprising a pivoted rocking lever, a latch pivotally connected to said rocking lever, an abutment for preventing movement of said latch in one direction and two links pivotally connected to said element and respectively to said rocking lever and to said latch, a pivoted operating lever, a-stop for limit- I ing movement of said operating lever in one direction, and resilient means interconnecting said operating lever and said toggle and arranged upon movement of the operating lever in said one direction while the collapsible mechanism is in the rigid condition to effect movement of the toggle over center against its stop.

6. An electric switch comprising a pivoted circuit controlling member and mean for moving said member to and maintaining it in the closed circuit position comprising a pivoted resetting element, a collapsible mechanism operable to a rigid condition upon movement of said resetting element in one direction to hold the resetting element in a given position comprising a movable rocking lever, a latch pivotally con nected to said rocking lever, two links connected to said resetting element at the same point and respectively to said rocking lever and to the latch, and a releasable abutment for holding said collapsible mechanism in the rigid condition, linkage means interconnecting said circuit controlling member and said resetting element for effecting movement of the circuit controlling member to the closed circuit position, and means adapted to be operated in one direction when the resetting element is held in said'given position by said collapsible-mechanism for actuating said interconnecting means to effect movement of the circuit controlling member to the closed circuit position and in the reverse direction to move the member to the open circuit position.

7. An electric switch comprising an arm pivoted for movement about a stationary axis, a contact mounted on said arm, a cooperating con tact, and means for moving said arm to effect engagement of said contacts and for maintaining such engagement comprising a resetting lever pivoted for movement about a stationary axis, a stopsa toggle interconnecting said arm and said resetting lever movable over center against said stop to effect engagement of said contacts when the resetting lever is in a given position, a collapsible mechanism operable in a rigid condition to hold said resetting lever in said given position comprising a rocking lever pivoted for movement about a stationary aids, a latch pivotally connected at one end to said rocking lever at an intermediate point thereof, an abutment at the pther end of said latch for preventing movement thereof in one direction, and two links pivotally connected to said resetting lever and respectively to the free end of said rocking lever and to an intermediate point of said latch, an operating lever pivoted for movement about a stationary axis, a stop for limiting movement of said operating lever in one direction, and resilient means interconnecting said operating lever and said toggle, the construction and arrangement of the operating lever and the resilient means being such that movement 01' the operating lever in said one direction while said collapsible mechanism is in the rigid condition effects movement of said toggle over center against its stop in a direction to cause engagement of said contacts.

8. An electric switch comprising a. pivoted circuit controlling member and means for moving said member to and maintaining it in the closed circuit position comprising a pivoted resetting element, a collapsible mechanism operable to a rigid condition upon movement of said resetting element in one direction to hold the resetting element in a given position, and over-center resiliently actuated means between said resetting mechanism and said circuit controlling member adapted to be operated in one direction when the resetting element is held in said given position by said collapsible mechanism to actuate the circuit controlling member to the closed circuit position and in the reverse direction to move the member to the open circuit position.

9. An electric switch comprising a pivoted circuit controlling member and means for moving said memberto and maintaining it in the closed circuit position comprising a pivoted resetting element, a stop, a toggle interconnecting said member and said element movable over center against said stop to effect movement of the member to said closed circuit position when the element is in a given position, a trip-free collapsible mechanism operable in a rigid condition to hold said element in said given position, a pivoted operating lever, a stop for limiting movement of said operating lever in one direction, and over-center resiliently actuated means between said resetting JOHN A. ravnn'

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