US2802080A

US2802080A - Circuit breaker

Info

Publication number: US2802080A
Application number: US493636A
Authority: US
Inventors: Ross E Locher
Original assignee: ZINSCO ELECTRICAL PRODUCTS
Current assignee: ZINSCO ELECTRICAL PRODUCTS
Priority date: 1955-03-11
Filing date: 1955-03-11
Publication date: 1957-08-06
Anticipated expiration: 1974-08-06

Description

R. E. LOCHER CIRCUIT BREAKER Aug. 6, 1957 Filed March l1, 1955 3 Sheets-Sheet 1 2 n Nt Rass Loc/fsa,

TMre/wwe .Ey MS rmR/ vg/s. Hanes. K/Ecw, sa-'e me/ers R. E. LOCHER CIRCUIT BREAKER 3 Shets-Sheet 2 Aug. 6, 1957 Filed March 11, 1955 Q. M. 1 E m E wl S ,E m/ S r Shy, i e m R. E. LOCHER CIRCUIT BREAKER Aug. 6, 1957 3 Sheets-Sheet 3 Filed arch 11, 1955 um 'l n 'Ross Loc-Hee,

United States Patent Oiiice 2,811.2,1'180v Patented Aug. 6, 1957 CIRCUIT BREAKER Ross E. Locher, San Marino, Calif., assignor to Zinsco Electrical Products, Los Angeles, Calif., a corporation of California Application March 11, 1955, Serial No. 493,636

9 Claims. (Cl. 200-116) This invention relates toan electric switch and more particularly to an electric switch of the automatic circuitbreaker type, which may be defined as a device through which an electric current is passed and which opens the circuit automatically to interrupt the circuit whenever predetermined conditions occur in the circuit. The invention also relates to an automatic circuit breaker which is capable of manual operation to interrupt the circuit.

The invention further relates to a device by which the circuit is interrupted whenever the current in the circuit increases to a predetermined or overload Value so that it becomes desirable to open the circuit.

The invention also relates to an overload circuit breaker or interrupter which includes a thermostatic element which, when heated above a predetermined temperature by the passage of an excessive amount of electrical current therethrough, expands to release an engagement and interrupt the electrical circuit through the circuit breaker.

It is an object of this invention to provide an improved electrical switch of the class described in which manual means are provided 4for closing the switch and opening the switch, the manual means being inoperative to maintain the switch closed when the thermostatic element is heated to a predetermined overload state.

A further object of the invention is to provide a circuit breaker in which the electrical contacts move into engagement through a rolling action which assures a good electrical contact.

- Anotherobject of the invention is to provide a circuit breaker in which the tripping mechanism is automatically reset when the thermostatic element returns to its normal operating position after a circuit has been interrupted.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. However, the drawings merely show and the following description merely describes a preferred embodiment and certain modifications of the present invention, which are given by way of illustration or example only.

IIn the drawings, wherein like reference characters designate similar parts in the several views:

Fig. l is a front elevational view of one embodiment of the invention;

Fig. 2 is a sectional View taken on the line 2--2 of Fig. 1, showing the circuit breaker in the closed or on position;

Fig. 3 is a sectional view similar to Fig. 2, showing the circuit breaker opening when an overload occurs;

Fig. 4 is a partial sectional view similar to Fig. 2, showing the circuit breaker in the open or off position;

Fig. 5 is a partial sectional View similar to Fig, 2, showing the circuit breaker being closed;

Fig. 6 is a sectional view taken on the line 6-6 of Fig. 2;

Fig. 7 is a` sectional view taken on the line 7-7 of Fis- 2;

Fig. 8 is an isometric view of the latch of the embodiment shown in Fig. 2;

Fig. 9 is a sectional view similar to Fig. 2 of another embodiment of the invention;

Fig. 10 is a sectional view taken on the line 10--10 of Fig. 9;

Fig. l1 is a broken sectional view taken on the line 11-11 of Fig. l0; and

Fig. l2 is a similar sectional view showing the operation of the latch device illustrated.

A preferred embodiment which has been selected to illustrate the invention comprises a case or outer housing 20, which is formed of a suitable electrically non-conducting material such as molded plastic. Two terminals 21, 22 are located at opposite ends of the case and provide for the connection of the circuit breaker into an external electrical circuit. Continuity of the circuit between the terminals 21 and 22 is maintained through the circuit breaker and is interrupted when the circuit breaker is opened automatically or manually.

Mounted within the case 20 and shown as integral therewith is a shaft 23. A circular manually operable handle 24 having a thumb lever portion 25 extending outwardly from the case 20 is rotatably mounted on the shaft 23. The rotation of the handle 24 is limited by the engagement of the thumb lever 2:3 with the case 20 at

surfaces

26, 27.

Extending from the terminal 21 within the case 2i) is an electrically conducting contact arm 30, which is bent to form a leaf spring. The contact arm Stb has a fixed contact 31 attached to the end thereof, and it is preferred that the fixed contact 31 have a convex contact surface.

A guide in the form of a slot 32 is provided on the inside of the case 20. A Contact carrier 33, which is pref* erably formed of metal, has a pin 34 rigidly `att-ached thereto, as by welding. The pin 34 rides in the slot 32 in the case 20. A second Vcontact 35 is mounted on the carrier 33. The second contact 35 will be referred to as the movable contact and is preferably of the same convex shape as the iixed contact 31.

A current responsive release element 36, which may be a bimetallic strip, is attached to the carrier 33. As illustrated, one end of the bimetallic strip 36 is welded between two portions of the carrier adjacent the pin 34. The bimetallic strip 36 is connected to the terminal 22 by a flexible electrical conductor 37.

When the xed contact 31 and the movable contact 35 engage, an electrical circuit is completed and electrical energy may iiow from the terminal 21 through the contacts 31 and 3S, through the current responsive release element 36 and through the exible conductor 37 to the terminal 22. An arc blowout element 39 is provided adjacent the xed contact 31 to aid in extinguishing any arc produced as the contacts engage or disengage.

The contact carrier 33 is provided with a righteangle extension 40 which has a guideway 41. The guideway 41 may be a groove or a slot or the like, and is shown as an L-shaped lslot of varying width. A pivot pin 42 is mounted in the rotating handle 24 and extends through the slot 41. A latch 43 is mounted on the pivot pin 42 so that the latch 43 may rotate with respect to the handle 24. The latch 43 is shown separately in Fig. 8.

The latch 43 is provided with a boss or cam 44 which engages the guideway 41 of the carrier 33. The latch has an elongated portion 45 which is provided with a surface 46 adapted to engage the free end of the bimetallic strlp 36, as shown in Fig. 2.

A spring 47 is mounted between the case 2li and the carrier 33 to urge the contacts out of engagement and to provide a quick opening action when the circuit breaker is tripped due to an overload current. The spring 47 may be a coil spring attached to a boss 50 on the case and a lug 51 extending from the carrier.

Another spring 52 is mounted between the case 20 and the rotating handle 24 to bias the handle toward lthe olf or contact disengage position so that the handle will return to the off position when the circuit breaker is tripped. The spring 52 may -be a coil spring attached to a boss 53 on the case and a boss 54 on the handle.

The relationship and co-operation of the elements will -be more fully understood from their interaction when the circuit breaker is in use. Referring first to Fig. 2, this shows the circuit breaker in its closed contact position. The

contacts

31 and 35 are engaged and a circuit is completed between the terminals 21 and 22 through the current responsive element 36. The edge of the slot 41 in the carrier 33 bears against the cam 44 of the latch 43 and tends to rotate the latch in a counterclockwise direction as viewed in Fig. 2. This pressure is produced by the spring action of the contact arm 30 and by the spring 47. Rotation of the latch is prevented by the engagement of the surface 46 of the latch with the free end of the current responsive element 36. The pivot pin 42 is to the left of a line extending from the point of contact engagement to the center of the shaft 23, hen-ce the force exerted by the carrier 33 on the latch via the slot and cam acts to maintain the rotatable handle 24 in the on or contact engaged position. This relation is sometimes referred to as a toggle or over center action.

When the current in the bimetallic strip 36 becomes excessive, the strip changes from its normal shape and bends away from the latch 43, due to the difference in the coefficients of expansion of the two metals comprising the strip. The strip 36 co-ntinues to bend until its free end slides out of engagement with the surface 46.

When this occurs, the circuit breaker leaves the static state described above and enters a dynamic state wherein the following movements take place. The latch rotates counterclockwise to the position shown in Fig. 3. The cam 44 moves out of the short arm of the L-shaped slot 41 into the long arm. The carrier 33 is quickly moved away from the iixed contact 31 by the action of the spring 47 aided by the arm 30. Simultaneously the handle 24 is rotated clockwise toward the off position by the action of the spring 52. The movement of the carrier 33 away from the fixed contact 31 ceases when the pin 34 reaches the end of the guideway 32 4(Fig. 4). The handle 24 comes to rest with the lever 25 against the surface 2.6. During the movement, the cam 44 is forced back into the short arm of the L-shaped slot 41 and the coaction of the cam and the wall of the slot rotates the latch 43 clockwise into the position of Fig. 4 where it is able to engage the bimetallic strip -when the latter returns to its normal shape. Thus the circuit breaker is `automatically reset and again ready for use following interruption of an overloaded circuit.

When the bimetallic strip has returned to its normal condition the contacts may be again engaged by manually rotating the handle in a counterclockwise direction as shown in Fig. 5. Continued rotation of the handle urges the surface 46 of the latch 43 into engagement with the end of the bimetallic strip 36 thereby urging the carrier 33 upwardly. The contact 35 first tou-ches the contact 31 at a point near their respective edges (Fig. 5) and then rolls across the convex surface to the static engaged position of Fig. 2. The reverse of this action takes place on disengagement. Thus any pitting and burning due to arcs created as the contacts touch and part are restricted to the edges of the contacts and the central portions remain smooth and clean.

Another embodiment of the invention is illustrated in Figs. 9 through l2. This differs from the previous ernbodirnent in the details of the mass employed for controlling the rotation of the latch 43. rIhepivot pin 42 is mounted on the latch 43 and rotates freely in the handle 24. A portion of the pivot pin is removed where the pin passes through the guideway or slot 41, leaving a section 6u semicircular in cross section (Fig. 11).

A spring 61 is mounted on a boss 62 on the handle 24 and in a notch 63 in the carrier 33. The spring 61 urges the carrier 33 away from the contact arm 30 and also urges the handle toward the o or open circuit position. A notch 64 is provided in the handle 24 and a mating projection 65 is provided on the case 20. The circuit breaker is held in the closed circuit position by the engagement of the projection 65 with the notch 64 and of the surface 46 with the strip 36.

When in the closed contact position (Figs. 9 and 1l) the edge of the slot 41 bears against the semicircular section 60 at a point 66 and tends to rotate the latch in a counterclockwise direction. As in the first embodiment, the engagement of the surface 46 of the latch with the bimetallic strip prevents any movement of the latch.

The movement of the various elements when the circuit breaker is tripped by the bending of the strip 36 is the same as in the first embodiment with the following exception. The rotation of the latch into a position to re-engage the strip is accomplished in a different manner. The end 67 of the latch opposite the surface 46 is conical in shape. A cam guide 70 with a V-shaped groove 71 is attached to the extension 40 of the carrier 33. Just after the contacts have been disengaged the latch is in the position shown as 43a of Fig. l2. As the carrier and handle approach the off position, the latch moves to the position shown as 43h and the conical end 67 engages the V-groove 71 of the cam guide, and as the elements continue toward the off position, the end 67 and cam guide 70 coact to rotate the latch into position for reengaging the bimetallic strip.

While the invention that has been illustrated and described is now regarded as the preferred embodiments, the constructions are, of course, subject to modifications Without departing from the spirit and scope of the invention. It is, therefore, not desired to restrict the invention to the particular forms of construction illustrated and described, but to cover all modications that may fall within the scope of the patent claims.

This application is a continuation-in-part of my copending application entitled Circuit Breaker, Serial No. 414,624, filed March 8, 1954.

I claim as my invention:

1. In a circuit breaker, the combination of: a case; a substantially stationary contact mounted in said case; a movable contact carrier having a cam surface and a contact engageable with and disengageable from said stationary contact; a manually operable handle rotatably mounted in said case; latch means pivotally mounted on said handle and operatively connected to said carrier for closing said .circuit breaker, said latch means having a cam; and a current responsive release element mounted on said carrier and normally engaging said latch means to lock said latch means and said carrier in fixed relationship, said cam and said cam surface coacting to rotate said latch means to re-engage said latch means and said release element after said contacts are disengaged.

2. In a circuit breaker, the combination of: a case; a substantially stationary contact mounted in said case; a movable contact carrier having a contact engageable with and disengageable from said stationary contact, said carrier having a guideway and a cam surface; a manually operable handle rotatably mounted in said case; latch means pivotally mounted on said handle, said pivotal mounting extending into said guideway, said latch means including a cam for engaging said cam surface; and a current responsive release element mounted on said carrier and normally engaging said latch means to lock said latch means and said carrier in fixed relationship whereby said contacts are engaged when said handle is rotated and said contacts are disengaged when said release element is tripped.

3. In a circuit breaker, the combination of: a case;

a substantially stationary contact mounted in said case; a movable contact carrier having a contact engageable with and disengageable from said stationary contact, at least one of said contacts having a convex surface, said con* tacts making a rolling engagement, said carrier having a cam surface; a manually operable handle rotatably mounted in said case; latch means pivotally mounted on said handle and operatively connected to said carrier, said latch means having a cam for engaging said cam surface; and a current responsive release element mounted on said carrier and normally engaging said latch means to lock said latch means and said carrier in fixed relationship whereby said contacts are engaged when said handle is rotated and said contacts arev disengaged when said release element is tripped.

4. In a circuit breaker, the combination of: a case; a substantially stationary contact mounted in said case; a movable contact carrier having a contact engageable with and disengageable from said stationary contact, said carrier having a guideway including a cam surface; a manually operable handle rotatably mounted in said case; latch means pivotally mounted on said handle, said pivotal mounting extending into said guideway, said latch means including a cam; and a release element mounted on said carrier, said cam and cam surface coacting to engage said latch means and said release element when said contacts are disengaged, whereby said carrierand said latch means are locked in fixed relationship and said contacts are engaged by rotating said handle and disengaged by rotating said handle in the opposite direction and by disengagement of said latch means and said release element.

5. In a circuit breaker, the combination of: a case having a straight groove therein; a substantially stationary contact mounted in said case; a movable contact carrier having a contact engageable with and disengageable from said stationary contact, said carrier having a boss riding in said groove and having a guideway including a cam surface; a manually operable handle rotatably mounted in said case; latch means pivotally mounted on said handle, said pivotal mounting extending into said guideway, said latch means including a cam; and a release element mounted on said carrier, said cam and cam surface coacting to engage said latch means and said release element when said contacts are disengaged, whereby said carrier and said latch means are locked in fixed relationship and said contacts are engaged by rotating said handle and disengaged by rotating said handle in the opposite direction and by disengagement of said latch means and said release element.

6. In an automatic reset circuit breaker, the combination of: a case having a straight groove therein; a substantially stationary contact mounted in said case; a movable contact carrier having a contact engageable with and disengageable from said stationary contact, at least one of said contacts having a convex surface, said contacts making a rolling engagement, said carrier having a boss riding in said groove and having a guide way including a cam surface; a manually operable handle rotatably mounted in said case; latch means pivotally mounted on said handle, said pivotal mounting extending into said guideway, said latch means including a cam; and a release element mounted on said carrier, said cam and cam surface coacting to engage said latch means and said release element when said contacts are disengaged, whereby said carrier and said latch means are locked in fixed relationship and said contacts are engaged by rotating said handle and disengaged by rotating said handle in the opposite direction and by disengagement of said latch means and said release element.

f7. In a circuit breaker, the combination of: a casing;

' trol member rotatably disposed in said casing; a latch pivotally mounted on said manually actuated control member, said pivotal mount extending into said guideway; a thermostatic element attached to said carrier arm and adapted to receive electrical current when said contacts are engaged, said thermostatic element having a free end adapted to engage said latch, said manually actuated control member being adapted to move said carrier arm and engage said contacts, said free end of said thermostatic element being adapted when overheated by the flow of electrical current to flex away from said latch and become disengaged therefrom to disengage said contacts; and a first spring attached to said manually actuated control member and said casing to bias said carrier arm contact away from said fixed contact, said carrier arm and said manually actuated control member being in an over center position when said contacts are engaged.

8. A circuit breaker as defined in claim 7 including a second spring attached to said carrier arm and said casing to bias said carrier arm away from said lixed contact.

9. ln an automatic reset circuit breaker, the combination of: a casing having a pair of terminals; a contact arm disposed within said casing, said contact arm being bent to form a leaf spring and having a contact thereon, said contact being in conductive relation with one of said terminals; a carrier arm having a contact thereon and a slot including a cam surface, said carrier arm being adapted to move toward said contact arm to engage said contacts; guide means disposed within said casing to guide the movement of said carrier arm; a manually actuated control member rotatably disposed in said casing; a rst spring attached to said casing and said manually actuated control member to bias said carrier arm away from said contact arm; a second spring attached to said casing and said carrier arm to bias said carrier arm away from said contact arm; a latch rotatably mounted on said manually actuated control member, said rotating mount passing through said slot, said latch having a cam for engaging said cam surface; and a thermostatic element secured at one end to said carrier arm and in conductive relation with the contact thereon, another portion of said thermostatic element being in conductive relation with the other of said terminals, said thermostatic element having a free end adapted to engage said latch, said manually actuated control member being adapted to move said carrier arm to engage said contacts when said thermostatic element and said latch are engaged, said free end of said thermostatic element being adapted, when overheated, to flex away from said latch and become disengaged therefrom, permitting said manually actuated control member to be rotated and said carrier arm to be moved away from said contact arm to disengage said contacts, said manually actuated control member being adapted upon rotation in the opposite direction to move said contacts back into engagement, said cam and cam surface coacting to rotate said latch and re-engage said ylatch and said thermostatic element.

Sachs July 30, 1940 Johnson June 22, 1943