US2037544A

US2037544A - Circuit breaker contact

Info

Publication number: US2037544A
Application number: US685572A
Authority: US
Inventors: Joseph W Seaman
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1933-08-17
Filing date: 1933-08-17
Publication date: 1936-04-14
Anticipated expiration: 1953-04-14

Description

April 1935- J. w. SEAMAN 2,037,544

CIRCUIT BREAKER CONTACT Filed Aug. 17, 1933 3/28 Irn/erflor' 61 Joseph W Seaman b H ATTorne Patented Apr. 14, 1936.

UNITED STATES 2,0375% CIRCUIT BREAKER con'rac'r' Joseph W. Seaman, Lansdowne, Pa, assignor to General Electric (Jompany, a corporation of New York Application August 17, 193?, Serial No. 685,572

8 Claims. (Cl. 200-46) My invention relates to circuit breakers of the type arranged to be operated with a snap action between open and closed circuit positions, and has for an object the provision of inexpensive contacts having resilience in the contacts themselves for absorbing the blow incident to the engagement of the contacts in closing an electric circuit.

While not limited thereto, my invention is particularly applicable to circuit breakers wherein a movable contact is arranged for operation into and out of abutting engagement with a stationary contact. Heretofore considerable difficulty has been experienced in the operation of a switch contact at high speed into engagement with its cooperating contact by reason of the fact that the movable contact upon striking its cooperating contact at a relatively high speed tends to rebound and often does rebound sufficiently to draw an arc betweenthe contacts whereby they are welded together to such an extent that it is impossible to separate the contacts in the normal manner.

In carrying out my invention in one form thereof, I provide one of the contacts with a longitudinal slot or slots to thereby form resilient por-' tions sothat when the other contact comes into engagement with it the energy of the moving contact is largely dissipated by'the resilient portion of the slotted contact.

For a more complete understanding of my invention, reference should now be had to the drawing wherein I have shown in Fig. 1 my invention applied to a circuit breaker; Figs. 2 and 3 illustrate modifications of the construction of the contacts, while Fig. 4 shows an end view of the stationary contact shown in Fig. 1.

Referring now to the drawing, I have shown my invention in one form as applied to a circuit breaker l0 consisting of an operating handle ll, an over-center spring I2 and alink l3. The operating handle II andthe link 13 are mounted upon a stationary pivot pin I5." supported in'the frame (not shown). The over-center spring l2, forming a yieldable connection between the handle II and the movable contact .I 6. serves to operate the movable contact lfi'into and out of engagement with the stationary contact. H with a snapaction. As shown, these contacts l6 and I1 are formed ofsolid cylindrical conductors. The overcenter (spring 12 biases the handle ll against the stationary stop 'l 9 securedto the frame andalso biases the link l3 against a sta-v is pivotally'gsecmed to the movable. contact 16..

vertical slot 222 formed in the movable contact It. If the operating handle It is rotated in a clockwise direction the over-center spring [2 is moved past its dead center position and serves to operate the contact l6 into abutting engagement with the stationary contact I! with a snap action. Rotation of the handle II in a clockwise direction is limited by the stationary stop 24 and it will be seen that when the handle H en gages the stop 24, the spring I2 biases the contact l6 into abutting engagement with the contact II.

In order to absorb the blow delivered by the movable contact Hi, the stationary contact as shown is provided with two longitudinally extending slots 28 and with a conical recess 29, the longitudinalslots providing four relatively stiff laterallyyieldable portions 28a. The movable contact l6 has its end beveled somewhat to form a contact surface 30 which can enter the recess 29. As shown in the drawing, the beveled contact surface 30 and the contact surfaces formed by the walls of the recess 29 are inclined at an angle of thirty degrees with respect to the center line C or the line of movement of the movable contact 5. Consequently, as the beveled contact surface 30 of the movable contact I6 is operated into the recess 29 a component of the force moving the contact acts radially to spread the stationary contact sections 28a apart. As shown in the drawing, the abrupt beveled portion 36 insures an abutting engagement with the stationary contact I! so that there is no frictional opposition to the operation of the movable contact from the closed to the open circuit position. Since the stationary contact is of resilient material, the resilient sections or portions 28a absorb the blow incident to the closing of the sectional area. As shown in Fig. 4, the portions 28a form sectors-ofthe cylindricalcontact l1. When the contact lfi is snapped to the closed position the contact surface 30 upon engaging the walls of the recess 29 causes the portions 28c to yield laterallya slight amount and thereby I absorbthe kinetic energy Qfthe'm Vin'g parts'as workth e work required to move the portions 28a. Theangle between the contact surfaces I and the line of movement. of thecontactl-fi while providing for lateral yieldingmovement of the p rusin mr ric i lr ipp th m le portions28a. ,i s ;suiiicientlygreat, to prevent these contact surface 30. In other words the engagement of the contacts is an abutting one, there being no frictional gripping action between the engaging surfaces.

If the contact engaging surfaces were normal to the path of movement, the movable contact when operated at high speed into engagement with the stationary contact would tend to re bound sufficiently to cause an arc to form between the contacts. arcing at the contacts might cause the contacts to weld together and prevent normal operation of the circuit breaker. Furthermore, if the contacts were frictionally bound together the proper snap action of the contacts could not be obtained.

Thus it will be observed that I have related or proportioned toeach other the strength of the overcenter spring i2 comprising the yieldable operating means, the stiffness of the yieldable contact portions 28a and the angle of the contact surfaces in such a manner that the contact portions 28a flex upon impact and thereby absorb the kinetic energy stored in the movable contact after which the contact portions return to their Consequently, an abutting relanormal shapes. tion is maintained between the contacts.

As shown in Fig. 2, the movable contact 3| is provided with longitudinally extending slots 32 and with a conical recess 33. In this modification of my invention the stationary contact 34 has its end 35 beveled. The resiliency of the portions 3|a of the movable contact 3i absorbs the blow incident to the closing of theswitch and prevents arcing at the contacts during the closing operation.

In Fig. 3, I have shown a conical recess 38 in the slotted movable contact 40 while the sta-' tionary contact 4| is provided with longitudinal slots 42 and a beveled end 43. The operation is similar to the arrangement described in connection with- Figs. 1 and 2, although in the present modification the radial forces act on both contacts, the portions 4la of the stationary contact being bent laterally and inwardly to absorb the kinetic energy of the movable contact whilst the portions 4.5 of the movable contact are bent laterally and outwardly.

In each form of the invention shown the beveled portion of one contact slidably engages the conical recess of the other contact so that a relatively large contact area is obtained. However, one contact can be made concave and the other convex to produce a substantial contact area and to produce the radial component of force on .the resilient portion whereby the tendency of the contacts to rebound is eliminated. Furthermore, in all forms of my invention it will be observed that the abutting engagement of the contacts insures a minimum frictional resistance of the contacts when the circuit breaker is operated to the open circuit position.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

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

1. A circuit breaker comprising cooperating Even a slight amount of predetermined amount of kinetic energy being stored in the movable contact during its high speed movement, one of said abutting ends of said contacts being provided with relatively stiff laterally yieldable portions, said contacts being formed with contact surfaces at a substantial angle to the line of movement of said movable contact thereby to provide for fiexure of said relatively stiff portions to absorb said kinetic energy to prevent separation of said contacts by rebound, the stiffness of said portions, the strength of said yieldable operating means and said angle of said contact surfaces being related to each other to provide for return of said portions to their normal shapes after flexure to absorb said kinetic energy. v

2. A circuit breaker comprising cooperating movable and stationary contacts, means mounting said movable contact for relative movement with respect to said stationary contact, yieldable operating means for moving at high speed said movable contact into abutting engagement with said stationary contact, a predetermined amount of kinetic energy being stored in said movable contact and said yieldable means during its high speed movement, one of said abutting ends of said contacts being provided with relatively stiff laterally yieldable portions, the abutting ends of said relatively stiff portions being formed to provide contact surfaces at a substantial angle to the line of movement of said movable contact, and the other of said abutting ends having a contact surface substantially parallel to said first contact surfaces, said angle of said contact surfaces having such a-value as to provide for flexure of said relatively stiff portions to absorb said kinetic energy to prevent separation of said contacts by rebound, the stifiness of said portions, the strength of said yieldable operating means and said angle of said contact surfaces being related to each other to provide for return ofsaid portions to their normal shapes after flexure to absorb said kinetic energy.

3. A circuit breaker comprising a stationary stationary contact, a predetermined amount of kinetic energy being stored in said movable contact and in said yieldable operating means during said high speed movement of said movable contact, the abutting end of said stationary contact being provided with relatively stiff laterally yieldable portions, said abutting ends of said portions being formed to provide contact surfaces at a substantial angle to the line of movement of said movable contact, and the abutting end of said movable contact having a contact surface substantially parallel to said contact surfaces, said angle of said contact surfaces having such a value as to provide for ilexure of said relatively stiff portions to absorb said kinetic energy to prevent separation of said contacts by rebound of said movable contact, the stiffness of said portions, the strength of said yieldable operating means and said angle of said contact surfaces being related to each other to provide for return of said portions to their normal shapes after fiexure to absorb said kinetic energy.

4. A circuit breaker comprising a movable contact and a stationary contact, yieldable operating means for moving at high speed said movable contact into abutting engagement with said stationary contact, a predetermined amount of kinetic energy being stored in said movable conangle of said contact surfaces having a value tact and in said yieldable operating means during the high speed movement, the abutting end of said movable contact being provided with relatively stiff laterally yieldable portions, and the abutting ends of said portions being formed to provide contact surfaces at a substantial angle to the line of movement of said movable contact,

the abutting end of said stationary contact having a contact surface substantially parallel to said contact surfaces, said angle of said contact surfaces having such a value as to provide for flexure of. said relatively stiff portions to absorb said kinetic energy to prevent separation of said contacts by rebound of said movable contact, the stiffness of said portions, the strength of said yieldable operating means and said angle of said contact surfaces being related ,to each other to provide for return of said portions totheir normal'shapes after flexure to absorb said kinetic energy.

5. A circuit breaker comprising cooperating contacts, yieldable operating means for relative- I ly moving at high speed one of said contacts into abutting engagement with'the other of said contacts, a predetermined amount of kinetic energy being stored in said movable contact during the high speed movement, said contacts being provided with relatively stiff laterally yieldable portions adjacent their respective abutting ends, the abutting end of one ofsaid contacts being formed to provide a contact surface at a substantial angle to the line of movement of said one contact and the other of said abutting ends having a contact surface substantially parallel to said first contact surface-said angle of said contact surfaces having such a value as to provide for flexure of said relatively stiff portions to absorb said kinetic energy to prevent separation of said contacts by rebound of .said onecontact, the stiffness of' said portions, the strength of said yieldable operating, means and said angle of said contact surfaces being related to each other. to provide for return of said portions to their normal shapes after flexure to absorb said kinetic energy.

6. A circuit @breaker comprising a stationary contact and a movablecontact, a link pivoted .at one end and connected at its other end to said movable contact, an over-center spring connected to said link for operating said movable contact at high speed into abutting engagement with said stationary contact,. a predetermined amount of kinetic energy.being stored in said movable contact, said link and said spring dur:

ing said high speed movement, one of said contacts being provided with relatively stiff yieldable portions; said relatively stiff portions being formed to provide abutting contact surfaces at a substantial angle to theline of movement of said movable contact, and the abutting end of said other contact having a contact surface substantially parallelto saidc'ontact surfaces, said turn of said portions to their normal shapes after flexure to absorb said kinetic energy.

7. A circuit breaker comprising cooperating at high speed one of said contacts into abutting engagement with the other'of said contacts, a predetermined amount of kinetic energy being stored in said movable contact during its high speed movement, one of said abutting ends of said contacts being provided with relatively stiff yieldable portions, an abutting end of one of said contacts being formed to provide a contact surface at substantially an angle of thirty degrees to the line of movement of said movable contact, and the other of said abutting ends having a contact surface substantially parallel to said first contact surface, said substantially thirty degree angle and said contact surfaces providing for flexure of said relatively stiff portions to absorb said kinetic energy to prevent separation of said contacts by rebound, the stiffness of said portions; the strength of said yieldable operating means and said angle of said contact surfaces being related to each other to provide for return of said portions to their normal shapes after flexure to absorb said kinetic energy.

8. A circuit breaker comprising stationary and movable contacts, means mounting said movable contact for relative movementwith respect provided with a plurality of relatively stiff yieldable portions extending a predetermined distance from its abutting end, the free ends of said por-' tions being. formed to provide a plurality of concontacts, yieldable operating means for moving tact surfaces, each surface being inclined at an angle of substantially thirty degrees to the line of movement of said movable contact, and the other of said abutting ends having a contact surface substantially parallel to said plurality of contact surfaces, said angle of substantially thirty degrees providing for flexure of said relatively stiff portions to absorb said kinetic energy to prevent separation of said contacts by rebound,

' the stiffness of said portions, the strength of said yieldable operating means and said angle of said contact surfaces being related to each other to provide for return of said portions to their normal shapes after flexure to absorb said kinetic energy.

JOSEPH w., SEAMAN.