US2728823A

US2728823A - A. c. attachment plug with automatic circuit breaker

Info

Publication number: US2728823A
Application number: US450446A
Authority: US
Inventors: Maximilian A Auth
Original assignee: HAROLD K ANDREWS; M A AUTH Inc; MARIETTA HAYTHORNE
Current assignee: HAROLD K ANDREWS; M A AUTH Inc; MARIETTA HAYTHORNE
Priority date: 1954-08-17
Filing date: 1954-08-17
Publication date: 1955-12-27
Anticipated expiration: 1972-12-27

Description

M. A. AUTH Dec. 27. 1955 A.C ATTACHMENT PLUG WITH AUTOMATIC CIRCUIT BREAKER Filed Aug. 17, 1954 lNVENTOR %MQ J ATTORNEYS v/gilv 0/0 :5335

nited States Patent A. C. ATTACHMENT PLUG WITH AUTOMATIC CHKCUIT BREAKER Maximilian A. Auth, Stratford, Conn., assignor of onethird to M. A. Auth, Incorporated, Stratiord, Conn, a corporation of Connecticut; one-=third to Marietta Haythorue, New York, N. Y., and one-third to Harold K. Andrews, Stratford, Conn.

breaker, and has for an object to provide an attachment plug for plugging into electrical outlet receptacles to supply electric current to various devices, as household electrical devices or attachments, in which the circuit isautomatically made and broken in the plug by the :act of either inserting the plug into or removing it .from the receptacle.

Another object is to provide a device of this character which may be used both as an attachment plug for use in supplying current to the various electrical devices, and as a connector for use with a standard attachment plug.

Another object is to provide a device ofthis character which is of very simple construction and may be manufactured at low cost.

With the foregoing and other objects in view, I have devised the construction illustrated in the accompanying drawing forming a part of this specification. It is, how ever, to be understood the invention is not limited to the specific details of construction and arrangement shown, but may embody various changes and modifications within the scope of the invention.

In this drawing:

Fig. l is a side elevation of the internal elements of an attachment plug involving this invention, showing them mounted in one of the insulating body members, and with one half of the insulating body removed;

Fig. 2 is a side view of the assembled plug looking from the right of Fig. l, but with both body members assembled;

Fig. 3 is a view similar to Fig. l, but showing in section a wall outlet receptacle into which this plug is inserted;

Figs. 4 and 5 are transverse sections substantially on lines 44 and 5-5 respectively of Fig. 1;

Fig. 6 is a perspective view of one of the blade contacts;

Fig, 7 is an inside view of one of the body members with the various electrical contacts removed;

Fig. 8 is a perspective view of one of the stationary contacts, and

Fig. 9 is a view similar to Fig. 1, showing the plug modified so that it may be used as a connector for use with standard attachment plugs.

In withdrawing the usual attachment plug from a wall outlet receptacle, there is likely to be arcing between the plug contacts and the receptacle contacts, as the plug contacts separate from the receptacle contacts, and this may cause fire, explosion or a short circuit under certain conditions. it is, therefore, an object of this invention to provide an attachment plug which is so constructed as to break the circuit in the plug itself and outside the receptacle when withdrawing the plug from the receptacle, the circuit being broken in the plug before the plug contacts are separated from the receptacle contacts, so that there will be no breaking of the live circuit and therefore no arcing in the outlet receptacle itself, but

spaced somewhat from each other.

2,728,823 Patented Dec. 27, 1955 any arcing would occur within the plug itself and outside the receptacle instead of in the receptacle.

The device of Figs. 1 to 7 comprises an insulating body member 10 comprising two sections 11 of insulating ma terial placed side by side, and when assembled connected by any suitable means, such as the cross bolt 12. These two body members preferably are molded of insulating material and are identical so that they may be formed from the same die. Mounted in this body are two or more blade contacts 13, in the present case the usual two, for insertion in any standard type of wall outlet receptacle 14, or suitable connector, having stationary receptacle contacts 15 connected to the usual house Wiring system (not shown), the-blades 13 being insertabie through the usual slots 16 in the front plate 17 of the receptacle to engage the receptacle contacts 15. The blade contacts 13 in the form shown each comprise a flat strip of resilient conductor metal bent upon itself intermediate its length at 18 forming the free end of the blade, and inner and

outer side members

19 and 20 side by side but normally The inner member 19 is substantially straight and anchored or secured at its 'free end in the body 141'- A simple and effective means for securing this member and therefore the blade inthe body is to provide it with a substantially L-shapedoifset including a free end portion 21 connected by the intermediate portion 22 at substantially right angles to the straight portion of the member 19, and this offset seating in a similar L-shaped recess 23 formed a half in the inner face of each of the body members 11, so that when assembled the contact blade is mounted partly in each ofthe body members 11. When so mounted, the outer member 20 of each blade extends through a slot or opening 24 in the end wall 25 of the body into a chamber 26 formed by longitudinal channels in the inner walls of the body members 11, which channels in the two body members arein alignment and face each other to form the chamber 26. The free end portion 27 of the outer member 20 is movable laterally in this chamber and forms one element of a switch, the resilient action of the metal forming this member tending to hold it in its outer position against the outer wall of the chamber 26, as shown in Fig. l. The exposed portion of the member 20 is also inclined, as shown in Fig. 1, from its free end 18 inwardly, and outwardly away from the section 1 19 toward the body 10.

29 in the inner surface of each of the body members 11,

with this plate opposite to the free end 27 or" the blade contact. At their outer ends the plates 28 are located in chambers 29a in the body, and each has on its opposite edges laterally bent flanges 30 between which is mounted any suitable means for securing the conductor wires 31 in an insulated cord 32 to the stationary contacts 23. In this case the securing means comprises the usual binding post screw 33 threaded into the contact plate 28. The cord 32 and the conductor wires pass through a suitable inlet passage 34 leading inwardly from the end Wall of the body to the chambers 29a and formed by channels half in each of the inner surfaces of the members 11.

Referring to Fig. 1, it will be seen the free end portions 27 of the contact blades are movable to and from the stationary contacts 28, and to increase the life of these contacts and prevent burning out by arcing, each of the

contacts

27 and 28 may be provided with silver or

similar contacts

35 and 36 respectively, which engage each other when the movable contact 27 engages the stationary contact 28.

The use and operation of the device is illustrated in 3 Fig. 3. of the blade contacts 13 are normally separated from the stationary contacts 28 by the resilient action of the blades 13. When these blades 13 are inserted into the slots 16 in the face of the receptacle 14, as the outer portions 24) of the blades are inclined they have a camming action on the sides of these slots and the stationary contacts within the receptacle, forcing the free end portions 27 inwardly toward the stationary contacts 28, and as they engage these contacts 28 they close the circuit from the receptacle contacts 15 to the conductor wires in the cord 32 leading to the electrical attachment to be operated. The blade contacts 13 are so designed and arranged that the

contacts

35 and 36 do not come together until after the exposed portions of the blades 13 are in engagement with the receptacle contacts 15. For this reason, when withdrawing the plug from the receptacle, the blades 13 are still in engagement with the receptacle contacts 15 when the free ends 27 carrying the contacts 35 separate from the stationary contacts 36, thus breaking the live circuit in this plug instead of in the receptacle. Thus when the blade contacts 13 separate from the receptacle contacts 15 they are already in a dead or open circuit and there is no arcing between the contacts 13 and the receptacle contacts 15. Any arcing is therefore within the plug and outside the receptacle instead of in the receptacle. Arcing is also reduced because both sides of the circuit are broken at the same time.

In the form of Figs. 1 to 7, the means shown for connecting the conductor wires of the insulating cord 32 from the attachment to be operated with the

stationary contacts

28 and 36 are indicated as binding post screws 33. In Fig. 9, a somewhat different means for electrically connecting these conductors with the stationary contacts 36 is shown as resilient spring receptacle contacts 37, these comprising substantially U-shaped spring contacts bent upon themselves at 38 forming a spring blade 39 inclined inwardly from inlet slots 40 in the end of the insulating body 41 corresponding to the body 10, these slots 40 leading to the chambers 42 in which the contacts 37 are mounted. The other end of the spring contact 37 comprises a flat plate 43 of the same size and shape as the blade 28 and mounted in the body members 41 in slots 29, the same as in the first form, and each plate 43 carries the stationary contact 36 opposite the movable contact 35 of the plug contact blades 13. The stationary contacts 43 and the blade contacts 13 are the same as in the form of Figs. 1 to 7, and cooperate in the same way to make and break the circuit when plugged into a wall outlet receptacle, as indicated in Fig. 3, the only change being that instead of the binding post screws 33, as shown in the first form, for connecting the cord conductors 31 to the stationary contacts, receptacle or connector contacts 39 are mounted in suitable chambers in the body and the end of the body is provided with inlet slots 40 leading to the connector contacts 39, so that the contact blades of the standard attachment plug can be inserted in these slots 49 to engage the connector contacts 39 for supplying current to the attachment to be operated. Thus the contacts 39 function as means for connecting the conductor wires 31 from the attachment to be operated with the stationary contacts 36 in this form the same as do the binding post screws 33 in the first form. This structure of Fig. 9, therefore, makes it unnecessary to disassemble this plug to connect these conductor wires with the attachment plug, as is required in the form of Figs. 1 to 7, it being necessary, to secure the advantages of this improved plug, merely to plug the standard attachment plug blades into the slots 40.

To facilitate use of the device in plugging it into and removing it from the wall outlet receptacle, the

body

10 or 41 may be provided with elements to improve the hand grip on this member in inserting it or removing it from the receptacle. For this purpose, at the outer end of the body and on its opposite side edges it is provided As previously indicated, the free end portions 27 with rounded nubs or bosses 44. These will increase the hand grip on the body. They could be located on the opposite fiat sides of the body, but it is preferred to place them on the narrower side edges, as in this case they do not increase the effective thickness of the body, which might be objectionable if the plug is used in duplex or similar multiple receptacles, so that the plugs lie side by side. In other words, placing these grips on the narrower surfaces of the body provides greater clearance between the plugs when two or more are plugged into a duplex or other multiple receptacle.

It will be seen from the above that this is a very simple device involving a minimum number of parts, and that in use the circuit to the attachment to be operated is made and broken in the plug itself instead of in the wall outlet receptacle, and that any arcing caused by this making and breaking of the circuit therefore occurs within the plug and outside of the wall outlet receptacle, greatly reducing the danger of explosions, fires, or the like under certain conditions which might occur. Also it will be seen that this making and breaking of the circuit within the plug is performed automatically by the mere act of inserting the blades of the plug in the wall outlet receptacle and removing them therefrom with the same operations as is used with the standard attachment plug not provided with this safety feature.

Having thus set forth the nature of my invention, I claim:

1. In an electrical device of the character described, a body member of insulating material, attachment plug contacts projecting from one end of the body and adapted for insertion in the entrance slots of an electric receptacle to engage the contacts therein, each of said plug contacts comprising a strip of resilient metal folded upon itself forming laterally spaced members side by side with the folded end forming the free outer end of the contact, the free end of one of said side members secured in the body, stationary contact members in the body, the free ends of the other side members of the plug contacts being movable to and from engagement with the stationary con tacts and normally held spaced therefrom by the resilient action of said strips, the free side members of the plug contacts being inclined so that as they are inserted in the receptacle they will have a camming action therewith to shift said movable free ends of the plug contacts into engagement with the stationary contacts to close a circuit therewith, and means for connecting conductor wires with the stationary contacts.

2. In an electrical device of the character described, a body member of insulating material, attachment plug contacts projecting from one end of the body and adapted for insertion in the entrance slots of an electric receptacle to engage the contacts therein, each of said plug contacts comprising laterally spaced side members connected at their outer ends, the other end of one of the side members being secured in the body, stationary contacts in the body, the free end of the other side member being movable to and from a stationary contact and normally separated therefrom by resilient action of said member, said latter side members being inclined so that as they are inserted in the receptacle they have a camming action therewith to shift their free ends into engagement with the stationary contacts, and means for connecting conductor wires with the stationary contacts.

v3. In an electrical device of the character described, a body member of insulating material, attachment plug contacts projecting from one end of the body and adapted for insertion in the entrance slots of an electric receptacle to engage the contacts therein, each of said plug contacts comprising laterally spaced side members connected at their outer ends, the other end of one of the side members being secured in the body, stationary contacts in the body opposite the inner free ends of the other side members of the plug contacts, the latter side members of the plug contacts being inclined outwardly and inwardly toward their outer ends and resilient so that their inner free ends are normally held spaced from the stationary contacts by their resilient action, said inclined members adapted to have a camming action with the receptacle when inserted therein to shift their inner free ends into engagement with the stationary contacts, and means in the body for connecting conductor wires with the sta tionary contacts.

4. In an electrical device of the character described, a body member of insulating material, attachment plug contacts projecting from one end of the body and adapted for insertion in the entrance slots of an electric receptacle to engage the contacts therein, the plug contacts each comprising a pair of side members arranged side by side connected at their outer ends and one of each pair secured at its inner end in the body, the others of said side members having free ends within the body, stationary contacts in the body opposite the free ends of the latter side members, said latter side members being resilient and normally spaced at their inner free ends from the stationary contacts by their resilient action, said latter side members being longitudinally inclined so that they will have a camming action with the receptacle when inserted therein to shift their inner free ends into engagement with the stationary contacts, and means in the body for connecting conductor wires with the stationary contacts.

5. In an electrical device of the character described, a body member of insulating material, attachment plug contacts projecting from one end of the body and adapted for insertion in the entrance slots of an electric receptacle to engage the contacts therein, the plug contacts including side members having free ends within the body, stationary contacts in the body opposite the free ends of the side members, said side members being resilient and normally spaced at their inner free ends from the stationary contacts by their resilient action, said side members being longitudinally inclined so that they will have a camming action with the receptacle when inserted therein to shift their inner free ends into engagement with the stationary contacts, means in the body for connecting conductor wires with the stationary contacts comprising connector contacts mounted in the body and connected with the stationary contacts, and said body provided with entrance slots leading to the connector contacts for insertion of the contact blades of standard attachment plugs to engage the connector contacts.

6. In an electrical device of the character described, a body of insulating material comprising a pair of like members side by side, the opposed inner faces of said members being formed with opposed aligned grooves and opposed channels opening through one end of the body forming chambers therein, attachment plug contacts projecting from the end of the body each including laterally spaced side members connected at their outer ends, the inner end of each of one of said side members being seated in said grooves to mount the contacts in the body with the inner ends of the other side members located in the said chambers, said body members also provided with other aligned grooves in their inner faces, stationary contacts comprising plates seated at their opposite edges in said latter grooves and located opposite the free ends of the second side members of the plug contacts, said second side members being resilient so as to hold their inner free ends spaced from the stationary contacts by their resilient action and longitudinally inclined so that they will have a camming action with the receptacle when inserted therein to shift their inner free ends into engagement with the stationary contacts, and means in the body for connecting conductor wires with the stationary contacts.

References Cited in the file of this patent UNITED STATES PATENTS 2,005,441 Shearer June 18, 1935 2,013,596 Becker Sept. 3, 1935 2,245,986 Krauss June 17, 1941 2,419,585 OBrien et a1 Apr. 29, 1947 2,452,967 Thomas Nov. 2, 1948