US2119080A - Electric switch - Google Patents

Description

May 31, 1938. E. c. KENNEDY 2,119,080

ELECTRIC SWITCH Filed July 19, 1957 2 sheets-sheet 1` #of ,H /f/ Ernest @.Zennedy INVENTOR ATTOR N EY@ E. c. KENNEDY ELECTRIC SWITCH May 31, 193s.

Filed July 19. 1957 2 Sheets-Sheet 2 ynlavENTos Patented May 31, 1938 UNITED STATES PATENT OFFICE Application July 19,

1 Claim.

This invention relates to electric switches and has tor an object to provide a switch adapted to retain the circuit closed a brief predetermined interval oi time after the switch has been opened so that one may retire or reach the switch of another room before the light actually becomes extinguished.

A further object is to provide a switch of this type having a novel resistance element i'or heating a thermostat arm, which curves outward and breaks the circuit at the end oi a predetermined lapse of time after the switch has been opened.

A further object is to provide novel means lor timing the switch so that a greater or less interval oi time may lapse before the circuit is opened.

A further object is to provide a device of this type which will be formed of a few strong simple and durable parts, which will be inexpensive to manufacture, and which will not easily get out of order. y

With the above and other objects in view the invention'consists of certain novel details of construction and combinations of parts hereinafter fully described and claimed, it being understood that various modiiications may be resorted to within the scope of the appended claim without departing from the spirit or sacrificing any oi' the advantages of the invention.

In the accompanying drawings forming part of this speciiication,

Figure 1 is a plan view of a switch constructed in accordance with the invention.

Figure 2 is a longitudinal sectional view taken on the line 2--2 of Figure 1 showing the switch in closed circuit position.

Figure 3 is a view similar to Figure 2 but showing the switch in open circuit position and the circuit held closed by the pivoted auxiliary contact on the switch blade and the thermostat controlled contact.

Figure 4 is a cross sectional view taken on the line 4-4 of Figure 1.

Figure 5 is a longitudinalk sectional view taken on the line B-l of Figure 1 showing the thermo- V stat controlled contact and the timing mechanism.

Figure 6 is a detail cross sectional view taken on the line 8-8 of Figure 5 showing the means for mounting the controlling spring oi' the thermostat operated contact to vary the tension of the spring.

Figure 7 is a detail perspective view of theguide bracket for the thermostat controlled contact.

Figure 8 is a detail perspective view ci the 1937, Serial No. 154.484

(Cl. 20o-122) bracket for coupling the thermostat to the thermostat controlled contact.

Figure 9 is a plan view oi the parts involved in lay-passing the circuit around the blade and throughthe thermostat alter the switch has been opened.

Referring now to the drawings in which like characters of reference designate similar parts in the various views, i0 designates the switch receptacle, the same being formed as usual of insulating material. 'A bar il is secured .to the receptacle and is terminally provided with openings I2 for the reception of screws or the like for mounting the switch in a conventional outlet box.

The main contacts of the switch, here shown as a single pole structure, comprise a long contact Il and a short contact i4. best shown in Figures 2 and 3. The contacts are anchored in the walls of the receptacle by brackets B which are equipped with binding post screws i5 which receive the line and load wires of the circuit.

The switch body I8 is provided with oppositely extending blades I1 and il and the blade i'i in both the open or the closed position of the switch engages the long contact i3. The switch is of the snap type in the present embodiment controlled by a spring IB and is limited in throw by spaced horns 2li engaging a stop pin 2i on the plate ii. A lever 22 projects through a suitable opening in the plate.

A bi-metallic lever arm 23, best shown in Figure 9, is iixed stationary at one end to the wail of the receptacle by a bolt 24 or other connector and secured to the other end of the arm is a resistance element 25 having a heating coil 2C sleeved loosely around the lever arm. An electrical conductor 21 is connected to one end of the coil and is connected to the short stationary main contact i4.

A channeled auxiliary contact 28 is pivoted on the side o! the blade i8 by a pivot pin 2l and a spring 30 is sleeved on the pin within the channel of the contact to hold the contact against accidental movement. The contact is provided with a lateral extension 3| which is adapted to extend transversely across the lever arm Il. as best shown in Figure 9. When the switch is turned oil, as best shown in Figure 3, the auxiliary contact engages a plunger 82, as best shown in Figure 3, which is slidably mounted in a guide bracket 33, best shown in Figure 7, and has an upturned end 34 which is conilned in the bight of a U-shaped bracket 35, best shown in Figure 8. The bracket is riveted, as shown at IB in Figure 5 to the projecting end'l, shown in Figure 9, 55

oi' the lai-metallic lever arm 2l. An electrical conductor 3l connects the bracket with the end of the resistance coil. When the switch is turned oi! the current will be by-passed around the short main contact I4 and may be traced through the conductor 21, resistance element 2l. plunger l2. auxiliary switch contact 2l and switch blades I3 and i1 tothe long switch contact Il so that the circuit is maintained energized. After the switch has been turned oi! for a predetermined period oi' time. the bi-metailic lever will be heated sutilciently to curve outwardly and withdraw the plunger 32 from engagement with the auxiliary contact Il with the result thatthe circuit is broken.

The period during whichathe plunger remains in engagement with the auxiliary contact is varied by means of a rotary screw 89 upon which a traveling sleeve 4l is threadedly engaged. as best shown in Figure 6. The sleeve is provided with s wing 4| having an obliquely disposed slot l! therein which slidably receives a spring 4l which is carried by an arm Il that projects from the bracket Il shown in Figure 8. As the tension of the spring is increased by movement of the spring to one end ot the slot the plunger 32 lwill be held to project further under the auxiliary contact 2l and thus increase the length ot time during which the resistance element must heat the bi-metallic lever arm. and vice versa.

From the above description it is thought that the construction and operation of the invention will be fully understood without further explanation. s

What is claimed is:

In an electric switch, fixed contacts one of which is longer than the other. a movable blade adapted to bridge the contacts and in any position engaging the long contact, a bi-metallic lever arm secured stationary at one end, a resistance element secured to the other end of the arm, a conductor extending from the arm to the short stationary contact. a spring pressed auxiliary contact pivotally mounted on the blade, a plunger connected to the bi-metall'ic arm and normally engaging said blade when the switch has been turned to the of! position, the bimetallic arm being heated and being adapted to curve out@ wardly and withdraw the plunger from engagement with the auxiliary contact to break. the circuit at the end of a short lapse of the switch is turned to oir position, a manually operable rotary screw. a tension spring secured at one end to the plunger, and a sleeve threadedly engaged with the screw and provided with a web having an inclined slot receiving the free end oi.' the spring. rotation oi the screw varying the tension o! the spring to time the period during which the plunger remains in engagement with the auxiliary contact after the switch is turned to of! position.

ERNEST C. KENNEDY.

time after

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