US1888559A - Electric switch - Google Patents

Description

Nov. 22, 1932. J, w s 1,888,559

ELECTRIC SWITGH Filed April 30, 1930 6 Sheets-Sheet 1 INSULATION INSULATION gwumtoc Jail/11s Nov. 22, 1932.

M. J. LEWIS ELECTRIC SWITCH Filed April 30, 1930 6 Sheets-Sheet 2 47 4 40 56 :5; 55 6l 62 do Nov. 22, 1932. M. .1. LEWIS ELECTRIC SWITCH Filed April 50. 1930 INSULATION INSULATION 6 Sheets-Sheet 4 gwueml ov M Jbelwls I 8% www M. J. LEWIS ELECTRIC SWITCH Nov. 22, 1932.

Filed April 50. 1950 e Sheets-Sheet 5 gwmmto'o MJAe Nov. 22, 1932.

Filed April 30. 1930 6 Sheets-Sheet 6 INSULATION INSULATION gwmnio'o Patented Nov. 92, 1932 UNITED STATES MORGAN J. LEWIS, OF MASSILLON, OHIO madame swrrcn Application filed a 'i-u 80, 1930. Serial No. 448,593.

The invention relates to electric switches and particularly to a Switch which will automatically open a circuit immediately upon the occurrence of an abnormal overload and 6 after a brief lag upon the maintenance of a slight overload.

It is known that automatic circuit breakers have been made in the past, but such circuit breakers have been provided with a brush 10 type of contacts, which are objectionable because of a speck of dirt or the like, or a slight projection upon the face of one of the contacts, caused by arcing or the like, frequently prevents a positive contact from being made.

The object of the improvement is to overcome the objections and difiiculties encoun tered in such devices, by providing an automatic switch having blades receivable within contact jaws whereby a positive contact is assured when the switch is closed.

Another object of the improvement is to provide a switch of this character in which a latch is provided for normally holding the switch blades in closed position, a spring pressed device being provided for releasing the latch, means being provided for immediately operating said 5 ring ressed device upon the occurrence 0 an a normal overload and for actuating the spring pressed device after abrief lag upon the occurrence of a slight overload.

The above and other objects may be attained by providing a hook-shaped latch for normally holding the switch blades in closed position, a spring operated device being operatively associated with said latch and normally held in' the inoperative position by means of a hooked thermostatic bar formed of laminated strips of metals welded or otherwise fastened together and having different coeflicients of expansion, a magnet coil being located adjacent to the thermostatic bar for attracting the same.

A toggle link device may be connected to the switch blades and operatively associated with the operating handle and adapted to be broken bythe operation of said spring pressed device.

An embodiment of the invention is illus-' ing the same in position to be closed by the switch handle;

Fig. 7, a section on the line 7-7, Fig. 1; Fig. 8, a longitudinal section showing the iwitfii in the act of being opened by the an e;

Fig. 9, a plan section of the latch mechanism;

Fig. 10, a detail perspective view of the thermostatic device;

Fig. 11, a side elevation of a modified form of the invention for use upon switchboards and the like.

Fig. 12, a plan view of a switch provided with three blades;

Fig. 13, a side elevation of the same; and

Fig. 14, a plan section of the latch mecha nism of the three blade switch shown in Figs. 12 and 13.

Similar numerals refer to similar parts throughout the drawings. The improved switch mechanism to which the invention pertains may be mounted u on an insulation block 12 located within a switch box of any usual and well known construction, as shown generally at 13. The invention is applicable to switches having one, two, three or four blades, and for the purpose of illustration it is shown in Fi 1 to 10 inclusive as applied to a switch having two blades.

A pair of pivot contacts 14 are fixed upon the insulation block spaced from each other and located near one end of the block to which are pivoted, as at 15, the switch blades 16 connected to the insulation crosspiece 17 at points spaced from their free ends which are adapted to engage the contact jaws 18 mounted upon the insulation block 12 near the other edge'thereot and having connected thereto the terminals 19.

A bracket 20 may be fixed upon the insulation block 12 adjacent to each of the pivot contacts 14 and carries a magnet coil 21, one

wire, as indicated at 22, being connected to the adjacent terminal 23, fixed upon the insulation block 12 at a point spaced from the corresponding pivot contact 14.

An angle bracket 24 is fixed upon each pivot contact 14 and the lower end of one arm 25 of a U-shaped thermostatic device is connected to said angle bracket as by a screw 26,

theother arm 27 of the thermostatic device being connected, at its lower end, to an angle bracket 28, as by the screw 29.

The bracket 28 is fixed upon the insulation block 12 as by the screw 30 and nut 31, to

-which is also attached the other wire 32 'leading to the adjacent magnet coil 21;

The thermostatic device'referred to may be formed of two layers of metal welded or otherwise fastened together and having difrent flows through the arms 25 and 27 for relatively short time, the layers of metals comprising the arms will expand ditleren tially, due to their diflerent coeihcients of expansion, and the arms will bend outwardly toward the adjacent magnet 21.

' A frame is mounted longitudinally upon the central portion of the insulation block 12 and is formed of the spaced side members 35 which may have their upper portions connected as by the crosspiece 36 on the end of the frame adjacent to the thermostatic devices.

The latch mechanism is located in the opposite end portion of this frame and may be in the. form of the hook 37 pivoted at its lower end between the side members of the frame, as at 38, and provided with a spring v39 for normally urging the upper hooked end 40 thereof inward to hold the switch blades in closed position, as will be later described.

The latch releasing mechanism may include the releasing plates 41, one end of each late being pivoted upon the pin 38, the ot er end having the upwardly disposed and outwardly inclined arm 42 arranged to benormally engaged under the hook 34 of the adjacent thermostatic device.

A coil spring 43' is connected to the adja- 56 being carried cent end portion of each releasing plate 41 and to the upper portion of the frame 35 for normally urging each of the releasing plates into the position shown in Fig. 4, so that the arm 44, upon the opposite end thereof-L will tend to move the latch 37 intothe releasing position.

A coil spring 45 may be fixed upon the insulation block and adapted to be compressed by contact with the insulation crossbar 17 of the switch when the blades are in the closed position and tending to throw the blades out of engagement with the contact jaws 18 when the latch is released.

For the purpose of quickly throwing the switch blades to the fully opened position, as .shown in Fig. 5, a pull spring 46 may be connected at one end to the insulation cross bar 17, the other end being connected to the opposite end portion of the frame 35-.

For the purpose of manually closing the switch and also for manually opening the same when desired, a switch operating handle may be provided inthe form of a crankshaft 47, of a design which is usual and well known in switch boxconstruction and which. may be journaled through opposite side walls of the box 13 and provided upon" one end with the handle portion 48 located upon the exterior of the box.

A toggle link construction may be provided between the switch handle and the insulation cross bar 17 and comprising the link 49, preterably of channel cross sectional shape and having the pivot pin 50 located through the elongated slot 51 in the bracket 52, which is fixed upon the upper side of the insulation cross bar 17, as by the screw 53.

The link 54 may also be of channel cross sectional shape and is pivotally connected to the link 49 as by the pin 55, the spring by said pin and having its opposite ends engaging the under sides 0 the links 49 and 54 and tending to urge them into alinement with each other, as shown in Figs. 3 and 6, with the inner end 57 of the link 54 butting against the shoulder 58 of the link 49.

The outer end of the link 54 has the elongated slot 59 which receives the crank portion 60 of the switch operatinglever. As best shown in Figs. 3 and 6, the pivotal point 55, between the links 49 and 54, is below a straight line passing through the centers of the ivotal points 50 and 60.

. ith the switch in the closed position, as shown in Figs. 1, 2 and 3, the crank portion 60 of the operating handle is at the lighter inner end of the elongated slot 59 in the link 54, the links 49 and 54 being located in alinement with each other and the central upright leg 61 of each releasing plate contacting at its up er end with the pivot pin 55 of the tog le lin rs.

-The hoo 40 of the latch is engaged over' the iii) pin 50, preventing the switch blades from being withdrawn from the contact jaws. Assuming there is a sudden heavy overload in the circuit, one or the other of the magnet coils 21 will immediately attract the cross bar 33 of the corresponding thermostatic device, pulling the hook 34 out of engagement with the upturned arm 42 of the corresponding releasing plate, the spring 43 thereof immediately pullin the releasing plate into the position shown in Fig. 4, the upright central leg 61 of the plate throwing the pivotal connection between the toggle links upward, breaking the joint as shown in said figure.

Atthe same time the inner end of the re= leasing plate will force the latch book 37 outward, releasing the same from engagement with the pin 50 ot the switch. The compressed spring-45 will immediately force the switch blades upward out of engagement with the contact jaws and the spring 46 will continue to move the switch blades to the fully opened position, as shown in 5.

As the insulation cross bar 17 engages the central upright leg 61 of the releasing plate it will push the same back and down to the normal position, moving the arm 42 at the end thereof back beneath the book 34 of the thermostatic device, while the insulation cross bar 17 comes to vrest within the notch 62 in the leg 61.

Uh the other hand, if a slight sustained overload of current occurs in the circuit, which overload is not sufficient to energize v the magnets 21, after a brief pause the layers metal in the thermostat? c members will by differential expansion bend to release the hooks 34, and the cooperating parts will immediately function to open the switch in the manner above described.

.ln order to close the swit h from the position shown in Fig. 5, the handle 47 is first swung counterclockwise to bring the links 49 and 54 into straight line position as shown in Fig. 6 with the pivot below dead center. Upon then swinging the handle in the opposite or clockwise direction, the switch blades are forced into engagement with the contact jaws 18 against the action of springs 46 and 45 when the hook 40 will engage the pin 50 to hold the blades in closed position.

llf it is desired to manually open the switch, assuming the parts to be in closed position as shown in Figs. 1, 2 and 3, the handle 47 is moved counter-clockwise as viewed in said figures. During the initial art of this movement, the portion of t e handle travels from the right end of the slot 59 of link 54 to the left end of the slot rotating the link 54about the pivot 55, which is supported on the leg 61 of the releasing plate, and breaking the joint between the links as shown in Fig. 8. At this point further counter-clock wise rotation of the handle will, by engagementof the portion 60 with the left end of the slot, move both links 49 and 54 to the left until the pin 50 is released from engagement with the hook 40 of the latch 37, When the springs 45 will throw the switch blades out of the contact jaws and the springs 46 will pull the switch blades to fully open position.

In Figs. 12 to 14 inclusive the invention is illustrated as applied to a three blade switch, otherwise similar to the switch shown in Figs. 1 to 10 inclusive. In this form of the invention the switch mechanism may be mounted upon the insulation block 12s, the pivot contacts 14a and 14b being fired thereon in spaced relation and having pivoted thereto the switch blades 16a and 166, .all of which are connected near their free ends to the insulation cross bar 17a.

The free ends of the blades 16a and 166 are adapted to engage the contact jaws 18a and 187) respectively, which are fixed upon the insulation block 12a near the opposite edge thereof and having connected thereto the terminals 19a and 197) respectively.

The brackets 20a and 20?) are mounted upon the block 12a, the brackets 520a being preferably located adjacent to the pivot contacts 14a and the bracket 20?) preferably near the adjacent edge of the insulation block, a point between the brackets 20a. 'lhese brackets carry the magnet coils 21a and 216 respectively connected at one side to the terminals 23a 23b.

The other side of each coil 21a is connected to the corresponding pivot contact 14a through the bracket 24a and the other side of the coil 215 is connected to the pivot contact 141) as through the bus bar 524?).

A thermostatic device, similar to that described above in the two blade switch illustrated in Figs; 1 to 10 inclusive, is associated with each of the magnet coils, these thermostatic devices being illustrated generally at 250. and 25b.

The frame 35a. is mounted longitudinally upon the central portion of the insulation block and houses the latch and releasing mechanism which includes the latch hook 374; similar to the hook 37 above described.

The releasing mechanism includes three releasin plates similar to the plates 41 above descri ed, the central plate 41?; cooperating with the thermostatic device 256 and magnet coil 21?) while the two outer plates 41a cooperate with the thermostatic device 25a and magnet coils 21a in the manner above described pertaining to Figs. 1 to 10 inclusive. Y

The'remainder of the switch illustrated in Figs. 12 and 13 is of the same construction as above described and illustrated in Figs. 1 to 10 inclusive, and the operation of the switch is the same as above described, a sudden heavy overload energizing either of the magnets 21s or 216 to immediately throw out the switch, while a sustained slight overload will operate any one of the thermostatic devices 25a or 25?) to throw out the switch after a brief pause.

In Fig. 11 is. shown an adaptation oi the invention to a switch adaptable for use upon switchhoards and the like, in which the mechanism is mounted upon the insulation block 120, the switch blades 160 being pivoted upon the pivot contacts l lo and their free ends adapted to enga e the contact jaws 18c.

A magnet coi is mounted upon a bracket 20c adjacent to each pivot contact and associated with a thermostatic device such as above described and illustrated in Fig. 10 and adapted to cooperate with the corresponding releasing plate ila, housed. within the frame 350, in the manner above described.

The releasing plate cooperates "with the latch hook 37 as above described, this hook engaging the pin 500 in the bracket upon the insulation crosspiece 170, all as illustrated in Figs. 1 toll) and above described.

The operating handle may be in the form of a segment 65, pivoted as at '86 upon the frame 350 and provided with a knob 67 for operating the same. The links 490 and 540 are pivotally connected together as by the pin 550 and are similar to the links 49 and 54 above described and illustrated in Figs. 1 to in clusive, the link 490 being pivoted to the. bracket 520 by the pin 50c, and the link 540 having the elongated slot 590 which receives the pin 600 carried by the segment 65.

In-the closed pos tion of this switch, the

pivotal point 550 is below a line drawn through the centers c and 500 and contacts with the upright linger 610 of the releasing plate 410. With the exception of the handle arrangement, the operation of the switch is the same as above described.

I claim:

1. An electric switch, a latch. for normally holding the switch in closed position, a spring operated releasing plate for releasing the latch, means for automatically opening the switch when the latch is released, a thermostatic device-in circuit with the switch for normally holdin the releasing plate inoperas tive and for re casing said releasing plate after a. brief lag upon the maintenance of a slight overload, and a magnet coil in circuit with the switch for attracting said thermostatic device to release the releasing plate immediately upon an abnormal overload:

2. An electric switch,a handle for manual- 1y operatinglthe switch, links connecting said switch and andle and having a pivotal connection with each other forming a joint, a latch for normally holding the switch in closed position, means engaging the pivotal connection between the links for automatically breaking the joint of the links and opening the switch when the latch is released, and a thermostatic device in circuit with the switch for releasing said latch.

3. An electric switch, a handle for manualnssatee ly operating the switch, links connecting said switch and handle and forming a joint, a. latch for normally holding the switch in closed position, means operating independentlyof the handle for automatically breaking the joint of the links and opening the switch when the latch is released, and a magnet coil in circuit with the switch for releasing said latch.

An electric switch, a handle for manually operating the switch, links connecting said switch and handle and having a pivotal connection with each other forming a ioint a latch for normally holding the switch in closed position, means engaging the pivotal connection between the links for automatically breaking the joint of the links and opening the switch when the latch is released, and a thermostatic device in circuit with the switch for releasing said latch after a hriei lag upon the maintenance of a slight overload.

5. An electric switch, a handle for manually operating the switch, links connecting said switch and handle and having a pivotal connection with each other forming a joint, a latch for normally holding the switch in closed position, means en aging thepivotal connection between the lin s for automatically breaking. the joint of the links and opening the switch when the latch is released, a

thermostatic device in circuit with the switch for releasing said latch after a brief lag upon the maintenance of a slight overload, and a magnet coil for operating said thermostatic devce immediately upon an abnormal overloa 6. An electric switch, a handle for manually operating the switch, links connecting said switch and handle and forming a joint, a

latch for normally holding the switch in closed position, a spring operated releasing plate for releasing the latch and breaking theioint of thelinks, means for automatically opening the switch when the latch is release and a thermostatic device in circuit with the switch for normally holding the releasing plate inoperative.

"7. An electric switch, a handle for manual ly operating the switch, links connecting said switch and handle and forming a joint, a latch for normally holding the switch in closed position, a spring operated releasing plate for releasing the latch for braking the'joint of the links, means for automatically opening the switch whenthe latch is released, an armature for normally holding the releasing plate inoperative, and a magnet coil in circuit with the switch ior attracting said armature immediately upon the occurrence of an abnormal overload. V

8. .An electric switch, a handle for manual- 1y operating the switch, links connecting said switch and handle and forming a joint, a. latch for normally holding theswitch in closed position, a spring operated releasing MORGAN J. LEWIS.

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