US2752442A - Pull-operated switch with arc snuffer - Google Patents

Description

June 25, 1956 G. B. BENANDER 2,752,442

PULL-OPERATED SWITCH WITH ARC SNUFFER Filed March 30, 1955 2 Sheets-Sheet 1 HA9 Attorney J1me 1956 G. B. BENANDER PULL-OPERATED SWITCH WITH ARC SNUFFER 2 Sheet s-Sheet 2 Filed March 30, 1955 [)7 van t 02". Ge 0236 B B enanaen PULL-OPERATED SWITCH WITH ARC SNUFFER George B. Benander, Oaklawn, R. I., assignor to General Electric Company, a corporation of New York Application March 30, 1955, Serial No. 497,902

Claims. (Cl. ZOO-51.15)

The present invention relates to a pull-chain-operated electric switch and in particular to a switch having a ratchet-operated mechanism.

Pulloperated switches commonly employ a pull chain to actuate a ratchet mechanism for making and breaking the circuit to the switch. At the present time these switches are made and used in huge quantities; therefore, it has always been desirable to simplify the design as new techniques and materials are discovered and made available. The first improvement that has been made in the present design is the addition of an arc snufiing means in cooperation with the edgewise blades of the rotary contactor of the switch which considerably extends the life of the switch. While there are other switch mechanisms on the market which have the same high electrical rating as the present switch, they are much more expensive to manufacture which in turn dictates a considerable price differential over the lower rated constructions. The improvement of the present invention is primarily in the configuration of the rotary contactor having blades disposed edgewise with relation to the fixed contacts so that narrow grooves may be formed between the fixed contacts to prevent an are from spreading and eventually burning the contacting parts. This feature is considered to be an important part of the present invention for it brings about unexpected results which enable the switch to have a higher electrical rating at a lower cost than has been possible heretofore.

Another advantage of the present invention is that all of the separate switch parts may be assembled in onehalf of the hollow switch housing which is closed by simply placing the remaining half of the housing in cooperative engagement therewith, and finally in connecting the two housing parts together. This is an important consideration for it must be remembered that this switch will be made literally by the millions each year. Since the design does not require the housing parts to be turned over in order to complete the assembly, it is much simpler to handle and easier to assemble. It is interesting to note that the design of the present invention is to replace an old construction made by the present assignee which contained a total of 22 parts whereas this design contains only 14 parts or 36% less parts. T 0 give an example of the saving, it 3,000,000 switches were to be manufactured per year, the present design would eliminate the manufacture and handling of 24,000,000 parts.

The principal object of this invention is to provide a pull-operated electric switch having an arc-snutfing means to increase the electrical rating and the useful life of the switch.

A further object of this invention is to provide a pulloperated switch with a rotary contactor having edgewise blades for making connection with the fixed contacts of the switch.

A further object of this invention is to provide an electric switch having a ratchet type mechanism wherein edgewise blades of the rotary contactor may be seated ited States Patent ICC within narrow grooves which serve to extinguish the are between the contactor and the fixed contacts of the switch.

A further object of this invention is to provide a ratchet type switch mechanism having a minimum number of parts which are simple in design and easy to assemble within a short time on a mass production basis.

My invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

Figure 1 is an elevational view of a socket interior having a pull-chain operated switch mechanism embodying my invention.

Figure 2 is a back elevational view of the socket interior of Figure 1.

Figure 3 is a view of the socket interior of Figure l with the screw shell and one-half of the insulating housing removed to show the relationship of the switch parts mounted therein.

Figure 4 is a left end elevational view of the socket interior of Figure 1.

Figure 5 is a top plan view of the socket interior of Figure 2.

Figure 6 is a bottom plan view of the socket interior of Figure 2.

Figure 7 is an exploded perspective view of a socket interior embodying my invention.

Referring in detail to the drawing, Figure 1 shows a lamp socket interior 10 comprising a metal screw shell 11 and a hollow split housing 12 of suitable insulating material for enclosing a ratchet-type switch mechanism. Looking at Figure 7 of the drawing, the split hollow housing 12 is formed of two recessed molded pieces 13 and 14 of suitable phenolic insulating material. The part 13 will be referred to as a base member since all of the switch parts are assembled therein, while the part 14 serves as a cover member to complete the enclosure of the switch mechanism. There is an integral stud member 15 molded in the base 13 which serves as the focal point of the fixed and movable contacts of the ratchet mechanism. Disposed around the stud 15 are a series of inclined, arcuate ratchet. steps 16 which it will be seen serve to provide a snap action for the switch mechanism. Two of the opposed steps are adapted to receive the fixed contacts 17 and 18 that are spaced from each other by the narrow ratchet steps 16'.

The terminal end 19 of the fixed contact 17 is provided with a tapped opening 20 for receiving a terminal screw 21 and is of such a size and shape that it may be seated in the aperture 22 formed in the base 13. The hook portion 23 of terminal end 19 is arranged to be seated on the ledge 24 of the base 13 near the aperture 22 to assist in supporting the fixed contact within the switch housing. Looking at Figure 7, there is an apertured boss 55 on the cover 14 which is adapted to receive the end of the terminal screw 21 as well as to mate with the terminal end 19 of the fixed contact 17 to insure that it is held firmly in place within the base 13. Thus, it will be seen that it is possible to connect a lead wire (not shown) to the switch mechanism by means of the terminal screw 21 which has its head arranged outwardly of the switch housing.

Considering Figures 3 and 7 of the drawing, it will be seen that the fixed contact 18 has at one end a center contact strip 28 serving as the center contact for the screw shell socket 11. In Figure 3 of the drawing, fixed contact 18 is shown seated on the ratchet step 16 and opposite the remaining fixed contact 1'7. A slot 29 is formed in one edge of the base 13 and a similar slot 29 is formed in one edge of the cover 14 so that the strip 30 which connects the fixed contact 18 with the center contact 28 is fitted within the said grooves 29 and 219 to be centrally located in the screw shell 11, as is best seen in Figure 6.

A rotary contactor 35 which serves as the movable contact between the fixed contacts 17 and 18 is provided with a central opening 36 so that it may be fitted over the stud member of the base 13 to rotate with respect thereto. Edgewise blades 37 are formed on opposite sides of the contactor to have sliding engagement with the fixed contacts 17 and 18. The lower edge 38 of each blade 37 is inclined in the same manner as the fixed contacts 17 and 18 so that there is a fiat edgewise engagement between the movable and fixed contacts. Spaced between the blades 37 are a pair of ratchet teeth 39 which are adapted to cooperate with the insulating ratchet member 49 that is fitted over the stud 15 on top of the contactor 35.

The ratchet member 40 is of fiber material with a central pivotal opening 41 and a series of four ratchet openings 42 equally spaced around the aperture 41. An integral arm 43 extends from one side of the ratchet member 40 and it has an opening 44 containing the link member 45 for making engagement with a pull-chain 46 of the usual construction. An adjustable torsion spring 59 is also fitted over the stud 15 after the ratchet member 40 is in place. The lower end 51 of the spring is shaped to fit into the pinhole 47 of the ratchet member 40 to fix that end of the spring with respect thereto. The opposite end 52 of the spring 50 is rounded to fit into one arm of the cross-shaped slot 53 formed in the cover member 14, as is best seen in Figure l.

The purpose of the cross-shaped slot 53 in the cover member 14 is to permit the adjustment of the spring tension of the torsion spring 50. Thus, it is possible to use a special tool (not shown) having a bifurcated end to depress the spring 50 until the rounded end or tongue 52 is free of the slot 53 and then by turning the spring the necessary amount to obtain the desired spring tension after the switch is assembled in the switch housing. When the adjustment is correct, the spring may be released by withdrawing the tool so that the rounded end 52 of the spring is again seated in one of the arms of the cross-shaped slot 53. By using such a slot it is possible to obtain the fineness of a quarter-turn adjustment.

The method of assembling this switch mechanism is quite simple in that the base member 13 may be placed on the operators work bench and the fixed contacts 17 and 18 are dropped onto their respective ratchet steps 16 in the base 13. Then in quick succession the rotary contactor 35 is fitted over the end of the stud 15, and in turn the ratchet member 40, torsion spring 50, and finally the cover member 14 are assembled to form a completely enclosed switch mechanism. After this it is merely necessary to adjust the spring tension of the torsion spring so that the switch will be ready for use. The switch is operated by moving the rotary contactor 35 into and out of engagement with the fixed contacts 17 and 18. This movement is effected by exerting a pulling force on the pull chain 46 which tends to oscillate the member 41! about the stud 15. The ratchet teeth 39 of the contactor 35 are seated within the ratchet openings 42 of the ratchet member 40 so that any counterclockwise movement of the member 40 likewise moves the eontactor 35.

When the line of force of the pull chain 46 extends through the pivotal axis of the stud 15, any additional pull on the chain will be inefiective in rotating the ratchet member 40. When the chain 46 is released, the torsion spring 50 will take over, since it was tensioned by the counterclockwise movement of the ratchet member 40, and it will tend to return the member-4t) to its normal position. During this return movement of the ratchet member 40, the contactor 35 remains fixed due to the shape of the ratchet steps 16 and 16 in the base 13. Consequently, the ratchet openings 42 of the ratchet member 40 will move out of driving engagement with the ratchet teeth 39 of the contactor 35. The raised ratchet teeth 39 also serve as a detent mechanism in cooperation with the ratchet openings 42 of the member 40 so that normally the teeth 39 are disposed within opposite ratchet openings 42. Thus, when a pulling force is applied to the pull chain 46, the contactor 35 will be driven by the movement of the ratchet member 40 to make or break the electrical circuit through the fixed contacts 17- and 18. The screw shell 11 has a. partial base 56, as seen in Figure 7, which is nearly cut-away by the enlarged central opening 57. A pair of lanced tabs 58 are struck out f the base 56 to lie opposite and parallel to each other. The tabs 58 of the screw shell 11 are each provided with aligned slots 59 so that when the switch parts are assembled in the base member 13 and the cover member 14 is disposed thereover, the tabs 58 of the screw shell ll may be arranged tostraddle the parts 13 and 14 at a point where there are openings 60 and 61 in the base 13 and cover 14 respectively. Thus, a ground contact such as.

strip 62 may be fitted through the slots 59 in the tabs 58 as well as through the openings 60 and 61 in the housing parts. Finally, the free end of strip 62 is bent or twisted to complete the assembly and finally hold all of the parts in assembled relation. The terminal end 63 of the ground contact 62 is bent at a right angle and provided with a tapped opening 64 for receiving the terminal screw 65 so that a second lead wire (not shown) may be connected to the switch mechanism for completing the circuit through the switch.

Itwill be appreciated by one skilled in this art that I have provided a simplified design for a ratchet-type switch mechanism having a rotary contactor with edgewise blades for making and breaking contact with the fixed contacts of the switch mechanism. Because of the use of these cdgewise blades, it is possible to provide narrow grooves between the fixed contacts so that when the blades are seated therein, the clearances between the blade andthe side walls of the grooves are so slight as to prevent an electrical are from spreading and burning the switch parts. it is this feature which has brought about. the new and unobvious result of extinguishing the arc and extending the life of the switch as well as making it possible to obtain a higher electrical rating for the switch at a minimum cost.

A second important feature of this invention is the unique manner of supportingthe fixed contact 17 within the base by utilizing the hook member 23 and ledge 24 which cooperates with the apertured boss 55 in the cover 14 to hold the terminal end 19' firmly in place in the switch housing. Also, the adjustable torsion spring means is another improvement which contributes to the high quality of this device. Likewise, the simple ground contact 62 and the mannerin which it is used to finally assemble this switch mechanism is a unique feature of this present invention.

While this invention has been disclosed as combined in a lamp socket interior, it should be appreciated that this ratchet-type switch mechanism has general utility in the switch art and that it could also be used in feed through switches for portable electrical cords and any place where a rotating movable contactor may be used to advantage.

Modifications of this invention will occur to those skilled in this art and it is to be understood, therefore, that this invention is not limited to the particular embodiments disclosed but that it is intended to cover all modifications which are within the true spirit and scope of this invention.

What Iclaim as new and desire to secure by Letters Patentof the United States is:

l. Ina-.rotary, switch comprising a hollow housing having a series of arcuate ratchet steps formed on an inner wall surface of said housing centered around an inwardly projectingstud member, fixed contacts located on-ppppsite steps of the housing and being-separated by arcuate steps of relatively narrow width, and a rotary contactor mounted over said stud for making and breaking the circuit through the fixed contacts, said contactor having a pair of contact blades oppositely arranged thereon for edgewise engagement with the fixed contacts, the said edgewise blades of the rotary contactor serving to open the switch when positioned in the arcuate steps of narrow width, whereby the small clearances between the edgewise blades and the side walls of the narrow steps act to extinguish the are formed between the blades and the fixed contacts.

2. In a rotary switch comprising a hollow housing having a series of arcuate ratchet steps formed on an inner wall surface of said housing centered around an inwardly projecting stud member, fixed contacts located on opposite steps of the housing and being separated by arcuate steps of relatively narrow width, and a rotary contactor mounted over said stud for making and breaking the circuit through the fixed contacts, said contactor having a pair of contact blades oppositely arranged thereon for edgewise engagement with the fixed contacts, and an oscillating ratchet member arranged over the said stud member for driving engagement with the said rotary contactor, and adjustable spring means for returning the insulating ratchet member to its normal starting position once it is released from manual control, the said edgewise blades of the rotary contactor serving to open the switch when positioned in the narrow arcuate steps whereby the small clearances between the edgewise blades and the side walls of the narrow steps act to extinguish the arc formed between the blades and the fired contacts.

3. A rotary switch as recited in claim 2 wherein the spring means has a tongue portion seated in an opening in the outer wall of the switch housing so that the tension of the spring means may be adjusted after the switch is completely assembled in the switch housing.

4. In a rotary switch comprising a hollow housing formed of a base member and a cover member, a series of arcuate ratchet steps formed on an inner wall surface of said base and centered around an inwardly projecting stud member, fixed contacts located on opposite steps of the base and being separated by arcuate steps of relatively narrow width, one of said fixed contacts having a terminal end seated over an opening in the base so that a terminal screw may be threaded therein, and a rotary contactor mounted over said stud for making and breaking the circuit through the fixed contacts, said contactor having a pair of contact blades oppositely arranged thereon for edgewise engagement with the fixed contacts, the said edgewise blades of the rotary contactor serving to open the switch when positioned in the arcuate steps of narrow width, whereby the small clearance between the edgewise blades and the side walls of the narrow steps act to extinguish the are formed between the blades and the fixed contacts, and a ratchet mechanism for driving engagement with the said rotary contactor upon the manual actuation of the switch, the said cover member having a boss which engages the said terminal end of one of the fixed contacts to hold it firmly within the switch housing.

5. In a pull chain operated lamp socket interior comprising a hollow housing formed of a base member and a cover member, a series of arcuate ratchet steps formed on an inner wall surface of said base and centered around an inwardly projecting stud member, fixed contacts located on opposite steps of the base and being separated by arcuate steps of relatively narrow Width, one of said fixed contacts having a terminal end seated over an opening in the base so that a terminal screw may be threaded therein, one portion of said terminal end seated on a ledge on the base member adjacent the said opening, the said cover member having a boss which engages the said terminal end of one of the fixed contacts to hold it firmly within the switch housing, and a rotary contactor mounted over said stud for making and breaking the circuit through the fixed contacts, said contactor having a pair of contact blades oppositely arranged thereon for edgewise engagement with the fixed contacts, the said edgewise blades of the rotary contactor serving to open the switch when positioned in the arcuate steps of narrow width, whereby the small clearances between the edgewise blades and the side walls of the narrow steps act to extinguish the are formed between the blades and the fixed contacts, and a ratchet mechanism for driving engagement with the said hotary contactor upon the manual actuation of the said pull chain, and an adjustable torsion spring having a longitudinally extending tongue at one end extending into a slotted opening through the said cover member so that its tension may be adjusted from the outside after the switch is completely assembled, and a screw shell fitted over the said base and cover members and fixed thereto.

References Cited in the file of this patent UNITED STATES PATENTS 1,006,296 Seeley Oct. 17, 1911 1,024,365 Rowntree Apr. 23, 1912 1,097,210 Barr May 19, 1914 1,530,847 Mollik Mar. 24, 1925 2,044,291 Grant June 16, 1936 2,079,800 Grant May 11, 1937 2,124,337 Popp July 19, 1938

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