US2313291A - Circuit controller - Google Patents

Description

-March 9, 1943.

CIRCUIT CONTROLLER Original Filed March so, 1932 2 Sheets-sheaf. 2

N. c. SCVHELITENGER A '2 ,313,291

- Patented Mar. 9, 1943 CIRCUIT CONTROLLER Newton 0. Schellenger, Chicago Telephone S El Paso, Tex, assignor to upply Company, Elkhart,

Ind, a corporation of Indiana Original application March 30, 1932, Serial No.

now Patent No.

2,198,277, dated April 23, 1940. Divided and this application March 22, 1940, Serial No.

7 Claims.

This invention relates to circuit controllers or electric switches, and refers particularly to a snap switch adapted to be combined with a volume control or other similar radio control instrumentality to form one compact unit.

This application is a division of the copending application of Newton 0. Schellenger, Serial No. 602,006, filed March 30, 1932, now Patent No. 2,198,277.

One of the primary objects of this invention is to provide a snap switch of exceptionally compact construction and reliable in operation and which lends itself readily methods of manufacture.

In the interest of simplicity, it is a further object of this invention to provide a switch wherein all moving parts are mounted directly in an insulating casing or housing which eliminates the necessity for separate frame structures to carry the moving parts and in which the contactor is directly incorporated in the mechanical structure of the switch to eliminate the usual yoke and insulating mounting.

Another, object of this invention is to provide a switch structure wherein the actuating mechanism is insulated from the live parts so that the need for electrical clearances within the switch itself is avoided and a more compact construction made possible.

Another object of this invention is to provide a switch or circuit controller wherein the movto low cost production able contactor is made up of two portions of dissimilar metal, one of which provides the necessary mechanical strength and rigidity, and the other of which is resilient to insure good contact upon switch closure.

Another object of this invention is to so arrange the composite elements of the contactor that the resilient portion thereof constitutes the main current carrying element, while the other provides an arcing tip to protect the current carrying member from the destructive effects of arcing during opening of the switch.

Another object of this invention is to provide an improved manner of supporting and carrying the toggle spring which acts to hold the contactor in one position or the other.

Still another object of this invention is to provide a switch of the character described having a simple kickoff embodied therein by which the contactor may be manually propelled in the event of its tendency to stick in either open or closed position.

A still further object -of this invention resides in the provision of an exceedingly simple manner of mounting the switch on a rheostat or other control instrumentality to combine therewith in .the formation of a compact unitary structure and to enable switch actuation from the operating member of the control instrumentality.

In this connection, it is another object of the present invention to provide a switch so designed and constructed as to enable its combination with a volume control or other control instrumentality in such a manner that a short operating lever on the switch cooperates with a relatively long driving arm driven from the shaft of the control instrumentality so that a slight rotation of the control shaft is suflicient to operate the switch.

A still further object of this invention isto form the switch actuating member or operating ing lever and thus also preclude the possibility of grounding the switch parts through the rheostat.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in theprecise embodiment of thehereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention, constructed in accordance with the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is an external switch embodying this invention;

- Figure 2 is a plan view of, the switch mounted on the metal cover of .a volume control which is broken away to show the internal structure of the switch, said view'showing the switch open;

Figure 3 is a view similar to Figure 2 but omitting the volume control cover andillustratin the switch in a partially open position;

Figure 4 is a view similar to Figure 3 illustrating the switch closed and the manner in which the kickoff functions to force-its opening;

Figure 5 is a cross sectional view through the switch with the movable elements thereof on dead center;

Figure 6 is a fragmentary sectional view on the actuating member or operat: f-

perspective view of a which would be used in production to plane of the line 6-6 of Figure 4 illustrating the manner in which the contacts engage Figure 7 is a view similar to Figure 6 illustrating the manner in which one element of the contactor provides an arcing tip, said view being taken on the plane of the line 1-1 in Figure 3;

Figure 8 is a detail sectional view through the pitman assembly on a plane adjacent to the switch actuating lever or cam;

Figure 9 is a perspective view of the switch actuating lever or cam;

Figure 10 is a partial cross sectional view through a combined switch and volume control unit constructed in accordance with this invention; 1

Figure 11 diagrammatically illustrates the manner in which the switch is driven from the volume control;

Figure 12 is a perspective exploded view show ing in detail the volume control cover which serves as an electrostatic shield between the switch and the volume control and the insulating gaskets interposed between the switch and the cover;

Figure 13 is a plan view of the, eccentric switch driving lever shown in Figure 10 illustrating the same in its condition before attachment to the operating shaft; and

Figure 14 illustrates the lever of Figure 13 mounted on the shaft.

Referring now particularly to the accompanying drawings, in which like numerals indicate like parts, the numeral 5 designates the body or housing within which the switch mechanism is mounted. This 'body or housing is made of insulating material and is preferably molded of Bakelite or other suitable material. Its general configuration is that of a triangular shallow box having a bottom wall 6 and a side wall 1 extending therefrom.

Lugs 8 project laterally from the side walls to provide for the attachment of the entire 'assembled switch structure to the back of a volume control or rheostat, as illustrated in Figure 10; To this end, the switch housing is secured to a circular cup-shaped metallic .cover 9 by rivets,

screws, or other suitable means which enter the lugs 8.

Attention is directed to the fact that the top faces of the lugs lie a substantial distance below the outer or top surface of the housing. As a consequence, the heads or upset ends of the rivets secure the switch housing to the metal cover, are protected from contact with live terminals on the exterior of the housing or the leads attached thereto.

Attention is also directed to the fact that the edge of the side wall lies in a single plane. This enables the switch housing to be mounted on a flat support with a tight fit between the support and the entire side wall edge.

The metal cover 9 closes the open top of the switch housing except for an opening H through which a driving connection is established between the volume control and the switch mechanism in a manner to be hereinafter described.

The metallic cover plate 9 thus serves as an electrostatic shield or barrier between the switch mechanism contained within the housing and the variable resistance mechanism of the volume control to be hereinafter described.

The switch mechanism comprises a stationary contact I2 and a cooperating movable contactor, indicated generally by the numeral l3. movable contactor is pivoted on a stud l4 secured The in the apex of the switch housing to swing with an arcuate motion flatwise across the bottom wall 6 of the housing to and from engagement with the stationary contact l2.'

The stationary contact I! is secured in place on a shelf l5 formed within the switch housing by a rivet Or other securing means IS. The rivet l6 also passes-through a terminal l1 seated in a recess or pocket formed on the exterior of the bottom wall 6. The rivet thus electrically connects the stationary contact with the terminal l1.

The stationary contact has'two substantially right-angularly disposed arms, one of which projects beyond the edge of the shelf l5 to be spaced from the adjacent inner surface of the bottom wall and provide the portion with which the contactor engages. Rotation of the stationary contact about its pivot is prevented by having its arms engage the adjacent side walls of the housing, as at l8.

The movable contactor [3 comprises two superimposed arms l9 and 20 held assembled by tongues 2| extended from the sides of the arm is andengaged over the arm 20. The arm I9 is made of relatively stiff metal such as hard brass and provides the mechanical strength and rigidity for the contactor. The arm 20, which is made of relatively more resilient material such as phosphor bronze, provides the main current carrying portion of the contactor and the spring contact pressure to insure good electrical contact with the stationary contact.

Both contactor arms are apertured to engage the mounting stud l4, and both are offset, as at 22, for a purpose to be hereinafterdescribed.

The lateral or side edges or both contactor arms which face the stationary contact are flared outwardly, as at 23 and 24, to facilitate engagement of the contactor with the stationary contact.

Upon enfagement of the contacts, the projecting portion of the stationary contact enters between the outer portions of the contactor arms, the arm 20 flexing to provide spring contact pressure. The engagement between the stationary contact and the movable contactor is thus comparable to that of a knife switch.

As illustrated in Figures 6 and '7, the flared ends 23 and 24 of the contactor arms l9 and 20, respectively, are so disposed that during opening the flared end 23 leaves the stationary contact last and thereby serves as an arcing horn or tip. As a consequence, the contact engaging portion of the spring arm 20 is not subjected to the destructive arcing forces. This insures a good clean contact between the stationary contact and the contactor arm 20.

Provision is also made against the accumulation of corrosion on the flared edge 23 of the contactor arm l9 which, if permitted, would interfere with its functioning as an arcing horn or tip and throw part of the arcing load onto the edge 24.

The protection against this possibility is specifically illustrated in Figure 7. 'It consists in having the contactor arm l9 normally depressed below the plane of the top surface of the stationary contact so that the flared end 23 rides up and down the edge of thestationary contact under spring tension as the switch closes and opens.

The contactor is electrically connected with a terminal 25 through the stud l4. The terminal 25, like the terminal I1, is received in a recess or pocket on the exterior of the bottom wall 6 where it is held by a nut 26 or other suitable securing means by which the stud is held assembled with the housing 5.

The limits of motion of the contactor are defined by inward projections or bosses 21 and 28 extending from the side walls of the housing. Motion toward open position is defined by the engagement of the contactor with the projection or boss 21; while motion toward switch closing position is defined by the engagement of the contactor with the projection or boss 28. These inward projections or bosses also provide kickoff abutments which function in a manner to be hereinafter described to assure positive opening and closing motion of the contactor.

The contactor is yieldingly urged to either of it limits of motion by a toggle spring 29. This springis confined between an abutment 30 on When the lever or cam engages the side wall portion ll. the direction offspring thrust is such aslto yieldlngly hold the .contactor in its open position, as shown in Figure 2. When the lever or cam engages the stop portion 42, the direction of the spring thrust is such as to hold the contactor in its closed position engaging the stationary contact.

The contactor, in conjunction with the pivoted lever or cam and the pitman assembly, thus eonstitutes a toggle structure to provide the desired snap action and insure quick opening and closing of the switch.

the contactor arm and the end 3! of a switch actuating lever or cam 32 pivoted on the stud Hi. The abutment is preferably an upstruck portion of the contactor arm [9.

The switch acuatin'g lever or cam 32 is formed of insulating material, and like the housing 5, is preferably molded of Bakelite or other similar material. As best shown in Figure 9, the lever or cam has a hub portion 33 apertured to receive the stud l4 and counterbored to receive the head 34 of the stud. Y

As clearly shown in Figure 5, the head 34 is spaced from the inner surface of the bottom wall adjacent to the stud a distance sufficient to accommodate the thickness of the contactor arms, the lever or cam portion under the head, and a thin washer 35 interposed between the contactor and the actuating lever or cam.

In the event the contactor, for some reason or the rocking of the supported spring about the fulcrum provided by the projection or bOSs 28.

The actuating lever or cam 32 in this position of the parts has not as yetreached the full limit of its'clockwise-rotation so that the posi- Projecting radially from the hub portion is the lever 3! against which the force of the toggle tured, as at 31, and the abutment 30 on the outer end of the contactor has an aperture 38. These apertures provide for the reception of a pitman 39 upon which the toggle spring is mounted.

In toggle switches heretofore in use, the spring generally has been unsupported and as a'consequence, was very apt to buckle'and pop out" of place. This objection is entirely overcome with the present construction.

The specific construction of the pitman is another feature of particular importance from the standpoint of simplicity and low production cost. It consists merely of a U-shaped link having its closed end received in the aperture 31 and the outer ends of its two legs or reaches slidably received in the aperture 38. While this U-shaped link may be formed of any suitable wire or rod stock, it is preferable to use half round cotter-key stock since it is cheap and readily obtainable in the open market.

Proper support for the end of the toggle spring which is adjacent to the lever 3| is provided by an H-shaped thrust plate 40 positioned between the legs of the U-shaped link (see Figure 8) and between the end of the spring and the round edge of the lever 3|. An exceptionally inexpensive and dependable construction is thus tively propelledclockwise motion of the lever or cam forcibly rocks the supported spring on its fulcrum.

The instant the contactor is freed in the manner above described, the kickoff is no longer effective and the contactor moves solely in response to the toggle spring. Figure 3 illustrates the parts in the positions they occupy when the conmoves under the force of the toggle spring be- Attention is directed to the-fact that although a desirably long toggle spring is employed, the overall length of the pitman is held to a minimum to insureicompactness. This is the direct result of the novel pitman and spring arrangement andthe fact that the fulcrum abutments 21 and 28 engage the sides of the spring medial 1y of its ends.

Inasmuch as the pivotal connection between the contactor and the stud carries fcurrent, it

is important that this connection have a low electrical resistance. Ordinarily,' some special provision would be required to insure this condition; butwith the structure of this invention,

the toggle spring 29 at all times urges the contactor outwardly and draws the edge of the opening therein against the stud with a force. sufficient to keep the resistance of the connection satisfactorily low.

As noted hereinbefore, the contactor is composed of the two superimposed arms I9 and 20, the former providing mechanical strengthand rigidity, while the latter serves as the main current carrying member.

To enable the knife action with which engage-j.

ment is effected between the contactor and the stationary contact, the low resilient contact arm is oifset, as at 43. This construction has been found exceptionally effective; but it is desired to point out that the contactor might be formed of merely the single arm I9 for the reason that the toggle spring exerts a downward thrust on the contactor which normally depresses the contactor arm l9 below the plane of the top .surface of the stationary contact and could be used for contact pressure.

In such a construction, however, it would be 55 occupies the position indicated in dotted lines at 59 and the arms 36 of the actuating lever or cam are substantially equi-spaced therefrom, as shown in dotted lines. In this position of the parts, the contactor of the rheostat is at the position of maximum resistance so that as the operating shaft ismoved in a direction to cut out necessary to space the actuating lever or cam its flat compact construction isobviously susceptible to a wide variety of uses, it is especially adapted for mounting on the back of a rheo-- stat or volume control of the type employed in radio receivers. Adaptation of this use is illustrated in Figure 10. .As here shown, the metal cover 9 is substantially cup-shaped and provides the back of a housing 45. It is secured thereto ln'any suitable manner preventing relative rotation, as by a plurality of ears 46 projected from the edge of the cup-shaped cover and connected with the side wall of the resistance housing 45.

The variable resistance mechanism, indicated generally by the numeral 41 enclosed within the housing 45, forms no part of this invention and may be of any suitable design or construction. For the purposes of this invention, it is sufiicient to note that the variable resistance mechanism,

in Figure 13, is a stamping having a flat body portion 52 bifurcated at one end to provide inwardly curved arms 53 with a tongue 54 extending centrally therebetween.

The outer opposite end of the body has a laterally projected lug 55 extended therefrom which engages one or the other of the arms 36 on the lever or cam 32 during opening and closing of the switch.

The arm 5| is nonrotatably secured to the shaft end by having its tongue 54 extend into a hole or slot 56 diametrically therethrough and by having its arms 53 received in and embracing an annular groove 51 in line with the hole or slot, as clearly shown in Figure 14.

The manner in which the shaft carried arm actuates the switch is diagrammatically illustrated in Figure 11. As here shown, the lug on the outer end of the" shaft carried arm travels in a circular path, indicated by the arc 58 which intersects one or the other of the two arms 36 on the lever or cam 32.

When the switch is in its off position, the lug the resistance, it first carries the driving lug 55 to the left, as viewed in Figure 11. During this motion, the left arm 36 is engaged and the lever or cam 32 is swung to its full line position.

After swinging the lever or cam to its full line position which effects closure of the switch, further clockwise rotation of the operating shaft efiects only the adjustment of the rheostat. The driving connection between the rheostat and switch is thus transient in character. To turn the switch off, a reverse rotation is imparted to the shaft which carries the driving lug into the space between the arms 36 to swing the lever or cam to its dotted line position.

It is to be observed that the space between the arms 36 is sufliclent to provide the necessary lost motion in the transient driving connection to insure the switch being what is known as trip free." In other words, the speed with which the switch moves from one position to the other is not dependent upon the rate of manual adjustment of the operating shaft,

While the switch actuating lever or cam is carried by the switch assembly and the actuating arm is carried by the rheostat assembly, proper cooperative engagement thereof is assured by virtue of the fact that the lever or cam 32 projects through the hole II in the cover and is thus brought into alignment with the driving lug 55.

The switch housing may be mounted directly 'on the cover 9 in which instance the housing must be deep enough to space all parts of the switch mechanism from the plane of its open side to prevent contact with the metal cover. However, insulating gasket members 60 and 6! may be interposed between the cover and switch housing to obviate increasing the depth of the housing. These gaskets have an external configuration substantially corresponding to the outline of the switch housing.

The gasket 6| which is considerably thicker than the gasket 60 is cut out to correspond to the outline of the cavity in the housing so that it forms in effect an extension of the housing side wall, while the gasket 60 overlies the inner surface of the metal cover wall to preclude the live switch parts contacting the metal wall; and.like the metal cover wall, it has a hole 62 of substantially the configuration of the hole ll positioned to align therewith.

The hole 62, like the hole II in the cover, accommodates the movement of the switch actuating lever or cam and being slightly smaller than the hole I l, guards against the possibility of having the lever or cam strike the raw metal edge of the hole H.

Assurance of proper alignment or registry between the hole in the cover and the hole 62 in the gasket 60, as well as proper location of the gaskets with respect to the switch housing and the metal cover, is obtained by having the fasten- .ing means l0 pass through aligned holes in the metal cover, the gaskets and the lugs 8.

From the foregoing description takenin connection with the accompanying drawings, it will be readily apparent to those skilled in the art that this invention provides an exceptionally compact switch which, by virtue of the fact that all moving parts thereof travel in parallel planes, permits the entire mechanism to be assembled within a relatively shallow housing. This is desirable from the standpoint of keeping the overall dimensions of a combination volume control and switch down to a minimum.

What I claim as my invention is:

1. In a snap switch, the combination of: a housing; a stationary contact secured in the housing; a movable contactor pivoted in the housing for engagement with the stationary contact; projections on the side walls of the housing engageable with the contactor for defining its limits of motion; an actuating member pivoted in the housing; and spring operating means connected between the actuating member and the contactor including a coil spring supported on a pitman, said supported spring being engageable medially of its ends with said projections and rockable thereon by the actuating member to force the contactor positively away from its limits of motion. a

2. In a snap switch: a movable contactor memher; an actuating member; a link connecting said members; a thrust plate carried by said link comprising a pair of parallel lateral portions spaced apart by a transverse portion; and a spring bearing against said lateral portions, said actuating member bearing against said transverse portion to oppose the force of the spring.

3. In a snap switch: a movable contactor comprising a pivoted rigid carriermember, said carrier member having a contact portion at its outer end provided with a flaredlateral edge; a coaxially pivoted resilient member secured to said carrier member and having a contact portion opposite that of the carrier member and provided with afiared lateral edge spaced inwardly from the flared edge of the contact portion on the carrier member; and a stationary contact engageable between said contact portions.

4. In a snap switch, the combination of a recessed housing member; switch mechanism in the recess of the housing member including contactor means movable between defined limits; an actuator; means mounting the actuator in the recessed housing member for movement between defined limits; a spring connecting the actuator with the movable contactor means, said spring acting to snap the movable contactor means from one position to the other as the actuator is moved from one to the other of its limits of motion; and I spaced abutments defining the limits of movement of the contactor and engageable by the side of said spring medially of its ends to increase the force appliedtothe movable contactor means and insure response of the contactor means to operation or the actuator.

5. In a snap switch, the combination of: a base of insulating material; a stationary contact mounted on the .base: a pivot post mounted on the base and spaced from said stationary contact; a contactor pivoted on said. post to swing'across the base to and from'engagement with the stationary contact; an actuator pivoted on said post; means for defining the limits of pivotal motion of the actuator; a toggle spring connecting the actuator and contactor and operable to snap the contactor from one position to the other as the actuator is moved across dead center; and spaced abutments on the base in the path of the contactor and the spring medially of its ends so that said abutments define limits between which the contactor may swing and provide fulcrums engageable by the spring medially of its endsand about which the spring rocks to impart additional force to the contactor and thus initiate motion of the contactor in the event said contactor fails to respond.

6. In a snap switch of the character described: a switch base of insulating material; a stationary contact mounted on the base with a projecting portion thereof spaced from the base; a fixed pivot mounted on the body at a distance from said stationary contact with its axis normal to the plane of the base; a contactor mounted to swing about said pivot toward and from said stationary contact, said contactor having superimposed contact portions adapted to engage under and over said projecting portion of the stationary contact, the contact portion which engages over the stationary contact extending beyond the other contact portion to engage the stationary contact first and leave the stationary contact last during closing and opening of the switch, respectively; means for snapping the contactor from one position to the other including a spring so connected with the contactor as to impart a downward thrust thereon to normally yieldingly maintain the upper contact portion of the contactor slightly below the plane of said projecting portion of the stationary contact: and means for guiding the upper contact portion onto and over the pro- :le'cting portion of the stationary contact. I

7. In a snap switch: a movable contactor having two superimposed contact portions, both of which have outwardly flared lateral edge portions, one of saidcontact portions being resilient and the other rigid, the rigid contact portion having its flared edge portion extending beyond the other to provide an arcing horn; a pivot mounting the contactor so that its contact portions with their flared edge portions are movable in an arc and a stationary contact mounted on said arc to be engageable between the contact portions of the movable contactor.

NEWTON C. SCHELLENGER.

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