US2831082A - Switch construction - Google Patents

Description

April 15, 1958 H. F. MASON 2,831,082

' SWITCH CONSTRUCTION Filed Dec. 11, 1952 4 Sheets-Sheet l INVENTOIP.

HOWFMD F. lvmso/v BY H/S fiTTOR/VEYS.

HERE/S; K/ECH, F05 r51? a'Hnmels EMU-M}.

H. F. MASON SWITCH CONSTRUCTION April 15, 1958 4 Sheets-Sheet 2 Filed Dec. 11, 1952 573 Z/a 5 26 22a ll'l/Ifll'llllllll lNl/ENTOR. Howe/e0 F. A/mso/v BY HIS HTTORNEYS. Hake/s K/EcH, Foam/e & HQRR/S \BY QLQ.

United States Patent SWITCH CONSTRUCTION Howard F. Mason, Los Angeles, Calif., assignor to Mason Electric Corporation, a corporation of California Application December 11, 1952, Serial No. 325,401 12 Claims. (Cl. 200--68) This invention relates to snap action switches and one object of the invention is to provide a combination of elements operating with fast make and break that may be embodied in diverse types of switches including lever switches, rotary switches, push-type switches and various types of relays. It will be apparent that the invention is widely applicable to various specific uses. For the purpose of disclosure and to illustrate the principles involved, the invention will be described herein as embodied in two specific switches for aircraft use, one switch being of the lever type and the other switchbeing of the rotary type. These specific disclosures will provide adequate guidance for those skilled in the art who may have occasion to apply the same principles to the construction of other switches for other specific uses.

It is an important object of the invention to provide a snap action switch that operates in a positive manner in the sense that the circuit-controlling switch member of the switch snaps from one predetermined position to another for opening or closing a circuit without any possibility of pausing or stopping between the two predetermined positions. The desired snap action occurs regardless of how the switch is manually manipulated by the operator. In general, this object is attained by the combination of a carrier for the switch member and an actuating means to move the carrier with lost motion between the actuating means and the carrier, these elements being acted upon by cooperating yielding means. In a preferred form of the invention, a first yielding means provides a detent action tending to hold the switch member at predetermined positions along its path of movement, and a second yielding means provides the snap action to shift the switch member without pause from one predetermined position or station to another.

The path along which the switch member moves is provided with recesses at each of the predetermined stations for the switch member and the first yielding means continuously presses the switch member laterally toward this path to cause the switch member to releasably engage'the recesses. Each of these detent recesses provides a pair of oppositely sloping cam surfaces at each station for cooperation with the switch member. Thus the path along which the switch member moves is divided into zones for Cam action of the switch'member at the predetermined stations and zones of free movement of the switch member between the predetermined stations. The first yielding means, which may be termed a detent yielding means, is effective in the cam zones to tend to center the switch member at each station and the second yielding means is effective in the zones of free movementbetween the stations to provide the required snap action from station to station. In the preferred embodiments'of the invention the switch member is in the form of a rotary member rotatably carried by the carrier to roll along the described path from station to station. The use of such a rotary switch member not only improves the cam action at ICC each station but also reduces friction to facilitate the snap action from station to station.

To carry out the purposes of the invention the range of lost motion between the actuating means and the contact carrier operated thereby is at least equal to the length of a zone of free movement between stations to permit the second yielding means to function over the length of a zone of free movement independently of the actuating means. Preferably, the second yielding means which produces the snap action is so constructed that it tends to maintain the carrier at a central position with respect to this range of'lost motion. Thus with the switch member engaging a recess at a given station and the actuating means free to move, the second yielding means will tend to hold the actuating means at a position centralized with respect to the given position. On the other hand, if the actuating means is manually shifted progressively out of this centralized position the second yielding means will tend to cause the carrier to follow the movement of the actuating means. The detent yielding means, however, is strong enough to prevent the carrier from initially following the actuating means.

By virtue of this arrangement and the described relationships there are four stages of the operation of the switch to shift the switch member from a given station to the next station. These four stages occur in sequence as the actuating means is manually moved progressively from a position centralized at the given station toward a position centralized at the next station. In the first stage of switch operation the rotary switch member lingers in the contact recess to store energy in the second yielding means. in the second stage the actuating means forces the switch member to the brink of the recess. In the third stage the second actuating means snaps the rotary switch member to the brink of the recess at the next station. The last stage is the seating of the rotary switch member in the recess by cam action.

It is another object of the invention to meet certain problems involved in the construction of a heavy duty switch of this type, for example, a switch for frequent operation to control fifty or more amperes of current at 30 or more volts. Some of these problems are primarily electrical since they arise from arcing in the making and breaking of circuits. Other of the problems are more or less mechanical.

The snap action for fast make and fast break is, of course, part of the solution for modifying the undesirable effects of arcing at thecontacts. If it is further contemplated that relatively large contact bodies will be employed which, by virtue of their massiveness, tend to remainrelatively cool and therefore tend to quench arcs. A special feature of the invention in this regard, however, is the employment of a switch arrangement that divides the arcing effect between two arcs in series. At each circuit closing position of the switch member, the switch member shorts or bridges a pair of contacts thus dividing the arcing effect between the two contacts.

Some arcing is, of course, inevitable and a further object of the invention is to keep the effect of arcs on the material of the contacts from reducing the efliciency of the switch. This object is accomplished largely by extending the contacts into the zones of free movement of the switch member so that arcing occurs at points spaced away from the recesses in which the switch member is normally seated. This object is also attained in part by the use of a rotary switch member which tends to polish the contact surfaces and thus restore the effectiveness of any surfaces that may be damaged by arcing.

A further object of the invention is to provide for accurate positioning of the switch member at the pair of contacts at each station with adequate pressure against a each of the two contacts. A feature of the invention is that this object is attained by giving the switch member several degrees of freedom so that it may accommodate itself to the pairs of contacts regardless of structural inaccuracies and so that the switch member may equalize its pressure between the two contacts in each pair.

The various objects, features, and special uses of the invention may be understood from the detailed description to follow considered with the accompanying drawings.

in the drawings, which are to be regarded as merely illustrative:

Figs. 1 to 4 are simplified diagrammatic views showingfour successive positions of a switch mechanism constructed in accord with-the invention;

Fig. 5. is a longitudinal sectional view of a. two-pole, double-throw switchof the lever type embodying the invention, the section being taken asindicatedby the line of Fig. 6;

Fig. 6. is .a sectional viewtaken along the. line 66 of Fig.

Fig. 7 is an enlarged fragmentary detailed view of the structure shown in Fig. 5, the fragmentary view being partly in section and partly in elevation;

Fig. 8 is a greatly enlarged fragment of Fig. 6;

Fig. 9 is asection taken along the broken line 99 of Fig, 6 to disclose the pairs of contacts of the switch in plan view;

Fig. 10 is a longitudinal sectional view of a rotary gang switch embodying the invention;

Fig. 11 is a transverse sectiontaken as indicated by the line lit-ll of Fig. 10;

Fig. 12 is an enlarged fragmentary section taken as indicated by the line 12-12 of Fig. 10;

Fig. 13 is a transverse section taken as indicated by the line 13.13 of Fig. 10;

Fig. 14 is a view similar to Fig. 13 showing the parts in a second position;

Fig. 15 is an enlarged detail of Fig. 10;

Fig. 16 is an enlarged fragmentary section taken as indicated by the line 1616 of Fig. 15;

Fig. 17 is an enlarged fragmentary view of a pair of contacts of the switch as seen in plan; and

Fig. 18 is aview similar. to Fig. 14 illustrating a modi' fication of the; structure.

In the diagrammatic Figures 1 to 4 illustratingthe principles underlying the invention; a series of switch contacts 20, 21, 22 together withtintervening portions of a-body of non-conducting material 23 provides a path for acircuit-controlling switch member 25. The switch member 25 is preferably in the form of a metal roller. A recess 26 is, provided at. each of the three stations represented by the. threecontacts 20, 21 and 22,to form seats for releasable engagement by the switch member 25. In this instancesince the'switch member 25 is in the form of a roller, preferably each of the recesses 26 has the same curvature as the periphery of the roller. In the construction shown, the recesses 26 are formed in the contacts and each contact is wider inthe direction of the path than the recess.

The rotary switch-.member 25, is journalled in a suitable carrier 30 which, in this instance, is in the form of a block of rubber or other similar elastic material. A suitable actuating means generally designated 31 to shift the carrier 3% and the switch member 25 from station to station is operatively connected with the carrier in a suitable manner to provide a range of lost motion between theactuating means and the carrier. In the construction shown, the actuating means, 311 is inthe. form of a lever and one arm of the lever is in the form of an actuating handle 33. To provide thev desired lost motion between the actuating means andthev carrier the. second arm of the lever may be in the form. of a yoke 35 having two arms 36 straddling the carrier.

Cir

It is contemplated that suitable yielding means will be provided to press the rotary switch member 25 laterally towards the path along the contacts thereby to cause the rotary switch member to releasably engage the recesses 25 at the various stations. Such yielding means may incorporated in the carrier 30 or in the actuating means 31 or may act between the actuating means and the carrier or between the carrier and the rotary switch memher. in the present example of the invention the desired yie' use is incorporated in the constructionof the actuating means 3].

The actuating means 31 is made in two sections that are slidingly telescoped' together and are continuously urged apart by a coil spring 37. One of the two sections comprises the handle 33 and a ball enlargement 4i) integral therewith by means of which the actuating means is pivotally mounted in a suitable bearing assembly 41. The other section of the actuating means comprises the yolre 35' which'has'a shank 42 slidingly extending into the handle section against the coil'spring 37.

Inaddition to the'coilspring 37 the switch mechanism has a second yieldingmeans effective between the actuating means 31 and the carrier 3ii=to tend to position the carrier centrally inits range'of'movement relative to the actuating means. In the combination shown in Figs. 1 to 4 this second yielding means isin the form of a leaf spring 43 mounted-on-the yoke ES-to' provide two leaf spring arms 45 between the two yoke arms 36. These two leaf spring arms 45-tendto hold the carrier 38 and the yokeI-id'ccntralized with-respect to each other with the axis of the rotary switch-member in line with the axis of the actuatingmeans.

As may be seen in Fig. l the-carrier 30 moves through its range of relative movementwith arocki'ng action which is resisted by the leaf spring arms 45 and is limited in a positive manner by the yoke arms 36. It is also to he noted that when the carrier 30 is rocked out'of itsnormal central. position it is placed under diagonal compression between the base of the yoke 35' and'the rotary switch member 25. The compression of the elastic carrier body cooperates with the coil spring 37 'innrgingthe rotary switch member into engagement with the recesses 26.

The path for the rotary switch member- 25 providcdby the contacts 20, 21 and 22 together with thedntervcning non-conducting material is concentricito'tne nivot axis of the lever actuating means 31'. Since the'rotary switch member 25 is yieldingly pressed toward this arcuatc'path, each of the recesses 26 in eifectconstitutesa pair of op positely inclined cam shoulders for the rotaryswitch member. Thus the arcuate path is divided into cam zones represented by,the recesses 26 and intervening. zones where the rotary switch member 25 may move freely, the intervening zones of free movement being arcuate raceways for the rotary switch. member. Since the contacts 259, 21 and 22 are wider than the corresponding. recesses 26 formed therein each of the arcuate'raceways for free movement of the rotary switch member includes portions of the contacts.

The mode of operation of the switch mechanism shown in Figs. 1 to 4 may be readily understood when it is considered that when the actuating means is shifted out of its normal central position relative to the carrier andswitch member, the yielding tendency of the switch member 25 to remain seated in a recess 26 is sufficient to resist the'yielding tendency of the leaf spring #33 to dis lodge the switch member, and when it is further coir sidered that the range of movement of the carrier 3-9 relative to the yoke 35 and .the ability of the leaf spring the four stages which: will'now be described in more" detail.

In the normal position of the switch mechanism with the switch member 25 in a recess 26 at one of the contact stations, say at the contact 21, and with the'handle 33 of the lever actuating means free from manual restraint, the first yielding means 37 in the handle 33 exerts pressure to hold the switch member 25 seated in the recess of the contact 21. The two leaf spring arms 45 yieldingly engaging opposite sides of the carrier 30 hold the handle 33 centralized with respect to the contact 21 with the axis of the handle in line with the axis of the rotary switch member 25. When the handle 33 is manually rocked progressively counterclockwise, as viewed in the drawings, toward a position centralized with respect to the next contact 22, initially the rotary switch member 25 remains snugly seated in the recess of the contact 21. As a result the carrier 30 rocks relative to the moving actuating means 31 with consequent storing of energy by stressing of the left leaf spring arm 45:. This first stage terminates at the end of the range of relative movement between the carrier and the actuating lever when the left arm 36 of the yoke 35 abuts the left leaf spring arm 45.

The second stage of the operation of the switch consists in the positive or direct action of the actuating means on the carrier 30 as the left yoke arm 36 forces the carrier to move and cause the rotary switch member 25 to climb up the slope of the recess of the contact 21. In Fig. 1 illustrating this second stage, the handle 33 has been swung 8 from its starting position. As the rotary switch member 25 climbs up the right cam shoulder provided by the recess it causes energy to be stored not only by compression of the spring 37 in the handle 33 but also by diagonal compression of the elastic body of the carrier 30. When the arm 33 has been moved 11 from its starting position, as shown in Fig. 2, the rotary switch member 25 nearly reaches the right brink of the recess in the contact 21. Only slight additional movement will place the rotary switch member at the edge of the arcuate raceway or zone of free movement.

The third stage of the operation then takes place automatically and independently of the actuating means 31, this third stage consisting in the snap action of the carrier 30 across the zone of free movement into the cam zone at the next contact 22. In this snap action the left leaf spring arm 45 releases its stored energy to the carrier 33 and there is a certain further release of stored energy as the carrier swings out of-its diagonally compressed position. The momentum of the carrier and the rotary switch member is sutficient to throw the carrier past the center of its range of relative movement in opposition to the right leaf spring arm 45 as well'as in opposition to the compression of the carrier as it assumes a second diagonalposition. In all instances of compression of the carrier 30 whether diagonally or centrally there is, of course, also accompanying compression of the spring 37 in the handle 33.

The fact that the throw of the carrier 30 is sutficient to stress the right leafspring arm 45 does not result in return movement of the carrier, however, because the throw is sufficient to cause the rotary switch member 25 to cross the left brink of the recess in the next contact 22 where cam action again becomes effective. In comparing Figs. 2 and 3 it will be noted that the handle 33 has been advanced counterclockwise from an 11 position to a 12 position and the carrier has been snapped across the arcuate raceway into the cam zone at the next contact 22.

If at this time the handle 33 were released, the cam action provided by the pressure of the rotary switch member 25 against the left cam surface of the contact 22 would be sufiicient for carrying out the fourth stage of the switch operation which consists of the switch mem ber 25 rolling down the cam shoulder to seat firmly in-75 the bottom of the recess at the contact 22. The released actuating means would follow this camming movement of the rotary switch member 25 and the leaf spring 43 acting between the actuating means and the carrier would centralize the position of the actuating means relative to the contact 22. In the normal operation of the switch, however, the handle is not released at the position shown in Fig. 3, the normal follow-through by the operators hand continuing through the final cam operation at the contact 22.

Certain important features of the invention may be appreciated by further analysis of the switch operation. In the first place there is a unique cycle of storing and releasing energy. The first stage of the described switch operation stores energy in the left spring arm 45, the second stage in which the switch member climbs up the cam surface at the contact 21 results in further storage of energy in the coil spring 3'7 as well as in the elastic material of the carrier 30, the third stage results in the release of a major quantity of energy from the let leaf spring arm 45 and the storage of a lesser quantity in the right leaf spring arm 45, and the fourth stage results in final release of the energy stored in the coil spring 37, in the right leaf spring arm 45, and in the resilient body of the carrier 30.

A second feature is the manner in which the currentcarrying eificiency of the switch is maintained by increase of pressure between the switch member 25 and the contact 21 as the switch member rolls from its normal seated position to the brink of the contact recess. In its normal seated position the switch member has a maximum area of mutual contact with the contact 21. This mutual area is reduced as the switch member is dislodged from its seat, but the resulting cam action increases the pressure between the switch member and the contact, the increase being along a steep pressure gradient because of the diagonal compression of the carrier in combination with the compression of the coil spring 37. Thus the increase in pressure between the switch member and the contact as the switch member climbs a recess slope compensates for reduction of the area involved, and such pressure compensation maintains the current-carrying ability of the cooperating parts.

A third feature is that each of the contacts is wider than the corresponding recess 26 in the contact so that arcing in making and breaking circuits occurs at edge portions of the contact spaced away from the recess. Thus the arcing is remote from the normal contact seat of the switch member. It is to be further noted that any effect of arcing on an edge portion of a contact is offset by the tendency of the rolling switch member to restore damaged surfaces of the contacts, especially since the rolling action occurs under substantial pressure.

A further feature of the invention with regard to arcing is the fact that the edge portion of each contact lies in a zone of free movement of the switch member. in the snap action of the carrier the rotary switch member attains substantial velocity before it leaves one contact member and, of course, the switch member approaches the edge portion of the next contact member at even higher velocity. Such rapid make and break minimize the arcing eifect and, as heretofore stated, each ofthe contacts 20, 21 and 22 will tend to stay cool and therefore tend to quench any arcs that occur.

Figs. 5 to 9 show how the basic switch mechanism of Figs. 1 to 4 may be embodied in a lever-type switch to serve the purpose of a conventional toggie switch. The parts of the switch previously described 1 to 4 are indicated by corresponding numerals. In this instance the mechanism is adapted to serve the purpose of a single-pole, double-throw switch.

The switch construction shown in Figs. 5 to 9 inciudes a box-like housing 50, preferably of plastic nonconducting material, which is closed on its lower side by a thick arcuate wallSl concentric to the pivot axis of the acuat a! ing means The thick wall 51 is unitary with a-pair of parallel side walls 52 which, as shown in Fig. 5, telescope into the housing 50 and are suitablybonded thereto.

The previously mentioned contacts 20, 21 and'22 are embedded in the arcuate wall 51 but in this instance there is a second row of three contacts a, 21a and 224 (Fig. 9) to provide a pair of contacts at each station to be bridged by the rotary switch member 25. The contacts 20 and 22 in the first row are connected, respectively, with external terminals 53 and 54 and the external terminals are provided with the usual terminal screws 55. The intermediate contact 21 in the first row is a dummy or dead-end terminal. The three terminals 20a, 21a and 22a of the second row are all integral parts of a single conductor 56 which is united with a third terminal 57 having a terminal screw 55.

The arcuate wall 51 and the two side walls 52 form an arcuate channel of non-conducting material to confine the yoke and the carrier 36 for guidance of the rotary switch member 25. non-conducting arcuate rib 60 that extends. between the two rows of contacts, the rib being of the same height as the six contacts out being formed with recesses 61 at each of the three switch stations, these recesses being deeper than the corresponding contact recesses 26. By virtue of this arrangement the rotary switch member 25 rides and seats on the pair of contacts at each station, but rides on the central arcuate rib 66 between stations. The arcuate raceway for free movement of the switch member between stations is formed in part by the arcuate rib 60 and in part by edge portions of the contacts adjacent the contact recesses 26.

Preferably the switch is of fluid-tight construction with the arcuate wall 51 bonded to the housing 50in a fluidtight manner and with the actuating means 31 also sealed off in the region of the pivotal mounting of the ball enlargement 40. In the construction shown a tubular member 62 mounted on the switch housing 50 has the usual external threads 65 to receive the usual retaining nut (not shown) for permanently mounting the switch. The tubular member 62 is in threaded engagement with the wall of the housing 50 and is provided with a radial flange 66 on its inner end for cooperation with an inner sealing gasket 67 of suitable material. This particular switch has what may be termed a momentary return spring 70 to cooperate with the yoke 35, as will be explained later, which spring is a leaf spring having a base portion 71 apertured for engagement between the flange 66 and the sealing gasket 67.

The tubular member 62 may be adapted in any suitable manner to serve as a fluid-tight bearing for the ball enlargement 40. For example, the tubular member 62 may be formed with an internal tapered shoulder 72 and may be threaded to receive a bushing 73 having a similar tapered shoulder 74, the two tapered shoulders serving to confine a pair of bearing rings 75. The two bearing rings 75 have spherically curved surfaces to embrace the ball enlargement 40 and are made of suitable material to permit universal movement of the ball enlargement and at the same time to form an eifective seal around the ball member. A feature of the invention is the use of rings for this purpose made of a plastic having the trade name Teflon which offers exceptionally low resistance toarotary movement of the ball enlargement 40.

The elastic body of rubber-like material that comprises the carrier 30 is yieldingly embraced by the leaf spring arms 45 which tend to maintain the carrier and actuating means centralized relative to each other. Preferably the elastic body is cut away centrally to form a p'air, of up.- wardly extending corner portions 78 for contact'with the base portion of the yoke 35, which corner portions are stressed in compression diagonally when the carrier rocks relative to the yoke as heretofore described.

In the construction shown inthe drawings, the carrier body 30 is hollowed out to receive'the rotary switch mem- This channel is formed with a central 8 ber.25 and: to"form,lparal1el side walls. 79 to support the opposite ends of an axle pin 80 for the rotary switch member. As best shown in Figs. 5 and 7 the rotary switch member 25: is preferably in the form ofa metal ably the axle pin 80 is sufficiently flexible to add to this freedom of the rotary switch member and for this purpose the axle pin may be made of piano wire.

It is apparent that the rotary switch member 25 has several'degrees of freedom for movement. It is movable along'the arcuate path of contacts concentric to the pivot axis of the lever or actuating means 31; it is movable radially of that axis by virtue of'the telescoped construction of the leveractuatingmeans; it is rotatable about the axisof thelever, i. e., about anaxis radially of the pivot axis of the lever; and ithas freedom to rock about an axis perpendicular to the radial axis, i. e., about the normal axis of the axle pin 80. it will be apparent that the elasticity of the carriage 30 contributes to all of these various degrees of freedom.

The momentary return spring 7 0, which may be omitted, has an effective range of elastic movement sufficient to cause the rotary switch member 25 to be shifted from the station at the contacts 22-22a to the station at the intermediate pair of contacts 21-21a. Thus, if the lever 33 is manually shifted to carry the switch member to the pair of contacts 22-22a from the contacts 21-21a, the switch will stay in the new position only so long as manual force is applied to the handle 33 and when the handle is released the switch will'return automatically to the middle position shown in Fig. 6. In this middle position no circuits are closed by the rotary switch member 25 but in the left position as viewed, in Fig. 6, the switch terminal 57 is connected to the switch terminal 53 and'in the right position the switch terminal 57 is connected to the switch terminal 54.

Figs. 10 to 17 illustrate how the principles of the invention may be incorporated'in a rotary switch having eight positions and sixteen switch contacts. Preferably the rotary switch is of a construction that facilitates the uniting of any desired number of switch units to form a gang switch operated by a single actuating shaft. Fig. 10, by way of example, shows two such switch units united to provide a rotary gang switch having eight positions with two separate rotary switch members electrically interconnecting corresponding-pairs of switch terminals at each of the eight positions.

Each of the two switch units shown in Fig. l0 comprises the basic combination of a stator in the form of a thick-walled cylinder. of a suitable plastic nonconducting material, an actuatingmeans 91in the form of a rotor also made of nonfconducting plastic material, and a carrier, generally designated 92, which carries a rotary switch member 95. Each of the two stator cylinders 90 has embedded therein eight pairs of contacts 96 which extend'to the exterior of the switch and are provided with external'terminal screws 97.

The housing for the two-unit gang switch comprises the two cylindrical stators, 90, an end plate 98, a second end plate 99 and an intermediate transverse plate 106',

\ this assembly being united by a series of longitudinal tie rods 101 andnuts 102.

The end plate 98 is formed with an externally. threaded boss or tubular extension 105 in which is;journalled an actuating shaft 106 that is operatively connected to the rotor 91 of the left-hand switch unit as viewed in Fig. 10. In the construction. shown the actuating shaft 106 is unitary with a thin disc 107 at its inner end, which dischas a fiangedrim portion 108 embedded in the material of the left-hand-rotor; Thus one end of the rotor is 9 supported by the actuating shaft 106, the other end being journalled in the intermediate transverse plate. 100.

The left-hand rotor 91 is formed with a circular series of lugs or longitudinal projections 110 which mate with corresponding recesses in the right-hand rotor 91 to operatively interconnect the two rotors and to rotatably sup port one end of the second rotor. The other end of the second rotor is journalled in the second end plate 99. Each of the rotors 91 is suitably hollowed out diametrically to house a carrier 92 and to permit the required freedom for the carrier to move relative to the rotor through a range of sufiicient extent for the snap action heretofore described.

As best shown in Fig. 15, the principal parts of the carrier 92 are: a U-shaped frame 114 pivotally mounted in the rotor 91 for rotation coaxially of the rotor; a diametrical tubular member 115 mounted on the U-shaped frame; a pair of opposed torsion springs 116 which tend to hold the U-shaped frame in a central position with respect to its range of movement relative to the rotor; a yoke 117 which journals the rotary switch member 95 and has a shank 118 extending into the tubular member 115; and a coil spring 120 in the tubular member 115 which surrounds the shank 118 and urges the yoke 117 radially outward.

A tubular member 115 extends through the base portion of the U-shaped frame 114, being welded thereto, and is additionally supported by two axial pins 124. Each of the axial pins 124 is mounted in one of the legs of the U-shaped frame 114 and has an enlarged head 125 welded to the outside of the frame to serve as a trunnion for pivotally mounting the frame in the rotor 91. -As indicated in Fig. 10, the rotor 91 is formed with a pair of radial slots 127 the inner ends of which serve as bearings for the trunnions with the trunnions positioned on the same axis as the rotor.

Each of the two torsion springs 116 is wrapped around an axial pin 124 with one leg of the torsion spring resting on the base of the U-shaped frame 114 and with the other leg normally resting on an angular support 130 carried by the U-shaped frame and also normally resting on a corresponding shoulder 131 at the end of a corresponding slot 132 in the rotor 91. Normally the two torsion springs 116 are in balanced opposition to maintain the carrier 92 in a normal position centralized with respect to the rotor 91. This normal position is shown in full lines in Figs. l0, ll, 13 and 15.

Preferably the rotary switch member 95 is mounted on an axle pin 135 in the manner heretofore described to give the rotary member a certain freedom to rock relative to the normal axis of the axle pin. The axle pin 135 is mounted in the two legs of the yoke 117 with end portions of the axle pin extending beyond the yoke. The extended end portions of the axle pin 135 are guided by radial grooves 136 formed in the legs of the U-shaped frame 114.

It is apparent that the rotary switch member 95 has the various degrees of freedom heretofore described and that the coil spring 120 continually urges the rotary switch member outward against the surrounding stator 90. The stator 90 in combination with the two circular rows of contacts 96 provides a continuous circular path for the switch member 95 and the individual contacts 96 are formed with recesses 137 that serve the same function as the recesses in the contacts of the first form of the invention.

Preferably the brinks of the recesses 137 are slightly chamfered or rounded off as shown at 138 in Fig. 12. It has been found that forming the contact recesses with the rounded shoulders 138 eliminates a certain troublesome tendency for the metal of the contacts to be upset by impact of the switch member against the walls of the contact recesses. By virtue of the rounded shoulders 138 the switch member 95 moves into a recess 137 in smooth manner without damaging impact and the polish ing action of the switch member on the metal of the contact eliminates any minor damage to the contact that may i tend to occur at the two shoulders 138.

The operation of the rotary switch may be readily understood since it is fundamentally the same switch operation as heretofore described. When a rotor 91 is rotated progressively by the actuating shaft 196 away from the normal centralized position of the rotor with respect to the carrier 92 at a given switch station, the pressure exerted by the coil spring 120 is sufficient to maintain the switch member initially in the recess 137 at the switch station. Consequently initial rotation of the rotor 91 out of its normal position causes one of the torsion springs 116 to be stressed. Fig. 14 shows in full lines how continued progressive rotation of the rotor 91 eventually brings inclined wall surfaces 140 of the rotor against the two legs of the U-shaped frame 114 whereupon the rotor acts in a positive manner to dislodge the switch member 95 from the recess 137.

With continued rotation of the rotor 91 the switch member 95 is carried to the brink of the recess 137 whereupon the stressed torsion spring 116 snaps the carriage 92 toward the next switch station where the switch member enters the next cam region as heretofore described.

The cam action powered by the coil spring tends to center the switch member and carrier at the new station and the two torsion springs 116 cooperate to tend to centralize the position of the rotor 91 relative to the new station.

The modified rotary switch shown in Fig. 18 is largely identical to the structure heretofore described as indicated by the use of corresponding numerals to indicate corresponding parts. The modification consists in changing the internal configuration of the rotor 91a so that the rotary movement of the carrier 92 relative to the rotor is limited by abutment of a wall surface 141' against the end of the tubular member 115.

In all forms of the invention the actuating means that cooperates with the carrier has what may be termed a kicker portion for impact against the carrier at the end of the range of relative movement of the carrier. The purpose is to kick the switch member out of engagement with the recess at the station so that the snap action can occur to carry the switch member towards the next switch station. It is desirable, of course, that the arcuate path for free movement of the rotary switch member 95 be provided by smooth and accurately concentric surfaces. To this end it is contemplated that the two rows of contacts 96 will be embedded in the stator 90 when the stator is molded or cast and that subsequently the stator together with the embedded contacts will be machined and processed to achieve the desired accurate concentricity.

The specific embodiments described in detail for the purpose of illustration will suggest to those skilled in the art various changes, substitutions and other departures from my disclosure that properly lie within the spirit and scope of the appended claims.

I claim as my invention:

1. In a switch, the combination of: an arcuate, concave contact path having a center of curvature and having circumferentially spaced, radially inwardly directed, recesses therein and having thereon at least one stationary contact in which one of said recesses is formed; a freely rotatable roller contact engaging and movable along said contact path and receivable in each of said recesses; a contact carrier for said roller contact located radially inwardly of and movable adjacent and parallel to said contact path; an axle carrying said roller contact and mounted on said contact carrier and providing free rotation of said roller contact relative to said contact carrier; actuating means movable about said center of curvature of said contact path for moving said contact carrier adjacent and parallel to said contact path; means providing a lostmotion connection between said actuating means and said contact carrier; kicking means carried by said actuating means and engageable with said contact carrier for limiting the range of lost motionbetween. said actuating. means and said contact carrier soas to kick said roller contact out of each of said recesses; and resilient means for biasing said roller contact into engagement with said contact path.

2. A switch as defined in claim 1 including another resilient means connecting said actuating means and said contact carrier for centering said contact carrier insaid range of lost motion between said actuating means and said contact carrier.

3. A switch as-defined in claim 1 wherein said. resilient means comprises means for progressively increasing the force biasing said roller contact into engagement with said contact path in response to movement of said roller contact toward-the center of said contact path.

4. A switch as defined in claim 1 wherein said means providing said lost-motion connection comprises a reel:- able connection between said actuating means and said contact carrier, whereby said contact carrier may, rock relative to said actuating means Within said range of lost motion provided by said limiting means.

5. A switch as set forth in claim 4 wherein said con tact carrier is engageable with said actuating means at either or" two circumferentially spaced points between said contact path and the center of said contact path to provide said rockable connection between said contact carrier and said actuating means.

6. A switch as defined in claim 1 wherein said recesses have substantially the same cuivature in crosssection as said roller contact.

7. A switch as defined in claim 1 wherein said contact path defines part of a cylinder.

S. Aswitch according to claim 1 wherein said contact path defines a full cylinder.

9. A switch as set forth in claim 1whereinsaid stationary contact is circumferentially wider than said recess therein.

1%. A switch according to claim 1 wherein said range of lost motion is at least equal to the distance between said recesses.

11. A switch according to claim 1 wherein said axle is flexible and. resilient and wherein said roller contact engages said axle throughout a central portion thereof only with clearance on either end of said central portion to permit said roller contact to rock relative to said axle.

12. A switch including a roller contact and a flexible and resilient axle carrying said roller contachsaid roller contact engaging said axle throughout a central portion thereof only with clearance on either end of said central portion to permit said roller contact to rock relative to said axle.

References Cited in the file'of this patent UNITED STATES PATENTS 1,921,765 Meuer Aug. 8, 1933 2,163,919 Siegel June 27, 1939 2,505,548 Hutt Apr. 25, 1950 2,565,863 Linn Aug. 28, 1951 2,625,619 Rigert Jan. 13, 1953 2,707,741 Collura May 3, 1955 2,708,227 Collura May 3, 1955 FOREIGN PATENTS 23,423 Great Britain Nov. 3, 1908 of 1908 571,395 Great Britain Aug. 22, 1945

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