US3025373A - Relay - Google Patents

Description

March 13, 1962 E. BULLIS, JR 3,025,373

RELAY Filed Aug. 29, 1956 4 Sheets-Sheet l March 13, 1962 E. BULLIS, JR 3,025,373

RELAY Filed Aug. 29, 1956 4 Sheets-Sheet 4 United 3,025,373 Patented Mar. 13, 1962 Fine assignor to The Bryant Bridgeport, Conn., a corporation This invention relates generally to electrical relays, and more particularly to a simplified form of such a relay having a relatively low cost.

The illustrative embodiment of this invention is in the form of a so-called hot wire type of relay, wherein the relay contacts are operated by the linear expansion and contraction of an electrically conducting wire. While various types of relays, including relays of the hot wire type, have been known in the past, they have been relatively complex in structure and expensive to manufacture.

Accordingly, one object of this invention is to provide a novel simplified form of electrical relay which is relatively inexpensive to manufacture.

Another object of this invention is to provide an electrical relay of the type described having a novel motion transmitting means for operating the relay contacts.

Another object of this invention is to provide an electrical relay of the type described having a novel supporting structure for an expansible and contractible operating wire.

Still another object of this invention is to provide an electrical relay of the type described having a supporting structure for a plurality of turns of an expansible and contractible operating wire constructed so that the supporting structure can be mounted on a standard type of winding machine for winding the wire thereon.

Another object of this invention is to provide an electrical relay of the type described having novel means for adjustment for calibration purposes.

Another object of this invention is to provide an electrical relay having a multi-part supporting frame assembled in a novel manner by securernent of the relay terminals thereto.

Another object of this invention is to provide an electrical relay having a multi-part supporting frame capable of partial assembly in a novel manner suitable for winding an operating wire thereon, but with certain clearances between the parts of the frame which are taken up by final assembly of a spacer member to form a rigid assembly.

These and other objects of this invention will be more apparent upon consideration of the following detailed description of preferred embodiments thereof, when taken in connection with the attached drawings, in which:

FIGURE 1 is a side view of a relay constructed in accordance with this invention, with the side cover being broken away, and with one part of the relay being shown in section;

FIG. 2 is a longitudinal cross section view of the relay shown in FIG. 1, partially assembled and taken substantially on line IIII of FIG. 4;

FIG. 3 is an end view of the relay shown in FIG. 1, looking at the right-hand side of the relay as viewed in FIG. 1;

FIG. 4 is a horizontal transverse cross sectional view of the relay shown in FIG. 1, taken substantially on the line IVIV of FIG. 1;

FIG. 5 is also a vertical transverse cross section view of the relay shown in FIG. 1, taken substantially on the line VV of FIG. 1;

FIG. 6 is a top view of the relay shown in FIG. 1;

FIG. 7 is a top view of the relay shown in FIG. 2 prior to assembly of the top cover; and

FIG. 8 is a side elevation view of a modified form of relay with the side covers removed.

While relays constructed in accordance with this invention may take many forms, the illustrative embodiment of the invention shown in FIGS. 1 to 7 of the drawings is presently preferred because of its simplicity of construction, and because it is economical in manufacture. The form of relay construction shown in FIGS. 1 to 7 comprise a frame for the relay which is essentially of U-shape, comprising three separate parts. The relay parts include a pair of legs 2 and 4 which are identical in construction, and a connecting bight portion 6. These three parts of the relay frame should be formed of an insulating material, preferably a molded insulating material, such as a synthetic resin. The bight portion 6 is provided at opposite ends with integral, downwardly olfset supporting extensions 8, which are also laterally extended to one side, as illustrated in FIGS. 4 and 6. The laterally extended parts of supporting extensions 8, may be provided with mounting openings 10, for receiving any suitable securing means to secure the relay to a support. The upper surface of the bight portion 6 of the relay supporting frame is provided with a longitudinally extending groove 12, as illustrated in FIG. 5, and each of the supporting extensions 8 thereof is provided with an opening 14, having an outer wall which tapers inwardly toward the inner wall from the top to the bottom of each of the supporting extensions 8. The inner wall of each of the openings 14, is provided with a semicircular recess formed with a plurality of ribs 16 which extend longitudinally of each opening 14, for a purpose to be described. The bight portion 6 of the frame is also provided with four elongated terminal openings 18, there being two provided at each end in each of the supporting extensions 8, located at opposite sides of the central opening 14.

Inasmuch as the legs 2 and 4 of the relay frame are identical in structure, like reference numerals will be employed to identify like portions of these legs. Each leg 2 and 4 has at its lower end a projection 20 adapted to be received in an opening 14 in the extensions 8 of the bight portion 6 of the frame, and having a tapered outer wall so that the projection will fit in an opening 14 with a wedging action due to cooperation of the outer tapered walls of the projections 20 and openings 14. A semicircular groove 22 is provided on the inner side of each projection 29 of the legs 2 and 4, so that when the projections are inserted in the respective openings 14, each groove 22 will line up with the recess having ribs 16 so that a circular opening will be formed, for a purpose to be described. The groove 22 in each projection 20 is preferably formed with half screw threads, as illustrated in FIG. 2. Each leg 2 and 4 is offset intermediate its ends, as at 28, and has integral bracing flanges 30 at the inner side of each leg, located adjacent opposite sides of each leg. The flanges 30 proceed upwardly from the lower end of each leg 2 and 4, and then are inclined toward their respective legs and merge with them at a point adjacent the upper end of each leg. -A longitudinally extending groove 32 is provided at opposite sides of each of the legs 2 and 4, outwardly of flanges 30, for a purpose which will be hereinafter referred to. In addition, each of the legs 2 and 4 is provided with spaced ribs 34 at the inner side of each leg, which extend upwardly from the lower end of each leg to the offset portion 28 thereof. The ribs 34 of each leg are spaced inwardly from the adjacent flanges 39 so as to form a slot 35 therebetween. It will be noted that when the legs 2 and 4 are mounted in position on the bight portion 6, with the leg projections 20 received in the openings 14, respectively, that each leg has an outer ledge 24 which is adapted to seat on the upper surface of a supporting extension 8 of the bight portion 6, and each leg has an upwardly spaced inner ledge 26 which is adapted to be located in the same plane as the adjacent upper surface of the bight portion 6, when the outer ledge 24 of that particular leg seats on the upper surface of the adjacent supporting extension 8. It will also be noted that when the legs 2 and 4 are mounted in operative position as described above, on the bight portion 6, that the lower end wall 38 of each slot 36 in the inner surface of the legs will be located somewhat below the plane of the inner ledge 26 to be aligned with the upper surface of the adjacent supporting extension 8. Each of the supporting extensions 8 of the bight portion 6 is provided with terminal openings 18 as previously described, and these are aligned with the lower ends of the slots 36 and the legs 2 and 4, respectively.

In this embodiment of the invention, four terminals for the relay are illustrated, which also function to secure the legs 2 and 4 in operative position relative to the bight portion 6. These terminals 42, 44, 46 and 48 are all formed of a good electrical conducting material, such for example as copper or an alloy thereof, such as brass. The terminals 42 and 48 are identical in construction and are located at one pair of diagonally opposite corners of the bight portion 6, with the other terminals 44 and 46 being located at the other pair of diagonally opposite corners of the bight portion 6. Each of the terminals is provided with a male terminal portion 50 adapted to project beneath the bight portion 6, and with a somewhat wider securing portion 52 immediately thereabove. The terminals are preferably all made of flat plate material, so that the terminal portions 50 can act as contact prongs to be merely plugged into any suitable outlet receptacle. The securing portion 52 of each of the terminals is somewhat longer than the terminal portion 50, being slightly longer than the thickness of the supporting portion 8 of bight portion 6. Each of the terminals 42 and 48 has an upper portion 54 with an extension 56 at one end thereof to engage over the top of the inner ledge 26 on the leg 2, and a terminal extension 58 at the other side thereof which extends at an angle.

After the legs 2 and 4 have their projections 20 assembled in openings 14 in the bight portion 6 of the frame, respectively, to the operative position previously described, the terminals 42 and 48 may then be inserted from the upper side of the bight portion 6 into the slots 36 and openings 18 until the extensions 56 and 58 of these terminals engage the bottom end surface 38 of its notch 36 and the upper surface of supporting extension 8, respectively, whereupon the outer end of the securing portion 52 of each terminal may be staked in position by separating portions thereof from the terminal portion 50, as illustrated at 60. This prevents removal of the legs '2 and 4 from the bight portion 6, and forms an initial frame assembly comprising the legs 2 and 4 and bight portion 6.

The terminal 44 also is provided with a terminal portion 50 and a securing portion 52 but has an integral upper terminal part 62 which is wider than the securing portion 52 so as to engage the upper surface of its supporting portion 8 and the lower end 38 of its slot 36, whereupon the lower end of its securing portion 52 may be staked in place as previously described, to also assist in securing leg 2 to the bight portion 6. Formed integral with the upper portion 62 of terminal 44, and extending substantially at right angles thereto, is an elongated conducting bridge 64 adapted to extend longitudinally over the upper surface of the immediate portion of bight portion 6 and centrally thereof. The end of the conducting bridge portion 64 of the terminal 44 which is adjacent the termirnal is upwardly curved as at 66, while the opposite end thereof has an indented portion 68. The curved end 66 of the conducting bridge portion 64 of the terminal 44 is adapted to engage the adjacent inner surface of leg 2 to bias it in an outward direction, and for this purpose the material comprising the terminal should have some inherent resiliency. The indentation 68 in the free end of the bridge portion 64 of the terminal 44 is provided for engagement by an adjusting screw 70, which can be threaded into cooperative engagement with the threads formed in the groove 22 at the inner side of the lower projection 28 of the leg 2, and be threaded upwardly and it will form its own threads on the ribs 16 formed on the adjacent semi-circular groove in the inner side of openings 14 in the supporting portions 8 of the bight portion 6.

The remaining terminal 46 is also provided with a terminal portion 50 and a securing portion 52 identical with the other terminals, and with an enlarged upper portion 71 which, when the terminal 46 is inserted in its terminal opening 18, is adapted to extend upwardly to substantially the mid point along the length of supporting leg 4. This upper portion 71 of the terminal 46 forms opposed shoulders at its juncture with the securing portion 52 of this terminal, which shoulders are engageable with the upper surface of the adjacent supporting extension 8 of the bight portion 6 and the lower end 38 of the adjacent notch 36 in leg. 4. Terminal 46 may then also be staked in place in the same way as the other terminals, to further assist in securing leg 4 to the bight portion 6. The upper end of terminal extension 71 has an integral part directed laterally inwardly at 72 so that this part is located substantially centrally of the frame. One end of the laterally extending part 72 is curved upwardly as at 74 to resiliently engage the leg 4 in substantially the same way that upturned portion 66 of terminal 44 engages leg 2, and the inner end of the laterally extending portion 72 of terminal 46 is provided with an upwardly angularly extending contact end 76 having a contact 78 secured thereto in any desired manner, such for example as by the rivet portion 80. The contact 78 should be of a good electrical conducting are resistant material, such for example as a silver alloy.

Referring now to FIG. 2 of the drawing, it will be observed that the legs 2 and 4 are slightly biased outwardly so that they diverge outwardly toward their free ends, due primarily to the outward bias exerted on these legs by the engagement of terminal portions 66 and 74, respectively, which has the effect of taking up all of the tolerances existing in the engagement of the legs 2 and 4 with the bight portion 6, and the engagement of the terminals with both of these members, in an outward direction.

A contact actuator 82 is adapted to be mounted at the outer ends of legs 2 and 4, and as illustrated, it comprises a generally U-shaped metallic member having a rectangular cutout portion 84 at each of its sides, with an intermediate semi-circular recess 86 in each of the cutout portions 84. The bight portion of the contact actuator 82 is extended at each end, with one extended end 88 comprising a pivot extension having a reduced end portion which is adapted to fit into a keyhole type of slot 89 provided at the upper end of each leg. In this instance, the pivot extension 88 is illustrated as being engaged in the keyhole slot 89 of leg 2. The other extension 90 of the bight portion of contact actuator 82 then terminates short of the inner surface of leg 4, being received in a slot 91 formed at the upper end of each of the legs 2 and 4. The bottom or lower end 93 of the slot 91 in leg 4 thus acts to limit clockwise pivotal movement of the contact actuator 82 about its pivot extension 88, as viewed in F168. 1 and 2 of the drawings. An equalizing plate 92 is adapted to be mounted on the actuator 32, and it should be of an electrical insulating material, such as porcelain. The equalizing plate 92 has a main body portion which fits freely in the contact actuator 82, and is provided with a generally V-shaped under side 94. The equalizing plate 92 has a flange 96 at each side thereof which is adapted to extend freely through the rectangular cutout portions 84 in each side of the actuator 82, and the lower surface of each of the flanges 96 is provided with a depending integral pivot projection 98 to be received in the semi-circular recesses 86 in the actuator.

A leaf type of actuating spring 100 is provided for directly actuating the relay contacts, and it preferably is of a good electric conducting material having resilient properties, such for example as a Phosphor bronze alloy. The leaf actuating spring should be quite flexible, and in one embodiment of the invention may be about .01 inch thick. The actuating spring 100 carries a contact 102 at substantially the mid point thereof which may be of a material similar to the contact 78, and is adapted to engage the contact 78. As illustrated in FIG. 5, the upper end of the actuating spring 109 tapers from the mid point so that the sides thereof converge upwardly to a wider upper end portion 104, and this in turn has a reduced tip 106 adapted to fit into a transverse slot 198 provided in the contact actuator 82, to thus locate the upper end of the actuating spring 100* relative to the actuator 82. The lower end of the actuating spring 100 is also tapered with the sides thereof diverging, to the lower end of the spring which is provided with a notch 110 for receiving the bridging portion 64 of the terminal 44 adjacent the free end thereof. In order to properly locate the lower end of the actuating spring 100, with respect to the terminal bridge 64, the latter is provided with spaced projections 114 at each of its sides for receiving the integral tabs 112 at the lower end of the actuating spring formed at opposite sides of the notch At this point in the assembly of the illustrative embodiment of the invention, the frame may be mounted on a conventional type of winding machine for winding of the wire 116 thereon. For this purpose, each of the legs 2 and 4 may be provided with an opening 45 substantially intermediate the length thereof for receiving opposed pins on the winding fixture to properly locate the relay on the winding machine. The wire 116 is preferably of a material having relatively high electrical re sistance, such as a nickel-chromium alloy, which in one form of the invention has been successfully used having a diameter of about 3 mils, and a total resistance of about 550 ohms, so that it attains a temperature of 500 to 600 F. when electrically energized. Prior to the winding of the wire 116, an insulating strip 118 is preferably provided on the lower surface of the bight portion 6 intermediate the supporting portions 8 thereof, and this preferably should be of a relatively rigid insulating material, which is capable of having the wire 116 partly embedded therein by forces exerted during winding and adjustment for calibration purposes, or to at least have good frictional contact therewith, such for example, as asbestos, and should be of a length to be received in the recesses 119 provided in the adjacent lower surfaces of the supporting extensions 8 of the bight portion 6. In winding the wire 116 on the relay frame, one end may be initially secured to one of the terminals 42 or 48, for example, terminal 42, whereupon the winding can proceed with a plurality of turns being wound over the bight portion 6 and insulating strip 118 thereon, and over the equalizing plate 92, under tension, so that actuating spring 100 will be maintained in a bowed condition as illustrated in FIGS. 1 and 2 with the contacts 78 and 192 separated. Alternatively, just enough tension may be employed in winding the wire 116 to maintain the parts assembled, and then contact adjustment attained by manipulation of the calibrating screw 70. In either case, the other end of the wire when the proper number of turns have been wound on the frame is then secured to the terminal 48, with the ends of the wire being secured to the terminals 43 and 42 in any desired manner, such for example as by soldering, welding or by using a suitable cement. The relay frame may then be removed from the winding machine and the stress on the turns of wire 116 equalized by applying a suitable force, such as a weight, on the actuator 82 and then supplying an overvoltage to the wire 116 to stress-anneal it, to equalize stresses in the respective turns. It will be observed that the assembly maintains the resistance wire 116 under stress due to deflection of the actuating spring 100, and the stress on the respective turns of wire 116 is maintained equalized irrespective of movement of the actuator 82, due to the pivotal mounting of the equalizing plate 92 In order to complete the assembly of the illustrative embodiment of the relay, it is necessary to apply a top cover strap 120, which has its ends bent downwardly at 122, with the downturned portions 122 being T-shaped in form. The extremities of the downturned T-shaped portions 122 are bent into recesses 47 formed on the outer sides of the legs 2 and 4 to prevent removal of the cover 120. Moreover, the upper side 49 of each recess 4'7 is inclined downwardly as shown in FIG. 1 so that when portions 122 are bent into the recesses 47, there is a cam action of the portions 122 on the upper sides 49 of the recesses 47 which tightens the cover on the legs 2 and 4. The ends of the cover 120 are narrowed so that they can pass through notches 124 on the upper end of each leg 2 and 4 just inwardly of the downturned ends 122. Preferably, the length of cover 120 is made to be less than the spacing of the assembly as shown in FIG. 2 where the legs diverge outwardly under the influence of terminal portions 66 and 74, so that the free ends of the le s 2 and 4 must be brought together somewhat, preferably into parallelism, while additionally stressing the terminal portions 66 and 74, in order that the cover 126 will fit over the free ends of the legs, and so that the cover will thus hold the legs in a predetermined assembled position against the resilient stress exerted by the terminal portions 66 and 74. This all effects a rigid final assembly of the frame in a relatively simple manner.

After the cover 120 is mounted in place, side cover plates 126, preferably of an insulating material, such as a molded insulation material or fiber, may then be assembled. These are simply slipped into place from the top of the frame by having opposite side edges thereof received in the grooves 32 at opposite sides of the legs 2 and 4, and then the covers may be simply slid into place where they cover opposite sides of the frame. The side covers 126 may be solid, or they may be provided with a number of openings 130 to permit circulation of air. Preferably the top cover 120 has a pair of tabs 12S integral with opposite sides thereof which extend out over the top edges of the side covers 126 to prevent their removal, and in assembling the covers 126, it will be necessary to slightly bow them outwardly to clear the tabs 128.

It will now be apparent that there is a control circuit for the relay connected between terminals 42 and 48, which are connected internally by the resistance wire 116, as described above. The remaining two terminals 44 and 46, have the contacts 78 and 102 connected to them, respectively, inasmuch as the contact 78 is mounted directly on the terminal 76, and the circuit for the contact 102 extends through the lower portion of the actuating spring 106 to the contact bridge 64 which forms a part of the contact 44. It will be noted that the position of the lower end of the actuating spring may be adjusted by the adjusting and calibrating screw 70. Depending upon the procedure for winding the wire 116 on the relay, the adjusting screw 70 can be used to make a final adjustment of the lower end of the actuating spring 106, so that it will normally be stressed substantially as indicated in FIG. 1 with its contact 102 separated from the stationary contact 78. Under this condition when control current is applied to terminals 42 and 48, the re sistance wire 116 will heat up and expand. As the wire 116 expands it allows the length of the chord of the are formed by the actuating spring 116 to increase as the spring causes upward pivotal movement of the actuator 82. As the chord of the arc of spring 161] lengthens, the middle of the actuating spring 1% moves toward the chord of the arc of the spring, and its contact 182 moves toward stationary contact 78 until they ultimately engage to complete the circuit between terminals 44 and 46. When the control current flow through the wire 116 is interrupted, the wire will cool and contract. As the resistance wire 116 contracts, the contact actuator $2 is pulled downwardly in a pivotal manner about its pivot extension 88, thus decreasing the length of the chord of the are formed by the actuating spring Hill. As the length of this chord decreases, the center of the spring carrying contact 102 moves away from stationary contact 78 and the power circuit is then opened.

The amount of movement of the center of the body spring is dependent upon the initial bow of the actuating spring 109 and upon the elongation of the chord of the arc formed by this spring. For a given spring length (S), a given chord length (L), a given initial bow (Y and assuming a definite increase or decrease in the length of the chord of the are (A) formed by the body spring (S), the amount of motion (DY) of the contacts at the center of the body spring is expressed as follows:

The length of actuating spring (S) required for a cer- D tain initial bow (Y and chord length (L) is 1r Y 4L The contact movement (Ay) in the center of the spring due to a change in length (6) of chord length (L) is expressed as follows:

This indicates that the amount of movement at the center of actuating spring 106 which is imparted to its contact 192 is dependent upon the initial bow of the spring (Y and the amount of elongation or decrease in the length of the chord of the arc formed by the actuating spring 100. In any case it is plain that the amount of movement of contact 102 will be greater than the amount of elongation or contraction of the chord of the spring 100.

During the time when resistance wire 11% is heated and it expands, the contact actuator 52 rotates about its pivot extension 88 where it reacts in the opening 8-9 in log 2 of the relay frame, under the influence of the actuating spring lilil. As the actuator 82 rotates upwardly, the equalizing plate 92, which is pivoted on the actuator 32 at its center, pivots in such a manner as to maintain the top and bottom extremities of the turns of wire lilo parallel to each other. This double pivotal arrangement of the actuator 82 and the equalizing plate 92 relative to frame leg 2 insures that all turns of the resistance wire will be maintained stressed equally, so that the tension in all turns is kept the same. This feature is important as it materially increases the life of the relay.

It will be noted that the actuating spring ran makes contact with the terminal bridge 64 through what is essentially a knife edge type of bearing maintained in place by the projections 114- on the terminal bridge to insure proper location of the actuating spring, and good electrical contact between it and the terminal bridge. Of course, if desired, a flexible conductor could be employed to conduct current from the actuating spring 1% to the contact bridge 62, or instead of making these two elements separately, they could be made of a one-piece type of construction.

The top cover 12% serves at least two purposes in that it has shoulders at opposite ends which abut against the inner surfaces of legs 2 and 4, respectively, to insure the proper spacing between the legs 2 and 4, and it also serves to tie the legs 2 and of the frame securely together by means of its end portions 122, to thereby provide a rigid structure. As previously mentioned, the terminal portions 66 and 7d operate to force the legs 2 and 4 outwardly relative to each other to take up the free play inherent in the joint between the legs and the bight portion 6 of the frame. When the top cover 12b is then applied and the top ends of the legs 2 and 4 pulled together, all looseness is automatically taken out of the assembled frame.

This type of relay inherently provides a time delay dependent on the time required for heating and cooling the resistance wire lid, and the distance through which the contact 102 must move to engage the stationary contact 78. This time delay can be varied by varying the characteristics of the wire, such as the size, mass and resistance thereof, or by varying the applied voltage or current, or varying the length of the wire or the rate of heat dissipation therefrom. Similarly, the distance which the contact 1492 must move to engage the stationary contact 38 may be varied by varying the length of the actuating spring rat, by varying the contact gap, by varying the mechanical advantage of contact actuator 82 or by varying the relationship between the total length of the resistance wire H6 and the length of the actuating spring ltit One feature of a relay constructed in accordance with this invention is that it will always fall safe in the event the resistance wire 116 breaks. This will interrupt heating of the wire 116, of course, which will cool and contract to open the contacts 78 and 192, as in normal operation. This can occur because the turns of wire 1H. being at least partly embedded in or at least in good frictional engagement with the strip 118, are frictionally held thereby so that the unbroken turns of the wire can function in the normal manner.

The time delay in the operation of the contacts 78 and 1% may also be varied by providing a complete enclosure or by varying the amount of circulation of air or other fluid within the disclosure to thus change the heating and cooling times of the resistance wire iii if desired. the entire casing may be sealed and evacuated. This has been found to be effective to reduce the control wattage requirements by as much as a factor of 5, and to increase the time delay in heating and cooling the wire 116, by a factor 15 to 30.

It should be noted that when the wire 116 is heated and expands, the stress thereon will be substantially relieved as soon as the movable contact 102 engages the stationary contact '73, thus preventing any creep stress on the wire when it is at a high temperature. In order to insure preservation of the spacing between turns of the wire 116 on the insulating strip 118 and equalizing plate 92, the wire and strip 118 and plate 92 may be coated after winding with any suitable insulating varnish or adhesive.

While the relay illustrated in FIGS. 1 to 7 of the drawing is of the type having normally open contacts, of the single-pole single-throw type, additional contacts could be added to provide additional poles or back contacts.

Alternatively, the relay can be constructed with contacts which are normally closed, as illustrated in FIG. 8 of the drawings. Nearly all of the parts of the relay shown in FIG. 8 are identical with the parts of the relay shown in N68. 1 to 7, and accordingly, the same reference numerals are employed to designate such identical parts. Another difference in the relay shown in FIG. 8 is that it only has three terminals, in that the terminal 42 has been omitted, with the adjacent end of the wire 116 being secured directly to the bridging portion 6 5 of the terminal Another difference resides in the contact -respective turns of the wire 116.

actuator 132 shown in FIG. 8, in that it does not have a reduced pivot extension 88, as in the previously described embodiment of the invention, but the bight portion thereof merely has a pair of supporting extensions 134 at each end thereof adapted to be slidably received in the grooves 91 provided at the inner sides of the outer ends of frame legs 2 and 4. This permits the contact actuator 132 to be rectilinearly slidably mounted on the outer ends of the frame legs 2 and 4.

A further difference in the embodiment of the invention shown in FIG. 8 resides in the location of the actuating spring 100 which has been moved so that the ends thereof engage the actuator 132 and terminal bridge 64 substantially midway between the legs 2 and 4. The terminal 136 in this case has an upper extension 144 of increased width which has an integral right angularly extending contact support 138 at its upper end, having the rounded projection 1 .6 adjacent frame leg 4 to engage this leg and bias it outwardly. The other end of the laterally extending part 138 of terminal 136 is slotted longitudinally to receive the actuating spring 10%, with the free ends of the sides of the slots being joined and bent upwardly to form an angular contact end portion 140 on which is secured a contact 142, similar to the contact 73 in the previously described form of the invention.

It will be noted that the operation of the embodiment of the invention shown in FIG. 8 is essentially similar to that of the previously described embodiment, in that energization of resistance wire 116 will cause it to heat and expand thus permitting the actuating spring 100 to move the actuator 132. upwardly, and move its contact 102 away from the fixed contact 142. However, an equalizing plate 82 is not necessary in this case, inasmuch as the force exerted by the actuating spring ltlil is located at a midpoint relative to the coils of the resistance wire 116, and since both ends of the actuator 132 are free to move, it is inherently self-balancing to equalize the stress on the Consequently, it is merely necessary to employ a flat plate 148 of insulating material which may directly engage the actuator 132 as illustrated. In all other respects, the form of relay shown in FIG. 8 is similar to that previously described.

Another way in which both forms of the invention may be employed, is to utilize the relay either without side plates 126 or with perforate side plates 12 6. If perforate side plates 126 are provided the wire 116 may be energized at a predetermined level, and the relay mounted in a stream of fluid, the temperature of which, or the rate of flow of which may vary to thus vary the heating and cooling times of the resistance wire 116, and thus cause the contacts 78 and 102 to open and close dependent on predetermined variations in either or both of these two factors.

Having described and illustrated detailed preferred embodiments of this invention, as required by the patent statutes, it is desired that the invention be not limited to the particular constructions disclosed herein as it will be obvious to persons skilled in the art that many changes and modifications may be made in these particular structures without departing from the broad spirit and scope of this invention. Thus, a number of such modifications and variations have been referred to above, and others will readily occur to those who are skilled in the art. Accordingly, it is desired that the invention be interpreted as broadly as possible and that it be limited only as re quired by the prior art.

I claim as my invention:

1. A relay comprising, a support, a supporting bar pivotally mounted adjacent one end on said support, said support including a relatively fixed bar portion located in spaced opposed relation to said supporting bar and in the plane of pivotal movement of said bar, a plurality of spaced turns of relatively high resistance wire Wound on said bar and bar'portion, a leaf spring having its opposite ends engaging said bar and bar portion, respectively, and held in bowed condition by said wire, and separable contacts mounted on said support and an intermediate portion of said spring, respectively, so as to be operable to open and closed circuit positions by movement of said intermediate portion of said spring in response to thermal expansion and contraction of said wire.

2. A relay comprising, a support, a supporting bar pivotally mounted adjacent one end on said support, said sup port including a relatively fixed bar portion located in spaced opposed relation to said supporting bar and in the plane of pivotal movement of said bar, a plurality of spaced turns of relatively high resistance wire wound on said bar and bar portion, a leaf spring having its opposite ends engaging said bar and bar portion, respectively, and held in bowed condition by said wire, separable contacts mounted on said support and an intermediate portion of said spring, respectively, so as to be operable to open and closed circuit positions by movement of said intermediate portion of said spring in response to thermal expansion and contraction of said wire, and adjusting means on said support for adjusting the position of the end of said spring engaging said bar portion.

3. A relay comprising, a support, a supporting bar pivotally mounted adjacent one end on said support, said support including a bar portion located in spaced opposed relation to said supporting bar, a plurality of spaced turns of relatively high resistance wire wound on said bar and bar portion, an equalizing member interposed between the turns of said wire and said bar which is directly engaged by the turns of said wire and is pivotally supported intermediate its ends on said bar, a leaf spring having its opposite ends engaging said bar and bar portion and held in bowed condition by said Wire, and separable contacts, operable to open and closed circuit positions by movement of an intermediate portion of said spring in response to thermal expansion and contraction of said wire.

4. A relay comprising, a support, a supporting bar pivotally mounted adjacent one end on said support, said support including a bar portion located in spaced opposed relation to said supporting bar, a plurality of spaced turns of relatively high resistance wire wound on said bar and bar portion, an equalizing member interposed between the turns of said wire and said bar which is directly engaged by the turns of said wire and is pivotally supported intermediate its ends on said bar, and separable contacts, operable to open and closed circuit positions in response to thermal expansion and contraction of said wire.

5. A relay comprising, a support, a supporting bar pivotally mounted adjacent one end on said support, said support including a bar portion located in spaced opposed relation to said supporting bar, a plurality of spaced turns of relatively high resistance wire wound on said bar and bar portion, a leaf spring having its opposite ends engaging said bar and bar portion and held in bowed condition by said wire, the plane of deflection of said spring being in substantially the same plane as said bar and bar portion, and separable contacts, operable to open and closed circuit positions by movement of an intermediate portion of said spring in response to thermal expansion and contraction of said wire.

6. A relay comprising, a support, a supporting bar pivotally mounted adjacent one end on said support, said support including a bar portion located in spaced opposed relation to said supporting bar, a plurality of spaced turns of relatively high resistance wire wound on said bar and bar portion, a leaf spring having its opposite ends engaging said bar and bar portion and held in bowed condition by said wire, the plane of deflection of said spring being in substantially the plane as said bar and bar portion and passing between opposed courses of said wire, and separable contacts, operable to open and closed circuit positions by movement of an intermediate portion of said spring in response to thermal expansion and contraction of said wire.

spacers 7. A device of the type described comprising, a generally U-shaped supporting frame having opposed legs overlapping the bight portion of the frame, electrical terminal members extending through aligned openings in the overlapping portions of said frame to secure the legs to said bight portion, means biasing said legs in opposite directions, respectively, means connecting said legs at a point spaced from said bight portion to restrain said legs from movement under the influence of said biasing means, separable contacts mounted on said frame, and contact operating means also mounted on said frame and reacting between different portions of the frame.

8. A device of the type described comprising, a supporting frame formed of a plurality of angularly disposed members of insulating material to form a substantially closed frame having an opening in its perimeter, said members having adjacent overlapping end portions which have interfitting projections and openings, respectively, to properly locate adjacent members relative to each other, electrical terminals extending through aligned openings in the overlapping end portions of said members for securing said members together, means biasing opposed members in opposite directions, respectively, to take up the clearances of said interfitting projections and openings in one direction, means bridging the opening in said frame and connecting the members adjacent said opening to restrain said members against movement under the influence of said biasing means, electrical terminal members extending through aligned openings in said overlapping parts for securing said members together, separable contacts mounted on said frame, and contact operating means also mounted on said frame and reacting between at least two of said frame members.

9. A device of the type described comprising, a generally U-shaped supporting frame, the legs and bight portion of said frame having interfitting projections and openings, respectively, to properly locate the legs relative to the bight portion, means biasing said legs laterally in opposite directions to take up the clearances of said interfitting projections and openings in one direction, electrical terminal portions engaging the legs and bight portion of the frame to hold them assembled, means engaging said legs adjacent the free ends thereof for restraining movement of the legs under the influence of said biasing means, separable contacts mounted on said frame, and contact operating means also mounted on said frame and reacting between different portions thereof.

10. A device of the type described comprising, a supporting frame formed of a plurality of angularly disposed members of insulating material to form a substantially closed frame having an opening in its perimeter, said members having adjacent overlapping end portions which have interfitting projections and openings, respectively, to properly locate adjacent members relative to each other, electrical terminals extending through aligned openings in the overlapping end portions of said members for securing said members together, said terminals having means biasing opposed members in opposite directions, respectively, to take up the clearances of said interfitting projections and openings in one direction, means bridging the opening in said frame and connecting the members adjacent said opening to restrain them against movement under the influence of said biasing means, electrical terminal members extending through aligned openings in said overlapping parts for securing said members together, separable contacts mounted on said frame, and contact operating means also mounted on said frame and reacting between at least two of said frame members.

11. A device of the type described comprising, a relatively rigid generally U-shaped supporting frame, a supporting bar pivotally mounted for movement in the plane of said frame at a point adjacent one end on one leg of said frame adjacent the outer end thereof and extending across the space between the legs of the frame into proximity with the other leg of said frame, a plurality of spaced turnsof relatively high resistance wire wound on said bar and the bight portion of said frame, a resilient contact operating member reacting between said bar and bight portion to maintain the turns of said wire under tension, and a movable contact operated by said contact operating member into and out of engagement with stationary contact means mounted on said frame in response to thermal expansion and contraction of said wire.

12. A device of the type described comprising, a relatively rigid generally U-shaped supporting frame, a supporting bar pivotally mounted for movement in the plane of said frame at a point adjacent one end on one leg of said frame adjacent the outer end thereof and extending across the space between the legs of the frame into proximity with the other leg of said frame, a plurality of spaced turns of relatively high resistance wire wound on said bar and the bight portion of said frame, a bowed leaf spring having its opposite ends engaging said bar and bight portion, respectively, to maintain the turns of said wire under tension, and a movable contact mounted on an intermediate portion of said leaf spring to be moved thereby into and out of engagement with stationary contact means mounted on said frame in response to thermal expansion and contraction of said Wire.

13. A device of the type described comprising, a relatively rigid generally U-shaped supporting frame, a sup porting bar pivotally mounted for movement in the plane of said frame at a point adjacent one end on one leg of said frame adjacent the outer end thereof and extending across the space between the legs of the frame into proximity with the other leg of said frame, a plurality of spaced turns of relatively high resistance wire wound on said bar and the bight portion of said frame, a bowed leaf spring having its opposite ends engaging said bar and bight portion, respectively, to maintain the turns of said wire under tension, a movable contact mounted on an intermediate portion of said leaf spring to be moved thereby into and out of engagement with stationary contact means mounted on said frame in response to thermal expansion and contraction of said wire, electrical terminals for said contacts mounted on said frame, with the terminal for said movable contact having a portion interposed between the bight portion of the frame and the adjacent end of said bowed spring for conducting current through the bowed spring to said movable contact.

14. A device of the type described comprising, a relatively rigid generally U-shaped supporting frame, a supporting bar pivotally mounted for movement in the plane of said frame at a point adjacent one end on one leg of said frame adjacent the outer end thereof and extending across the space between the legs of the frame into proximity with the other leg of said frame, a plurality of spaced turns of relatively high resistance wire wound on said bar and the bight portion of said frame, a bowed leaf spring having its opposite ends engaging said bar and bight portion, respectively, to maintain the turns of said Wire under tension, a movable contact mounted on an intermediate portion of said leaf spring to be moved thereby into and out of engagement with stationary contact means mounted on said frame in response to thermal expansion and contraction of said wire, electrical terminals for said contacts mounted on said frame, with the terminal for said movable contact having a portion extending along the inner side of said bight portion to be interposed between the bight portion of the frame and the adjacent end of said bowed spring for conducting current through the bowed spring to said movable contact.

15. A relay comprising, a support, a supporting bar slidably mounted on said support for movement transversely of said bar, said support including a relatively fixed bar portion in spaced opposed relation to said supporting bar and in the plane of sliding movement of said bar, a plurality of spaced turns of relatively high resistance wire wound on said bar and bar portion, spring 13 means biasing said bar away from said bar portion to maintain said wire under tension, and separable contacts operable to open and closed circuit positions in response to deflection of said spring means due to thermal expansion and contraction of said wire.

16. A relay comprising, a support, a supporting bar mounted on said support for movement in a plane transversely of said bar, said support including a relatively fixed bar portion in spaced opposed relation to said supporting bar and in the plane of movement of said bar, a plurality of spaced turns of relatively high resistance wire wound on said bar and bar portion, means of frictional insulating material interposed between said wire and one of the members on which it is wound, spring means biasing said bar away from said bar portion to maintain said wire under tension, and separable contacts operable to open and closed circuit positions in response to deflection of said spring means due to thermal expansion and contraction of said wire.

17. A relay comprising, a support, a supporting bar mounted on said support for movement in a plane transversely of said bar, said support including a relatively fixed bar portion in spaced opposed relation to said supporting bar and in the plane of movement of said bar, a plurality of spaced turns of relatively high resistance wire wound on said bar and bar portion, means of deformable insulating material interposed between said wire and one of the members on which it is wound, spring means biasing said bar away from said bar portion to maintain said wire under tension, and separable contacts operable to open and closed circuit positions in response to deflection of said spring means due to thermal expansion and contraction of said wire.

18. A device of the type described comprising, a substantially U-shaped supporting means including a pair of separate leg members and a connecting member, means for securing said connecting member to one end of said leg members, means biasing said leg members laterally in opposite directions to initially take up all clearances in the connection between said members in one direction, a supporting bar pivotally mounted on one of said leg members adjacent the outer end thereof and extending across the space between said leg members into proximity with the other of said leg members, means on said other leg member for guiding said bar in its pivotal movement but permitting lateral movement of said leg members in a direction opposite to said bias, a plurality of spaced turns of relatively high resistance wire wound on said bar and said connecting member, resilient contact operating means reacting between said bar and said connecting member in a direction to maintain said wire under tension, and an outer end connecting member engaging said leg members outwardly of said bar to hold said leg members laterally at an intermediate position against said bias.

References Cited in the file of this patent UNITED STATES PATENTS 1,408,307 Oakes Feb. 28, 1922 1,868,500 Hanel July 26, 1932 1,927,322 Peacock Sept. 19, 1933 2,117,048 White May 10, 1938 2,177,671 Schnidinger Oct. 31, 1939 2,326,239 MacLaren Aug. 10, 1943 2,555,801 Mallory June 5, 1951 2,601,918 Huetten et a1. July 1, 1952 2,719,893 Brady Oct. 4, 1955 FOREIGN PATENTS 385,283 Great Britain Mar. 17, 1931 757,112 France June 17, 1933

Images