US2700709A - Thermostatic electromagnetic switch assembly - Google Patents

Description

P. M. BYAM THERMOSTATIC ELECTROMAGNETIC SWITCH ASSEMBLY 1950 Jan. 25 1955 Filed Feb. 8

3 Sheets-Sheet l pmwzw BY & ATTORNE Jan. 25, 1955 P. M. BYAM THERMOSTATIC ELECTROMAGNETIC SWITCH ASSEMBLY Filed Feb. 8 1950 3 Sheets-Sheet 2 INVENTOR ATTORN Jan. 25, 1955 p BYAM 2,700,709

THERMOSTATIC ELECTROMAGNETIC SWITCH ASSEMBLY Filed Feb. 8, 1950 3 Sheets-Sheet 3 I NVEN TOR FEVER 11BX42? A TTORNE United States Patent THERMOSTATIC ELECTROMAGNETIC SWITCH ASSEMBLY Peter M. Byam, Rochester, N. Y., assignor to Fasco Intxl ustries, Inc., Rochester, N. Y., a corporation of New ork Application February 8, 1950, Serial No. 143,078 11 Claims. (Cl. 20088) The present invention relates to improvements in a switch assembly and more particularly to a thermostatic and electromagnetic flasher type of switch assembly.

While in general switch assemblies having contacts opened and closed by alternate domination of an electromagnet and of a thermostatic element are well known, the switch assembly of the present invention offers several improvements in performance and in structure of such a switch assembly.

The primary object of the present invention is the proprecise operating conditions are readily accomplished in mass production at a minimum cost. A further ob ect is the provislon of switch arm but, nevertheless, in good electrical contact lwlith one current-carrying member of the switch assem- Still another object is the provision of a contact member mounted on the base, spring pressed against the magnetic frame, and provided with an opening within which the armature member moves.

Other and further objects of the invention will be suggested to those skilled in the art by the description which follows. 1

Reference is now made to the accompanying drawings wherein similar reference characters designate similar elements and wherein:

Fig. l is a top view of one form of the switch assembly of the invention with the cover removed;

Fig. 2 is a vertical and longitudinal cross-section through the complete switch assembly taken on the line 22 of Fig. 1;

Fig. 3 is a vertical and transverse cross-section of the complete switch assembly taken on the line 33 of Fig.

Fig. 4 is another vertical and longitudinal cross-section of the switch assembly taken on the line 4-4 of Fig. 1;

Fig. 5 is an exploded perspective of said one form of the switch assembly showing the component parts prior to production assembly;

Fig. 6 is a top view of the switch assembly of the invention including two pairs of contracts;

Fig. 7 is a vertical and longitudinal cross-section of the switch assembly taken on the line 77 of Fig. 6'

Fig. 8 is a bottom view of the switch assembly showing three terminal members; and

Fig. 9 is a wiring diagram illustrating the manner of connecting the switch assembly of the invention to the signal light system of an automobile.

In the illustrated embodiments, the switch assembly is composed principally of a base, a magnetizable frame and armature associated therewith, a pair of switch arms positioning and holding the aforementioned elements pre cisely inoperative postiions. However, it is to be understoodthat certain structural features of the switchas- 2,700,709 Patented Jan. 25, 1955 1s rectangular in form, and is proedge thereof and a cover 13, preferably drawn from sheet aluminum, frictionally engages the side walls 14 of base 10 and may be fastened thereto in any of several known ways. A dimple 15 is provided in each end of the cover 13 for engagement with a mounting bracket not shown.

Near one end, the upper surface 16 of the base 10 has a protuberance 17, for a purpose to be later mentioned, and is provided with a circular recess 18 from which a hole 19 extends through to the bottom surface of base 10. A terminal has prongs 21 and 22. A hollow rivet 23, see Fig. 4, fits into hole 19, has a head 24 within circular recess 18, extends through terminal member 20 and is deformed or recess 11 accurately ber 20 against turning.

Near its other end, the base 10 has formed thereon, and preferably integral therewith, a raised portion 26 which has an upper surface 27 substantially parallel to the upper surface 16 and which is provided with a rectangular recess 28. A boss 29, preferably circular, is formed on upper surface 27 and a bore 30 extends through said boss 29 and the base 10 to the bottom surface thereof. A pair of side walls 31 and 32 are at each side of raised portion 26 and extend above it to a height determined by the elements to be mounted thereon.

A magnetizable frame 33 is composed of iron of good permeability and is provided in the form of a flat plate generally U-shaped. Said frame 33 has a central portion 34, has one leg 35 having opposed substantially parallel edges 36 and 37, and has another leg 38, leaving a recess 39 between said legs 35 and 38. Said leg 35 is provided with an opening 40 for fitting over the boss 29 while edges 36 and 37 abut, respectively, against the inner faces of side walls 31 and 32. n insulating band 41 of plastic or insulating material is fitted over the end cure end 44 of coil 42 thereto in good electrical contact therewith.

An armature member 46 is normally spaced from the frame .33 and is attracted thereto by energization of the coil 42. Such armature member 46 is preferably also made of iron having good permeability and is in the' shape of an elongated rectangular strip. A flexible switch arm 47 is fastened to armature member 46 at one end as by soldering or welding and is deformed at its other end to be spaced from said armature member 46. A contact 48 is mounted in known manner upon the free end of switch arm 47. Preferabiy the switch arm 47 is A hinge strip 49 is soldered or welded at one end to the under-surface of leg 35 of the magnetizable frame 33 and at its other end to the switch arm 47 As a result, the armature member 46 is movably mounted with respect to the, insulating band 41 on said leg 38 and normally engages and 51 are Q preferably and. 32, and. and 53, respectively, in

alignment with the bore 30 through the base and boss 29. A satisfactory material for layers 50 and 51 is a cambric base impregnated with a phenolic resin and readily available commercially. The insulating layer 51 is provided in one or both of its other edges with a notch 54.

A main bimetallic element 55 comprises a bimetallic sheet having a body portion 56 substantially coextensive with and between the insulating layers 50 and 51, an elongated switch arm 57 extending from portion 56 and carrying a contact 58, a bent portion 59 fitting into notch 54 of layer 51 and interengaging therewith, and an overlsyling portion 60 adjacent the upper surface of said layer A fastening means such as a rivet 61 has a flat head 62 making surface contact with the overlying portion of bimetallic element 55 and has a stem 63 extending through the holes and openings in portions 56 and 60 of element 55, in layers 50 and 51, in frame 33, boss 29 and base 10 and has an end 64 extending through a terminal member 64, such end 64 being peened or spun over to secure said rivet 61 and all the associated parts securely and accurately in their assembled positions.

It is clear that the switch assembly of the invention can be very rapidly assembled. The main bimetallic element 55 is first placed in inter-engagement with the insulating layer 51 and the notch 54 therein. Then magnetic frame 33 carrying the hinge strip 49 and armature member 46 is placed between side walls 31 and 32 with opening 40 fitting over boss 29. Insulating layers 50 and 51 with bimetallic element 55 are stacked between said side walls 31 and 32 and the holes therein aligned with each other and the bore 30 in boss 29. The stem 63 of rivet 61 is inserted through said holes and bore and the terminal member 65 fitted over the rivet end 64 which is spun or riveted over to draw all the parts penetrated against the upper surface 27 of raised portion 26 and to create considerable contact pressure and very good electrical contact between rivet head 62 and overlying portion 60 of the main bimetallic element 55.

As a result, magnetic frame 33 will be fixed in parallel spaced relation to the upper surface 16 of the base 10 and will be precisely located angularly or oriented so that the free end of armature member 46 will normally lie against protuberance 17 on base 10 and will be opposite and in spaced relation to the insulating band 41 on the end of leg 38 of frame 33. At the same time the end 44 of coil 42 extends into hollow rivet 23 and is soldered thereto and the other end of armature member 46, switch 47 and hinge strip 49 are within and movable within the rectangular recess 28 in the raised portion 26 of the base 10. Also the main bimetallic element 55 is sandwiched between insulating layers 50 and 51 to be well insulated from heating by conduction from other parts of the switch assembly and the interengagement between layer 51 and portion 59 and between the edges of layer 51 and the inner r faces of the side walls 31 and 32 locate switch arm 57 directly over switch arm 47 with their respective contacts 58 and 48 opposite and normally in engagement with each other. The switch arm 57 has the higher expansion side of the bimetallic sheet forming the same adjacent the switch arm 47 so that heating of arm 57 causes a thermal deflection in a direction to open said contacts 58 and 48. The electrical resistance of the bimetallic material forming switch arm 57 is considerably greater than the electrical resistance of the unimetal or bimetal sheet material for switch arm 47 for reasons that will soon be explained.

The operation of the switch assembly constructed and assembled according to the invention will now be described and explained. With no current passing through the switch assembly, as when no flashing signal is desired, the relative position of the parts is as shown in Fig. 2, and contacts 48 and 58 engage each other with a predetermined contact pressure.

When an electric current, such as the load of automotive signal lights, is applied to the terminals and 65, a circuit is completed through wire coil 42, frame 33 is magnetized and armature 46 is attracted toward the leg 38 and into contact with the insulating band 41 thereon in the dotted line position shown in Fig. 2. At the same time, switch arm 47 is moved toward switch arm 57 and the pressure between contacts 48 and 58 is increased to some extent. Also, the connected circuit or automotive signal lights are immediately energized or turned on. Simultaneously the current passing through switch arm ever, the switch arm 47 and hinge strip the armature member 46 by means of a rivet 72 as shown 57 rapidly heats the same because of the relatively high electrical resistance thereof and causes said switch arm to flex away from contact arm 47 and to separate contacts 48 and 58.

It should be noted that switch arm 57 and contact 58 are arranged so that the attraction of armature 46 by the magnetic field does not in any way hinder or oppose the thermal deflection of switch arm 57. Instead the arrangement of the contacts 48 and 58 for movement along the minor axis of the ellipsoidal magnetic field is advantageous because any magnetic influence on the switch arm 57 and contact 58 is minimized and the magnetic field acts to quench magnetically any spark which may be drawn by separation of said contacts 48 and 58.

Upon separation of said contacts 48 and 58, the circuit through coil 42 is broken, armature 46 is retracted and the spacing between contacts 48 and 58 is rapidly increased beyond that caused by deflection of switch arm 57. This increased separation of said contacts 48 and 58 increases the time for switch arm 57 to cool and remake contacts 48 and 58 so that the off time of the flasher is more nearly equal to its on time which is highly desirable. The rather complete thermal insulating of bimetallic element 55 as a whole form the remainder of the switch assembly also contributes to this equalizing of the off and on times of the flasher switch assembly.

The switch assembly operation just described assumes that switch arm 47 is of unimetal material and that the switch assembly is being operated in a rather uniform ambient temperature. However, if the switch assembly is to operate satisfactorily under varying ambient temperature conditions, which at times may be rather extreme, then the switch arm 47 should be made of bimetallic sheet material of substantially the same bimetallic characteristics as switch arm 57 but of considerably lower electrical resistance. Thus, even though no current is passing through the switch assembly, a lowered ambient temperature will cause both switch arms 47 and 57 to be deflected toward the armature 46 by approximately the same amounts and the pressure between contacts 48 and 58 remains substantially the same. Consequently, the off and on frequency of the switch assembly remains the same for variation of ambient temperatures over a considerable range.

Otherwise, that is when switch arm 47 is of unimetal, lowering of the ambient temperature and downward deflection of switch arm 57 would increase the pressure between contacts 48 and 58, and greater deflection of switch 57 by the electrical resistance heating thereof would be required and the initial on time would be considerably increased. Conversely, a high ambient temperature would decrease the initial on time and, if high enough, might cause the contacts 48 and 58 to separate and render the switch assembly inoperative.

Specifically, and with the dimensions of switch arms 47 and 57 shown, the results hereinbefore described are obtained by making switch arm 47 of a bimetallic sheet material 0.005 of an inch thick and commercially known as Trufiex FZOR and switch arm 57 of a bimetallic sheet material 0.004 of an inch thick and commercially known as Chace 6650. However, it is to be understood that equivalent bimetallic sheet materials are available and may be used.

Figs. 6-8 show a modification of the switch assembly of the invention including a pair of contacts for controlling another circuit such as a pilot lamp and with certain structural variations that may be desirable. The molded base 10 is for the most part like that shown in Figs. 1-5 and differs only in that side walls 31a and 32a have inclined forward edges to facilitate molding, a back wall 66 connects the rear edges of said side walls 31a and 32a to strengthen the same and protect the mounting for the frame 33 and main bimetallic element 55, and a transverse ridge 67 extends across the rectangular recess 28 in raised portion 26. Also the bottom of base 10 is provided with a rectangular recess 68 and with pentagonal recesses 69 and 70. Said recesses 69 and 70 have inclined edges in alignment as shown in Fig. 8 and are in spaced relation to leave a ridge 71 therebetween.

The frame 33, coil 42, layers 50 and 51, and main bimetallic element 55 are constructed and assembled the same as described in connection with Figs. 1-5. How- 49 are fastened to in Fig. 7. While the other end of binge strip 49 is soldered or welded to the under surfacev of leg 35 of magnetizable frame 33, such fastening of the hinge strip 9 is primarily to facilitate assembly because, after assembly, said other end of the hinge strip 49 is clamped between the upper surface 27 of raised portion 26 and leg 35 of frame 33 by the pressure exerted by the fastening means or rivet 61. Also after assembly the upper edge of transverse ridge 67 is spaced from the armature member 46 so as to allow normal movement thereof but yond the elastic limit of the material of hinge strip 49 as may be caused by external shock and the relatively large mass of the armature member 46.

member 73 is mounted at one end on base and has its other end spring pressed against the insulating band 41 on leg 38 of the magnetizable frame 33. Specifical ly, the contact member 73 comprises a flat end 74 fastened to base 10 by a rivet 75, the upper surface of base 10 being recessed to receive end 74, and a pair of intermediate strips 76 and 77 extending upwardly, one on each side of armature member 46, to a flat contact 78 which is spring pressed against the insulating band 41 on frame 33. The armature member 46 extends through and is free to move within the opening provided in the contact member 73. The upper end surface of armature member 46 has a silver contact layer 79, see Fig. 7, for good electrical contact with flat contact 78 when the armature member 46 is attracted toward leg 38 of frame 33.

A terminal member 80, see Fig. 8, is fastened in place within recess 68 by the end 64 of rivet 61. A terminal member 81 has a triangular base 82 fitting into the recess 69 and engaging the inclined Walls thereof. The peened over end of hollow rivet 23 engages and holds said base 82 of terminal member 81 in proper and fixed position. Another terminal member 83 has a triangular base 84 fitting into recess 70, engaging the side walls thereof, and is fixed in place by the end of rivet 72. The triangular form of terminal bases 82 and 84 and their positioning with one side of each in alignment and the other side of each abutting the ridge 71 provides an extremely compact arrangement which can be rapidly and accurately assembled.

Fig. 8 also shows one manner of fastening cover 13 to base 10 as by deforming portions 85 of said cover 13 into recesses 86 provided in the side walls of base 10.

Fig. 9 illustrates connection of the switch assembly of the invention into an automotive lamp signal system and demonstrates certain advantages of its operation. The standard storage battery B has one side grounded and its other side connected to the bimetallic switch arm 57 which normally engages switch arm 47, even when armature 46 is not magnetically attracted, and then through coil 42, one side of a four pole double throw signal control switch S and the left front and left rear signal lamps Li and L1- or the right front and right rear signal lamps Rf and Rr to ground. It will be. apparent that such circuit is immediately completed and the signal lamps lighted as soon as switch S is closed and is opened when bimetallic switch arm 57 is deflected sufficiently to beseparated from switch arm 47.

The pilot lamp signal circuit extends from contact 78, through the other side of signal control switch S and left pilot lamp Lp or right pilot lamp Rp to ground. While the pilot lamp will not be lighted simultaneously with the closing of switch S, the circuit to it will be completed upon attraction of armature 46 which follows the closing of switch S in a fraction of a second, likewise there will be a similar extremely small lag in lighting and extinguishing the pilot lamp for each cycle or operation of the flasher switch assembly.

It is understood that variations of the switch assemblies illustrated are possible within the scope of the invention and that structural features of the two forms of switch assemblies illustrated can be interchanged. Also the embodiments of the switch assembly are merely illustrative and the scope of the invention is defined by the claims which follow.

Having now particularly described my invention, what tact on said armature member facing in the direction.

the armaturemember is moved upon energization of said coil, and a bimetallic contact arm located on the side of having a free end extending in the same direction as the free end of said armature member, and a bimetallic contact arm located on the side of the armature member having the contact, having one end supported at a point adjacent the supported end of the armature member, and having a free end carrying a contact normally engaging said contact on the armature member and constructed and arranged to be deflected, upon heating by a predetermined electric current therethrough, away from said coil, a contact arm having one end mounted on said armature member and having a free end extending in the same direction as the free end of said armature member, and a bimetallic contact arm located on the side of the armature member having the contact, having one end supported at a point adjacent the supported end of the armature member, and having a free end extending in the same direction as the first mentioned contact arm and carrying a contact normally engaging said contact on the armature member and constructed and arranged so that the pressure between said normally closed contacts is increased by movement of said armature member upon energization of said coil and to be deflected, upon heating by a predetermined electric current through said bimetallic contact arm, away from said armature member and to separate said contacts independently of the position of said armature member and of energization of said frame.

4. A flasher switch assembly comprising a magnetizable frame, a coil thereon for magnetizing said frame, an armature member movable about a fixed end and having a free end normally spaced from said frame and moved toward said frame upon energization of said coil, a bimetallic contact arm of relatively low electrical resistance carried by said armature member on the side thereof toward which the same is moved by energization of said coil and having a free end spaced therefrom extending in the same direction as the free end of said armature member and carrying a contact, and a second bimetallic contact arm of relatively high electrical resistance having a free end extending in the same direction as the free ends of said armature member and the first mentioned bimetallic contact arm and carrying a contact normally in engagement with the first mentioned contact, said bimetallic contact arms being connected in series with said coil and having their sides of higher coeflicient of expansion on the sides toward said armature member.

5. A flasher switch assembly comprising a magnetizable frame, a coil thereon for magnetizing said frame,

an armature member movable about a fixed end and havlng a free end normally spaced from said frame and moved toward said frame upon energization of said coil, a bimetallic contact arm of relatively low electrical reslstance carried by said armature member on the side thereof toward which the same is moved by energization of said coil and having a free end spaced therefrom extending in the same direction as the free end of said armature member and carrying a contact, and a second bimetallic contact arm of relatively high electrical resistance having a free end extending in the same direction as the free ends of said armature member and the first mentioned bimetallic contact arm, carrying a contact normally in engagement with the first mentioned contact, and deflected, upon heating by a predetermined electric current therethrough, in the same direction as said armature member moves when attracted toward said frame to separate said contacts.

6. A flasher switch assembly comprising a base, a plane magnetizable frame having a pair of parallel legs, a coil encircling said frame and adapted upon energization to magnetize the same and create between said legs an ellipsoidal magnetic field having the minor axes thereof perpendicular to the plane of said frame, an elongated armature extending across the space between said legs, movable about a fulcrum and having a free end normally spaced from one leg of said frame and moved perpendicularly thereto by said magnetic field, a contact arm having one end mounted on said armature, movable therewith and connected to said coil and having a free end extending in the same direction as the free end of said armature member and carrying a contact, and a bimetallic contact arm having a free end extending in the same direction as the free ends of said armature member and first mentioned contact arm and carrying a contact normally engaging the first mentioned contact to complete the circuit to said coil, adapted to be thermally deflected by the electrical load carried thereby, both of said contact arms being mounted so to be movable in the direction of the minor axes of said ellipsoidal magnetic field.

7. A switch assembly comprising an insulating base having a raised portion, a pair of opposed side walls extending above said raised portion, and a boss therebetween and provided with a bore extending through said base, a magnetizable frame provided with an opening fitting over said boss and having opposed lateral edges abutting the inner faces of said side walls, a contact arm carrying a contact on one end and having its other end attached to said magnetizable frame, a pair of insulating layers having opposed lateral edges abutting the inner faces of said side walls and each provided with a hole in alignment with said bore, a bimetallic sheet between said layers including a contact arm having a free end carrying a contact and having a portion deformed to interengage and overlie the upper insulating sheet, and a fastening means having a head contacting the overlying portion of said bimetallic sheet and extending through the holes in said layers and frame and the bore in said base accurately to position said contact arms with the contacts thereon in juxtaposition.

8. A switch assembly comprising an insulating base having an upright wall and provided with a bore extending through said base, a pair of insulating layers each having a lateral edge abutting said wall and each provided with an opening in alignment with said bore, one of said layers being provided with a recess in an edge thereof, a bimetallic sheet between said layers, having a portion deformed to engage said recess and overlie the upper surface of said layer, and a fastening means having a head in surface contact with the overlying portion of said sheet and having a stem extending through the openings in said sheets and the bore in said base.

9. A switch assembly comprising an insulating base having a plane surface and a raised portion, a flat magnetizable frame mounted at one end on said raised portion and extending in parallel spaced relation to said plane surface, a flat armature member having a free end between said base and frame normally spaced from said frame and attracted thereto upon magnetization thereof, and a contact member having one end attached to said base and its other end resiliently abutting said frame and located to be engaged by the free end of said armature member in its attracted position.

10. A switch assembly comprising an insulating base having a plane surface and a raised portion, a flat magnetizable frame mounted at one end on said raised portion and extending in parallel spaced relation to said plane surface, a flat armature member having a free end between said base and frame normally spaced from said frame and attracted thereto upon magnetization thereof, and a contact member having one end attached to said base, an intermediate portion at one side of said armature member, and its other end resiliently abutting said frame and located to be engaged by the free end of said armature member in its attracted position.

11. A switch assembly comprising an insulating base having a plane surface and a raised portion, a flat magnetizable frame mounted at one end on said raised portion and extending in parallel spaced relation to said plane surface, a flat armature memberhaving a free end between said base and frame normally spaced from said frame and attracted thereto upon magnetization thereof, and a contact member having one end attached to said base, a pair of intermediate strips on each side of said armature member, and having its other end forming a contact integral with both intermediate strips and resiliently abutting said frame, the free end of said armature member extending through and being movable within the opening in said contact member between said ends and said strips.

References Cited in the file of this patent UNITED STATES PATENTS 1,513,247 James Oct. 28, 1924 1,651,408 Peacock Dec. 6, 1927 1,772,442 Hanny Aug. 5, 1930 2,014,958 Wilhelm Sept. 17, 1935 2,132,627 Jackson Oct. 11, 1938 2,262,344 Shaw Nov. 11, 1941 2,264,027 Holmes Nov. 25, 1941 2,280,281 Clayton Apr. 21, 1942 2,303,153 Woodworth Nov. 24, 1942 2,338,731 Morse Jan. 11, 1944 2,418,831 Hamilton Apr. 15, 1947 2,429,784 Whitted et al. Oct. 28, 1947 2,451,618 Gross Oct. 19, 1948 2,452,508 Ulanet Oct. 26, 1948 2,477,408 Gross July 26, 1949 2,486,365 Youhouse Oct. 25, 1949 2,558,219 Kohl June 26, 1951 2,568,323 Dales Sept. 18, 1951 2,601,152 Kmiecik June 17, 1952

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