US2687502A - Magnetic switch assemblage - Google Patents

Description

W. C. FURNAS ET AL MAGNETIC SWITCH ASSEMBLAGE Aug. 24, 1954.

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Aug. 24, 1954 w. c. FURNAS ET AL MAGNETIC SWITCH ASSEMBLAGE 4 Sheets-Sheet 2 Filed July 21, 1951 INVENTORS Q/a/d/ 1954 w. c. FURNAS ET AL 2,687,502

MAGNETIC SWITCH ASSEMBLAGE Filed July 21', 1951 4 Sheets-Sheet 3 157;? gmmvrozes MW; MW

6/ 19.7 TOE/VA? 491 1954 w. c. FURNAS ETAL MAGNETIC SWITCH ASSEMBLAGE 4 Sheets-Sheet 4 Filed July 21, 1951 EEEEEEE IN VEN TORS mgww Patented Aug. 24, 1954 2,687,502 MAGNETIC SWITCH ASSEMBLAGE William C. Furnas, Batavia Township, Kane County, and Harold E.

signors to Furnas Electric Company,

Cobb, Aurora, 111., as-

Batavia,

111., a corporation of Illinois Application July 21, 1951, Serial No. 237,948

2 Claims. 1

The present invention relates generally to improvements in switches for controlling the performance of other electrical equipment, and relates more specifically to various improvements in the construction and operation of electromagnetically actuated switch assemblages.

The primary object of our present invention is to provide diverse improvements in magnetic switch assemblages whereby the manufacture and installation thereof is simplified while their eificiency is enhanced to a maximum.

In our U. S. Patent No. 2,649,521, granted August 18, 1953, we have disclosed an improved magnetic switch comprising a main frame providing a support for a terminal board and an inverted U-shaped laminated magnetic field piece having an energizing coil cooperating therewith, and a vertically reciprocable inverted T-shaped laminated armature slidably confined within the field piece and coil and carrying movable contacts cooperating with fixed contacts enclosed within the terminal board, the armature being the energized coil to close the contacts and being reversely movable by gravity to break the circuits. While this prior switch assemblage has proven highly satisfactory in actual use for certain purposes, it was rather difficult to construct, assemble and dismantle some of the parts thereof, and especially the magnet, movable contacts, and the terminal board.

It is therefore an important object of this invention to provide various improvements especially applicable to magnetic switches of the and removal of parts is durable switch unit results.

Another relatively important object of the in- I vention is to provide an improved electrically energized laminated magnet for motor starting switches or the like, in which the armature is most effectively guided during normal operation, and wherein the armature and the field energizing coil are readily removable for inspection and replacement if necessary.

A further important object of our present invcntion is to provide a simple but durable mount.- ing for the contacts of a magnetic switch, where.- by the fixed contacts are ported and protected while the movable contacts are normally flexibly mounted upon the actuating armature but may be quickly removed without removing terminals or connecting wires.

Still another important object of the present normally firmly supinvention is to provide improved laminated armature and field piece assemblages for a magnetic switch, in which the laminations may be stacked against the opposite sides of and secured to central assembly plates to produce effectively cooperating elements regardless of slight variation in thicknesses of the individual laminations.

An additional object of this invention is to provide an improved sheet metal coil retainer for the energizing coil of a switch actuating magnet, the protruding ends of which may be bent to hold the coil in place without distorting the remainder of the retainer.

Another object of the invention is to provide an improved movable contact carrier bar for supporting the movable contacts from the armature of a magnetic switch unit, which may be easily removed from the open front portion of the unit without necessarily removing other parts such as the starter switch mounting plate.

A further object of our invention is to provide an improved resetting mechanism for the overload relays associated with a magnetic switch, which will positively prevent closing of the switch contacts while resetting is being effected but will automatically release the same thereafter.

Still another object of the present invention is to provide an improved two-piece terminal board formed of insulation and adapted to normally eliminate short circuiting and undesirable arcing by confining each set of cooperating contacts in an independent segregated enclosure, and the parts of which are readily separable to provide free access to the fixed contacts.

An additional object of this invention is to provide improved mounting means for a magnetic switch or the like, which will efiectively resist and reduce objectionable vibration to a minimum, and also facilitates installation of such switch units within their housings.

These and other more specific objects and advantages of the invention will be apparent from the following detailed description.

A clear conception of the several new features involved in the present invention and of the construction and functioning of a typical commercial magnetic switch embodying the same, may be had by referring to the drawings accompanying and forming part of this specification in which like reference characters designate the same or similar parts in the various views.

Fig. 1 is a front view of one of the improved magnetic switch assemblages with the housing and terminal board covers removed showing the movable contacts thereof in open position, and having two overload relays applied thereto and an auxiliary switchlet associated with each of the opposite sides of its terminal board;

Fig. 2 is a vertical section through the housing of the switch assemblage of Fig. 1, showing a side view of the switch with the contactsopen and the overload resetting mechanism in normal inactive position;

Fig. 3 is a fragment of a side view similar to that of Fig. 2, but showing the overload relay resetting device in active position;

Fig. 4 is a horizontal section through the rear casing of the housing taken above the switch and showing a top view of the confined switch assemblage;

Fig. 5 is a side view of the laminated magnet and armature assembly of the magnetic switch, a section having been taken through the magnet energizing coil directly adjacent to the outermost laminations';

Fig. 6 is a transverse vertical section through the movable contact pusher of the laminated magnet and armature assembly, taken along the line 6-8 of Fig. 5 but with the energizing coil omitted;

Fig. 7 is another transverse vertical section taken through the laminated magnet and armature assembly and the energizing coil, along the line l'l of Fig. 5;

Fig. 8 is a top view of a few of the movable contacts of the switch, showing the same applied to a fragment of the contact carrying cross arm;

Fig. 9 is an enlarged vertical section through one of the fixed and movable contact confining chambers of the terminal board and cover assemblage, taken along the line 5-9 of Fig. 10 and showing a fragment of one of the movable contact guides; and

Fig. 10 is a similarly enlarged transverse horizontal section through the terminal board and cover assemblage, taken along the line lfili! of Fig. 9 and showing all of the movable contacts confined therein.

The gist of our present invention is the provision of an improved electro-magnetically actuated switch unit embodying a simplified magnet, and effective contact carrying and housing structures which may be readily manufactured, assembled or dismantled while normally safeguarding the contacts against undesirable arcing and short-circuiting and permitting convenient attachment of the terminals and conductors; and while only one commercial embodiment of the improved features has been illustrated and described, it is not our desire or intention to unnecessarily restrict the utility thereof by virtue of this limited showing. It is also contemplated that specific descriptive terms be given the broadest possible interpretation consistent with the actual disclosure.

Referring to the drawings, the improved electro-magnetic switch shown therein, comprises in general, an enclosing housing consisting of a rear cup-shaped casing Hi and a front cover it; a main switch s spension frame l6 detachably secured within the casing M and having a laminated electro-ma-gnet ll fixedly mounted upon its lower portion and a terminal board it likewise mounted upon its upper portion; a laminated armature i9 cooperable with the lower poles 2B of the magnet I1, and having an inverted U-shaped pusher 2i secured to its opposite ends and supporting three pairs of movable contacts 22 through an, insulation crossbar 23;

three pairs of stationary contacts 24 mounted within the terminal board 18 and being cooperable with the movable contacts 22 to make and break the electric circuits controlled by the switch; a terminal board cover or closure 25 detachably secured to the board i8 and normally confining the contacts 22., 2% within segregated chambers 25; a thermal overload relay 2'! mounted upon the main frame [6 at each side of the magnet i7; and a reset mechanism for the relays 2'! adapted to positively prevent closing of the contacts 22, 24 while the relays are being reset.

The casing i4 and cover l5 of the housing are formed of durable sheet metal and may be provided with the usual openings for the conductors and for a starting and stopping push button switch of the type shown in our patent No. 2,559,777 when such a control switch is applied directly to the cover it and frame it of the unit; and the cover 65 may also be detachably secured to the casing M by means of lugs 29 formed on this casing and coacting with slots in the cover and a pair of cooperating hasps 30 secured to the lower portions of the casing and cover, see Figs. 1 and 2. The housing cover i5 also has an overload relay reset button 3! slidably confined therein by a leaf spring 32 which constantly urges the button 3i outwardly into the position shown in Fig. 2 but may be pressed into the position shown in Fig. 3 during resetting of the relays 21'.

The switch mounting frame it may also be formed of heavy sheet metal with the aid of punches and dies, and is preferably provided with a central forwardly offset stiffening area 3% and with rearwardly offset peripheral portions 35, to provide clearance for attaching screws. The upper offset portion 35 of the frame it is provided with a slot adapted to cooperate with a suspension element 3? secured to the rear wall of the casing i i, and the lower portions 35 have holes 33 therein for the reception of retainer screws, not shown. The electromagnet ii is firmly secured to the offset area 34 of the frame it by means of four bolts '59, while the terminal board it is likewise fastened to the frame area 35 by three cap screws es coacting with metal bushings :il embedded within the insulation of which the board H5 is formed see Figs. 1, 9 and 10. The overload relays 2% are also mounted upon the main frame it by means of sheet metal brackets 2 2 and attachin screws or rivets, so that the entire switch unit may be readily suspended within or removed from the casing i l upon removal of the cover i5.

The improved laminated magnet il consists of a stiff and relatively heavy center plate i3 having an equal number of similarly shaped sheet metal laminations disposed on its opposite sides and secured thereto by rivets M, and has the depending opposite end poles 2i thereof embraced by shading coils 65, see Figs. 5, 6 and 7. This magnet is also provided with an integral depending central projection it located midway between the poles 28 but of less vertical length than the poles, and this projection it is embraced by an energizing coil i'i of approximately the same height as the end poles 28. The annular magnet energizing coil ii? is held in position by a sheet metal inverted U-shaped retainer it which spans the top of the magnet ii and has opposite side walls 43 extending downwardly through the space be tween the magnet projection 56 and the interior of the coil 4?. Each of these side walls 49 is provided with an integral inwardly projecting reinforcing flange U snugly engaging the magnet projection 46, and after the retainer 48 has been inserted the lower ends 5! of the walls are bent outwardly against a coil Washer 52 as shown in Fig. 7 to firmly hold the coil 41 in place without distorting the flanged portions of the side walls 49. The core of the magnet H is also provided with bracket plates 53 secured to the opposite outer side laminations by the rivets 14, and which are firmly fastened to the main frame It by screws or the like.

The laminated armature l9 which cooperates with the magnet poles 25, also consists of a central rather heavy and stiff plate 55 having a like number of thinner sheet metal laminations on its opposite sides and secured thereto by rivets 56 which also clamp side plates 57 against the outer laminations. The armature I9 is of inverted T-shape by virtue of the provision of a central integral upwardly directed projection 58 thereon, which is slidably engageable with the smooth parallel flanges 55 formed on the core retainer 43 as illustrated in Figs. 5 and 7, and the side plates 57 are provided with opposite end lugs 55 adapted to coact with notches in the pusher 2|. When the coil 51 is energized, the armature I8 is lifted into engagement with the magnet poles 20 so as to elevate the movable contacts 22, but upon deenergization of the magnet ll the armature l9 and the elements carried thereby will promptly drop by gravity to lower the contacts 22.

The inverted U-shaped pusher 2! is also formed of sheet metal and has opposite depending side walls 69 slidably engaging the outer surfaces of the magnet poles 2t and in which the notches for receiving the lugs 59 are formed. A single central screw 6| coacts with the lower extremities of the pusher side walls 60 to clamp the lugs 59 within these notches, and upon removal of this screw 6| the walls 66 may be spread apart so as to permit free downward removal of the entire armature assembly.

relay resetting mechanism as will be explained later.

The cross bar 23 which carries the movable contacts 22 is formed of insulating material and springs 12 and tilting the plates H sufiiciently to clear the flanges 10 and by thereafter lifting these mounting plates out of the guides.

The terminal board I 8 which is fastened to the main frame It by the cap screws 40 coacting with the threaded insert bushings 4|, and which cooperates with the front closure 25 to form the contact confining chambers 26, is of improved construction, and both this board l8 and its closure 25 are formed of insulating material and these elements are detachably connected by screws 14, as illustrated in Figs. 9 and 10. The board I8 is provided with forwardly extending lower flanges '55 with which the rear flange 6'! of the cross bar 23 is cooperable to substantially close the chambers 26, and the interior of the board 18 has integral partitions 76 adapted to coact with similarly spaced partitions 17 formed in the closure 25 along tongue and groove joints as shown in Fig. 10, thereby effectively alining these parts and segregating the chambers 25 from each other.

The fixed contacts 24 are suspended from L- shaped front and rear contact carriers 18, 19 respectively each of which has an upper recess coacting with a screw pin 80 and which are firmwithdrawing the screws '14.

A switchlet or auxiliary switch 86 of the type forming the subject of U. S. Patent No. 2,562,420, granted July 31, 1951, may also be mounted on one or both ends of the terminal board 18, in order to increase the number of circuits conalinement with one of the end extensions 69 of the movable contact supporting cross bar 23. These switchlets 86 will therefore be actuated simultaneously with the main switch, and the terminal screws 88 of the auxiliary switches are also freely accessible when the housing cover I5 is removed.

The overload relays 21 which are mounted upon the brackets 42 at the opposite sides of the magnet and armature assemblages, are of the type forming the subject of U. S. Patent No. 2,597,068, granted May 20, 1952, and each of these relays has a solder pot 90 adapted to open cooperating and the crank ends 92 of the wire 93 are constantly urged upwardly by coil springs 97 as shown in Fig. 1. A sheet metal yoke 98 secured to and swingable with the wire 93, has a reset plate 99 attached to its medial swinging portion in line with the button 3|, and is also provided with lower extensions I60, thus completing the overload relay resetting mechanism.

The overload resetting mechanism including the button 3| mounted in the housing cover I5, is normally positioned as shown in solid lines in Figs. 1 and 2, with the relay actuating plungers 9| in lowermost position. When the relays 21 are sprung by an overload, the plungers 9| rise to the dot-and-dash line positions in substantial contact with the cranks 9'2 and the magnet ll will be deenergized thereby causing the armature l9 to drop by gravity and to pull the movable contacts 22 out of engagement with the fixed contacts it as in Fig. 1. The reset button 3i may then be pressed to swing the yoke 98 and wire 93 into the position shown in Fig. 3, whereupon the crank ends 92 will force the plungers 9! of the relays 2i downwardly and will restore these relays to normal operating osition if the overloadin has been eliminated. While the button 31 is thus depressed, the mid-portion of the yoke 93 will swing over the plate (53 carried by the movable contact pusher, and will positively prevent closing of the contacts 22; and when the button Si is released, the springs 32, 9'! will restore the resetting mechanism to inactive position with the yoke extensions in contact with the stop plate 65.

During normal operation of the improved magnetic switch assemblage, the starting and stopping control switch which may be mounted either directly upon the main switch or at any other conveniently accessible location remote from the main unit, may be actuated to either make or break the electric circuit for energizing the magnet coil it. When this circuit is closed by the control switch, the magnet ill quickly attracts and elevates the armature is thus causing the movable contacts 22 to rise and to engage the fixed contacts 26% within the chambers 26, and also closing the switchlets 85 if used. When the energizing circuit is opened by means of the control switch, the magnet H is promptly deenergized thus causing the armature it to drop by gravity and to move the contacts 22 away from the fixed contacts 25 thereby breaking the main switch circuits and those controlled by the switchlets 86. The improved switch is thus closed magnetically and opened by gravity at the will of the operator, and is also effectively protected against overloading. It is also noteworthy that the magnetic switch may be opened by merely pressing the reset button 3!, even if the overload relays Z'i are not sprung.

From the foregoing description of the construction and operation of our electro-magnetic switch unit it will be apparent that this unit embodies a simple, compact and durable magnetic switch and terminal board assemblage all parts of which are readily accessible for inspection and attachment of terminals; The improved laminated magnet and armature structures embodying the central stiffening plates 43, 55 and the heavy side plates, may be readily assembled to properly coact with the coil 4'! and with each other, even if the laminations should vary slightly in thickness; and the coil retainer 48 not only effectively holds the coil ill in proper position, but it may also be easily applied and serves as a guide for the central projection 58 of the armature. The armature l9 may also be readily assembled with or removed from the pusher 2| by merely manipulating the single screw 6! and slightly bending the pusher side plates (59, and the entire magnet and armature structures are efiectively supported by the main frame it.

The movable contacts 22 while being normally mounted for most efficient cooperation with the stationary contacts 26, may be readily removed and replaced without disturbing connections or other elements of the unit aside from the housing and terminal board covers terminal board it and its closure cover 25 cooperate with the fianged and widened crossbar 23 to thoroughly conceal and protect the contacts 22, 25 within the segregated chambers 26, and the partitions l6, ll of the terminal board assembly permit rapid removal and replacement of the closure 25 and inspection of the contacts without releasing any terminal screws. The movable contacts 22 may be released by merely depressing and tilting them sufficiently to clear the retainer flange while the fixed contacts 2 1 are removable by merely releasing the screws 83 which are freely accessible upon removal of the terminal board closure 25.

All elements of the improved switch are sturdily' constructed of suitable materials so as to prevent possible objectionable arcing and short-circuiting, and the overload relays 2'? protect the switch against possible damage due to overloading. The resetting of these relays 2i may also be quicklyand positively effected by merely pressing the button 3! without removing the cover 55, and the yoke as functions to hold the contacts 22 open until after resetting operations have been completed. The main frame it is of simple but durable construction and may be easily installed within or removed from the casing i l to provide an effective three point support for the switch unit. The improved switch is especially adapted for use in electric circuits subject to strong current, and requires little a tention after proper assembly and installation thereof.

It should be understood that it is not desired to limit this invention to the exact details of construction and to the precise mode of use of the typical switch assemblage herein shown and described, for various modifications within the scope of the appended claims may occur to personsskilled in the art.

We claim:

1. In an electro-hiagnet, an upright supporting frame, a laminated magnet core having laterally spaced upright end poles and a central intervening shorter upright projection all formed integral with and depending from an upper horizontal bridge piece, brackets rigidly attached to the opposite sides of said core and having a transverse stop plate coacting with one of said end poles and flanges adjacent to the other end pole secured to said frame, an annular energizing coil surrounding said central core projection between said end poles, a unitary inverted U- shaped sheet-metal coil retainer spanning said bridge piece and having opposite side walls extending downwardly between said core projection and the interior of said coil beyond the latter and being provided with integral inwardly extending flanges snugly engaging the opposite sides of said central core projection to prevent distortion of said retainer when the downwardly extending lower wall ends are bent outwardly beneath the coil, an inverted laminated T-shaped armature beneath said core and coil having a lower cross-- bar and the opposite end portions of which are engageable with the lower ends of said poles and. also having a central upright stem slidable along said retainer flanges, and an inverted U-shaped sheet-metal pusher spanning the upper bridge piece of said core transversely of said retainer and having depending opposite side walls guided for upright movement along the opposite sides of the core and which are interconnected at their lower extremities and attached to the outermost I5, 25. The improved I ends of said armature cross-bar, said pusher also having a stop plate cooperable with the stop plate of said bracket.

2. In an electro-magnet, an upright supporting frame, a laminated magnet core having laterally end poles and a central intervening shorter upright projection all formed independing from an upper horizontal bridge piece, brackets rigidly attached to the opposite sides of said core, one of said brackets having a transverse plate spanning one of said both of said brackets being secured adjacent to the other end pole, an annular energizing coil surrounding said central core projection between said end poles, a unitary inverted U-shaped sheet-metal coil retainer spanning said bridge piece and having opposite side walls extending downwardly between said core projection and the interior of said coil beyond the latter and being provided with integral innated T-shaped armature beneath said core and coil having a lower cross-bar the opposite end portions of which are engageable with the lower ends of said poles and also having a central upright stem slidable along said retainer flanges, and an inverted U-shaped sheet-metal pusher spanning the upper bridge piece of said core transversely over said retainer and having depending opposite side walls guided for upright movement along the opposite sides of the core and which are interconnected at their lower extremities and attached to the outermost ends of said armature cross-bar.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 20,094 Wilms et a1 Sept. 1, 1936 2,071,149 Wilms et a1 Feb. 16, 1937 2,227,434 Bierenfeld Jan. 7, 1941 2,347,934 Christensen et a1. May 2, 1944 2,348,556 Matthias May 9, 1944 2,358,568 Furnas et a1 Sept. 19, 1944 2,387,033 Matthias Oct. 16, 1945 2,399,575 Schleicher Apr. 30, 1946 2,424,776 Stapleton July 29, 1947 2,434,096 Ayers et al Jan. 6, 1948 2,492,726 Ayers et a1. Dec. 27, 1949 2,499,958 Knowlton Mar. 7, 1950

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