US2875288A - Electric switch - Google Patents

Description

`Feb. 24, 1959 P, F, wHn-E 2,875,288

ELECTRIC SWITCH Filed DSG. 3l, 1956 Z @13.1 Il@ 5 INVE/YTOR.

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United States Patent O ELECTRIC SWITCH Paul F. White, Glen Ellyn, lll., assignor to Furnas Electric Company, Batavia, Ill., a corporation of Illinois Application December 31, 1956, Serial No. 631,753

2 Claims. (Cl. 20G-6) This invention relates generally to improvements in electrical controllers, and it relates more specically to .improvements in the construction and operation of electric switches especially .adapted to control the functioning Aof reversible electric motors or the like.

The primary object of the present invention is to provide an improved electric switch which is simple in construction and eiiicient in operation.

When controlling the functioning of a reversible electric motor or similar equipment with the aid of a two-way switch, it is essential that the forward and reverse circuits of the motor be quickly and positively established and interrupted by durable and reliable switch mechanism. While it has heretofore been proposed to utilize a reversing switch for such purposes, wherein one or more pairs of 4electrically interconnected movable contacts were adapted to alternately engage the medial and either of two other stationary contacts disposed on opposite sides of the medial one, constituting fixed contact rows corresponding in number with the movable contact pairs, these prior switches have not proven entirely satisfactory for several reasons. Perhaps the main objection to the previous switches of this type was their relatively complicated structure which made it diicult to assemble and to maintain them in prolonged operation without necessitating repairs, while also increasing the cost of production thereof.

It is therefore an important more specific object of the present invention to provide an improved switch assemblage of the above described type comprising few relatively simple and durable parts which can be readily assembled or dismantled.

Another important object of this invention is to provide -an improved switch unit which may be readily installed and operated to make or break the` forward and reverse circuits of a reversible electric motor at several spaced points during each actuation of the switch.

A `further important object of the invention is to provide an improved switching device wherein a pair of movable contacts is alternately cooperable by oscillatory motion with a common and two alternative fixed contacts lying in the same plane, and in which the movable contacts are constantly maintained in a plane parallel to that of the stationary contactsthroughout their movement, so that all circuits are always made or broken simulaneously at both of the movable contacts.

Still another important object of my invention is to provide an improved sturdy electric switch adapted to effectively control the operation of reversing motors of both the alternating and direct current types and having diverse voltages, phases, windings, and capacities, therefore making the switchA flexible in its adaptations.

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

A clear conception of the several fetaures constituting the present improvement and of the construction and operation of atypical commercial reversing-switch emrice bodying the invention, may be had by referring to the drawing accompanying and forming a part of this specitication wherein like reference characters designate the same or similar parts in the various views.

Fig. 1 is a part sectional side view of the improved reversing switch looking directly toward the movable contact carrier, and the section having been taken centrally through the closure cover and through the spring actuated mechanism for biasing the movable contacts toward open position;

Fig. 2 is an end elevation of the same switch assemblage looking inwardly toward its mounting frame and with the closure cover removed;

Fig. 3 is another side view of the switch but looking directly toward the side thereof opposite to that of Fig.. l, but with the closure cover also omitted;

Fig. 4 is a transverse section through the same switch unit, taken along the irregular line 4-4 of Fig. 1, and illustrating the position of the movable contact actuating mechanism in one contact closed position;

Fig. 5 is another transverse section through the unit, taken along the line 5-5 of Fig. l, and showing the movable contacts in open position; and

Fig. 6 is a fragmentary section through the same unit, similar to that of Fig. 5, but illustrating the position of the movable contact actuating mechanism in the opposite contact closed position from that shown in Fig. 4.

While the invention has been illustrated and described herein as having been embodied in a typical switch especially adapted to control the actuation of a reversible electric motor, it is not intended to conine the use of the improved switches to such purposes; and it is also contemplated that specific descriptive terms employed herein be given the broadest possible interpretation consistent with the actual disclosure.

Referring to the drawing, the improved reversing switch unit illustrated comprises in general, a support consisting of a U-shaped frame 8 and a mounting board 9 secured to the Iframe and having thereon three sets or rows of stationary contacts 10,` 11, 12; a movable contact carrier 13 having thereon three pairs of movable contacts 14, 15 of which each pair is electrically interconnected by a conductor strip 16 while the contacts 14, 15 are spaced apart a distance equal to the distance between the medial stationary contact 10 and each of the other contacts 11, 12 of the same row; and a pair of shafts 17, 18 journalled in the frame 8 and having cranks 19, 20 respectively sup porting the movable contact carrier 13 and which are simultaneously swingable in the same direction to cause the movable contacts 14, 15 to alternately engage the adjacent intermediate stationary contact 10 and either of the other contacts 11, 12 of the same row.

The frame 8 of the main support may be formed of sturdy sheet metal with the aid of punches and dies, and has a mounting bracket 22 likewise formed of sheet metal attached to its base as by welding or otherwise, the frame base and bracket being provided with an openingv 21. One side wall 23 of the frame 8 may also be provided with an inwardly directed lug 24 to which a sheet metal U-shaped closure cover 25 adapted to snugly coact with all of the frame edges, may be detachably secured by means of a screw 26 as shown in Fig. 1. The opposite sidewall 27 of the frame 8 is provided with a recess 28 for facilitating assembly and dismantling of the switch, and this wall 27 also has an integral inwardly extending projection 29 thereon at the bottom of the recess 28, see Figs. 1, 2, 3 and 5. The recess 28 is normally closed by a bearing plate 30 of sheet metal which is detachably secured to the wall 27 by screws 31, and with which the cover 25 also coacts.

The stationary contact mounting board 9 is formed of insulating material and is provided with bifurcated inasvaass tcaral attaching .lugs 3.3 at .its .opposite .Sides which are detachably secured to the base of the frame 8 by screws 34 as shown in Figs. 1, 2 and 4. The stationary switch .CQIlacts 11, 1,2 are mounted on conductors 35V and lie in a V common plane facing the movable contacts 14, 15, and the conductors 35 extend kthrough the board 9 and are provided with lterminal attaching screws 36. Depending upon the purpose for which the switch is to be used, the stationary contact conductors 35 may be segregated or interconnected by jumper bars and electrically connected to different types of reversing motors or the like in various manners; and the several rows of stationary contacts 10, 11, 12 are segregated from each other by high -anges 37 while the terminal attaching screws 36 of the three rows a re likewise separated by high flanges 38 all of which are formed integral'with the board 9.

The movable contact support or vcarrier "13 is also formed ofY insulation and is provided with two parallel transverse grooves within which the cranks19, 20 of the two Vshafts 17', 18 are snugly kconfined .by a klJ-shapedclip 40 which is insertible beneath'and held in place by a Vpair of retainer anges`41 formed on the carrier block,

see Figs. 1, 2 and 5. The movable contacts 14, 15 each complementary pairl of which is bridged by and secured to the opposite ends of one of the conductor strips 16, all lie in a common plane which is parallel to the common plane of the Xed contacts 10, 11, 12, and the midportion of each bridge strip 16 is notched fortengagemcnt with a U-shaped fulcrum stirrup 42 secured to the carrier 13, and is lpressed against the fulcrum -ridge of the latter by a compression spring 43 when the switch is open, as illustrated in Fig. 5. As previously indicated, the movable contacts 14,V of each pair are spaced apart a distance equal to the distance between each medial stationary Contact 10 and the complementary end contacts 11, 12, so that when the movable contacts of a pair are brought into engagement with either corresponding pair of fixedcontacts 10, 11 or 10, 12, the bridge strip 16 will be lifted away from the adjacent stirrup 16 and the coacting contacts will always coincide.

The cranks 19, of the two shafts 17, 1S which movably support the contact carrier 13, have like throw or radii of swing, and the main shaft 17 is journalled in bearings 45, 46 carried by the frame wall 23 and by the bearing plate respectively while the auxiliary crankshaft 18 is pivotally mounted in the rigid frame projection 29, as shown in Figs. 1, 2 and 3. The end of the main shaft 17 which projects outwardly beyond the side wall 23,'has Van actuating lever 47 secured thereto, while the opposite shaft end which projects outwardly beyond the side plate 30 has a brake cam 48 attached thereto.v The side plate 30 has an annular sheet metal collar 49 attached thereto as by riveting, and this collar is surrounded by a helical movable contact return spring 50 having opposite ends projecting away from the shaft 17, one of which coacts with the iixed frame projection 29 while the other engages a sheet metal spring driver 51 fastened to'the shaft 17 adjacent to the bearing 46 whenever the switch is in either closed or on position, see Figs. l, 2 and 3. This assemblage is such that when the actuating force applied to the lever 47 is released, after the movable contact carrier 13 has been thrown in either direction from off position, the spring 50 will automatically return the carrier 13 to mid-position as in Figs. 1,v 2 and 5, and the brake cam 48 is used solely to actuate an external brake while the projection 29 returns the carrier 15 to midposition- When the various parts of the improved reversing switch have been properly constructed they may be readily assembled for use in connection with reversible motors of various types by applying suitable stationary contact conductors to the mounting board 9 adapted to cooperate with the particular circuit in which the switch is to be installed- For example, the switch may be uti- 'is .lizeel .in einer two. 0r three Phase three .winrar tw@ Phase four wire systems, in either single or split phase systems, or in shunt, series, or compound direct current systems, operating with various voltages. With the stationary contacts 10, 11, 12 properly assembled, the mounting board 9 may be attached to the frame 8 with the aid of the screws 34 coacting with the bifurcated lugs 33, and the movable contacts 14, 15 attached to the conductor strip 16 may be readily applied to the stirrups 42 with the springs 43 whereupon the movable contact carrierr13 may be quickly secured to the cranks 19, 20 of the shafts 17, 18 with the aid of the clipl 4t) applied to the flanges 41 as in Figs. l and 5.

After the spring 50 has been applied to the collar 49 and the projecting ends thereof have been brought into coaction with the frame projection 29 and with the spring driver 51, the collar and spring assemblage may be dropped into the frame recess 28 while the .end of the main shaft remoteY from the plate 30 is slipped through the bearing Y45 and the shaft 18 may be likewise applied to its bearing in the projection 29, whereupon the side plate 30 may be brought into contact with the frame side wall 27'and attached thereto with the screws 31. The actuating lever 47 may then be secured to the end of the main shaft 17 remote from the plate 30 .by means of a clamping nut 52; and when the necessary electrical connections have been made' with the aid of the terminal screws 36, the cover 25 may be applied to the frame 8 and fastened in place with the screw 26 and the completed unit may be suitably mounted with the aid of the bracket 22.

During normal operation of the assembled switch, the movable contact carrier 13 will be held in mid position as illustrated in Figs. 1, 2 and 5 with the contacts open, by the spring 5G and the projection 29. 'When the lever 47 Vis swung to rotate the main shaft '17 in aI counter clockwise direction as viewed in Fig. 4, the three pairs of movable contacts 14, 15 are carried into engagement with the fixed contacts 10, 11 of the corresponding rows thus effecting forward rotation of the motor controlled by the switch, and upon release of the lever 47 the spring 50 automatically returns the contacts 14, 15 to ott position as in Fig. 5. When the lever 47 is swung to rotate the main shaft 17 in a clockwise direction as viewed in Fig. 6, the three pairs of movable contacts 14, 15 are carried into engagement with the iixed contacts 10, 12'of the corresponding rows thus effecting reverse rotation of the motor, and upon release of the lever 47 the spring 50 again automatically returns the contacts 14, 15 Vto off position.

Since the two supporting cranks 19, 20 of the movable contact carrier 13 have the same radius of swing, this carrier and the movable contacts 14, 15 will always be disposed'in planes parallel to the common plane of the stationary contacts 10, 11,12, and the movable contacts are always brought into direct engagement with the fixed contacts, without objectionable wiping action. The springs 43 and the medial fulcrum coacting with the movable contact conductor strips 16, permits these strips to lift away from the stirrups 42 and the contacts 14, 15 to firmly engage the fixed contacts, and it is to'be noted that while the medial stationary contacts 1Y0 are always active whenever the switch is closed, the several contacts 11 become active only in forward operation position and the contacts 12 become active only in reverse operation position. It is also noteworthy that the throw or radius of swing of the cranks 19, 20 is considerably'greater than half the distance between the central contacts 10 and the flanking contacts 11, 12, so that these cranks will assume an acute angular position such as shown in Fig. v4 whenever the switch is thrown closed in either direction, but the springs 43 always insure uniform closing pressure at the engaged contacts.

Front the foregoing detailed description it will be noted that the present invention in fact provides a reversing switch which is exceedingly simple, compact and durable in construction, and which is also highly exible in its adaptations. The improved switch unit can be conveniently assembled, or dismantled, and installed for commercial operation, by merely manipulating a few screws with an ordinary screw driver. The several sections of the switch are well insulated from each other and the making and breaking of circuits is accomplished with great rapidity while the closing of the switch always results in good electrical connections between the contacts due to the travel of the movable contacts in parallel planes which are also parallel to the common plane of the fixed contacts. This result is obtained by utilizing several shafts having crank portions of equal throw and which are constantly maintained parallel to each other during displacement of the movable contacts. The improved switch unit has proven highly satisfactory and successful in actual operation, and can obviously be manufactured in various sizes and for diverse purposes.

It should be understood that it is not desired to limit this invention to the exact details of construction or to the precise mode of operation herein shown and described, for various modications within the scope of the appended claims may occur to persons skilled in the art.

I claim:

l. In an electric switch, a U-shaped sheet-metal frame having a base and integral end walls, a mounting board of insulation secured to said base between said side walls and having thereon at least one set of three equally spaced fixed contacts, a carrier of insulation also disposed between said side walls and having thereon at least one pair of similarly spaced movable contacts and also being provided with a pair of parallel recesses, a shaft journalled in said frame Walls and having an integral medial crank swingable between said walls and pivotally confined within one of said recesses and supporting said carrier, another crank journalled in one of said frame walls and pivotally confined within the other recess of said carrier for cooperation with said shaft crank to cause said movable contacts to constantly assume parallel positions, a single clip for frictionally confining said cranks within said recesses, and means for oscillating said shaft in opposite directions to alternately cause said movable contacts to engage and connect the intermediate xed contact with the opposite end contacts of the fixed set and to simultaneously likewise oseillate said other crank through the carrier.

2. In an electric switch, a U-shaped frame having a base and integral end walls, a mounting board detachably secured to said base between said walls and having thereon a set of three equally spaced ixed contacts, a carrier movable toward and away from said board and having thereon a pair of similarly spaced resiliently suspended movable contacts and also being provided with spaced anges and with a pair of transverse recesses on the opposite sides of the anges, a shaft journalled in said frame walls and having a medial integral crank swingably confined within one of said recesses and supporting said carrier, another crank journalled in said frame and swingably confined in the other recess for cooperation with said shaft crank to cause said movable contacts to constantly assume parallel positions, a single U-shaped clip frictionally coacting with said carrier lianges to detachably hold said cranks within said recesses, and means for swinging said shaft in opposite directions to cause said movable contacts to alternately engage and connect the intermediate fixed contact with the opposite end contacts of the fixed set.

References Cited in the file of this patent UNITED STATES PATENTS 2,158,657 Frank et al. May 16, 1939 2,513,649 Jensen July 4, 1950 2,590,658 Silvus Mar. 25, 1952 2,670,411 Dawe et al. Feb. 23, 1954 FOREIGN PATENTS 934,100 France Jan. 7, 1948

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