US2225344A - Electric switch - Google Patents

Description

Dec. 17, 1940. D Q KIMBALL 2,225,344

ELECTRIC SWITCH Inventor. Donald @.Kimball,

.His Attorney v Dec. 17, 194C. KI'MBALLv 2,225,344

ELECTRIC SWITCH Filed April 13, 1958 2 Sheets-Sham'l 2 /LOW oFF- MEDI/UM Inventor:

Donald @.Kmball,

His Attorneg.

Patented Dec. 17, 1940 2,225,344 ELECTRIC SWITCH Donald G. Kimball, Stratford, Conn., assignor to General Electric Company, a corporation of New York Application April 13,1938, Serial No. 201,786 l 4 Claims.

The present invention relates to electric switches, and more particularly to rotary switches having cam-actuated contacts and which are adapted for use with heater elements, or the like.

It is an object of the invention to provide an improved construction and arrangement in switches of this type in which the contact elements are completely enclosed and protected against the entrance of dirt and foreign sub;

stances and in which the mechanism is easily and quickly assembled within the housing.

In the accompanying drawings Fig. lis a side view of the switch; Fig. 2 is a side 'view in crosssection through the switch; Fig. 3 is a view'along the line 3 3 of Fig. 2; Fig. 4 is a'view along the line 4 4 of Fig. 2; Fig. 5 is a view along the line 5 5 of Fig. 2; Fig. 6 is a view along the line 6-*6 of Fig. 2; Fig. 7 is an exploded view of the switch positioning mechanism; Fig. 8 is a diagrammatic view showing the switch in off position, and Figs. 9, l and l1 are diagrammatic views show-v ing the switch in high, medium4 and lowV positions, respectively. k

Referring tothe drawings, the electric switch 'of this invention is indicated generally at III and comprises a two-part casing formed of-molded material, such as a phenolic condensation prod-` uct and ller, with the upper part II closely engaging the lower part I2 to form a completely sealed-in housing for the switch mechanism. The parts of the housing are held in assembled relationship by means of metal straps I3 which surround the housing on all four sides and are riveted `together at each end as shown at I4.

l Extending through the casing is a non-circular shaft I which is rotatably supported by means of circular openingsA (not shown-l formed in the front and rear walls of the casing. The rear portion of the shaft l5 extends through the cas,- ing and is provided with a split washer I6 disposed between the casing and a. bent-up portion of the strap I3 to prevent axial movement of the shaft. The front end of the shaft is provided with an operating handle I'I.

A plurality of operating cams I8, I9. and are spaced longitudinally along the shaft l5 and arev formed with appropriately positioned -depressions to cooperate witha plurality' of contact blades. The contact blades are supported from terminal members at one end and are provided at their other ends with silvered contacts which cooperate with corresponding contacts on other terminal members. The terminal `members are located in pairs and a plurality of contact blades are provided to cooperate with the re portion (Cl. 20G- 6) spective cams to` form a. multi-contact switch mechanism. l v

Cooperating with the cam element 20 (Fig. 6) is a contact mechanism including a lower terminal element 2l which may be connected to one of the 6 load lines and a corresponding upper Aterminal member 2l which may be connected to a heater element. The terminal member 2l' is provided with a horizontally disposed exible contact blade 22 provided at its end with a silvered contact-10 point which cooperates with a corresponding contact point on the terminal element 2l to form a contact 23. The blade is provided with Va depressed portion 24 which cooperates with the cam 20. The terminal member 2|' is likewise 15 provided with a depending contact blade 25 formed with a contact point at its outer end which engages a corresponding contact point on an adjacent terminal member 31 to form a contact 26. In order to cooperate with the cam 2U 20 the contact blade 25 is formed withan'extended The terminal element 2I is provided with an extension 21 which. is secured to a baille plate 28 by means of a hollow rivet 21'. f Correspondingly, the terminal member 2 I is pro- 25 vided with an extension 30 which is secured to the baille plate 28 by a hollow rivet 3 I 'I'he baille l plate 28 is disposed in grooves 28 formed in the upper and lower housing members I0 and l I, and thereby forms a chamber for the terminals l2| 30 and 2|', the contacts 23 and 26, and the cam element 20. A corresponding chamber is formed for each of the cam members I8 and I9 in which the cooperating terminals and contacts are placed.

Referring more particularly to Fig. 5, a second contact mechanism is provided including a terminal element 32 which may be connected to a load line and a corresponding terminal member 32' which may be connected to a heater element. The terminal member 32 is located centrally of 40 the casing adjacent the terminal member 2 I' and `is provided with an oilset portion 33 bearing a spring contact blade 3l having a depressed por- -31 of the terminal element 32 is bent at right angles to the terminal element and extends va depressed portion 4I.

through an opening 29' in the baille plate 28 to form the contact 28, as best shown by Figs. 5 and 6. 'Ihe terminal element 32 is secured to a second baffle member 33 by a hollow rivet 39 while the corresponding terminal element 32 is.

likewise secured to the baille member by a hollow rivet 33'. 'I'he baille member 39 cooperates with the walls of the casing' resting in grooves 29 to form a second chamber which houses the cam element I9 and the contact structure 36 immediately adjacent the baille plate 23.

The contact structure which cooperates with the third cam element I8 is best shown by Fig. 4, and comprises a terminal element 49 which may be connected to a load line and a corresponding terminal member 40' which may be connected to a heater element. The terminals extend through openings in the casing on opposite sides thereof adjacent the center terminals 32 and 32'. The terminal member I0' is provided with a longitudinally extending contact blade 4I provided at its outer end with a silvered contact point to cooperate with a corresponding contact point on the terminal element 40 thereby forming a contact structure 42. In order to engage the cam element I8, the contact blade 4I is provided with To secure the terminal element 40 to a baille plate 4l the terminal element is provided with an extension I5 fastened to the baille plate 44 by means of a hollow rivet I9. The terminal member I5' is provided with a depending arm 41 which is likewise secured to the baille plate 44 by means of a hollow rivet I8.

It will be apparent that the respective terminals are secured to the baille plates in such a manner as to form structures which may be inserted within the casing as units. To this end, the casing is provided with knock-out elements `49 which are punched out wherever a terminal is to extend and thereby the terminals are placed through the opening formed by the knock-out and the halves of the casing brought together to securely clamp the baille plates 28, 39 and M in the slots 29 and thereby hold the terminals securely in position with the contact structures properly positioned for cooperation with the operating cams.

The terminal elements 2I, 32 and 40 are each provided with clamping means comprising screws 5|! which cooperate with arms 5I. The arms are provided with arcuate ends 52 which may receive the load line wires and the other ends of the arms are bent at an angle and extend through openings 53 formed in the terminal elements. In this manner a highly effective securing means is provided which effectively maintains the load lines in electrical contact withthe terminal elements. In order to secure a heater conductor or cable to the terminal members 2l', 32' and I0', these members are each provided with securing meanscomprising screws 54 and the locking plates 55. 'I'he locking plates 55 are provided with indentations 56 which receive the heater cable and cooperate with the terminal members to clamp the cable. y

I'he switch is provided with a positioning mea-ns which is disposed between the front wall ofthe casing and the baille plate III. This positioningl means is best shown by Figs. 3 and 'l and comprises a plate 51 mounted upon the shaft I5 by means of an opening 5l contoured to the dimensions of the shaft. The plate 51 is provided with a plurality of diametrically opposed pins 59 which are seated within openings 69 forming part of the coil torsion springs 5|. The ends of the springs are provided with loops 62 which engage a lug 63 formed on each of the opposed links 64. The links are provided with extending pins 65 and arms 96, the latter being provided with keyhole slots 61. Anti-friction rollers 65' are mounted fonthefpins In the assembled relationship of 5 4the positioning means the pins 59 extend through the openings G0 forming part of the torsion springs and likewise extend through the keyhole slots 61 provided in the link arms 66. As shown more particularly in Fig. 3, the rollers 65 cooperate with indentations 68 formed in the front wall of the housing. The springs 6I bear against the lugs 63 and maintain the rollers 65' within the indentations S8. The indentations 68 are located in positions corresponding to that taken by the switch cams for the various positions of the switch. As the switch is rotated from one position to the other, rotation of the plate 5l will cause the looped ends of the springs to bear against the corresponding lugs 63, thereby pivoting the links 64 about one of the pins 59 so that the rollers 65 will ride up the side of theV indentations 68 and snap over into the adjacent one. In this manner the switch cams are accurately located for al1 positions of the switch.

One use of the device is as a heater switch for controlling the heat to a plurality of resistance heaters H1, H1. In practice it may be desirable to place these heaters in an oven and to regulate the heat oi the oven to three speeds such as high, medium and low. Figs. 8 to 11 inclusive show the switch connected to the heaters H1 and H2 and tothe load line which comprises a three-wire circuit including load wires L1 and L2 with a neutral wire N. customarily, 110 volts are applied on each side of the central neutral wire, although other voltages may be applied as occasion demands. The terminal elements 2I and 40 are connected to the outside load lines L2 and L1, respectively, and the terminal element 32 is connected to the center neutral line N. The heater elements H1 and H2 are connected in series with a center tap connected to the center terminal member 32'. 'I'he other end of the heater H1 is connected to the terminal 40' and the corresponding end of the heater H2 is connected to the terminal member 2i'. The various positions of the switch such as oil high, medium and low are shown by Figs. 8 to 11, respectively. It should be noted that the dwells or recesses in the cams are properly positioned to operate the depressed portions of the respec tive contact blades to open and close the contacts thereby controlling the current to the respective heater elements H1 and H2 for the various positions of the switch. l.

In Fig. 8 the switch is shown in of" position with the contacts 42, 36, 23 and 26 all open. In Fig. 9 the switch is shown in the high position and current is caused to ilow from each of the load lines L1 and L2 to each of the heater elements and back through the central or neutral terminal member to the neutral line N. Current from the line YL1 passes through the terminal element lll, contact I2, heater element H1, neutral `5 terminal member 32', contact 36, and back to the neutral line N. Similarly, current from the line L2 passes through terminal element 2|, contact 23,*heater element H2, neutral terminal 32', contact 36 and back to the neutral line. Thus the heaterA elements H1 and H2 are connected rin parallel and are each subjected to a potential position rearranges the contacts as shown in Fig. 10. In the medium position only one of the heater elements is employed, in this case the element H1. Current from the line L1 flows through terminal element 40, contact 42, heater H1, terminal 32', contact 3B to the center or neutral line terminal 32. Current cannot reach the other heater element H2 from the line L2 because both the contacts 23 and 26 are maintained in open position by the cam element 20.

In the low position, shown by Fig. 11, the voltage across one line is applied to both the heater elements H1 and H2 connected in series. Current flows from the line Lll through terminal element 40, contact 42, heater elements H1 and H2, terminal 2|', contact 26, and back to the i neutral terminal 32. No current is applied through the medium of terminal member 2l be' cause contact 23 is open and likewise the center or neutral terminal member 32 is disconnected from the circuit due to the opening of contact 36. It will be seen that a switch has been provided which permits the heater elements to be operated together to secure a high, medium and low temperature.

By making the cam elements I8, I9 and 20 symmetrically shaped, it is possible to secure a switch which may be rotated throughout a complete revolution, and which is provided with an olf position and three heat positions. By turning the handle clockwise, as shown in` Figs. 8 to 11, and continuing the rotation of the handle past the point illustrated by Fig. 11, it will be apparent that the heating cycle will again occur in the order given, that is, oli high, medium and low because similar cam surfaces will be presented to the depressed portions of the contact blades. Furthermore, the switch may be operated in either direction with equal eiectiveness. By providing a switch which is completely enclosed within a housing, the entrance of dirt, spillage, or foreign matter is prevented in those cases where the switch is employed in electric appliances such as an electric range. Moreover, by providing baliie plates between the respective terminals, chambers are provided which isolate the contacts one from the other, thereby preventing any possibility of short circuit between the various contacts. By mounting the terminal members upon the baille plates, a compactand rigid structure is secured which is easily assembled by placing the halves of the casing over the `respective terminals and disposing the terminals through the openings in the casing formed by the punched knock-outs. The assembled switch mechanism and housing is then held in completed form by the strap members I3.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric switch, a housing, a plurality of baille members disposed within said housing and forming adjacent chambers therein, a pair of terminal elements disposed 'in each of said chambers and connected to a corresponding baille member, there being openings in said housing through which said terminal elements extend for connection to electrical circuits, contact means in each of said chambers for interconnecting the terminal elements of each pair, a shaft rotatably mounted in said housing and a cam disposed n each of said chambers for actuating said Contact means, each of said cams being mounted on said shaft.

2. In an electric switch, a two-part `housing comprising upper and lower portions, said poi'-v tions being provided with spaced openings therein, a plurality of baille plates seated in said housing, a plurality of terminal elements secured to Said baille plates, a plurality of contact means interconnecting pairs of said terminal members, said terminal members projecting through said openings for connection to electrical circuits, said terminal elements moving through said openings to extended position as the parts of said housing are moved together to closed position clamping said baille plates whereby said contact means are sealed within said housing, means for securing the parts of said housing in closed position, and caml means cooperating with said contact structures for controlling the circuits.

3. In an electric switch, a two-part housing, each of said parts having an opening therein, a baille element mounted in said housing and forming a chamber therein, terminal elements disposed in said chamber and secured to said baille member, said terminal elements extending through the openings in said two-part housing for connection to electrical circuits, contact mea-ns adapted to interconnectsaid terminal elements, and a cam means for operating said contact means.

4. In an electric switch, a two-part housing, each of said parts having an opening therein, a baie element adapted to be mounted in said housing to form a chamber therein, terminal elements secured to said baille member, said terminal elements extending through .the openings in said two-part housing for connection to electrical circuits, said two-part housing being placed over said terminal elements and being secured together to clamp said baille element thereby forming a chamber in said housing, contact means secured to said terminal elements and disposed in said chamber, a cam means for operating said contact means, and means for holding said two-part housing in closed position to provide a completely enclosed switch.

DONALD G. KIMBALL.

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