US2288406A - Positioning means for electric switches - Google Patents

Description

June 30, 1942. D. G. KIMBALL 2,288,406

POSITIONING MEANS FOR ELECTRIC SWITCHES Original Filed April 13,11938 2 Sheets-Sheet l Invent-or: Donald @.Kmball,

His Attorneg.

' June 30, 1942. D. G. KiMBALL 2,288,406

POSITIONING MEANS FOR ELECTRIC SWITCHES Original Filed April 13, 1958 2 Sheets-Sheet 2 MED/UM Inventor:

Donald G. Kmbail,

His Attorneg.

Patented June 30, 1942 POSITIONIN G MEANS FOR ELECTRIC SWITCHES' Donald G. Kimball, Stratford, Conn., assgnor to General Electric Company, a corporation of New York Original application April 13, 1938, Serial No. 201,786. Divided and this application August 14, 1940, Serial No. 352,602

6 Claims. (C1. M -527) The present invention relates to positioning means for electric switches, and more particularly to positioning means for a rotary switch. This application is a division of my copending application Ser. No. 201,786 filed April 13, 1938, for Electric switches.

It is an object of the invention to provide an improved construction and arrangement in positioning means of this type which will accurately position a switch mechanism in any one of a plurality of angularly spaced positions without permitting the switch mechanism to remain in an intermediate position.

In the accompanying drawings Fig. 1 is 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 oil position, and Figs. 9, 10 and 11 are diagrammatic views showing the switch in high, medium and low positions, respectively.

Referring to the drawings, an electric switch of the type employed with my invention is indicated generally at I0 and comprises a two-part casing formed of molded material, such as a phenolic condensation product and ller, with the upper part I'I 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.

Extending through the casing is a non-circular shaft I5 which is rotatably supported by means of circular openings (not shown) formed in the front and rear walls of the casing. The rear portion of the shaft I5 extends through the casing and is provided with a split washer I 6 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 I1.

A plurality of operating cams I8, I9 and 20 are spaced longitudinally along the shaft I5 and r are formed with appropriately positioned depressions to cooperate with a 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 respective cams to form a multi-contact switch mechanism.

Cooperating with the cam element (Fig. 6) is a contact mechanism including a lower terminal element 2I which may be connected to one of the load lines and a corresponding upper terminal member 2| which may be connected to a heater element. The terminal member 2|' is provided with a horizontally disposed exible contact blade 22 provided at its end with a silvered contact point which cooperates with a corresponding contact point on the terminal element 2| to form a contact 23. The blade is provided with a depressed portion 24 which cooperates with the cam 20. The terminal member 2I is likewise 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 3l to form a contact 26. In order to cooperate with the cam 20 the contact blade 25 is formed with an extended portion 25. The terminal element 2I is provided with an extension 2l which 1s secured to a barile plate 28 by means of a hollow rivet 2l. Correspondingly, the terminal member 2I is provided with an extension 33 which is secured to the baille plate 28 by a hollow rivet 3|'. The baille plate 28 is disposed in grooves 29 formed in the upper and lower housing members I 0 and II, and thereby forms a chamber for the terminals 2| and 2I, the contacts 23 and 26, and the cam element 2li. 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 the casing adjacent the terminal member 2 I and is provided with an offset portion 33 bearing a spring Contact blade 34 having a depressed portion 34 for engagement with the cam I9. The blade 34 carries a silvered contact point at its outer end which cooperates with a Contact point formed on an extension 35 of the terminal element 32 to form a Contact structure 36. The terminal element 32 is provided with a second extension 31 opposite the extension 35 having a silvered contact point cooperating with the contact on the blade 25 to form the contact structure 26 above described. The extended portion El' of the terminal element 32 is bent at right angles to the terminal element and extends through an opening 23' in the baffle plate 28 to form the contact 23, as best shown by Figs. 5 and 6. The terminal element 372 is secured to a second barile member 35S by a hollow rivet 3Q while the corresponding terminal element 32 is likewise secured to the baffle member by a hollow rivet 33. The baiiie member 3B 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 5d immediately adjacent the baiile plate 28.

rEhe contact structure which cooperates with the third cam element 3 is best shown by Fig. 4, and comprises a terminal element Ml which may be connected to a load line and a corresponding terminal member 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 d is provided with a longitudinally extending Contact blade il provided at its outer end with a silvered contact point to cooperate with a corresponding contact point on the terminal element i0 thereby forming a contact structure 52. In order to engage the cam element i3, the contact blade il is provided with a depressed portion dii. To secure the terminal element l to a baffle plate lill the terminal element is provided with an extension i5 fastened to the baile plate lli by means of a hollow rivet 56. The terminal member QU' is provided with a depending arm 4l which is likewise secured to the barile plate lill by means of a hollow rivet Q8.

It will be apparent that the yrespective terminals are secured to the baiiie 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 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 baffle plates 28, 33, and lili 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 2l, 32 and it@ are each provided with clamping means comprising screws d which cooperate with arms 5l. The arms are provided with arcuate ends 52 which may receive comprising screws Ell and the locking plates 55.

The locking plates 55 are provided with indentations 5t which receive the heater cable and cooperate with the terminal members to clamp the cable.

The switch thus far described is provided with a positioning means constructed in accordance with my invention and which is disposed between the iront Wall of the switch casing and the baffle plate rlhis positioning mechanism, as best shown by Figs. 3 and 7, comprises a plate 57 mounted upon the shaft l5 by means of an opening 58 contoured to the dimensions of the shaft. The plate El is provided with a plurality of diametrically opposed pins E9 which are seated within openings 5B forming part of the coil torsion springs 5! The ends of the springs are provided with loops Z which engage a lug t3 formed on each of the opposed links 6s. 'Ihe links are provided with extending pins G5 and arms 5S, the latter being provided with keyhole slots Si. Antifriction rollers are mounted on the pins. In the assembled relationship of the positioning means the pins 59 extend through the openings B forming part of the torsion springs and likewise extend through the keyhole slots 67 provided in the link arms 65, As shown more particularly in Fig. 3, the rollers -65 cooperate with indentations t3 formed in the front wall of the housing. The springs 6l bear against the lugs 63 and maintain the rollers E5' within the indentations 62. The indentations t8 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 G3, thereby pivoting the links @fi about one oi the pins 59 so that the rollers 65 will ride up the side of the indentations 68 and snap over into the adjacent one. If the switch handle is stopped before the tops of the indentions are reached, the springs will cause the links to rotate back into the bottoms of the indentations. In this manner the switch cams are accurately located for all positions of the switch and the switch cannot be left in an intermediate position.

One use of the device is as a heater switch for controlling the heat to a plurality of resistance heaters H1, H2. In practice it may be desirable to place these heaters in an oven and to regulate the heat of 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 to the 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 2l and ii-S are connected to the outside load lines L1 and L2, 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. The other end of the heater H1 is connected to the terminal du' and the corresponding end of the heater H2 is connected to the terminal member 2i'. The various positions of the switch such as offj high, medium and lc-w are shown by Figs. 8 to il, respectively. It should be noted that the dwells or recesses in the cams are properly positioned to operate the depressed portions or" the respective 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.

In Fig. 8 the switch is shown in oir position with the contacts d'2, 35, 23 and 25 all open. In Fig. 9 the switch is shown in the high position and current is caused to iiow from each of the load lines Ll 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 L1 passes through the terminal element 40, contact 42, heater element H1, neutral 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 heater elements H1 and H2 are connected in parallel and are each subjected to a potential of 110 volts in the case where currents of that voltage are employed.

Turning the operating handle to the medium 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 36 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 2.

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 ows from the line L1 through terminal element 40, contact 42, heater elements H1 and H2, terminal 2l', contact 25, and back to the neutral terminal 32. No current is applied through the medium of terminal member 2| because 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 on position and three heat positions. By turning the handle clockwise, as shown in Figs. 8 to ll, 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, om 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 effectiveness. 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 baie 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 baffle plates, a compact and 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.

I claim:

l. In a positioning mechanism for an electric switch having a rotatable switch operating element, a stationary element having indentations formed in a wall thereof, a plate having opposed studs mounted on the rotatable element, links having rollers disposed in said indentations, said links being mounted on said studs, and torsion springs mounted on said studs bearing against said links to maintain said rollers within said indentations.

2. In an electric switch mechanism, means to locate the switch mechanism in predetermined positions for operation thereof, said means comprising a plurality of circumferentially disposed indentations formed in a xed portion of said mechanism a plate rotating with a rotatable portion of said mechanism, said plate having opposed studs thereon, a. link mounted on said studs and provided with means cooperating with said indentations and a torsion spring mounted on one said stud and bearing against said link to maintain said means within said indentations thereby positioning said plate and switch mechanism.

3. In an electric switch, a rotating circuitcontrolling member adapted to be disposed in a plurality of predetermined positions, means to locate said member in said predetermined positions, said means comprising an element formed with a plurality of circumferentially disposed indentations, a plate having opposed studs, said plate being rotatable with said rotatable member, a pair of opposed links mounted on said studs, said links having rollers cooperating with said indentations and torsion springs mounted on said studs and bearing against said links to maintain said rollers within said indentations and to mantain said rotatable member in any one of said predetermined positions.

4. An electric switch having a rotatable circuit controlling means adapted to be located in a plurality of predetermined circuit-controlling positions, means to locate said circuit-controlling means in said predetermined positions, said means comprising an element having a plurality of circumferentially disposed indentations corresponding to said predetermined positions, a member having opposed studs rotatable with said rotatable circuit-controlling means, a plurality of links having opposed arms provided with keyhole slots, said links being mounted on said element with said studs extending through said keyhole slots, said links being provided with means cooperating with said indentations and torsion springs mounted on said studs and bearing against said links to maintain said means in cooperating engagement with said indentations to locate said element and said circuit-controlling means in any one of said predetermined positions.

5. A' positioning mechanism for electric switches having a rotatable operating means movable to any one of a plurality of predetermined positions comprising, in combination, stationary means identifying the predetermined positions of the rotatable operating means, a member having opposed studs rotatable with the switch operating means, diametrically opposed links each having arms provided with keyhole slots for mounting said links on said studs, each of said links being provided with a projecting portion cooperating with said position-identifying means, and a spring mounted on each of said studs, each spring being provided with arms engaging said links to bias the links into engagement with the position-identifying means to locate the switch operating means in any one of said predetermined positions.

6. A positioning mechanism for electric switches having a rotatable operating means links movably mounted on said supporting studs, and spring means biasing said links into operative relationship with said stationary position identifying means upon rotation of the switch operating means.

DONALD G. KIMBALL.

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