US2286965A - Electric switch - Google Patents

Description

June 16, l942 D. w. JoHNsoN y 2,286,965

ELECTRIC SWITCH Ti Z..

June 16, 1942. D. w JoHNs'QN ELECTRIC SWITCH Filed April 12', 1941 2 Sheets-Sheet 2 60 Invenar DAVID W. JOHNSON by hzls a'arneys Patented June 16, 1942 2,286,965 ELECTRIC SWITCH David W. Johnson, New Britain. Conn., assigner to The Arrow-Hart a Hegeman Electric Co., Hartford, Conn., a corporation of Connecticut Application April 12, 1941, Serial No. 388,333

15 Claims.

This invention relates to electric switches. More particularly it relates to manually-operable electric switches having provision for automatic operation upon the occurrence of an overland current.

It is an object of my invention to provide improved switch structure provided with thermally-responsive means for causing separation of the switch contacts on the occurrence of an overload.

Another object of the invention is to provide in a switch of the above type improved means for adjusting the setting of the overload responsive means.

Another object of the invention is to provide in a switch of the above typemeans for causing opening of the contacts automatically and means for adjusting the overload characteristics by varying the position of the operating mechanism with respect to the thermally-responsive parts.

Other objects and advantages of my invention will become apparent as it is described in connection with the accompanying drawings.

In the drawings- Fig. 1- is a longitudinal section view of the invention taken substantially along the line I--I of Fig. 5, with the switch parts in manually openedv position;

Fig. 2 is a longitudinal section view, partly broken away, showing the switch parts in closed circuit position;

Fig. 3 is a side elevation view, partly in section, showing the Aswitch parts in the position they occupy after automatic'operation;

Fig. 4 is a longitudinal section view taken along line 4-4 of Fig. 5, with the parts in manually-opened position;

Fig. 5 is a plan veiw of the invention;

Fig. 6 is a transverse section view taken along line 6-6 of Fig. 5.

Referring to the drawings, the parts of the switch are mounted within a rectangular insulating block or base I that is hollowed out from the bottom to form communicating cavities for the switch parts.

Adjacent the sides of the base are cavities in which move mutually-insulated contact members 44 and 46 made from thin strips oi" springy highly-conductive metal. One end of each spring contact is anchored in position by a hollow rivet, such as B, which extends through the top of the base` The other ends of the contacts 44 and 4B are provided with contact buttons 44e and 46c which engage with stationary contact buttons 52e and 54o on the bottom ends of hollow rivets 52 and 54 that extend through the top of the base I0 at the opposite end from the rivets 58. Screw bolts 50s, 5I, 52s and 54s thread into each ofthe hollow rivets 50, 52, 54. The screws 50s, 52s and 54s are binding screws for lead wires.

(Cl. 20D-116) A slot ills extends through the top of the base I0 for the accommodation of a stamped sheetmetal operating lever I2, upon the outer end of which is a molded insulating handle I4 Qf conventional design. The operating lever I2 is of irregular shape, as may be seen in Figs. 1-4. It is pivoted at a central point about a iixed pivot I6 which is mounted in slots I8 in a central position in the side walls of the base cavity. On the bottom or inner end of the operating member I2 there is a hook-like formation around which is looped one end of a coiled tension spring 20. The other end of this coil spring is secured Yto the central portionl of a U-shaped oscillatory switching member 22. The switching member 22 preferably is stamped from sheet metal and provided with bifurcated ends. The bifurcations 22a extend through a pair of closely-spaced apertures in a' flat adjustment bar 26 straddling and pivoting about the narrow portion 26d of the plate between the apertures. The parts are proportioned and positioned so that as the handle member I2 is rocked, its lower end will pass over the pivotal axis of the switching member 22 carrying with it the line of action of the spring 20 whereby the member l 22 is moved from a positionv (Fig. 2) wherein its transverse portion abuts a vertical wall of the casing to another position (Fig. 1) wherein it stands relatively vertically.

Pivotally mounted upon one leg of the member 22 is a tripping or latching member 30 which is stamped from sheet metal into the angular shape as illustrated. The member 30 is pivotally mounted onv member 22 by a pin 2B passing through-its central portion and through an enlargement upon one side edge of one of the legs of the member 22. The upper end of the member 3l has an abutment iinger 32 turned out at right angles to the plane of the member in position to engage with and abut against one end of a bi- .metallie thermally-responsive member 34. The

other end of the member 30 has a foot portion 38 bent at right angles to the plane of the main portion of Athe member 30. The plane of the foot portion 38 is substantially parallel to and overlies the plane of the adjustment bar 26 in the open circuit positions of the switch parts, as illustrated Yin Figs. 1, 3 and 4.

For Vthe purpose of operating the movable switch contacts 44 and 46, a bar of insulating material 40 is positioned in a vertical slot 42 in the insulating base and has its lower edge resting upon the upper surface of the foot portion 38 of the member 30, so that as the foot portion 38 moves up and down, it will cause 'similar vertical movement of the insulating bar 40.

By referring. to Fig. 1, it. will be noted that with the handle member I2 inthe position there shown, the effort of the switch spring is to move the switching member 22 in a clockwise directhat position, the abutment 32 on the member 30 is disengaged from the end of the thermal member 34 so that the force of the spring contacts 44 and 464 exerted upon the insulating bar 40 and through it on the foot portion 38 of the member 30 causes the member 30 to rest its foot portion upon the upper surface of-the adjustment plate 26 with the xed and movable contacts disengaged. If.- now, the operating member is moved about its pivot i6 to the position of Fig. 2, the line of -action of the switch spring will be moved across thev pivotal axis of the switch member 22, causing that member to lmove counter-clockwise to theA position shown in Fig. 2. This movement will cause the pivotal connection 28 between the member-30 and the operating member 22 to move to the left from the position of Fig.- 1 to the position of Fig. 2. Such movement causes the abutment 32 to engage the end of the bimetallic member. and thereafter causesthe member 30 to pivot about its pivotal connection 28 with the switch member 22, in turn causing clockwise movement of the member 30, raising the foot portion 38 .thereof to the position of Fig. 2 and at the samei time moving the insulating bar 40 upwardly. The upward movement ofthe insulating bar carries the flexible contact members 44 and "46 upwardly, engaging the contact buttons on the ends thereof with the stationary contact buttons.

For the purpose of inuencing the bimetal 34, there is provided directly above the bimetal a heating coil 60, which may-b e housed within an insulating shield 62 to conserve its heat and ldirect the heat against the bimetal. The coil 60 is connected with the bimetal by having one end of the coil secured in position by the screw 5| that threads into the hollow rivet 50. The other end of the coil GII is secured by a screw 68 to a conductive bar extending transversely of the casing. A securing bolt 'l2 passes through the top of the casing into the bar 'I0 to'secure it in position. At the opposite side of the casing` from the attachment bolt or screw 68 a terminal screw 14 threads into the end of the conductive bar 10.

In connecting the switch to power lines, one wire of the power lines is attached beneath the head of the securing screw 54s, while the other power line is connected beneath the head of the securing screw 52s. The wires of the circuit to be controlled are connected to the terminal screws 50s and 14.

When the switch is in closed circuit po'sition, the current from one line enters through terminal 54 and passes through the movable contact 46 to the hollow rivet and terminal screw 50s and the circuit. The current from the other line enters through terminal 52 i and passes through the'movable contact 44 to the hollow rivet 50, heating coil il, transverse conductive bar 'l0 to the terminal screw 14 and the circuit.

Upon the occurrence of an overload, heat will `be generated in the coil ill, causing the bimetal member 34 to ex upwardly, disengaging its end from the Aabutment 32 on the member 30. The resilience of movable contacts, which tend nor- '.ly toseparate from the xed contacts, exerts a force upon the insulating bar 43 and through it on the foot of the member 30. This force is restrained while the switch parts are in closed circuit position due to the abutment 32 engaging the end of the bimetal member 34. However, when the abutment 32 is free from engagement I tion'v so as to hold it in the position shown. In

with the end. of the bimetal 34,. the member 3l can move in a counterclockwise direction, per.-

mitting the movable contacts to move down-A wardly and disengage from the xed contacts.

In order to adjust the relative position of the abutment 32 to the end of the bimetal 34, the adjustment bar 26 is mounted upon an adjustment bolt 80 which passes through the casing from top tok bottom. The lower end of the adjustment bolt is screw threaded and takes into a screw threaded aperture in the adjustment plate26. By this means,.rotation of the adjustment bolt 80 will cause the adjustment plate 2G to move up and down along the axis of the adjustment bolt. Since the contact moving parts of the switch mechanism are al1 supported by the adjustment plate 26, it will move up or down as a unit as adjustment is made. Thus, the relative position of the abutment 32 to the end of the bimetal 34 may be varied by bodily movement of the switching mechanism as a whole. By this means, adjustment may be made of the device without imposing any stress or strain upon the bimetal member and without varying its initial set or its inherent characteristic set. It is, therefore, possible to adjust the device very accurately and the device will operate according to its adresponsive, automatically and manually operable switch mechanism having few and simple parts which are easily manufactured and assembled and which operate in a very accurate and reliable manner. I have `furthermore provided a novel means for adjustment which can be operated without moving the thermally responsive element but by moving the switch mechanism instead.

Many modications of the invention will occur to those skilled in the art. Therefore, I do not limit it to the specific embodiment illustrated and described.

I claim:

l. In an electric switch, a manuallyvoperable spring biased operating mechanism, separable contacts engageable and Ydisen'gageable by said mechanism, overload operating `means operable to cause separation of said conta-cts, and means to adjust the overload setting of the switch by moving said-`operating mechanism relatively to said overload lmeans Without moving the over-` load meansi! l y 2. In an electric switch, a manually operable operating mechanism, separable contacts engageable and disengageable by said mechanism, overload operating means operable to cause separation of said contacts, and means to move said operating-mechanism yrelative to said overload means while the latter remains xed, for the purpose of adjusting the overload operating characteristic of the switch. ,l

3. In an electric switch, a manually operable operating mechanism, separable contacts vengageable and disengageable by said mechanism, overload operating means operable to cause separation of said contacts, and meansy to move said operating mechanism relative to. said overload means while the latter remainsv xed,vior the purpose of adjusting. the overload operating characteristic of the switch, an insulating base housing said mechanism and having exteriorly accessible terminals for making connections to the switch, and an adjustment member accessible at the front of the base for adjusting the position of said operating mechanism.

v4:. In an electric switch, a manually operable operating mechanism, separable contacts engageable and disengageable by said mechanism, a bimetallic member engaged by a part of said mechanism and adapted to disengage said part on overload to cause separation of said contacts, and means to adjust the relative positions of said bimetal and operating mechanism by moving said mechanism while said bimetal retains its position whereby the overload setting of the switch may be varied.

5. In an electric switch, a manually operable operating mechanism, separable contacts engageable and disengageable by said mechanism, means biasing said contacts toward separated position, overload operative means operable to release said mechanism and permit said biasing means to separate said contacts on overload and means to move said operating mechanism relative to said overload means while the latter remains xed, for the purpose of adjusting the overload operating characteristic of the switch.

6. In an electric switch, separable contacts, manual operating means, pivotal lmeans opera.- ble by said operating means, tripping means having a movable pivoted connection with said pivment of said operator, a tripping member pivotally mounted on said rockable member and movable by said rockable member, separable contacts otal means, said pivoted connection moving in y response to movements of said manual operating means to accomplish contact engagement' ble by said operating means, tripping means having a movable pivoted connection with said pivotal means, said pivoted connection moving in response to movements of said manual operating means to accomplish contact engagement and separation, and overload responsive means normally engaged by said tripping means and arranged to release said tripping means onoverload to accomplish contact separation.

8. In an electric switch, separable contacts, manual operating means, pivotal means operable by said operating means, tripping means having a movable pivoted connection with said pivotal means, said pivoted connection moving in response to movements of said manual operating means to accomplish contact engagement and cause separation and overload responsive means normally engaged by said tripping means` and arranged to release said tripping means on overload to accomplish contact separation, and

' means to adjust the position of said tripping means relative to said overload responsive means While the latter remains unmoved.

tacts ,engaged and separated by movements of engaged and separated by movements of said tripping member as said operator is moved, and overload means to release said tripping member to cause contact separation automatically, adadjustable supporting means for said rockable member causing movement of the switch mechanism toward or away from said overload-means to vary the overload characteristics of the switch.

11. In a switch, a pivoted operator, a rockable member having a spring connection with said operator and being movable in response to movement of said operator, a tripping member pivotally mounted on said rockable member and movable by said rockable member, separable contacts engaged and separated by movements of said tripping member as said operator is moved, and a bimetal strip engaged by said tripping member and releasing said tripping member on overload, and a movable support for moving said tripping member relative to saidbi-metal 'strip while the latter remains stationary, whereby variation of the overload setting can be made.

12. In an electric switch, a manually operable operating mechanism including spring biasing means, separable contacts engageable `and disengageable upon actuation of said mechanism, overload operating means operable to cause separation of said contacts, and means to move said operating mechanism relative to said overload means while the latter remains ilxed, for the purpose of adjusting the overload operating characteristics of the switch.

13. In an electric switch, separable contacts.

manual operating means, pivotal means operable' by said operating means, spring means to cause l said contacts to engage and disengage, tripping means having a movable pivoted connection with said pivotal means, said pivoted connection moving in response to movements of said manual operating means to accomplish contact engagement and separation.

14. In an electric switch, separable contacts, manual operating means, pivotal means operable by said operating means, spring means to cause said contacts to engage and disengage, tripping means having a movable pivoted connection with said pivotal means, said pivoted connection moving in response to movements of said manual operating means to accomplish contact engagement and separation, and overload responsive means normally engaged by said tripping means and arranged to release said tripping means on overload to accomplish contact separation.

15. In an electric switch, separable contacts, manual operating means, pivotal means operable by said operating means, spring means to cause said contacts to engage and disengage, tripping means having a movable pivoted connection with said pivotal means, said pivoted connection moving in response 'to movements of said manual operating means to accomplish contact engagement and separation, and overload responsive means normally engaged by said tripping means and arranged to release said tripping means on overload to accomplish contact separation, and means to adjust the position of said tripping means relative to said overload responsive means while the latter remains unmoved.

DAVID W. JOHNSON.

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