US2418831A - Electric switch - Google Patents

Description

April 15, 1947.

J. C. HAMILTON ELECTRIC SWITCH Filed Dec. 9, 1943 3 Sheets-Sheet l vf A Buneallic Jmea Cfamila ymffm (www ey April "l5, `i947. J. c. HAMxLToN 2,418,831

ELECTRIC SWITCH Filed Dec. 9, 1943 3 Sheets-Sheet 3 eff: f6

Patented Apr. 15, 1947 ELECTRIC S'WI'ECH hilton, Lexington, Mass., assigner to c cn, incorporated, Qainhridge, Mass.,

ci Massachusetts Appiicaticn December 9, 1943, Serial No. 513,571

(Cl. 26d-67) 5 Claims.

This invention relates to electric switches and. more particularly to thermally actuated rapidly operating spring switches.

It is one of the main objects of the present invention to provide mounting expediente for thermally operated switches of the type described and claimed in copending application Serial No. 513,563, filed on December 5, i943, including a housing permitting convenient and exact asn sembly of the electrical and mechanical elements, as well as secure operation ci such switches, and means permitting, in correlation with such housing, exact and convenient adjustment ci the relative effect of the temperatures upon which depends operation ci the switch.

In one ci its aspects, the invention echtem-- plates a mounting for a switch of this type which has a base block on which the moving switch parts can first be assembled, and additional blocks carrying fixed switch contacts and also serving as a protective housing; in another aspect, the invention provides a -niounting which permits the fastening thereto in cantilever fashion of two actuator strips at accurately predeterminahle distance; in a further the invention prevides a construction which permits mounting oi similarly shaped switch elements in various ways, as with connected or separated, open or enclosed actuator elements; and in still another aspect, the invention provides a pivot connection between two thermally responsive definitely distanced ac tuators and a snap switch spring, which con nection permits convenient and exact adj of the eiiect ci these actuators upon the switci spring.

These and other objects, aspects and features will he more fully apparent from the following description of several practical embodiments illustrating the genus of the invention. The description refers to drawings in which Fig. 1 is a side View, with the iront cover plooi; removed, oi a switch according to the present invention with communicating heat compartn ments;

Fig. 2 a section on line of Fig, l;

Fig. 3 a section on line 3 3 of Fig. 1;

Fig. 4 an expanded section on line ci Fig. 1;

Fig. 5 a fragmentary side view similar to Fig. 1 but with both cover blocks removed;

Fig. 6 a section on line G- of Fig. l;

Fig. 7 a front view of a second embodiment of the invention with one actuator compartment;

Fig. 8 a side view ci a switch according to Fig. 7;

Fig. 9 a section on line 9--9 of Fig. 7;

Fig. l0 a section on line I IJ-I 0 of Fig. 7;

Fig. li a fragmentary side View seen from the right-hand side of Fig, 8 and with the cover plate removed;

12 a fragmentary side View similar to Fig. il., but with the cover plate in place;

Fig, i3 an isometric View of the cover plate shown in Figs. 8, 9 and 12;

Fig. i4 the front view of a third embodiment of the invention with separated actuators;

Fig. l5 a section on line I5--I5 of Fig. 14;

Fig. 16 a fragmentary side View of the switch according to Fig. 14, seen from the right-hand side of Fig. l5;

Fig. l'l a perspective View of the insulation sleeve upon which the heater is wound as shown in Fig. 4;

Fig. 18 an isometric representation of the switch spring, indicating various possibilities of juncture with the connector; and

Fig. 19 a vertical detail section through a connector having three adjustment screws.

in the embodiment shown in Figs. 1 to 6, the switch assembly according to the invention is supported hy a housing made of insulating material such as molded plastic, and consists of a mounting block l and two similar cover blocks 2 and E3, which blocks are held together by screws ti and l?, and holt t. Screws 6 and 'I t into threaded inserts it, l? (Fig. 4) molded into block l, with their ends protruding into a round recess having an upper straight portion, as shown in Figs. 4 and 5. Holes II, I2, I3 may ce provided in blocks l, 2, 3 for the purpose of suitably fastening the switch to a support such as a chassis or switchboard. Ventilating slots I8 may he provided as indicated in Figs. 3 and 4.

r'wo heat- responsive actuator strips 22, 23, for example consisting of bimetal, have on one side widened ends with holes 25 (Figs. 4 and 5) which are slipped over the protruding ends of inserts it, l, recess it preventing strips 22, 23 from rotating on the inserts. The strips are held in place by bosses 25S, El on cover blocks 2, 3 (Fig. 3) which it into recesses 28 of block I.

The actuator strips may be provided with heater coils 32 and 33, preferably wound on insulating sleeves SI or the type shown in Fig. 17. The ends of the heater wire or wires may be connected to terminal bars 36, `3l, 38, 39 which have V-shaped deformations il and it into cor responding recesses i2 of block I wherein they are positively confined when the mounting blocks are screwed together.

Molded into mounting block l are two pivot bars whose pio uding ends are provided with pivot notches 53, (Figs. 1 and 2).

fe bar or rod 55 connects the free ends of actuator strips 22 and 23, the ends of bar 55 being secured within holes 24, for example by means of peripheral recesses 51 on adjustment; sleeves 515 screwed to the threaded ends of bar 55 and accessible through openings 5S of blocks 2 and 3, which openings may be closed by screws 59. Recesses 51 provide pivots permitting free movement of the actuators while determining the distance and eiect thereof, as will be described in detail below.

A conventional switch spring 55 (Figs. 4 and 5) has two compression branches Si, E2 and therebetween a tension branch 63. The common portion carries a contact point 65. The end or" the tension branch S3 is shaped to engage an intermediate point of connecting bar 55, for example by means of a simple perforation BS, a button hole 5? or a hook 5S (Figs. 18 and i9) contacting a central peripheral groove GS of bar 55. The ends '53, 'M or the compression branches El, rest in pivot notches 53, 54 of supports 5| riension branch is shorter than comoression branches i S2, so that the latter will slightly buckle when opening EG engages groove 53 and the tension branches rest in notches 53, 5:3, provided of course that, as shown in the present instance, the notches are arranged at the approximate height of the connector groove S9.

In the gures, the contact B5 is shown throughout in central position between faces 82 and 83; it should be understood that this position has been selected for the sake of convenient presentation only and that the movable contact will always rest on one or the other of these faces.

The contact point 65 cooperates with contact faces S S3 which are part of L- shaped Contact bars 54, 55 molded into cover blocks 2 and 3 which have recesses S1 forming together a chamber confining the contact point G5. The contact bars 84, protrude from blocks 2 and 3 with terminal ends 35 and 8S which, in order to provide proper spacing, may be staggered as indicated in 1. The terminal for the double throw switch spring dal, making contact either at 82 or 83, may be at S9, the circuit leading from contact point through branch 53, bar actuator 22 or 23, insert l5 or i1 to screws f5 and l, either of which may be used as a terminal. It will be understood that one contact face may be replaced by insulation if it is desired to provide a single throw switch.

The above-described embodiment is especially well adaptable for differential actuation when both actuators are provided with heaters as shown in these Figs. l to 6, or for use with only one heater on a controlling actuator while the other actuator compensates for ambient temperature within the switch.

Ii it is desired to apply to one actuator the temperature of the general environment rather than that of the switch structure, an embodiment may be preferable which is similar to that shown in Figs. '7 to i3 which will now be described.

In the embodiment according to Figs. T to i3, amounting block i0! carries inserts H6, ||1 holdactuators 23 and connecting to terminal 55 in a manner similar to that described with reference to Figs. l to G. The single heater coil |32 is connected to the single pair of heater terminals |35, 31. The mounting block |21 is extended upwardly beyond spring |33 and carries, moulded thereinto, a contact bar |89 whose face |83 coopcrates with Contact point |65 Within chamber |88, |31. The contact face |82 of the second bar |88 is moulded into a cover block |02 which is fastened to block |0| by means of screws |06, and bolt |08. Pivot supports |5I, |52 with notches |53, |54 are again moulded into block |0|, and the arrangement of actuators |22, |23, screws |06, |01, connecting bar |55, and switch spring |60 with branches |6|, |62, |63 is similar to that described with reference to Figs. l to 6.

The connector |55 reaches actuator |23 through an opening |20 which, if desirable, may be lined with heat-insulating material. Ventilation openings ||8 may be provided, as shown in Figs. '7 and 9.

The bare actuator |23 may be protected by a slotted cover plate |04 having a boss |21 tting into the corresponding recess |42 of block |0| and holding actuator |23 by means of screw |01; a top ange H0 fits a corresponding groove ||3 of block IN. Holes ||2 may be provided for fastening the switch to a. support.

If it is desired to apply the temperatures prevailing at two separate points by means of two bare actuator strips and to render the operation of the switch dependent upon the relation of these temperatures, an arrangement according to Figs. i4 to 17 may be used to advantage. In these figures, the mounting block 20| is provided with a ange 205 by means of which it can be fastened to a wall 203 separating the spaces at different temperatures.

The block 25|, similar to block |0| shown ln Figs. 7 to 13, has moulded-in inserts 2|6 and 2|1 holding the actuator strips 222 and 223 and notched pivot bars 25|, 252. Connecting bar 255 together with bars 25|, 252 hold the switch spring 260 in the above-described manner. Insert 2|1 may be contained in a boss 2|8 of block 29| which protrudes through an opening in wall 250 and carries, fastened thereto by screw 201, a slotted cover plate 203. A second slotted cover plate 202, fastened to block 20| by screw 206 and bolt 208, carries contact bar 288 moulded thereinto, corresponding to a contact bar 289 similarly fastened to block 20|. The contact point 265 is arranged between contact faces 282 and 283, as above described. In order better to separate the medium surrounding actuator 223 from that surrounding actuator 222, a heat-insulating bushing 250 may be provided for leading bar 255 through wall 200.

es shown in Fig. 19, the tension branch 263 of switch spring 250 may be pivoted in groove 20| of an adjustment nut 300 threaded to the connector between sleeves 256 With grooves 282, for actuators 222 and 223. In this manner it becomes possible to adjust the relative positions of actuators and switch spring very accurately in order to ascertain proper cooperation of the actuators in moving the switch spring. Means rendering these adjustment sleeves easily accessible may be provided. as indicated by way of example lat 259.

It will now be apparent that the inner faces of recesses I9, as shown in Figs. 1 to 6, permanently and accurately define the distance of actuators 22, 23 and that the construction as a whole provides rigid cantilever-like mounting of the actuators. rhis marmer of mounting permits the use of connectors 58 having fixed pivot points whose distance can be predetermined in relation to the actuator distance; it also permits, if desired, the accurate and permanent adjustment of the entire v` switch assembly by means of the screws shown in Fig. 19 or similar arrangements. Adjustment of the central pivot `at Sil permits change of contact between faces 282 and 283.

It will further be understood that the current conducting connection to the movable contact E5 must not necessarily lead through an actuator but that it may be preferable to connect this contact directly with a conveniently placed terminal, for example thro-ugh a flexible cord.

The abovadescri ed devices operate as follows.

The pivot points itl, M2, 293, 253, 254 of switch 222, 223, 25o (Fig. 19) are so adjusted, either by suitable initial dimensioning or adjustment with the aid of sleeves i355 or nut 39rd, that Contact point 265 assumes under normal conditions the desired position either on contact face 282 or on face 283.

The actuators are so dimensioned and mounted that they provide thev desired switch response. Referring for example to Figs. l. to 5, if the actuators are mounted to deflect inwardly with rising temperature, if their rate of deflection is the same and their heater elements similar, the switch will remain in normal position so long as the currents in the respective coils are the same, in which oase the equal tendencies to deflect in opposite direc tions cancel each other. i, however, one actu ator deection, due to the corresponding heating effect, outweighs the other, the switch will be operated. Assuming for example that point 65 rests normally on contact face S2 and that the actuator-s deilect inwardly with rising tempera ture, the contact point 55 will rapidly move from face 82 to face B3 when Aheater 33 becomes so much warmer than heater 32 that the denection of actuator 23 towards the left outweighs that of actuator 22 towards the right. Bar 55 will then move towards the left, thereby causing the lines of stress of the switch spring branches to move through a limiting relative position, with the directions of the forces acting on the pivots of the branches of the switch spring passing each other, and point E5 to move rapidly towards the right, connecting terminal Si! with terminal bil instead of 88. Ait the time, any ambient temperature effect is inherently excluded so long as the actuators are not deliberately hept separated as for example in the embodiments of Figs. 14 and l5. It will be evident that any change in ambient temperature will aiect both actuators equally but in opposite direction, the two virtual deflections cancelling each other. Upon reversal of the temperature relation of the two actuators, the switch will move back into initial position.

If only one heater element is used, as in the embodiment according to Figs. '.7 to 13, the second actuator merely provides compensation for ambient temperature changes, rendering the eiect of the actuating heater H52 independent of the ambient temperature so that it can be safely relied upon to operate the switch when its heating current attains a denitely determinable value.

In embodiments where the two actuators are not affected by the same ambient temperature conditions, as for example in that shown in Figs. 14 and 15, switches according to the invention can be operated responsive to an absolute difference of two temperature conditions. rlhese temperatures may either be ambient ones or, if one or both actuators are provided with heating coils, the algebraic sum of ambient and superimposed control temperatures will be effective in operating the switch.

It should be understood that the present disclosure is for the purpose of illustration only and that this. invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

l. A switch of the type having an operating member which is adapted to move with a member connecting the movable ends of two actuator strips having mounting means at their other ends, said switch comprising a mounting block adapted to receive saidr mounting means of said strips on opposite sides of said block, said mounting block having a wall portion extending crosswise of and having an opening for said connecting member, a cover block adapted to form with said mounting block an enclosure for said operating member and one of said actuator strips, and means for fastening said cover block to said mounting block.

2. A switch of the type having an operating member which is adapted to move with a member connecting the movable ends of two actuator strips, said switch comprising actuator strips having perforations at the ends opposite to their moving ends, a mounting block having a threaded insert extending beyond the inner face of a dee pression in said block said insert and said depression substantially tting one of said perforated ends, cover means fitting said depression, and means for fastening said end in said depression between said block and said cover means.

3. A switch of the type having an operating member which is adapted to move with a member connecting the movable ends of two actuator strips having mounting means at their other ends,

said switch comprising a mounting block having a recess formed to t said mounting means and a groove adjacent said recess, a conductor bar tting said groove, cover means fitting said mounting means on said recess and said bar in said groove, and means for fastening said mounting means and said bar between said block and said cover means.

fl. A switch of the type having a snap switch unit with a tension spring member and a compression spring member joined at a contact portion, one member being supported at fixed pivots and the other member being held at a pivot which is adapted to move with a connector between the movable ends of two actuator strips which extend substantially in the direction of the lines of stress of said members, and which have mounting means at their other ends, said contact portion moving rapidly when the directions of stress of said members pass a limiting relative position due to relative movement of said pivots; said switch l comprising a mounting block adapted to receive said mounting means of said strips in positions substantially parallel to said directions, and having means constituting said fixed pivots; a cover block extending alongside said spring members and substantially enclosing one of said strips, and carrying a contact member opposite said contact portion; and means for fastening said cover blocks to said mounting block.

5. A switch of the type having a snap switch unit with a tension spring member and a compression spring member joined at a contact portion, one member being supported at xed pivots and the other member being held at a pivot which is adapted to move with a connector between the movable ends of two actuator strips which extend substantially in the direction of the lines of stress of said members, and which have mounting means at their other ends, said contact portion moving rapidly when the directions of stress of said members pass a limiting relative position due to relative movement of said pivots; said switch comprising a mounting block adapted to receive said mounting means of said strips on opposite sides of said block in fixed positions substantially parallel to said directions, a mounting block having means constituting said xed pivots; a cover block extending alongside said spring members and substantially enclosing one of said strips, and carrying a Contact member opposite said Contact portion; means for fastening said cover block to said mounting block: and means associated with said connector for adjusting the distances of said moving pivot and of said Inovaole ends.

JAMES C. HAMILTON.

REFERENCES CITED The following references are of record in the iile of this patent:

Images