US1986507A - Thermostatic switch - Google Patents

Description

Jan. l, 1935. l. w. KNIGHT 1,986,507

THERMOSTATIC SWITCH Filed July 29, 1932 ,2f fm fl *ggf #lie/ww, BY Y M/ A TTORNEY. A

Patented Jan. 1, 1935 UNl-TEDSTATES PATENT OFFICE THERMOSTATIC SWITCH Ira W. Knight, Providence, R. I., assigner to General Fire Extinguislier Company, Providence, B. I., a corporation of Delaware Application July 29, 1932, Serial No. 625,778

3 Claims. (Cl. 20o-142) This invention relates to improvements inA Figure 4 is another elevation of tlie same as on thermostatic switches. More especially it relates line 4--4 o! Figure 3;

to improvements in the type of switch disclosed Figure 5 is an elevation like Figure 3 but with in Letters Patent No. 1,852,312 granted to me on the parts shown in the positions assumed upon 5 April 5, 1932. operation of the switch; and 5 The switch of the patent is adapted primarily Figure 6 is an elevation, partly in section, showfor surface mounting with the binding posts exing an alternative arrangement of the contact ternally arranged for connection with exposed Points f0 1 a dierent-standby ConditOn.'

wires. Indeed, one of the contact members, (the Befelrlng mOIe particularly t0 the drawing, the

diaphragm disk) is fully exposed, which is unliglh Shal a' tffekluomeddof 111511195151118' mii;- 10

desirable especially when said member is carryel f 1u: ils f a e I1,h!1 OIItlprlSlng a chding live current. And in the patented switch, if it Cut'r l? a eb a lfm W Ct Drolc S 9D one .S1 e

becomes necessary to inspect the contact points, :'ocklnlll i); Inangnho't sfr gollf,

rggngisnhn zee rgild :Sutwtle ls housed the contact points 2, 3, one (2) being subl5 stantially immovable and the other (3) being a preventing an operating test of the points while movable spring point These points are Shown thtsiwltch 1s dismantled' as riveted to bushings 4 which fit into suitabie s an object of the present invention to pro holes in the b tt u f th b d vide a switch for surface mounting with binding th 0, om Wa 0 e 0X an are posts internally arranged for connection with readed to receive binding screws 5. The'latter 20 may bind the terminal ends 6 of wires directly concealed wires. Indeed it isaieature of the imto the bushings 4 as Shown at the right in proved switch that all the electricity carrying i members are fully concealed. When inspection goglzoor liletnaype Prfvled fpla exteig; of the switch is desired the contact points are 2 is at on: 5d fetgn) 1S asme b efpf easily accessible without disturbing the circuit kinds de engin 0 e gxtn my $1 zo 25 connections, thus permitting operative tests to mantainpa circlgngrnwore cled nslrcnmlna mf'ely made while the switch 1s partly dls staiiby or quiescent conditions. If open, the

It is also an object of the invention to provide p0 2 is so dlspoed .as O, overhe the Sprtng not only a spring contact member whichfcndguelhnothmeuar; sen1f-lfled mg pomt 30 stantly tends to change its positionlbut to pro- In either case the movable point Sgiusrield in its vide separate resilient means for normally holdinitial or standby position by a button 7 of b mg uns .lmber against s.uch change sald sep' sulated material having an extended point 7a that arate resilient means being so arranged that engages the spring Contact point and having an 35 when the swltch as a' whole rsfponds to apre annular shoulder 7b that rests on the edge of a determined temperature condition the resilient hole 8a in a disk 8 The latter is a simple plain means acts to remove itself and leave the spring nat metallic disk having inherent but normauy' contact member entirely free to follow its own dormant resiliency. In the arrangement Shown 40 moving force' It is a eature of me mventlon its edge 8b is clamped between a seat la provided 40 to so mount a simple plain fiat metallic disk, havon the base and a ring 9 which threads into the ing inherent but dormant resiliency that this raised Socket rim la This Img has three up resliency is rendered active by the mere fast standing arms 9a which come together above the enmg of me fnsk button and form a supporting yoke for a ther- While itis intended that the patent shall cover many responsive element 10 that is inte d 45 by suitable expression in the appended claims between the yoke and the button Ip use whatever features of patentable novelty exists The element disclosed here is a Sealed frangiin the invention disclosed, a preferred embOdble vessel having 9, charge of fluid which upon l ment is shown in the accompanying drawing, in being heated to a predetermined temperature is which: adapted to completely shatter the vessel. The 50 Figure 1 is a plan of the improved Switch; latter is preferably of the bulb type with a some- Figure 2isan elevation; what attenuated neck 10a at one end that fits Figure 3is an elevation in sectionas on line 3-3 into a suitable hole '1c in the button and with of Figure 2 showing the switch in one standby a top or upper end that rests against a thimble condition; seat il secreted in head of are yoke. The dis- 55 tance between the top of the yoke and the point 'la of the button is such that when the yoke ring 9 is screwed into the socket rim 1c and firmly clamps the edge 8b of the disk to the base, the spring contact point 3 will be either separated from the point 2 as in Figure 3 or pressed into contact with it (2') as seen in Figure 6. In either case the spring point is bent against its own resilient resistance so that it stands ready to abruptly change its relation to the other point whenever the control of the button is removed.

This, as before indicated, takes place upon the giving way of the thermally' responsive element 10 which in the case of the charged frangible vessel illustrated means a complete annihila tion of the element. As this occurs the button 7 is snapped free of the spring contact point 3 by the action of the disk 8, leaving the full resilient force of the spring point 3 available to change its relation with the other point.

'I'his active force of the disk is insured by the novel manner in which its edge 8b is clamped so as to be held at an angle to the normal plane of the disk. That is, the edge is so held that the disk is dished upward with its concave side toward the contact points. The disk may be secured to either the base or the yoke member by suitable retaining means or, as herein disclosed, may be clamped between the yoke member and the base. The ring-shaped surface 1d of the latter, upon which the disk edge rests, is formed at a slight angle to the plane of the base with the inner edge of the surface being most removed from said plane and with the remainder of the surface approaching nearer to the said plane. The bottom edge 9b of the yoke ring is correspondingly disposed so that the face which engages the disk is parallel to the angularly disposed annular seat 1d of the base. In consequence, when the yoke is screwed into the raised socket rim 1c and comes to bear upon the disk, the edge of the latter is bent downward as c1ear` ly seen in Figures 3, 4 and 5. If there were no vessel or button interposed between the yoke arms and the disk, the latter would assume the position shown in Figure 5, in fact this is the position of the disc when the vessel has been destroyed. But in assembling the switch the vessel and button will be interposed between the yoke and disk so that as the yoke ring turns into the socket rim and firmly clamps the disk edge to the angular seat on the base the disk will be bowed or dished inward as seen in Figures 3 and 4. Since it would otherwise be dished outward, as already explained, it is clear that when dished inward there is established in the disk a resilient force tending strongly to snap the disk to the position shown in Figure 5.' Thus it is that when the vessel is destroyed the disk snaps outward due to the said resilient force and pushes the button 7 clear of the spring contact point 3 (indeed the button is usually thrown clear of the switch) leaving the latter free to move with respect to the other contact point.

The provision of force for moving the disk and button is of real advantage because it is not uncommon to nd switches, especially when installed With the yoke upward as herein shown, considerably loaded. That is, dust and other foreign matter collects on the disk and button and, in cases where a switch enjoys a prolonged period of idleness, this collection may have an appreciable weight. If this weight of foreign matter as well as that of the button and disk were to be moved solely by the force of the spring contact point, it is clear that the action of the latter would be at least impeded if not indeed prevented. In the switch of the invention the contact points are completely housed and so no loaded condition of the spring point can occur, and because of the resilient force imposed upon the disk by its manner of mounting the loading of the latter can be disregarded since the force thus imposed will insure the prompt movement of the disk and button and the immediate release 0f the spring point with all its own force available to cause its change in relation with the other Apoint.

Although the switch is shown and has been described as positioned with the yoke uppermost, it is to be understood that the switch can be installed in any position. Since all the current carrying parts are associated with the box, if the latter is placed in a recess with the circular plate 1a attached to the surface of the material surrounding the recess the said parts and the wires leading thereto may be entirely concealed. If it is desired to test the connections and determine the operativeness of the contact points the yoke can simply be unscrewed from the base,

and the vessel, button and disk lifted out. This will completely expose the contact points and they can be manually actuated to test the circuit.

To restore the switch to normal standby condition the removed parts need only be returned to their initial positions. If no testing of the switch is anticipated, the yoke may be sealed in the base to prevent its removal by an unauthorized individual.

'I'he three-armed yoke serves as a protector of the frangible vesselfrom accidental blows of passing objects, yet provides ample space for the fragments of the vessel to ny clear when its (shattering occurs. The provision of the box on one side of the base plate, so that it may be placed in a recess, makes the switch as a whole stand close to the surface towhich it is attached, making it less conspicuous, less` apt to excite the curiosity of an inquisitive observer, and less likely to be accidentally hit.

I claim:

1. A thermostatic switch comprising a base having an enclosed chamber on one side thereof; a substantially immovable contact point and a movable spring contact point arranged in said chamber; a disk mounted in position to form a yieldable cover for said chamber; a support attached to said base and outstanding therefrom on the side thereof opposite to said chamber; means interposed between said support and said disk comprising a charged frangible vessel adapted upon being heated to a predetermined temperature to destroy itself and a seating member for said bulb engaging the edge of a hole in the disk and extending therethrough into engagement with thespring contact point, whereby the said point is normally held in predetermined relation to the other point; the last said means of saidY disk havinga surface disposed at an angle to the normal plane of the disk whereby the disk being clamped to said seat it tends to dish outward with respect to the contact points; and means interposed between the member and said disk and engaging a contact point whereby the said disk is'normally held dished inward toward the contact points and the engaged point is held in predetermined relation to another point; the last said means remaining undisturbed as respects the said holdings until a predetermined temperature is reached and then giving way to permit said disk to snap outward and separate said means from said engaged contact point thereby permitting the said points to alter their relation to one another.

3. A thermostatic switch comprising a base having a chamber therein and an internally threaded rim; a seating surface within said rim disposed at an angle to the plane of said base; a resilient disk arranged with its outer edge overlying said seating surface and having a central opening; an open frame member having a base portion fitting said internally threaded rim and provided with a seating surface parallel to the said seating surface o1' the base, whereby upon the member being screwed into the rim the edge of the disk is clamped between said seating surfaces and the disk is caused to flex outward from the chamber; contact members in the said chamber capable of assuming a predetermined relation with one another; a button seated on the edge of the central opening of said disk having a portion extending therethrough; and heat actuated means interposed between said button and said frame member for holding said button against the resilient force of the disk' against one of the contact members to thereby alter their predetermined relation; the last means giving way when a predetermined temperature is reached to permit the disk to remove the button from contact with the contact member and thereby enable said contact members to assume their predetermined relation.

IRA W. KNIGHT.

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