US2604789A - Releasing device - Google Patents

Description

J. H. DERBY T AL RELEASING DEVICE July 29, 1952 Filed Aug. 5, 1950 2 SHEETS--S-IEET 1 INVENTORS NEY July 29, 1952 J. H. DERBY ETAL RELEASING DEVICE 2 SHEETS-SHEET 2 Filed Aug. 5, 1950 NVENTORS .20H/V DE/98) 5 G W n L N L R 6 5v. MB 0 y Patented July 29, 1952 UN IK"I`I`:`S.D` `S'ITA'I' ESY PATENT OFF ICE RELEASING DEVICE Johan.v Derby; sensuale, N. Y., ana Thomas-G. Collings, North Plainfield, N. J.

Applica-rimanga 5, 195o, serialNo. 177,877

01; vir- 72) covers,.valves which. control the releasel of` lid'-Y uicls or gases used for fire extinguishing, ete. Although release boxes nndtheir most important field'of utility in the re prevention artthey are'v also useful for other purposes where' it is desir; able that the operation or movement of some device held against operationv or movement' be controlled from a distance.

Release boxes as heretofore constructed, see for example U. S. LettersPatent to John H. Derby No. 1,187,135, granted Jne`13, 1916', and U. S. Letters-Patent to Tf G. Collings, No. 2,174,969; granted October 31.1939;v haveusually' comprised" a series'of powerniultiplyingbellcrank levers and a trppable detent comprising? a leverhaving a trip arm engageable with the last lofthe seriesof bellcranks; this'trippable detent" being normally urged toward its 'holding position by" a spring and being arranged to'A be" tripped" by.' an electromagl net energized by.y the closingoim a 'circuitV inWhich its coils are included.`

Unlessthe electrical parts of release boxesjust' described are in what are known'as supervisory'- circuits, that"is; closed circutsincluding trouf ble alarms'` and through which a small amount" of currentfbelow operatin'gllev'el; ows'consta'ntly; the release boxes` being operated by a sharp" rise in' the now oi'cu'rr'en't, there issome'danger that the operating circuit maybe brokenso that when" the 'operating'switchis closed the' detent tripping magnetwillnot be energized;V One of the objects of the present invention is to'provide a'simpler and less"l expensive release box whichwil'l have all of the' advantages of release' boxesv located insupervisory circuits, sofaras Warningof'its inoperativeness is concerned, the 'release box of the present" invention operating by the breakingY 2 A'n important feature of the invention is'the pro`` vision of'simple means for resetting therelease box after it has operated, Without the necessity for opening the box toget at the trip mechanism on the inside thereof; f

Another'important feature of theV invention is the constructionV of the' parts so that they are protected from dirt, adverse atmospheric condi-AV tions, corrosion and other things that might interfere with their operation when'operation is` desired. Still another important feature of the invention,V in" a release box in which a detent lever, which is'arranged to be held in holding` relation to the trip lever ofthe release box4 by an electromagnet so long as the magnet isenergized', is constantly spring urged toward releasing position, is the construction of the interengaging parts" of the detent'lever andthe load Y holding and releasing orv triplever so thatthe load' upon the trip or release lever will tend to` force the two leversinto separated relation, when the circuit is broken, even if the spring which normally urges' the detent lever out of engagement with 'the loadholding and releasing or trip lever 'has become more or less inoperative.

Other objects, important features'and advan--f tages of the invention, to'which reference has not Figure 1 is a front elevation, with parts brokenaw'ayto permit showing thereof on a larger scale,

of a release' box embodying the presentinventonv in operative retaining relation to an ordinary gravityecl'osing ire'door;

Figure 2 is'afront elevationof the interiorv mechanism of the release'box of Figure l, the'4 cover being shown as removed from the box and the trip lever and detent lever being shown inV their operative load-retaining position;

FigureS "is ad viewsimilar to Figure 2,- showingy the boxaiter ithas been tripped bythe breaking o'f' the circuit through' the detent-holding electromagnet;

2`looking' in the"direction ofthe arrows; y

Figure 5` isasection on'the linej 5`5j of Figure 2` looking irrthedirectionof` the arrows;

Figure'G isa section on the line 6e-li of Figure 2 looking in the" direction ofthefarrows. andv Figureis anenlarged detail side elevationjof the engagingV p'artsliof thedetent' lever andthe*- triporload'holding andrelease lever' showing 'the angular relations of 'the engaging faces tothe di# 3 rection of the force acting thereon, whereby the tripping movement is facilitated.

In the illustrative embodiment of the invention the main elements of the load holding and release mechanism are enclosed within a boxlike casing 2 having top and bottom flanges 4 and 6 through which retaining bolts or screws 8 may pass to connect the box to the wall or other stationary part adjacent to the redoor or other movable part to be held against movement. The box or casing 2 is provided with a cover i0 to protect the internal mechanism against dirt or corrosive fumes, vapors or gases, the cover being removably secured to the box by screws I2 at its corners.

A fulcrum shaft I4, having its bearings in a thickened part I6 of the wall of the casing, has fixed upon the part thereof which projects through the side wall to the outside a short load holding and releasing or trip arm I8 and has fixed upon its end which projects into the casing a long arm 20, the structure thus described constituting a power multiplying lever by which a relatively large pull upon the short arm i8, say 50 pounds, exerted by a hook 22 connected by a strapV 24 to the redoor 25, or other part to be held in its open condition or to be held against movement, may be resisted by the exertion of a relatively small retaining force upon the end of the arm 20.

The retaining means herein shown for resisting the tendency of the pull upon the arm i8 to rock the load holding and releasing or trip lever about the axis of the shaft I4 toward its release position comprise a detent lever 28 having a pawl-like end or dog 30 adapted to hook over the end of the long arm Z of the load holding and releasing or trip lever and thus to hold the lever in the position shown in Figure 2 against turning underthe pull of the load on the load hook 22.

As shown particularly in Figure 7 the pawl-like end or dog 30 of the detent lever 28 has its under face inclined to the direction of the force exerted upon it by the arm 2G at such an angle, and the part of the end of the lever arm 20 which engages the under face of the part 30 is also so correspondingly inclined to this direction of the said force, that, in the event of a failure of the spring 32, which ordinarily constantly urges the detent lever 28 to swing in a counter-clockwise direction in Figure 2 about its pivot 34, the pressure of these two engaging faces on each other will produce a component of force tending to move the paWl-like end 36 of the detent lever 28 out of its retaining relation to the end of the arm 2D and thus effect the release of the arm 20 and of the redoor 26 or other part held against movement by the trip arm I8.

As hereinabove pointed out, the detent lever 2S is held in its holding relation to the arm 20 of the trip lever by an electromagnet having coils 36 and 38 about the two legs of a laminated horseshoe-shaped core 40, the horseshoe-shaped core being supported upon a bracket 42 attached to the wall of the casing 2. The core 40 in turn sustains the coils 36 and 38. rlhe two poles of the electromagnet, constituted by the ends of the core legs, when energized act upon an armature 44 connected to the detent lever 28 and thus, by pulling the detent lever toward the poles of the electromagnet, maintain the pawl-like end 30 of the detent lever in retaining relation to the long arm 20 of the load holding and release or trip lever. An adjustable stop 4G, held in its adjusted ing screws 5S and 58 are provided for the connection of the coil terminals.

A stop screw 64 screwed into the wall of the casing 2 preferably limits the upward swing of the arm 28 of the trip lever. If desired the arm 20 may be provided with a rounded recess 66 to fit the shank of the screw 64.

To facilitate resetting of the release box after it has been tripped the end of the arm 2G of the trip lever is provided with a bevel 68 adapted to cooperate with the corresponding bevel 10 on the top of the pawl-like end 30 of the detent lever 28 to force the detent lever 28 away from the poles of the magnet in the event that the electromagnet has become energized before the box has been reset. The trip lever may be rocked for this purpose by means of its short arm IS. However, ordinarily the long arm 20 of the trip lever will gravitate back into its set relation, if there be no load on the short arm I8, by reason of its greater length, this movement of the lever being limited by a second stop screw '12. Energization of the electromagnet coils 35 and 38 will then move the detent lever 28 into retaining relation to the arm 20.

Referring again to Figure 7 of the drawings, it has been found in practice that if the meeting faces of the pawl-like end 30 of the detent lever 26 and the end of the lever arm 20 be inclined to the direction of force at an angle of 6.5 plus or minus .5", the desired releasing component of force will be provided, especially if the engaging faces of the pawl-like end 30 and the arm 20 be suitably plated with some protective metal coating such, for example, as chromium or cadmium.

Washers 14 of Bakelite or some suitable similar material on each side of the hub of the detent lever 28 help maintain this lever in good Working condition. It will be seen that by employing a power multiplying lever in which the arm 2O inside the casing is several times the length of the load-retaining and releasing arm I8 and having the detent engage the long arm 2G at its extreme end, the amount of force required to hold the load against release is comparatively small. It will further be seen that by arranging the detent lever in the manner shown so that it lies normally at right angles to the long arm 2] and having the armature located as shown, the pull upon the armature required to maintain the detent in its operative load-retaining position is comparatively small thus permitting low wound coils to be used in the electromagnets and thereby increasing the number of releases which can be connected in series. This reduces materially the installation cost where a number of releases are to be used.

What we claim as new is:

1. A release box operable upon the breaking of a closed electric circuit comprising, in combination with a box-like casing, a lever having a fulcrum shaft extending through a wall of the casing and having a short load retaining trip arm xed to said shaft on the outside of the casing and a power multiplying long arm fixed to said shaft on the inside of said casing, a detent lever having a pawl-like end adapted to be brought into retaining relation to the upper face of the free end of said long arm, said detent lever being rarranged to be brought into but spring-urged out of holding relation to said long arm, an armature on said detent lever and an electromagnet acting on said armature When energized to hold said detent lever in holding relation to said long lever arm, the engaging faces 0f the pawl-lke end of the detent lever and said long arm lying at such an angle to the radius of swing of said long arm that a component of the force transmitted from the load to be released through said long arm to said pawl-like end of said detent lever at least counterbalances the friction between said engaging faces, thereby facilitating the release of said long arm by said detent lever.

2. A release box according to claim 1 in which the detent lever is mounted to swing through an arc into and out of its operative relation to the long arm of the load holding and release lever f. load holding and release lever being inclined slightly to a tangent to the are of swing of the detent lever.

JOHN H. DERBY. THOMAS G. COLLINGS.

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

UNITED STATES PATENTS Number Name Date 502,487 Drake Aug. 1, 1893 2,174,969 Collings Oct. 3, 1939 Derby Oct. 16, 1945

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