US2768253A - Timing apparatus - Google Patents

Description

Oct. 23, 1956 F. J. BROCH TIMING APPARATUS 4 Sheets$heet 1 Filed Oct. 4, 1954 INVENTOR FREDRlCK' J. BROCH ATTORNEY Oct. 23, 1956 F. J BROCH TIMINGVAPPARATUS 4 Sheets-Sheet 2 Filed Oct. 4, 1954 lNVE/VTOI? FREDRICK J. BROCH WW ATTORNEY Oct. 23, 1956 J BRQCH 2,768,253

TIMING APPARATUS INVE/VTOI? .FREDRICK J. BROCH ATTORNEY F. J. BROCH TIMING APPARATUS Oct. 23,1956

4 Sheets-Sheet 4 Filed Oct. 4, 1-954 FIG.9

FIG."

INVENTOR FREDRICK J. BROCH ATTORNEY United States Patent TIMING APPARATUS Frederick J. Broch, Cambridge, Mass.

Application October 4, 1954, Serial No. 460,071

19 Claims. (Cl. 200-33) The present invention relates in general to the art of time delay mechanisms and more particularly concerns novel apparatus of unusual simplicity of design capable of reliably and repetitively performing a timing function in association with various types of equipment.

Although the concepts of the present invention are broadly applicable wherever interval timing is essential, electric switch-gear and in particular time delay electric switches have been chosen as the basis for practical illustration. In this connection, it should be observed that time delay switches constitute a substantial fraction of the commercial market for time delay mechanisms of all kinds.

In its most elementary form a time delay electric switch includes a contact arrangement which may either be normally open or normally closed, a mechanical linkage for either manually or automatically engaging and disengaging the switch contacts, and a timing mechanism so interposed in the linkage that either opening or closing of the contacts, as desired, may be made to occur at some predetermined time subsequent to actuation.

Examination of the art will reveal that the many types of time delay electric switches currently available commercially may be classified conveniently according to the extent of delay introduced by the delay mechanism, and that generally speaking the nature of the delay mechanism incorporated in each is similarly a function of the extent of the time delay specified. For example, where delay interval required is of the order of a fraction of a second, air or oil damped dashpot devices are in common use, and are relatively inexpensive and convenient, though frequently insufliciently rugged. When the requisite time delay is measured in seconds, bimetallic thermal sensitive units yield satisfactory performance, although here the durability of such thermal devices is often questionable.

However when minutes and even hours of delay are required, none of the aforementioned devices is capable of suitable performance, and for this reason switches offering such lengthy delays are almost universally driven by mechanical or electrical clockwork mechanisms.

Despite the widespread use of clockwork driven electric switches, their disadvantages are numerous and well known to equipment designers. Chief among these are high and frequently prohibitive initial cost, a complete lack of ruggedness and resistance to shock or impact due to the excessive number of delicate moving parts, and excessive size, weight and driving power. As a consequence there has existed an unfilled demand for a time delay electric switch having sufliciently low first cost, size and weight, usable even in household electrical wiring, as, for example, in attics and basements to prevent waste of energy due to lack of attention or forgetfulness.

The present invention contemplates as a primary object the provision of a basically novel time delay mechanism offering compactness and design simplicity heretofore unattainable, and which further, by virtue of its susceptibility to mass production techniques, is universal- ICC ly applicable to even the least expensive type of electric switch installations.

Broadly speaking, the time delay mechanism of the present invention utilizes a number of mechanical elements relatively rotatable within a body of substance exhibiting specialized viscosity characteristics.

One substance found eminently suitable in actual performance is a silicone putty, commonly referred to as bouncing putty, under which designation it has been distributed and sold as a novelty item. By virtue of the importance of this substance to the preesnt invention, it is deemed appropriate at this point to discuss in some detail the nature and properties of silicone elastic compounds, including silicone putty, without emphasis first, on the specific application thereof to the timing function which will be described more fully below.

For reference purposes, a comprehensive technical dis cussion of the precise properties of silicone putty and examples of the techniques of application in apparatus for shock absorption, vibration minimizing, pressure equalizing, and other similar devices, an article entitled Silicone putty as an engineering material appearing in the January 1950 issue of the publication Product Engineering will be found of considerable assistance.

From a somewhat more functional viewpoint, the properties of silicone putty may be sufliciently appreciated from a statement of its behavior under certain types of applied stress. Thus, a ball formed from a mass of silicone putty will bounce from rigid surfaces with an elasticity apparently greater than gum rubber. On the other hand, if the putty ball is permitted to rest on a smooth surface, the putty will flow, simply under influence of the gravitational forces involved, as would a highly viscous fluid under similar conditions. This unusual, dual characteristic of elasticity and liquidity of bouncing putty may be further described as being elastic under the influence of sudden stress or impact, while fluid with respect to persistent forces above some small threshold value. Further amplifying this concept, if a steel ball were dropped upon the outer surface of a cupful of silicone putty, the elastic properties would be controlling and the ball would bounce freely on impact. On the other hand, if the ball were placed in rest on the surface of the putty, under the influence of no other force than that imposed by its own weight, the ball would eventually sink to the bottom of the cup.

As will become apparent from the discussion which follows, the present invention is primarily concerned with apparatus which benefits materially from the novel properties of silicone elastic substances as above stated and permits its utility in inexpensive timing elements. It should be emphasized at this point that although the discussion which follows will often refer to silicone putty as an active element in the inventive combination, it will be understood that any other material exhibiting reasonably similar properties, whether compounded of silicone or otherwise, will be capable of performing equally well. In other words, the use of such terminology as silicone putty or bouncing putty should not be considered a limitation to this ingredient alone, but rather should be considered as definitive of substances of these general characteristics.

With the foregoing in view, it is another object of this invention to provide a novel time delay mechanism which derives its operational characteristics from the elastic-liquid properties of silicone putty.

A further object of this invention is to provide apparatus which optionally may be made to function as a substantially noiseless electric switch or as a time controlled switch whose delay is determinable first in the initial design and thereafter by straightforward adjustment of mechanical components.

Another object of this invention is to provide a compact and relatively shock-proof timing mechanism which, though not precise insofar as delay reproducibility is concerned, it is particularly well suited to use in the numerous control arrangements where accuracy is not the critical factor, as, for example, in general purpose time delay electric switches for home and industry, time-controlled electric or mechanical appliances, and the like.

These and other objects of the present invention will become apparent from the following detailed specification element which forms a part of the devices illustrated in the preceding figures,

Fig. 5 discloses a novel timing element operative generally as disclosed in the preceding figures, but modified for use in an alternate position,

Fig. 6 is a side view partially in section illustrating a practicalembodirnent of a time delay switch incorporating the principles of the present invention,

Fig. 7 is a top view partially in section of the switch illustrated in Fig'. 6,

Fig. 8 is a front view of elements of the switch shown in Figs. 6 and 7, a

Fig. 9 is a cross sectional view of the time delay mechanism taken along lines 9-9 of Fig. 7,

Fig. 10 is a front view of an element of the switch combination shown in Figs. 6, 7, and 8, and including an optional feature for switch control, and

Fig. 11 is a side view partly in section of a time delay switch similar in certain respects to that shown in Fig. 6, but disclosing certain novel variations in switch contact mechanism.

With reference now to the drawing, and more particularly to Fig. l, a time delay electric switch has been illustrated in diagrammatic form for the purpose of demons trating the underlying concepts of this invention. In order to simplify the drawing mechanical design and construction details have been omitted to the maximum extent possible; however, the manner in which the principles here disclosed may be incorporated into a practical device will be discussed below with reference to later figures.

Specifically in Fig. l(A)-(D) there is shown an electric switch 11 in co-operative association with a time delay element 12. Each of the views of Fig. 1(A)(D) show precisely the same mechanical and electrical components, the various views being used for the purpose of illustrating the sequence of events occurring in operation.

It will become apparent that the electric switch 11 need not be confined to any one design; rather, this switch may be selected from many standard products or may be of special design to meet needs of particular systems. Chosen for illustration in Fig. l is a common sensitive snap switch such as that marketed under the trade designation Microswitch. Switch actuation is effected by slight displacement of a spring loaded plunger 13 extending from the switch housing. In Fig. 1 illustration of the contact mechanism, output terminals, and wiring has been deliberately avoided since these do not in themselves form any part of the present invention. For the purpose of the present discussion it will be assumed that the switch 11 is normally open, or off, although any other arrangement of a single or multiple set'of contacts is usable.

In the drawing switch 11 is schematically shown as fixed, although it has notbeen deemed necessary to show the fixed reference frame. It will be understood, of course, that other fixed elements are considered with respect to the common reference.

The time delay mechanism 12 which controls the operation of electric switch 11 is comprised essentially of a substantially sealed cylindrical housing 15, which is rotatably operative about a smooth, relatively small diameter, coaxial fixed (non-rotatable) shaft 16. The housing end walls which serve to support the housing on the shaft are not shown, particularly since the necessary bearings are formed simply by aligned drilled holes of a diameter which permits smooth rotation on the shaft.

Directly attached to housing 15 is switch operating handle 21 by which the housing 15 may be angularly displaced about shaft 16. By a pair of rigid stops, diagrammatically shown at 17 and 18, angular motion of housing 15 may be limited between the two terminal positions designated in Fig. 1 as off and on, respectively.

Shaft 16 and switch 11 are fixed within the reference frame whereby the outwardly biased switch actuating plunger 13 engages the smooth outer surface of housing 15, the latter being operative as a cam by virtue of the provision thereon of detent 22. In the o1 position illustrated in Fig. 1(A), plunger 13 rests in detent 22.

Frictionally attached to rigid shaft 16, and freely operative and rotatable within housing 15, is vane 25, the function of which will be set forth in considerable detail below. The exact configuration of vane 25 is not critical. Evidently for relative freedom of movement, its axial dimension is less than the internal axial dimension of housing 15. The necessary frictional force between vane and shaft is achieved in the embodiment shown in Fig. 1 by use of a resilient sheet metal vane of hairpin-like cross section having cylindrical areas arranged to grip shaft 16 in the regions 25' and 25".

To complete description of the key elements diagrammatically shown in Fig. 1, housing 15 is substantially filled with a mass of bouncing silicone putty 26 or other substance exhibiting a comparable combination of viscous liquid and elastic properties. An air space 27, however slight, appears desirable.

Having set forth the general structural features, the mode of operation of the time delay electric switch illustrated in Fig. 1 will now be treated in detail.

ConsideringFig. 1(A), it will be observed that when the switch is allowed to remain in the OE position, the silicone bouncing putty will settle to the position shown. Switch contact plunger 13 resides in detent 22 and the switch contacts are correspondingly open.

Assume now that switch handle 21 is abruptly displaced to the on position shown in Fig. 1(B). Motion of the handle to this position correspondingly rotates housing 15 about fixed shaft 16, and by displacement of detent 22, switch plunger 13 is depressed to turn on the electric switch.

For an understanding of what occurs within housing 15 during this initial motion to the on position, one must now recall the specialized properties of bouncing putty. In resisting sudden or rapidly applied stress, the putty behaves as a relatively rigid mass, capable of transmitting large forces. Because of substantial friction between the mass of putty 26 and the inner surfaces of housing 15, including its side walls, the entire mass of putty will rotate with the housing in the abrupt change from off to on. Moreover, by virtue of the fact that vane 25 is embedded in the mass of putty, this rotation of the putty will cause equal rotation of the vane.

Since shaft 16 is rigidly and non-rotatably fixed in the reference frame, both vane 25 and the mass of putty 26 slip thereon during rapid rotation of the housing. But the back resistance resulting from the frictional engagementbetween vane and the shaft is relatively insignificant due to the leverage resulting from the fact that the actuating force is applied to the extended handle while the shaft diameter is small. Further, the mass of putty 26 readily fotates about shaft 16, since the shaft is smooth and has relatively little exposed surface areadue to the gripping areas of vane 25. In all, the resistance to switch motion is somewhat less than normally encountered in common toggle electric switches.

From an examination of Fig. 1(B) it will become apparent that the system there shown is in unstable equilibrium, primarily due to the weight of eccentr-ically disposed handle 21 which introduces a continuous bias torque normally tending to rotate housing about shaft 16 to the off position shown in Fig. 1(A). This bias torque, however, is far less than the torque required earlier to snap the switch from the condition shown in Fig. 1(A) to that shown in Fig. 1(B), and by itself is insufiicient to cause rapid rotation of both putty and vane about shaft 16 for return to the position shown in Fig. 1(A). In other words, friction between vane and shaft prevents rapid return of housing 15 to the off position under forces no greater than the, bias due to the unbalanced condition of handle 21.

However, recalling that under conditions of slight but persistent stress, bouncing putty is essentially a viscous liquid, under the influence of the slight but steady bias torque the housing and putty will now slowly rotate in a counter-clockwise direction, the silicone putty flowing as a liquid about vane 25, so that ultimately the housing 15 and attached handle 21 return to the off position as shown in Fig. 1(C). Here, the switch actuating button 13 has again fallen into deteut 22 to turn off the electric switch.

Although again in the off condition, a noteworthy distinction between the switch in Fig. 1(A) and again in Fig. 1(C) exists. As mentioned, the housing returns to off in response to the persistent stress imposed by the continuous bias torque. This stress, when transmitted through the putty to the vane, is insuflicient to overcome the frictional engagement between the vane and the shaft so that in its return to. the off position, the vane remains stationary upon the shaft. Thus, in Fig. 1(C) the vane 25 is displaced from that in Fig. 1(A) exactly by the angle through which the housingyand vane turned in change from off to on.

For the purpose of further clarifying operation of this invention, reference is made to Fig. 1(D) which shows the's witch manually displaced to the on position at some time subsequent to its arrival at the off position shown in Fig. 1(C). In Fig. 1(D), rota-tion has further displaced vane 25, the displacement angle again being equal to the angle through which handle 21 was displaced between ofl? and on. From the position shown in Fig. 1(D) handle 21 and attached housing will once again rotate slowly to the off position under the bias torque, leaving the vane in frictional engagement with shaft 16 in the position shown therein. Thereafter, if handle 21 were again snapped to the on position, vane 25 would rotate to the position indicated by the broken line in Fig. 1(D).

Thus reviewing the effect of a sequence of switch operations, each time handle 21 is snapped to the on position, vane 25 rotates clockwise in synchronism and through an equal angle. During the return to the off position, in completion a normal timing cycle, the switch-handle rotates counter-clockwise while vane 25 remainsstationary. Thus, in repeated operation, vane 25 progresses around shaft 16 in a stepwise manner; however, it will be clear that its effect in delaying return of the housing to the off position is nota function of angular position. Hence time delay remains unaffected by vane orientation.

The discussion immediately above has been confined to operation of the switch when snapped to the on position and allowed toreturn slowly during the delay interval to the off position under the influence of the continuous bias torque. But analysis will readily demonstrate that handle 21 may be snapped from the on to the off position as readily as from off to on as previously discussed. For example, by simply following the reasoning used to explain the motion of vane 25 from its position in Fig. 1(A) to that in Fig. 1(B), it is apparent that if handle 21 in Fig. 1(B) were abruptly snapped to off, the entire switch mechanism including vane 25 would return to the position shown in Fig. 1(A). In other words, although time delay is always available, the device shown in Fig. 1 may be used as a conventional snap switch, in that at any time, notwithstanding prior operation, the switch handle may be manually displaced from off to on, or from on to off. This is true not only when handle 21 resides in a terminal position, but at any intermediate point. Hence at any time during the interval normally required for housing 15 to rotate from the position shown in Fig. 1(B) to the position shown in Fig. 1(C), handle 21 may be abruptly returned to off. Conversely at any point in the timing cycle handle 21 may be snapped to on to renew the timing cycle.

This discussion illustrates the unusual degree of flexibility available with the timing mechanism associated with the electric switch, as shown in Fig. 1. Abrupt on-off operation is at all times possible, while if undisturbed after being placed in the on position, it will naturally return to off after the predetermined timing interval.

Duration of the timing interval is a function of many factors, such as relative dimensions of the structural members; spacing between fixed and movable elements, bias force magnitude, frictional retarding forces between relatively movable elements, and ambient temperature. It is immediately apparent that wide delay ranges may be achieved by control of certain of these factors in the initial design phase. Temperature, of course, is a variable which enters subsequently and must therefore be considered from an entirely different standpoint.

The relationship between delay interval and ambient temperature, all other factors being equal, need be considered only insofar as putty viscosity is affected by temperature change. For the silicone putty used as a novelty item, the delay interval varies over a fairly marked range, but by and large, for most applications this may be considered immaterial. For instance, if an attic light were being controlled, it would be of small consequence that the timing interval extended through a range of 30-45 minutes with seasonal variations in temperature. Thus, as noted earlier, accuracy and repro ducibility, though unavailable from this design, are not often functionally required. It should be pointed out, however, that some silicone compounds are noted for their viscosity stability under wide temperature swings, and that the properties of these may be advantageously embodied here.

By appropriately controlling all factors, however, time delays ranging from seconds to hours may be made available. Such design fiexibility is of considerable advantage since one basic mechanism may then with minor modification be adapted to the needs of different users.

For a given switch configuration, the magnitude of the bias torque is the factor most readily controlled. Clearly variation in the weight of handle 21 will result in a corresponding variation of the continuous torque. Although not shown in Fig. l, a small spring normally biasing handle 21 to the off position may be added to provide additional torque for the timing cycle. Or simply, an adjustable screw extending from the end of handle 21 may be used to increase or decrease the bias. As a precautionary note, the magnitude of the bias torque may not exceed the resistance to return motion imparted by the frictional grip between the vane and the shaft. That is to say, during the timing cycle, vane 25 must remain stationary, While the putty flows as a liquid in its return to a rest condition. An erratic timing cycle would result from slippage of vane 25.

In the. earlier discussion of the change in position betweenFig. 1(A) and Fig. 1(B), it was mentioned that frictional engagement between housing and the bouncing putty resulted in rotation in unison during abrupt motion of handle 21. Due to the relatively large internal surface area of housing 15, sufiicient friction is ordinarily available even though the interior surface is of smooth finish. However, if specific applications require additional friction between housing and putty, the inner wall of cylindrical housing 15 may be suitably corrugated or otherwise roughened, or a number of pins may be supported on th inner housing wall in engagement with the putty mass; caution being taken to avoid interference with operation of vane 25. On the other hand, special precautions are not required to minimize friction between shaft 16 and the mass of putty due to the fact that the area of contact outside the vane is relatively small.

Friction between the outer cylindrical surface of housing 15 and switch plunger 13 should be kept low to avoid retarding rotation of housing 15 under the influence of the fixed bias torque. No significant design problem is encountered here since snap action electric switches are normally finished with a smooth metallic plunger whose spring loading is relatively slight due to the sensitive nature of the contact mechanism.

Fig. 1 has served as the basis for a fairly comprehensive discussion of the basic novel concepts underlying the present invention. Figs. 2-5 disclose various alternatives which are conceptually similar, but by virtue of mechanical departures are better applicable to meet specific needs. Wherever possible similarity has been indicated in that corresponding structural elements in the various figures have been designated with like reference numerals.

Generallyspeaking, comparing Fig. 2 with Fig. l the functions of housing 15 and shaft 16 have been interchanged. Thus, in Fig. 2 housing 15 is suitably afiixed to'the reference frame together with switch 11, while shaft 16 is rotatable and radially supports actuating handle 21. Vane and putty 26 remain unchanged, however, cam formed with detent 36 is attached to the shaft by a suitable radial arm for actuation of the switch plunger 13.

Fig. 2(A) illustrates the time delay switch at rest in the on position. handle to the on position is shown in Fig. 1(B). With the shaft rotatable and housing fixed, abrupt shaft rotation will have no effect whatsoever on putty and vane, and hence the shaft will slip relative to these elements.

The cam 35 is fixed with respect to shaft 16 and hence rotates through an equal angle, thereby depressing switch plunger 13 to turn on the switch. When in the condition shown in Fig. 2(B), eccentricity of handle 21 imposes a continuous counter-clockwise bias torque on the shaft, insufficient to overcome the frictional engagement between shaft and vane to cause relative rotation between the two, but sufficient to induce gradual rotation of the shaft and the vane in unison, the putty flowing as a viscous liquid, until the position shown in Fig. 2(C) is reached. Here cam 35 is restored to its initial position and switch is now 0 The similarities between the devices shown in Figs. 1 and 2 are immediately apparent. A point of distinction, however, is that since the relative functions of housing and shaft have been effectively interchanged, vane 25 in Fig. 2 rotates stepwise in the opposite direction during a sequence of timing operations.

In Fig. 3 the basic principles of this invention are embodied in a device wherein both shaft 16 and housing '15 are rotatable. Vane 25 is rigidly rather than frictionally attached to shaft 16, while housing 15 is frictionally' restrained by a leaf spring 41 which engages the smooth outer surface thereof. As in Fig. 2, a cam 35 radially attached to shaft 16 is arranged to actuate switch plunger 13.. Fig. 3(A) illustrates the switch in its nor- The effect of abruptly snapping the mally off position. .Ifnew. handle 21 is abruptly r0 tated to on, the sudden stress is transmitted through vane 25 and putty 26 to housing 15, thereby causing equal rotation of the housing in the same direction. During this motion, housing 15 slips relative to sprin member 41.

Having arrived at the position shown in Fig. 3(B), the bias torque due to the eccentricity of handle 21, becomes the dominant force, but is insufficient by itself to slip housing 15 over spring member 41. However, the bias torque is sufficient to cause gradual rotation of the vane through the silicone putty which now behaves as a liquid, until the position shown in Fig. 3(C) is reached and the switch is again off.

In this embodiment of the invention, motion of the vane is confined to the region between the positions shown in Fig. 3(A) and Fig. 3(B), however, repeated actuation of the switch causes housing 15 to rotate in stepwise fashion. This has been illustrated in Fig. 3 by designation of a given point on the housingsurface by the letter X. In snapping the switch to the on position, point X rotates in synchronism with handle 21 as shown in Fig. 1(B). During the return timing cycle, however, point X remains stationary while the handle returns to the off position as shown in Fig.- l(C). As in the case of preceding figures, the switch may be turned on or off while in any intermediate position, or may be allowed to follow its normal timing cycle in return from on to off.

In Figs. 13, the same basic invention has been illustrated, although the relative functions of the elements have been interchanged. Still another possibility exists, in which housing is fixed as in Fig. 2, vane attached to shaft as in Fig. 3, but where the handle is frictionally slidable over the shaft, and carries the cam for switch actuation. Thus, when snapped to on or off, only cam and handle move, while during the timing cycle, handle, cam, shaft, and vane move in unison through the putty.

From Figs. l-3, it may be seen that silicone putty will lie against such bearings as are provided between shaft and housing. Normally, with closely fitted bearing surfaces, this need not create special problems; and even with loosely fitted bearings it has been found that seepage is soon halted since in effect the putty is self-sealing. V

In Fig. 4 there is illustrated a design variation with respect to vane and putty applicable to each of the devices shown in the preceding figures. For the purpose of explanation, however, all basic features of Fig. 1 have been retained. Vane 25, while still generally of hairpin cross section, is formed with three radially extending arms uniformly spaced apart. The silicone compound fills only about one-third of the interior of housing 15, and accordingly the upper surface thereof is below bearing 46 in the sidewall of housing 15.

Through the use of 120 spacing, there is assurance that at least one of the radially extending arms of the vane will at all times be immersed in the silicone putty. Consequently. the timing cycle occurs in precisely the manner already described in connection with Fig. l. The chief advantage, however, lies in the fact that at no time will the silicone be alongside the bearings, and hence seepage is avoided entirely even if lower viscosity compounds are employed.

In Fig. 5, a time delay switch, having the characteristics of the unit described in connection with Fig. 2, is shown arranged for horizontal rather than vertical operation. Fixed cylindrical housing 15 is sealed by a cover plate 52. Shaft 16 is vertically disposed in the housing axis and extends through the cover plate, resting in an internal bearing 54. Handle 21 is aflixed' to shaft 16 by set screw 55 and is consequently operative in a horizontal plane between on and- 05 stops (not shown); In

motion, handle 21 actuates switch 11 by a suitable cam arrangement, the details of which have been omitted. Vane 25, having the general physical characteristics of the vane shown in Fig. 2, is frictionally supported on shaft 16 and immersed within a body of silicone bouncing putty 26. Since unbalance of handle 21 will not provide a restoring torque, in horizontal operation, a small coil spring 63 has been added to rotate shaft 16 and handle 21 to the normally off position.

Step by step explanation of the operation of the time delay device shown in Fig. appears unnecessary at this point, in view of similarity to Fig. 2. But it should be observed that in this embodiment, as in that shown in Fig. 4, there is complete absence of contact between the putty and the bearing in the housing cover. Clearly the devices shown in Figs. 1 and 3 may correspondingly be arranged for horizontal operation.

Referring now to Figs. 6-10, there is illustrated a practical time delay electric switch incorporating the key concepts described with respect to the preceding figures. The techniques disclosed in connection with Fig. 2 have been selected for presentation in the figures now to be discussed; however, it will be understood that the arrangements disclosed in Figs. 1 and 3-5 are equally adaptable to similar practical switch embodiments.

With specific reference now to Figs. 6, 7, and 8, there is shown a time delay electric switch ideally suited as a replacement for the customary toggle wall switch. The entire switch assembly is housed in a standardized electric wall box 71, support for the switch being provided by front bracket 72 secured to flanges extending from the open face of wall box 71 by a pair of screws 7373. When the illustrated assembly is recessed into a wall, face plate 75, attached to front bracket 72 by screws 7676, conceals the mechanism contained within box 71 with the exception of operating handle 77, the latter extending out through a centrally located rectangular opening 81.

In the device shown in Figs. 6, 7, and 8, the switch contact mechanism consists of a normally off sensitive snap switch 82 having electrical terminals in the form of screws 8383 and a molded plastic contact actuating plunger 85 spring biased to extend from the switch housing.

To those familiar with this art, it will be immediately apparent that switch 82 which has been arbitrarily selected for illustration is of the type manufactured and marketed by the General Electric Company, Inc., under the trademark Switchette. Size, weight, and current characteristics combine to make this commercial switch advantageous in this system, but as indicated below, other switch mechanisms are equally applicable.

A pair of mounting screws 8787 extend through the body of switch 82 to support it upon a generally C-shaped mounting base 91, which is in turn affixed to side bracket 92 by a pair of supporting screws 93 and 94. Before discussing the details of this arrangement, it should be observed that the side bracket 92 is provided with a pair of integral flanges 9595 attached to the rear face of front bracket 72 by a pair of small machine screws 9696.

Although switch 82 is rigidly secured to switch base 91, a small degree of adjustability exists in the relationship between switch base 91 and side bracket 92. Thus, the uppermost opening in side bracket 92 is formed as a slot 98, whereby upon loosening screw 94 from associated nut 101, switch base 91 together with attached switch 82 may be pivoted to a small degree about supporting screw 93.

Evidently, the adjustability so provided permits lateral adjustment of plunger 85, the need for which will become apparent from the discussion which follows. But when the desired operating point is determined, screws 93 and 10 94 are fastened, preventing inadvertent displacement of switch 82 with respect to side bracket 92.

As is most clearly illustrated in Figs. 7 and 8, the face of side bracket 92 opposite switch 82 is provided with a rigidly attached cylindrical housing sealed by a circular end cap 106, threaded or otherwise conveniently fitted thereon.

A shaft 107 is smoothly journalled in an opening in side bracket 92 and in a recess 109 in cap 106. Within housing 105, a symmetrical section 111 of shaft 107 is reduced in diameter to frictionally support vane memher 112. The shoulders formed on opposite sides of reduced diameter section 111 preclude lateral displacement of vane 112, and consequently prevent possible interference between vane and housing inner surface.

The cross sectional view Fig. 9 discloses the details of housing, shaft and vane. The vane previously described in connection with Fig. 4 has been selected for illustration, and further, in accordance with the basic techniques described above housing 105 is substantially filled with silicone bouncing putty 115.

Returning to the structure on the opposite face of side bracket 92, shaft 107 is fitted with cam 121, this element being formed with an eccentric cam surface 122 in engagement with plunger 85 and with a suitably threaded opening for machine screw 123. This screw when tightened, draws together the upper and lower segments of cam 121, resulting in a firm grip between cam and shaft. Screw 123, moreover, serves to pivotally support switch handle 77.

Although the unbalanced weights of cam 121 and handle 7'7 ordinarily apply a constant, counter-clockwise bias torque to shaft 107, as viewed in Fig. 6, additional bias torque is furnished by a small coil spring 125, one end of which is hooked over cam 121 while the other end is held secure by the lower supporting bolt 87 for switch 82.

As shown in Fig. 6, plunger 85 engages cam surface 122 in a position such that the contacts of switch 82 are in the olf condition. When handle 77 is raised to the on position depicted by the broken lines 77', cam 21 is rotated clockwise and cam surface 122 drives plunger 85 inward to close the switch contacts and complete such electrical circuits as may be connected between terminal screws 83 and 84.

With specific reference to Figs. 7 and 9 and in view of the discussion of Fig. 2 hereinabove, it is apparent that the abrupt snapping of handle 77 to on will in addition to closing switch 82 cause rotation of shaft 107 while vane 112 and bouncing putty remain motionless. Having reached the uppermost position 77, shaft 167 will then rotate counter-clockwise under the influence of the constant bias torque furnished by spring 125 and unbalanced weight distribution of cam 121 and handle '77. While returning to oif during the delay interval, vane 112 will rotate in unison with shaft 107 through putty 115.

It may be seen that the on and off terminal positions of handle 77 are defined by the upper and lower edges respectively of slot 13.1 in front bracket 72. As is most clearly shown in Fig. 8, slot 131 is in the shape of an inverted L; consequently when in its uppermost position, handle 77 may be pivoted about machine screw 123 so that edge 132 prevents the normal return to off. In other words, the switch shown in Figs. 6-9 may readily be locked in the on position to prevent the normal delay cycle, whenever desired In Fig. 10, as an optional feature, front bracket 72 is provided with a pivoted stop 141 which, when secured by screw 142 in the position shown by the solid line, will not permit locking switch handle 77 in the on position. When this stop is rotated to the position shown by broken line 141', of course, advantage may again be taken of the upper slot and the switch locked on, if desired.

Fig. 11 illustrates a time delay electric switch having the general characteristics of the switch above described 11 in connection with Figs. 640. The points of similarity may be readily ascertained, since like reference numerals have been used wherever applicable.

The significant point of departure is not in the timing mechanism which may, in fact, be precisely the same as illustrated in these preceding drawings, but in the nature of the switch contact mechanism utilized. Hence no effort has been made to illustrate the mechanism behind side bracket 92, this being essentially the same as shown in Figs. 7-9, inclusive.

The electric switch device 151 selected for illustration in Fig. 11 is a widely used sensitive snap switch sold under the trademark Microswitch by the Minneapolis-Hone well Regulator Co., Inc. As incorporated in the structure shown in Fig. ll, however, the molded plastic cover normally furnished has been removed so that earn 122 bears directly against the leaf spring 153 which carries movable contact 155. Of course, a thin dust cover may be provided.

While normally off as shown in Fig. ll, movable contact 155 is engaged with fixed contact 156. When handle 77 is snapped to on, cam surface 122 depresses spring member 153, causing contact 155 to snap into engagement with fixed contact 157. In returning from the on to off, cam 122 effectively releases the depressed spring member 153, so that contact 155 again engages fixed contact 156.

By virtue of the direct mechanical contact existing between conductive leaf spring 153 and cam 122, it becomes necessary to insulate handle 77. This is most effectively accomplished by molding cam 122 from a suitable durable, but insulating substance, such as Bakelite.

Those operational characteristics of the switch shown in Fig. ll which have not been described are essentially the same as those discussed in connection with Figs. 6l0. The chief advantage of the arrangement shown in Fig. 11 is that by elimination of the molded cap and leaf spring operating plunger, space requirements are materially reduced. Of course, by reduction of the number of parts, lower costs are realized.

In the preceding discussion, a division has been arbitrarily drawn between Figs. l5, which disclosed various basic techniques for achieving a time delay through the utilization of bouncing putty and Figs. 6-11, which served to illustrate one of these techniques in use in practical use. This arbitrary division of subject matter was drawn for the purpose of facilitating explanation of this invention with a minimum of figures, and should not be construed as limiting the application of any of the mechanism shown in Figs. 1-5.

In illustrating practical switch embodiments, the Switchette and Microswitch were chosen for illustration because of their widespread use and, moreover, because mass production techniques have made these an economical source of contact mechanisms for this purpose. mercury contact button may be positioned on the movable element of the time delay mechanism or otherwise actuated therefrom, to obtain onoff operation without 'the use of snap contacts. In fact, in specialized applications it might be desirable merely to use a sensitive moving contact extending from the movable element of the time delay mechanism for engagement with a complementary fixed contact. But when using a contact arrangement which is not designed for snap action, a degree of caution should be observed since low contact velocity inherently limits use to circuits where it is not required to make or break currents of large magnitude.

The illustration of practical switches in Figs. 61l does not ext nd beyond the relatively small mechanism adapted for wall box use. However, nothing intrinsically limits the physical size of the time delay element shown in Figs. 1-5. and should. it be so desired, it may be made But without significant variation, the familiar V '12 sufficiently large to operate more complex, heavy duty circuit breakers, and the like.

It is again emphasized that the application of the novel time delay mechanism herein disclosed to electric switches has been an arbitrary choice, and that such mechanisms are capable of performing equally well in numerous other control systems, whether they be timers in paper towel dispensers, fluid flow controls, or toys.

Finally, the physical configuration of the elements of each of the timer combinations is subject to wide variation. For example, nothing basically requires a cylindrical housing, or cams in the shapes shown. Further, where the vane frictionally engages the operating shaft, other less expensive devices may be substituted for the sheet metal hairpin. Thus, a resilient element, formed of rubber or'neoprene, may be pierced to fit over the shaft with the necessary frictional grip, and perform the function as described for the metal vane. The term vane wherever used will accordingly be understood to include all devices capable of being used for this purpose.

In view of the fact, therefore, that numerous modifications and departures may now be made by those skilled in this art, the invention herein is to be construed as limited only by the spirit and scope of the appended 7 claims.

What is claimed is:

1. Apparatus for actuating an electric switch comprising, a rotatable structure having first and second angularly displaced terminal positions, means imparting a continuous force normally biasing said rotatable structure toward said first terminal position, means forming a chamber associated with said rotatable structure and including a substance exhibiting elastic properties in response to sudden forces while flowing gradually under application of continuous forces, said substance being arranged to restrict motion of said structure to gradual rotation from said second to said first position in response solely to said continuous bias force without restricting the rate of rotation of said structure either from said first to said second position or from said second to said first position in response to sudden forces applied thereto substantially in excess of said bias force.

2. Apparatus for actuating an electric switch comprising, first and second relatively rotatable elements enclosed in a body of silicone elastic substance, said first and second elements being mutually arranged whereby said elements are effectively linked through said substance for rotation substantially in unison in response to sudden rotation of one of said elements, said arrangement being also effective through said substance in permitting gradual rotation of one of said elements relative to theother in response to the application of rotational forces substantially less than the aforesaid sudden rotational forces.

3. Apparatus for actuating an electric switch comprising, first and second relatively rotatable elements closely associated with a body of silicone elastic substance, means for imparting a continuous torque normally tending to rotate said first element in one direction, said silicone elastic substance being effective to separate said first and second elements whereby said first element may be substantially independently rotated in response to the application thereto of rotational torques considerably in excess of said continuous torque in either said one direction or the direction opposite thereto, said substance being also effective to link said first and second rotatable elements for gradual rotation in unison in' said one direction when under the influence solely of said continuous torque.

4. Apparatus for actuating an electric switch comptising, first and second relatively rotatable elements closely associated with a body of silicone elastic substance, means for imparting a continuous torque normally tending to rotate said first element in one direction, said silicone elastic substance being effective to separate said first and second elements whereby said first element may be substantially independently rotated in response to the application thereto of rotational torques considerably in excess of said continuous torque in either said one direction or the direction opposite thereo', said substance being also effective to link to first and second rotatable elements for gradual rotation in unison in said one direction when under the influence solely of said continuous torque, and means limiting the extent of rotation of said first element in either of said directions.

5. Timing apparatus comprising, relatively rotatable housing and shaft elements, said shaft extending through said housing, vane means within said housing frictionally engaging said shaft with predetermined force, a mass of highly viscous silicone elastic putty substantially filling said housing and in contact with portions of said shaft and said vane means, said putty having the property of opposing sudden movement therein of said vane means while yielding and flowing as a fluid under the influence of slight persistent pressure of said vane means, means for applying a bias torque between said shaft and housing insufiicient to overcome said predetermined force and cause slippage of said vane means relative to said shaft but sufiicient to exert said slight persistent pressure, whereby upon abrupt relative rotation between shaft and housing the relative position of said vane means considered with reference to said putty remains substantially unchanged while upon cessation of said abrupt rotation said bias torque causes said vane means gradually to flow through said putty without effect upon the relative position of vane means upon said shaft.

6. Timing apparatuseomprising, relatively rotatable shaft and housing elements, said housing containing a mass of silicone elastic putty, a vane disposed for move ment within said housing and at least partially immersed in said putty and frictionally engaging said shaft with predetermined force, means for applying a continuous bias torque tending to cause relative rotation between shaft and housing in one direction but insutficient in magnitude to overcome said predetermined force to induce slippage between vane and shaft, and means permitting the application of a rotational torque in excess of said bias for abruptly relatively rotating shaft and vane in said one direction or the direction opposite thereto.

7. Timing apparatus comprising, in combination, a fixed shaft, a housing supported upon and journalled for rotation about said shaft between first and second angularly separated terminal positions, a vane frictionally engaging said fixed shaft with predetermined force and adapted to rotate thereon under the influence of a torque suflicient to overcome said predetermined force, said housing containing a mass of silicone elastic putty at least partially covering said vane, means for imparting a continuous bias torque normally tending to rotate said housing from said second to said first terminal direction, in one direction relative to said shaft, and means permitting the application to said housing of rotative torques of greater magnitude than said bias torque for rotating said housing in either said one direction or the direction opposite thereto, said housing, shaft and vane being arranged whereby, upon initial rotation of said housing to said second terminal position, said putty, vane, and housing rotate in unison, and thereafter said housing, when uder the influence of said bias torque only, slowly returns to said first terminal position, said vane remaining fixed upon said shaft while said putty flows between vane and housing, and whereby the cycle may be repeated with said vane rotating stepwise on said shaft in the direction of said initial rotation.

8. Timing apparatus as in claim 7 and including, an electric switch contact mechanism having actuating means associated with and operative during predetermined movements of said housing.

9. Timing apparatus comprising, in combination, a fixed housing, a shaft extending through said housing and rotatable relative thereto between first and second angularly operated terminal positions, a vane supported upon and frictionally engaging said shaft with predetefmined force within said housing, a mass of silicone elastic putty enclosed within said housing and at least partially covering said vane, means for applying a continuous bias torque normally tending to rotate said shaft from said second to said first terminal position in one direction relative to said fixed housing, and means permitting the application to said shaft of rotative torques in excess of said bias torque in either said one direction or the direction opposite thereto, said housing, shaft, and vane being arranged whereby upon initial abrupt rotation of said shaft to said second terminal position, said putty, vane, and housing remain unmoved, and thereafter said shaft, when under the influence of only said bias torque, slowly rotates to said first terminal position, said vane remaining fixed upon said shaft while moving through said putty, and whereby the cycle may be repeated with said vane rotating stepwise in the direction opposite said initial rotation.

10. Apparatus as in claim 9 and including an electric switch contact mechanism having actuating means associated with and operative during predetermined rotation of said shaft.

11. Timing apparatus comprising, in combination, a shaft rotatable between first and second angularly separated terminal positions, a housing lfreely journalled on said shaft and containing a mass of silicone elastic putty, a vane rigidly affixed to said shaft within said housing and at least partially immersed in said putty, retarding means for applying a predetermined force to said housing for normally retaining said housing in a relatively fixed position, means for applying continuous bias torque normally tending to rotate said shaft in one direction from said second to said first terminal position, and means permitting the application of rotative torques to said shaft in excess of said bias torque in either said one direction or the direction opposite thereto during which said shaft, vane, putty, and housing rotate substantially in unison, while during the application solely of said continuous bias torque with said shaft in said second terminal position, said shaft and vane rotate slowly through said putty to said first terminal position with said housing fixed by said retarding means, whereby the cycle may be repeated with said housing rotating stepwise in the direction opposite to rotation of said shaft under the influence of said bias torque.

12. Apparatus as in claim 11, wherein said retarding means includes a resilient member frictionally engaging a surface of said housing.

13. Apparatus as in claim 11 and including, an electric switch contact mechanism having actuating means associated with and operative during predetermined rotation of said shaft.

14. Time delay apparatus comprising, a housing having a plurality of horizontally aligned bearings, a horizontal shaft extending through said bearings, said housing enclosing a mass of silicone elastic putty normally occupying a volume entirely beneath said shaft and bearings, and a vane member having a central region frictionally engaging said shaft within said housing and formed with at least three symmetrically disposed separated vane elements radially extending from said central region, and vane elements being arranged whereby at least one is at all times partially immersed in said silicone putty, and means for providing relative rotation between said shaft and housing.

15. Timing apparatus for controlling the operation of an electric switch contact mechanism having an actuating member comprising, a housing having a vertically disposed axis, a shaft vertically extending through a hearing in the upper portion of said housing and rotatably supported in a bearing enclosed in the lower portion of said housing, a mass of silicone elastic putty within said housing and about said shaft, a vane member frictionally fitted to said vertical shaft Within said housing and at least partially immersed within said silicone putty, means normally applying a bias torque tending to rotate said vertical shaft to a first terminal position, means permitting the application of rotative torques to said vertical shaft either in the direction of said bias torque or in the direction opposite thereto, and means coupling said shaft to said actuating member.

16. A time delay electric switch comprising, a snap action switch contact mechanism having an actuating member, a bracket supporting said switch contact mech anism, a shaft rotatably extending through said bracket, a switch operating handle affixed to said shaft and formed witha cam surface arranged to cause displacement of said actuating member in response to handle movement between first and second terminal positions, a housing affixed to said bracket and enclosing a portion of said shaft, said housing being filled at least in part with silicone elastic putty, vane means frictionally supported upon said shaft within said housing and at least partially immersed in said silicone putty, and means normally applying a rotative torque for continuously biasing said handle and shaft to said first terminal position, said housing, shaft, vane, and handle cam surface being arranged whereby upon initial abrupt motion of said handle to said second terminal position, said putty, vane, and housing remain unmoved, and said switch is snapped, and thereafter, said shaft and handle when under the influence of only said bias torque slowly rotate to said first terminal position to return said switch to its initial condition, said vane remaining fixed upon said shaft while moving through said putty, and whereby the cycle may be repeated with said vane rotating stepwise in the direction opposite said initial rotation.

17. Apparatus as in claim 16 and including, means associated with said second terminal position for locking said handle thereat to preclude motion thereof under the influence of said bias torque.

18. Apparatus as in claim 16, wherein said handle is pivotally secured to and arranged for rotation in a plane substantially parallel to the axis of said shaft, a front bracket formed with an inverted L shaped opening 19. A time delay electric switch comprising, a switchrnechanism including within an enclosure a snap action leaf spring supporting a movable contact and at least one complementary fixed contact, a bracket supportingv said switch enclosure, a shaft journalled in said bracket, a switch handle affixed to said shaft and formed with a cam extending into said switch enclosure and engaging said leaf spring, a timing element secured to said bracket and including a housing enclosing a portion of said shaft and substantially filled with silicone elastic putty, and a vane frictionally engaging said shaft Within said housing and at least partially immersed in said putty, said cam being arranged to actuate said leaf spring to cause engagement and disengagement of said complementary contacts in motion of said handle between first and second terminal positions.

References Cited in the file of this patent UNITED STATES PATENTS

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