US2866862A - Time delay switch - Google Patents

Description

D66. 3o, 195s R. w. BACH. 2,666,862

TIME DELAY SWITCH Dec. 30, 1958 .R. w. BACI-n 2,866,862

TIME DELAY SWITCH i Filed oet. 14. 1955 l 2 sheets-sheet 2 United States Patent i TIME DELAY SWITCH Robert W. Bachi, Marion, Ind., assignor, by mesne assignments, to Controls `Company of America, Schiller Park, Ill., a corporation of Delaware Application October 14, 1955, Serial No. 540,475

8 Claims. (Cl. 200-34) This invention relates to time delay instrumentalities and refers more particularly to instrumentalities for effecting return movement of the actuator of an electric switch or other control device to a predetermined position after a time delay interval fo-llowing displacement of the actuator out of said position.

Time delay instrumentalities have numerous applications and uses, many of which are quite familiar to those skilled in the art. The forms which such instrumentalities may take vary almost as widely as their uses, and while the time delay instrumentality of the present invention is herein described as incorporating an electric switch, it will be understood that the principles o-f the present invention are applicable to time delay instrumentalities incorporating any type of control device having an actuator movable in opposite directions to and from a predetermined position.

The time delay mechanism of this invention operates on the familiar air bleed principle. It comprises means defining a substantially closed chamber having a wall member movable inwardly and outwardly of the chamber and biased outwardly thereof. ln addition to an air bleed orice for the chamber, one of the chamber walls has an exhaust port therein controlled by a check valve. This valve opens as a consequence of motion of the movable wall member inwardly of the chamber to permit air to be quickly expelled therefrom through the exhaust port; and the valve closes to prevent entry of air into the chamber except through its bleed orifice, as a consequence of motion of the movable wall member outwardly of the chamber. The restricted vent or'bleed orice admits air to the chamber at a predetermined rate after the check valve closes and thus regulates the rate at which the movable wall member moves outwardly of the -chamber in response to the bias thereon.

The movable wall member of the time delay mechanism has a motion transmitting connection with an actuator for a switch or other control instrumentality whereby displacement of the actuator out of a predetermined or normal position moves the wall member inwardly of the chamber, and dampingly retarded movement of the wall member outwardly of the chamber returns the actuator to its predetermined position after a time delay interval.

Since the accuracy of such an instrumentality is dependent upon the accuracy of calibration of the restricted vent and the accuracy and consistency of response of the switch or other control, it is an object of this invention to provide a time delay instrumentality of the character described wherein the movable wall member of the air bleed mechanism comprises a resiliently tiexible membrane forming part of a novel check valve subassembly, and wherein a relatively small eXure off the membrane displaces a large volume of air, thus at once facilitating calibration of the restricted vent and assuring accurate and consistent switch response.

Another object of this invention resides in the provision of a compact and inexpensive but very consistent time 2,866,862 f here# Dec- 30 1.95??y delay instrumentality of the character described wherein the check valve is not only carried by the membrane but a portion of the membrane itself serves as a seat for the check valve.

Still another object of this invention resides in the provision of a time delay instrumentality having an un-l usually simple, compact and inexpensive actuator which provides a motion transmitting connection between-the movable wall member of an air bleed time delay mecha-- nism and a switch or other control mechanism to be actuated. Y

A further object of this invention resides in the provision of a time delay instrumentality for controlling an electric circuit which is unusually compact and simple by reason of its having an actuator mounted for endwise back and forth movement and a switch arm mounted for back and forth swinging movement substantially in the path of travel of the actuator, and Yextending through an aperture in the actuator; and wherein the actuator pro-L vides a-motion transmittingh connection between the switch arm and the movable wall member of an air bleed time delay mechanism of the character described.

Still another object of this invention resides in the provision of a time delay instrumentality incorporating a switch or other control mechanism of a type which may be snapped from one position to another and an actuator for the control mechanism movable in opposite directions, wherein the actuator has substantial overtravel in one direction of its movement, beyond a position at which the contro-l'mechanism'snaps over, and wherein return movement of the actuator to the snap over position is delayingly retarded, the time interval required for return to said position being proportional to overtravel of the actuator beyond said position.

With the above and other objects in view which will appear as the descriptio-nproceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate two complete examples of the physical embodiments of the invention constructed according to the best modes so far devised for the practical application of the principles thereof, and in which: f

Figure l is a vertical sectional view of a time delay instrumentality embodying the principles of this invention, the mechanism ofthe device being shownfin its normal or inoperative position;

Figure 2 is a vertical sectional view taken on the plane of the line 2 2 in Figure l;

Figure 3 is a view similar to Figure 2 but showing the mechanism moved outof its normal position;

Figure 4 is a group perspective view of the elements comprising the check valve movable wall subassembl-y in the time delay mechanism of the instrumentality shown in Figures 1-3;

Figure 5 is a side View, partly in elevation and partly in section, showing a modified embodiment of the instrumentality of this invention, the mechanismbeing shown in its normal or inoperative position; and

Figure 6 is a view similar to Figure 5 but showing the actuator moved out of its normal position.

Referring now more particularly to the accompanying drawings, in which likenumerals designate like'parts.`

ator 8 movably mounted in the housing but projecting therefrom to provide a push-button 9 accessible at the exterior of the housing, and an air bleed time delay mechanism designated generally by 10.

The time delay mechanism comprises generally a resiliently flexible membrane 11 extending across the bottom of the housing body and a cup-like shell 12 secured to the housing body 6 beneath the membrane and cooperating therewith to dene a substantially closed chamber 13. The membrane is movableinwardly and outwardly of the Chamber and is biased outwardly thereof by a compression spring 14. The membrane carries a check valve, designated generally by 15, which permits air from the chamber to be readily expelled through an exhaust port in the chamber provided by an aperture 16 in the membrane when the latter moves inwardly -of the chamber. The check valve however, normally seals the aperture when the membrane moves outwardly of the chamber in response to the bias thereon of the spring 14, so that air then enters the chamber through a restricted vent or bleed orifice 17 which communicates the chamberv with the atmosphere.

The actuator 8 has motion transmitting connections with the membrane and with the switch, whereby depression of the push button 9 displaces the membrane inwardly of the chamber and the membrane returns the actuator to its normal position at a dampingly retarded rate, and whereby depression of the push button actuates the switch in one direction, out of its normal position, at one point in the path of travel of the actuator, while upon release of the push button the actuator returns the switch to its normal position after a time delay interval dependent upon the extent to which the push button was depressed beyond said po-int in the path of the actuator travel.

To describe the instrumentality more specifically, the housing body comprises a shell-like member of insulative material, such as Bakelite, having a circular lower section or base 18 which is-open at its bottom, and having a reduced upper section 18 providing a compartment to receive and enclose the switch mechanism. The upper section 18' includes a pair of spaced apart, substantially parallel side walls 19 projecting upwardly from the base 18 and a stepped top wall having an upper level 20 located substantially centrally over the base 18 and a pair of lower levels 20 and 20 adjacent to the end portions of the side walls 19.

The switch 7 is preferably an overcenter snap acting device of familiar type, .comprising apair 4of arms, namely an actuating arm 21 and a contact arm 22, connected by means of a substantiallyv Ufshaped 'overcenterA spring 23 Whichis confined under compression between the arms. Both switch arms are fixed at one endV of the housing and extend substantially horizontally thereacross, lengthwisebetween the `side walls thereof, and they are preferably formed as integral parts of -a single piece of spring strip material. The switch `arms are secured to vthe under surface of the lower top wallrlevel 20 ras by means of a rivet 24 whichv also `secures a spade-type terminal connector 25 tothe housingand electrically connects it with the contact blade. Another spade-type terminal 26 at the opposite end of the housing is likewisesecured by a rivetr27 to the other lower level 20" of the housing body .wall and hasanextension atits innerend carrying a fixed contact 28 with which a movable contact' 29 on the free end of the contactarrn 22 is normally engaged. The overcenter spring,23,.c,onnected betweenthe freeend portions of the switch arms, causes the contactarm to snap upwardly away from the xed contact as the actuating arm is moved downwardly through av critical position in which the arms Vare substantially coplanar, and snaps the `contact arm back idown into engagement with the xed contact as the actuating arm vis moved upwardly through the critical position. Although the-switch heretillustrated and ldescribed is of the normally "Closed type, it willl be readily understood that the invention is equally well adapted for use with a normally open switch, and that the switch mechanism just described may be readily embodied in a normally open switch, the fixed Contact 28 being located above the contact arm 22 rather than below it.

Movement of the switch actuating arm is effected by the actuator 8, which comprises a rigid substantially at member of insulative material having a pair of straight, parallel opposite side edge portions 30 which are slidably guided in opposed upright grooves 313 in the inner surfaces of the side walls 19. The push button portion 9 at the top of the actuator projects through a slot-like aperture 31 in the upper levelr 2l) of the housing body top wall to be accessible at the exterior thereof.

The actuator has a medial aperture 33 through which the two switch arms project, and up and down motion of the actuator is translated into swinging motion of the actuating arm 21 by means of a pair of spur-like projections 34 on the actuator extending into the aperture therein to provide spaced upper and lower shoulders engageable with the top and bottom faces of the actuating arm. While the switch actuating arm 21 is shown normally engaged with the upper shoulder (see Figure l), it will be understood that by reason of the spacing between the shoulders on the spur-like abutments it is possible to have the upper shoulder normally spaced a small distance above the arm so as to require a slight downward travel of the actuator from its uppermost position before it engages the arm and begins to swing the latter downwardly, thus providing an increased amount of pretravel of the actuator before the switch actuating arm is swung through its critical position. A downwardly facing abutment 35 on the bottom of the actuator provides a motion transmitting connection with the air bleed time delay device whereby depression of the actuator, by which the switch is snapped out of its normal position, is translated into downward motion of the movable wall (i. e., motion of the membrane inwardly of the chamber' 13) and whereby upward movement of the membrane causes the actuator to rise and thus restore the switch to its normal position. It will be appreciated that the actuating arm 21 of the overcenter snap acting switch described above is capable of substantial overtravel beyond its critical position, thus providing for suicient deflection of the diaphragm to afford delayed return of the switch to its normal position as hereinbefore described.

Feet 36 projecting laterally from the side edges of the actuator at its bottom normally engage the inside of the base 18, as seen best in Figure 1, to define the upward limit of `travel of the actuator.

The cup-like shell 12 which cooperates with the membrane ,11 to define the chamber 13 is preferably a metal stamping having its Arim portion clinched as at 37 around an annular shoulder 38 on the periphery of the base of the housing body. The marginal edge portion of the membrane is clamped between an upwardly facing annular abutment 40 on the circular base of the housing body, and since the membrane is made of neoprene or similar resilient material the chamber 13 is thereby effectively sealed from the interior of the housing body above it. A suitable mounting bracket 41 may be spot welded or otherwise secured to the shell.

Flexing motion of the membrane is transmitted to the actuator, and vice versa, through a dished, substantially rigid reinforcing disc 42 atwise overlying the upper face of the membrane and secured thereto. The lower edge of the actuator, which provides the downwardly facing abutment 35 thereon, engages the upper face of the disc, and the latter is apertured as at 43, to permit escape of air from the chamber 13 through the aperture or exhaust port 16 in `the membrane when the check valve means carried by the membrane is opened in consequence of downward exure of the membrane, inwardly of the chamber. The disc 42 is secured to the membrane by means of a plurality. of tits 45 integral with the membrane and projecting from the upper surface thereof for tight engagement in suitable holes in the peripheral portion of the disc.

In the embodiment of the invention shown in Figures 1-4, the check valve means comprises a substantially rigid valve disc 50, preferably formed as a stamping and secured to the underside of the membrane by means of tits 51 projecting downwardly from the membrane and tightly engaged in suitable holes in the peripheral portion of the valve disc. The central portion of the valve disc which lies beneath the exhaust port 16 is imperforate and is bounded by an annular upwardly projecting ridge 52 in the disc, concentric with the aperture 16 in the membrane but substantially larger in diameter than said aperture. Radially intermediate the mounting holes and the annular ridge 52, the valve disc has a plurality of clawlike lugs S3 struck downwardly therefrom to engage around circumferentially spaced areas of the uppermost convolution of the coiled compression spring 14 to hold the spring connected with the valve disc and to retain the spring against lateral shifting.

The valve disc 50 thus receives the upward thrust of the compression spring 14 and transmits it to the membrane, and as the membrane moves outwardly (up wardly) in response thereto the annular ridge 52 on the check valve disc sealingly engages the underside of the membrane to thereby obstruct entry of air into the chamber 13 through the exhaust port 16 in the membrane. It will be appreciated that the membrane will have good sealing engagement with the annular ridge when sub-atmospheric pressure exists in the chamber 13 because of the resiliency of the membrane, the compression of the disc against-the membrane by spring 14, and the force of atmospheric pressure exerted on the outer face of the membrane.

When the membrane is displaced inwardly of the chamber, by downward movement of the actuator, air flows out of the chamber through a plurality of vent apertures 54 in the valve disc, arranged in a circle radially outwardly of the annular ridge therein, and such air then flows radially inwardly across the top of the valve disc, raising the membrane off the annular ridge, and thence out through the exhaust port 16 in the membrane. The reinforcing disc 42 overlying the upper surface of the membrane, which serves to transmit downward motion of the actuator to the membrane, has a dished contour to enable the membrane to flex away from the annular shoulder on the valve disc when the membrane is displaced inwardly of the chamber, and the aperture 43 in the reinforcing disc permits escape of air from the exhaust port 16 in the membrane when the check valve is thus opened.

In the embodiment of the invention shown in Figures 5 and 6 the check valve comprises a resiliently flexible disc S6 which is retained in place over the-upper face of the membrane by means of a rigid, dished reinforcing member 42', which, like the reinforcing member 42 in the previously described embodiment of the invention, is similarly secured to the membrane and transmits motion of the actuator to the membrane and vice versa.

A disk-like stiffener 57 flatwise overlies and is secured to the lower face of the membrane, and like the check valve disc of the previous embodiment has claw-like lugs 53 formed thereon to hold the uppermost convolution of the compression spring 14 securely connected thereto. A central aperture 59 in the stiffener registers with the exhaust port 16 in the membrane to permit escape of air from the chamber 13 when the membrane is displaced inwardly of the chamber and the check valve is opened. Except for the claw-like lugs 53', the stiffener 57 is entirely flat.

The resilient check valve disc is preferably formed of neoprene or the like and has a coaxial upwardly projecting tit 60 whichtightly engages in a central hole in the reinforcing member 42' and whereby the resilient check valve disc is held concentric with the membrane. The marginal edge portion of the check valve disc comprises a resiliently flexible lip 61 which normally has sealing engagement with the upper surface of the membrane and thus prevents entry of air into the chamber 13 through port 16 in the membrane when the membrane is displaced outwardly of the chamber in response to the force of spring 14. However, a plurality of protuberances 62 on the underside of the check valve disc, engaged with the upper surface of the membrane around the exhaust port therein, hold the medial portion of the check valve disc spaced above the membrane, and as the membrane is displaced inwardly of the chamber 13, air flowing out of the chamber through the exhaust port 16 and between the membrane and the body portion of the resilient disc, flexes the marginal lip portion 61 of the check valve disc out of engagement with the membrane. The reinforcing member 42', of course, has a number of apertures 55 therein to permit such air to escape.

The vent through which air may bleed slowly into the chamber as the membrane rises in response to the force of spring 14 thereon may be provided with a needle valve 63, as shown in Figure 1, to permit adjustment of the rate at which air bleeds back into the chamber 13, or it may comprise a simple bleed aperture 17', as shown in Figure 5, the size of which regulates the rate at which air flows into chamber 13 and thus governs the time delay interval of the mechanism. In the construction shownin Figure l air entering the vent is constrained to pass through a collar 64 of porous filtering material.

From the foregoing description taken together with the accompanying drawings it will be apparent that this invention provides an inexpensive time delay instrumentality which will be accurate and consistent in operation, wherein the check valve means of the time delay mechanism is carried by the movable wall member thereof to form a subassembly therewith, and wherein a very simple and inexpensive actuator provides a motion transmitting connection between a control instrumentality and the movable wall member of the time delay mechanism.

What is claimed as my invention is:

l. In a time delay instrumentality having a member movable in one direction out of a defined position at a substantially unrestricted rate, means for effecting slow return of said member to its defined position, comprising: means, including a membrane, defining a substantially closed chamber in which atmospheric pressure normally obtains, said membrane being resiliently flexible inwardly and outwardly of said chamber and having a central aperture defining an exhaust port; a disk-like valve member overlying said port at one face of the membrane and having an annular portionfnormally in sealing engagement with the adjacent face of the membrane at an annular zone thereof spaced from but surrounding said port, said valve member being disengageable from the membrane upon flexure of the membrane inwardly of said chamber, and the valve member being imperforate within said annular portion thereof, so that it cooperates with the membrane to provide a check valve which opens only upon inward flexure of the rmembrane to provide for exhausting air from said chamber through the port in the membrane; means yieldingly urging said membrane outwardly of the chamber; means providing a motion transmitting connection between said member and the membrane by which the membrane is moved inwardly of the chamber by said member upon movement of said member out of its normal position; and means in one wall of said chamber defining a restricted vent communicating the interior of said chamber with the atmosphere and through which air is caused to flow in response to flexure of the membrane outwardly of the chamber under the influence of said biasing means, said restricted vent regulating the rate of such outwardflexing of the membrane `and consequently the return of said member to its normal position.

2. The time delay instrumentality of claim l, wherein the annular 'portion of said valve member is provided by a marginal edge portion thereof which is resiliently flexible toward and from engagement with the adjacent face of the membrane; and wherein said valve member has its imperforate portion spaced from said face of the membrane to permit air exhausting through said port in the membrane to flow between the membrane and the valve member when the membrane is iiexed inwardly of the chamber.

3. The time delay instrumentality of claim l wherein said valve member comprises a disk of resiliently fiexible material having a readily yieldable marginal edge portion which provides said annular portion thereof, and having a plurality of integral knobs engaged with the adjacent face of the membrane to hold the disk spaced therefrom a distance small enough to permit said marginal edge portion to iiex into engagement with the membrane; and securement means holding the valve member in place on the membrane and bodily movable theewith.

4. The time delay instrumentality of claim l wherein said valve member comprises a substantially inexible disk, said annular portion thereof comprising a ridge, said disk being secured to the membrane at points disposed radially outwardly of the annular ridge thereon to permit the membrane to flex away from engagement with said annular ridge, and said disk being apertured between said annular ridge and its securement to the membrane to permit air to pass through the space between the opposed faces of said disk and the membrane.

5. In a time delay instrumentality: a housing body comprising a pair of upright, spaced apart, substantially parallel walls having opposite vertically extending internal grooves, a top wall having an aperture vertically aligned with said grooves in the upright walls, and a circular base portion open at its bottom and to which the interior of the housing body opens; means defining a Substantially closed chamber below the housing body. said chamber defining means including a movable Wall member extending across the bottom of said base portion of the housing body and movable vup and down, outwardly and inwardly of said chamber; means biasing said movable wall member upwardly, outward of said chamber, to a predetermined position; means, including check valve means, permitting free explusion of air from said chamber upon movement of said movable wall member inwardly of the chamber but providing for return of air to the chamber at a slow regulated rate as said wall member moves back upwardly to its predetermined position in response to the bias thereon; a switch arm extending srb stantially horizontally between said upright walls and lswingable up and down; and an actuator having straight side edge portions received in said grooves to be thereby guided in up and down motion, said actuator having a portion at its top projecting through the aperture in the top wall of the housing body to be accessible at the exterior thereof and having a portion at its bottom engaging said movable wall of the chamber whereby said wall may be moved inwardly of the chamber in response to downward pressure upon the projecting top portion of the actuator and whereby the actuator is moved upwardly in unison with said movable wall as the latter returns to its predetermined position, said actuator having a cutout through which the switch arm extends and having abutmeuts engageable with the switch arm to swing the arm up and down with up and down motion of the actuator.

6. ln a time delay instrumentality for controlling an electricv circuit: a housing; means on said housing including 'a iiexible membrane dening a substantially closed chamber at one side of the membrane and a switch compartment at the other side of the membrane; a rigid switch actuator in the housing; means on the housing constraining lthe actuator to back and forth movement toward and from the membrane, said actuator 4having a projection at one end thereof projecting out of the housing through an aperture in a wall thereof to be accessible at the exterior of the housing, and said actuator having an abutment at its other end and a cutout; means on the membrane providing a rigid reinforcement therefor, at the face thereof adjacent to the switch compartment, and cooperable with said abutment on the actuator to translate motion of the actuator toward the membrane into liexing of the membrane inwardly of said chamber and to translate exing of the membrane outwardly of said chamber into motion of the actuator in the opposite direction; means yieldingly biasing the membrane outwardly of said chamber; check valve means cooperable with an apertured wall portion of said chamber to permit free escape of air from the chamber upon exure of the membrane inwardly of the chamber and to obstruct entry of air into the chamber through said aperture as the membrane flexes outwardly of the chamber; means providing a restricted vent communicating the interior of said chamber with the atmosphere to regulate the rate at which air ows into said chamber in response to outward ilexing of the membrane and to thus regulate the rate at which said actuator is moved in said opposite direction; and a switch carried by the housing in the switch compartment thereof, and said switch including a movable switch arm mounted in spaced substantially parallel relation to said membrane and movable toward and from the membrane to operate the switch, said switch arm extending through said cutout in the actuator and having a connection with the actuator whereby the actuator effects swinging of the switch arm toward the membrane as the actuator is moved toward the same and whereby the switch arm swings away from the membrane at a rate determined by movement of said actuator in said opposite direction.

7. In a time delay circuit controlling instrumentality: a body; a switch carried by the body and having a contactor movable to and from a normal position; a switch actuator movably mounted on the body and operatively connected with the switch contactor to eifect shifting of the same out of said normal position thereof upon application of force to the actuator to move the same in one direction; means on the body defining a substantially closed chamber having a movable wall, whereby shifting of sa-id movable wall out of a predetermined position varies the size of the chamber, yieldable biasing means acting on said movable wall for returning the same to said predetermined position thereof; means providing a motion transmitting connection between the actuator and said movable wall whereby the actuator, when moved in said one direction to effect the operation of the switch, shifts said movable wall out of said predetermined position thereof, and whereby return motion of said movable wall to its predetermined position under the inuence of said biasing means shifts the actuator in the opposite direction and eifects restoration of the switch to its normal condition; said movable wall having a port for communicating the chamber with the atmosphere; means on said movable wall of the chamber providing a check valve normally closing said port but arranged to open to communicate the chamber with the atmosphere in response to the pressure to which it is subjected as a consequence of actuator produced motion of said movable wall out of its predetermined position; and means on a wall of said chamber defining a restricted vent through which air is caused to ilow in consequence of return motion of said movable wall under the influence of said biasing means, said restricted vent regulating the rate of such return motion of the movable wall tol thus assure a delay in the return of the switch to its normal condition.

8. The time delay circuit controlling instrumentality set forth in claim 7 wherein the bias o f said movable wall is provided by a spring in the interior of said cham- 9 ber acting on the movable wall in a direction to moye 2,247,038 the same outwardly and increase the size of the chamber. 2,541,370 2,573,514 References Cited in the le of this patent 2,629,793

UNITED STATES PATENTS 5 1,451,323l Desplats Apr. 10, 1923 10 d Uriga .fune 24, 1941 Koonz et al. Feb. 13, 1951 Turner Oct. 30, 1951 Ponstingl Feb. 24, 1953

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