US2051654A - Elevator push button switch - Google Patents

Description

s. B. SANFORD ET AL 2,051,654

ELEVATOR PUSH BUTTON SWITCH Aug. 18, 1936.

Filed March 2, 1934 INVENTORS ATTORNEY Patented Aug. 18, 1936 UNITED STATES ELEVATOR PUSH BUTTON SWITCH Selden Bradley Sanford and David Carl Larson,

Yonkers, N. Y., assignors to Otis Elevator Company, New York, N. Y., a corporation of New Jersey Application March 2, 1934, Serial No. 713,636

1 Claim.

This invention relates to elevator push button switches. Characteristic of such switches are the push button switches, or elevator hall push buttons, as they are termed, provided in the halls of buildings for actuation by those desiring elevator service.

It has long been known in the elevator field that the provision of hall push button switches which are at once easy of operation, pleasing in appearance, economical to make and to maintain, and efiective as intended under all circumstances, is a diflicult undertaking. At the foundation of this problem is the fact that hall push buttons for elevators are subject to many forms of abuse, intentional as well as unintentional. Such abuse results either in the destruction of the push button switch, or of some part thereof, or in the alteration of the normal operation of the push button switch, with either of such results impairing the elevator service and necessitating repairs or replacements or both. The impairment of elevator service is a subtle, but vastly important I consequence of abuse of elevator hall push buttons. The abuse may result in failure of the push button switch, when actuated, to register desire for elevator service. The consequent long wait for an elevator car to stop at that floor is destructive to building prestige. In addition, it is usually not until this condition has existed for some time that the building management is apprised of it, and by then appreciable dissatisfaction with the elevator service may have accrued. The abuse, on the other hand, may result in causing the push button switch continuously to register desire for elevator service, regardless of whether there is anyone at the floor actually desiring service. As a consequence, elevator cars stopping at that floor in response to the apparent desire for service therefrom, many times find no one there. A false and useless stop'by the elevator car is not, at any time, complimentary of the elevator service, and since such a stop is clearly perceived by those in the elevator car, only a few such experiences cause users of the elevators to question the reliability of the elevator service, with consequent reflection against the character of the building. In addition, incident to every false and useless stop by an elevator car is the loss of a certain amount of time. In the aggregate; considering the number of elevator cars which make false stops at a floor where the hall push button switch is continuously registering, and the number of false stops made at that floor by each of such cars during the course of even only a fraction of a day, the total loss of time occa'- sioned by the continuously registering push button switch is enormous. This loss of time is detrimental to the elevator service, and thus, also to building prestige.

It is clear, therefore, that even if elevator 5 hall push button switches in a building are rendered ineffective or abnormally effective only occasionally, the situation is serious, not only in the direct repair and replacement costs involved, but also in the impairment of the elevator service and thus, in the impairment of the character and reputation of the building.

The need for elevator hall push button switches which always operate only as intended, regardless of abuse of every character, intentional and unintentional, is clearly apparent.

The principal abuses to which. push button switches are subject when provided as elevator hall buttons, are four. These are:

1. Blows or excessive pressure upon the pres sure-receiving element, either with blunt or sharp instruments, as, for example, umbrellas. These tend to fracture or otherwise injure the pressurereceiving element and other movable parts of the push button switch.

2. Sticking of the pressure-receiving element in the in position. This can be effected with the majority of push button switches by the use of tooth picks, pins, chewing gum, and similar articles.

3. Sticking of the pressure-receiving element in the out position. This is usually more diflicult of attainment than the preceding form of abuse, but in certain types of push button switches can be effected by the use of chewing gum, elastic bands, and the like. This, and the preceding form of abuse, are very frequently experienced in office buildings, where they are usually perpetrated by office, messenger and delivery boys.

4. Blows or force applied in a direction transverse to the motion of the pressure-receiving element. The most common form of this type of abuse results from the side-swiping'of the push button switch by trucks and other carriers, and is due to the fact that in many cases portions of the push button switches project outwardly from the wall an appreciable distance.

The object of this invention is the provision of a push button switch which is tamper-proof, which always operates only as intended, regardless of all forms of abuse and attempted abuse, which is simple in construction and operation, which is readily and cheaply manufactured and installed, which is pleasing in appearance, and

which, in spite of all forms of abuse, has a long, useful life.

The invention involves the provision of a small, thin, elastic, metallic diaphragm serving as a pressure-receiving member, the diaphragm being supported at its periphery by a suitable mounting. Manual depression of the diaphragm is transmitted to a movable contact member which engages or separates from a stationary contact member to close or open an elevator signal or control circuit. In the preferred construction, a stop is provided in rear of the diaphragm, over substantially the entire area of the pressure-receiving portion thereof, for limiting the inward motion of the diaphragm to a small value, with provision for causing movement of the contact portion of the movable contact member an amount greater than such limited motion of the diaphragm. Preferably the diaphragm is made of non-corrosive metal, such as beryllium copper, hardened after forming, with the pressure-receiving portion thereof self-returning. Preferably also the diaphragm mounting is arranged so that the edge thereof is substantially flush with the wall on which the push button switch is mounted.

In the drawing:

Figure 1 is a front elevation of a portion of the exterior of an elevator hall push button switch assembly in accordance with the invention;

Figure 2 is aside elevation thereof, with certain parts shown in section;

Figure 3 is a rear elevation thereof;

Figure 4 is a detail of certain of the parts thereof; and

Figure 5 is a sectional view thereof taken along the line 5-5 of Figure 2.

Referring to the drawing, the elevator hall push button switch assembly shown therein comprises a push button unit generally designated I I, a supporting plate l2, a receptacle I3, and a cover plate I4. For simplicity, only the immediately adjacent portions of the supporting plate I2, the receptacle I3 and the cover plate I4 are shown. Push button unit I I comprises a cylindrical plug member I5, a diaphragm I3, a contact assembly I1, and certain other parts to be described later. The push button unit is mounted in a suitable aperture in supporting plate I2 and secured therein by means of two fingers I8, one end of each of which is fastened, as by screws 23, to plate I2, and the other end of each of which fits into a circumferential groove 2| formed in plug member I5.

To receptacle I3 adjacent the top edge of sup porting plate I2 is adjustably mounted, as by screw 22, a bracket 23 having a front lip 24 and two rear lips 25. The space between the plane of the front lip and the plane of thetwo rear lips is such that, after bracket 23 is secured to receptacle I3, the top edge of supporting plate I2 may be inserted in such space and the plate moved upwardly from the position in which it is illustrated in order that the bottom edge of the plate may be inserted between the lips of a similar bracket at the bottom of receptacle I3. Cover plate I4 encloses the front of receptacle I3, and is secured in place by screws 26 (only one being illustrated) which extend through apertures therein and through suitably threaded apertures in supporting plate I2. Cover plate I4 is provided with one or more apertures corresponding to the number of push button units II enclosed by the cover plate, arranged so that each aperture fits over a corresponding plug member i5, with the circumferential edges of the diaphragm I5 substantially flush with the front face of the cover plate. Preferably receptacle I3 is mounted in the supporting wall (not shown) so that cover plate I4 is parallel thereto and substantially flush therewith.

Plug member I5 is preferably formed as a single solid metallic piece and arranged so that its front face 21 is substantially flush with the front face of cover plate I4. Diaphragm I6 is positioned over front face 21 of plug member I5 and is provided with a plurality of bent-over lips 39 engaging the sides of a circumferential groove 3| directly behind front face 21 to maintain the diaphragm in position. Diaphragm I 5 is made of extremely thin, elastic, metallic material and preferably is formed so that its pressure-receiving area. is displaced outwardly from the front face 2'! of plug member I5, the shape for such bulging pressure-receiving area being that of a spheroidal shell of relatively large radius. In addition, the elasticity and shape of the diaphragm are preferably such that the pressurereceiving area thereof is self-returning to its initial position so long as such area is not displaced past the plane of the circumferential edges of the diaphragm.

An aperture 32 is provided through plug member I5 from front face 21 to rear face 33, this aperture preferably being along the cylindrical axis of the plug member. Slidably fitted in aperture 32 is a push pin 34, preferably of insulating material, with the end thereof abutting against the inner surface of diaphragm I6. The other end of push pin 34 abuts against a push bar 35, preferably of insulating material and of rectangular cross-section. A transverse slot 36 is formed in push bar 35, and along the unslotted side of the push bar is positioned a key strip 31, the key strip being secured to the push bar, as by the rivet 43. The functions of push pin 34, push bar 35, slot 36 and key strip 31 will appear as the description proceeds.

The contact assembly generally designated I1 is mounted on rear face 33 of plug member I5. As illustrated, it comprises two leaf springs-a stationary one M and a movable one 42separated by an insulating washer 43 and secured to plug member I5 by two screws 44, insulating washers 45 being provided at either side of the leaf springs. It is preferred to provide also a metallic cap washer 46 and lock washers 41 adjacent the heads of screws 44, and an insulator piece 53, covering substantially all of rear face 33, between such face and the immediately adjacent washer 45. Stationary leaf spring 4| is shaped to provide a terminal tab 5 I. Movable leaf spring 42 may also be shaped to provide a similar terminal tab, but it is preferred to employ for this purpose a separate metallic spacing washer 52, with terminal tab 53, interposed between leaf spring 42 and insulating washer 43, metallic spacing washer 52 being less wide than insulating washer 43. Terminal tabs 5I and 53 may be connected into an elevator signal or control circuit by means of which intending passengers register their desire for elevator service.

Movable leaf spring 4?. is provided with an aperture 54 (see Figure 4) through which passes push bar 35 and key strip 31, with a tongue 55 of leaf spring 42 arranged to fit into slot 35 on the push bar. As a result of this construction, motion of push bar 35 to the right, as viewed in Figure 2, due to the application of pressure upon diaphragm l6 and the consequent displacement of push pin 34, causes leaf spring 42 to bend about its base so that the outer end of leaf spring 42 moves toward the outer end of leaf spring 4|. The ends of these leaf springs are providedwith suitable contact points 56, preferably of compositions in which silver or rare metals of the platinum group, such as palladium, predominate. The application of pressure upon diaphragm l6 thus results in the engagement of these contact points at the ends of the leaf springs, and thus in the completion of a circuit from terminal tab 5| to terminal tab 53.

At the side of aperture 54 in leaf spring 42 opposite to tongue is a shoulder 51. This shoulder, together with key strip 31 to which it is adjacent, prevents disengagement of push bar 35 from tongue 55. In assembling these parts, push bar 35, without key strip 3'! attached thereto, is first inserted in aperture 54 until slot 36 is opposite tongue 55. The push bar is then moved transversely in aperture 54 so that tongue 55 fits into slot 35. Key strip 31 is then inserted in aperture 54 along the back of push bar 35 and secured in place, as by the rivet 40. Push bar 35 and key strip 31 are preferably of such dimensions that, when secured together, they are guided by the sides of aperture 32 in plug member l5, as illustrated in Figure 5.

It is preferred to provide stationary leaf spring 4| with an enlarged aperture through which may extend the ends of push bar 35 and key strip 31. In this connection, it is to be noted that contact assembly I! may include leaf spring contacts in addition to the two illustrated, such additional contacts being readily mounted on plug member l5 by screws 44 in the same manner as are the two contacts illustrated so that a stack of contacts results, and the movable leaf spring contact of each pair of contacts in such stack being actuated by push bar 35 (elongated if necessary) in the same manner as leaf spring contact 42 is actuated. It is also to be noted that normally closed leaf spring contacts may as readily be employed as the normally open leaf spring contacts illustrated, and further, that contact assembly I! may include any combination of normally open and normally closed contacts.

Attention is directed to the fact that front face 21 of plug member l5 acts as a stop for diaphragm I 6 and thus restricts to a small value the inward motion of the diaphragm, regardless of the amount of pressure applied thereto. In addition, front face 2'! is preferably in the same plane as the circumferential edges of the diaphragm, as illustrated, so that the diaphragm cannot be deformed past such plane. Diaphragm l6, not being rigidly secured to plug member i5, is free to give a small amount at its periphery upon deformation by the application of pressure thereto. Upon the removal of the pressure causing the deformation of diaphragm IS, the diahragm returns of its own accord to its original position. Diaphragm I3 is preferably made of thin, elastic, metallic material that may be hardened after formation into the desired shape, although it may be made of any thin, hard, puncture-proof, elastic material. The preferred metallic material for diaphragm I6 is copper with about 2 beryllium, heat treated, after formation, at about 525 F. for an hour and then air cooled. The resulting diaphragm is almost as hard as steel, is non-corrosive, withstands much abuse, is not readily cut or punctured, and is elastic. It has been found that a diaphragm l6 of such material, with an inside diameter of 1 inches, a thickness of 5/1000 inch, and arranged in a push button unit such as illustrated so that the maximum inward motion is about inch, undergoes without failure service equivalent to over sixty years service as a hall push button in a heavy traific building.

Attention is also directed to the fact that by the construction herein described and illustrated, s

its ends, and enables, for a given amount of relative motion of the contact points, the use of a diaphragm of smaller diameter than is otherwise possible. The importance of a small diameter diaphragm from the viewpoint of artistic appearance in elevator lobbies is readily appreciated. Also of importance is a. construction in which only a comparatively small, but-discernible motion of the diaphragm is required to actuate the push button contacts, since constructions requiring large motions of the diaphragm will be insufliciently actuated by the general public. Multiplication of the diaphragm motion thus also results in obtaining sufficient relative motion of the contact points conjointly with the desired small amount of diaphragm motion. In the illustrated construction the multiplication ratio is approximately 2 to- 1.

The movable leaf spring 42 is preferably of thin, elastic, metallic material. Beryllium copper, similar to that of which the diaphragm is preferably made, and similarly heat treated, had been found to give satisfactory service for leaf spring 42. In order to minimize local bending in leaf spring 42, and thus to assist in attaining long life for leaf spring 42, aperture 54 is provided with special flares as illustrated, although other shapes may be employed.

It is to be noted that with the construction for the push button switch herein described, the installation thereof may be effected in stages as the progress of the building construction .advances. Thus, receptacle l3 may be mounted in the supporting wall at the time the conduit is installed, which is usually before any plastering takes place. At some later date, the wiring-is drawn through the conduit and the wire ends left free in the receptacle. At a still later date, when the building nears completion and the elevator installation is about to be set in operation, the push button unit or units H for each receptacle I3 have their terminal tabs 5| and 53 connected to the appropriate Wire ends. Push button unit or units H are then secured to supporting plate [2 and the supporting plate inserted between the lips of upper bracket 23 and a corresponding lower bracket (not shown). Cover plate I4 is then secured in place by screws 26, this operation also securing in place supporting plate l2. In the event replacement or repair of any part of push button unit II should become necessary, it is to be noted that the entire unit may be removed with ease and a complete new unit substituted in place thereof. The interruption of the elevator service from that floor is consequently a minimum, and, if desired, the repair or replacement of the injured part of the removed push button unit may be effected at a later and more convenient time.

Inasmuch as many changes could be made in the above construction and many apparently Widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

A tamper-proof elevator push button switch comprising; a cylindrical member having a front face, a rear face, an aperture substantially along the axis thereof between the two faces, and a circumferential groove just behind the front face to form a circular bead around the front end of the member, the front of said bead curving back from said front face to the periphery of the bead and the rear of said bead sloping back from said periphery into said groove; switching mechanism mounted on said rear face of said member; a manually depressible circular diaphragm of thin, elastic, metallic material having a body portion shaped as a portion of a spheroidal shell of relatively large radius, said diaphragm having lips for securing said diaphragm in position over said front face with said body portion extending outwardly therefrom, the edge of said diaphragm being curved to conform with the curvature of said bead up to the periphery of the bead and said lips extending inwardly from the periphery of the bead and being bent to fit against the rear of said bead, thereby securing the diaphragm to said member in such way that the diaphragm is free to give radially outwardly at its edge upon pressure being applied to the diaphragm, thus permitting the diaphragm to be depressed, said front face preventing inward motion of said diaphragm past the plane of the periphery of said body portion, and said diaphragm being self-returning from all resulting depressible positions; and a push rod abutting against the inside surface of said diaphragm and sliding in, and guided by, said aperture in said cylindrical member for operating said switching mechanism.

SELDEN BRADLEY SANFORD. DAVID CARL LARSON.

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