US3084235A

US3084235A - Tuning fork type relays

Info

Publication number: US3084235A
Application number: US157494A
Authority: US
Inventors: Reifel Harry; Karon Gerald
Original assignee: Stevens Arnold Inc
Current assignee: Artesyn North America Inc
Priority date: 1961-12-06
Filing date: 1961-12-06
Publication date: 1963-04-02
Anticipated expiration: 1980-04-02

Description

April 2, 1963 H. REIFEL ETAL TUNING FORK TYPE RELAYS Filed Dec. 6. 1961 l'awenior s: Har'fly RetfeZ, (Lara/a K812840371, 3 W J. WM

uibiba' ney U wd W Paren 3,034,235 r 1 TUNING FORKT IE'REIQAYS I Harry Reifel-,.Waltham-, and G'eraldKaron, Randolph, Mass, assignors tojxstevens-Arnqld ;Inc., South Boston; a s a cor o on of Mas a hu s Filed Dec. 6, 1961, Ser. l {o ,'1-57,494'

5 Claims. (Cl. 200-91) This invention relates to electromagneticrelays, and relatesntore particularly toelectrorna'gneticrelays having tuning fork type, vibratory tynes. v I

This invention uses a tuning fork having it's tyne's -and base stampe'dj in, one piece from magnetic sheet metal. An electromagnet, has a permanent ma e ole pi m of am h na n'e and m dwa b twee free ends of the tynes and whfch magnenzes the latt r to oppositepolarities. A.C. at the resonant frequency of the tuningfork isapplied to the coil of the electromagnet, and causes the free ends of the tynes to be alter n ey attracted by and repelled; byithe magnet insynchronism with the applied A.C. Since the phase, there is less vibration transmitted to a support than wherea'single vibratory reed is used. I A,

One of the tynes has a fixed contact on its innersurf c adjacent o i free and. nd ast al? m st e lirame of the relay, has aresilient contact strip canti lever supported thereto, with itjs free end oppositefthe contact on the one tyne. As the 'o'ne tynernoves' inwardly fat or near its resonant irequen'cy, it touches the free end of the resilient contact, closing a circuit in which the contacts are connected. The resilient contact hasa resonant frequency much higher than that of; the tuning" fork. This has the advantage that since the resilient contact does not load the tyne it touches, the so-called' holdregipn is a minimum. By hold region is meant the increase in band width to which the'tynies respond whenthe relay is in operation. It is desired that the tynes respond to a very narrow band of frequencies centered about their resonant frequency,- but when; loaded by stifr', lfi xed'contacts, the response band increases excessively during operation. This has-the disadvantagethat the tuning fork vibrates and closes its'contacts'at'frequencies outside its desired operating range, and is not sufiiciently selective.

The construction of the relay is simplified, and its cost is reduced by using as a frame, a single strap of nonmagnetic material, to the outer end of which the base of the tuning fork is attached, and by constructing the tuning fork in a single piece from sheet metal. The strap has a flange on its inner end which is cemented to a plastic disc on the adjacent end of a coil of an electromagnet, which is concentric with and has a larger diameter than that of the coil. A plug in type base has a recessed inner end at the other end of the coil, having the same diameter as the disc. A metal collar having an outside diameter equal to that of the disc and the recessed end of the base, extends around the coil with its edges in contact with the disc and base. A brass shield has a particylindrical outer portion with an open end which fits snugly around the recess in the collar and the disc and collar, and has a Patti-cylindrical, inner portion which has spaced-apart segments with ends whichcontact the side of the disc which is cemented to the flange. The inner shield portion forces the disc against the collar and the latter against the base, and the outer shield portion snugly contacts the outer surfaces of the discs, the collar, and the recess base portion, securing these components tightly together without the necessity for screws or bolts.

An object of this invention is to reduce the hold region of a tuning fork type relay.

Other objects of this invention are to simplify and to reduce the costs of tuning fork type relays.

ms vibrate ontofer CC This invention will now he described with reference to the annexed drawings, of which: I 7

FIG. 1 isa side elevation, in 'sectiomof a relay embodying this invention, showing the edge of the tuning fork, and the contact side of the support strap;

FIG. 2 is a side elevation, with the shield shown in section, of the relay rotated about its axis from the position shown by FIG. 1; 7

FIG. 3 is a side elev ati'onof the relay looking at the side opposite that shown by FIG. 1", and

FIG. 4 is afragmentary view of the relay, showing an alternative form of fixed contact structure.

A strap 10 of non-magnetic metal has a flange 12 on its 'inner end. A tuning fork '13" formed in one piece from ma'gnetiosheet metal, has a base 14 with an extension '15 which is'attached by a screw 16 to the outer end of the strap 10. The tuning fork has spaced-apart tynes 17 and 18; The tyne '17 "has a con-tact 19 on its inner surface adjacent to its free end. A fixed contact strip 20' of resilient metal, having a higher resonant frequency than the'tuning fork, is cantilever supported by a pin 21 in a disc 23 ofinsu-lation fitted in an'opening' in thestrap 10'. The strip 20 has a contact 22 near itsfree end; opposite and normally spaced'froni' the contact A circular dise 24 of plastic material is cemented on one side to the flange 12, and on its other side to one end of'cylindrical coil 25, to the opposite 'end' of which a smaller, concentric, circular disc'2'6 of plzisticihatefial is cemented. The

discs

24 and 26 can he ends of apla'stic spool for the coil. The disc 26 and the coil 25 have the same diameter. a I a A- circular base 27 of'insul'ationis opposite the disc 26', and has socket'p-ins 29, one of which is connected by wire 30 to the pin 21 and through the latter to the contact strip20, another of which is connected'by wire 31to the strap 10, and others of which are connected'hy Wires 32 to the ends of the winding of'the coil '25. The base 27 has a larger d iarneter'thanlthe disc 24, and has an inner, circular, i'eces'sedportion 28"Which the sarne diarne ter as that of the disc 24. I v

A 'per'r'rianentirnagnet 35in the formof a rod extends through the coil '25 along its axis, and forms the polpiece of the coil. One end of the magnet 35 extends through the disc 24 and the flange 12 to a position midway between the free ends of the

tynes

17 and 18.

A parti-cylindrical collar 37 of non-magnetic metal has the same external diameter as that of the disc 24 and the recessed base portion 28, extends around the coil 25 with one of its edges in contact with the disc 24, and its other edge in contact with the base 27 The collar has spacedapart ends with an opening 39 therebetween.

A shield can 40 of non-magnetic metal, closed at rtS outer end, has a particylindrical inner portion 41 having an outer diameter equal to that of the disc 24, with three, equally spaced-apart segments 42 having aligned inner ends which contact the side of the disc 24 which is cemented to the flange 12. The can 40 has a particylindric-al, outer portion 45 having an inner diameter the same as the outer diameter of the collar 37, and the same as that of the disc 24 and the recessed base portion 28, and has an inner end portion which fits snugly around the disc 24, the collar 37 and the recessed base portion 28. The can portion 45 has an edge thickness equal to the difference between the diameter of the base 27 and its recessed portion 28, so that the outer surface of the can extends flush with the outer surface of the base 27.

The outer shield portion 45 by fitting snugly around the disc .24, the collar 37 and the recessed base portion 28, and the inner shield portion 41 by pressing the disc 24 against the collar 37, and the latter against the base 27, secures these components tightly together, in addition to acting as the usual electrostatic shield.

Two adjacent segments 42 of the inner shield portion have a space 47 between their longitudinal edges, which is aligned with the space 39 between the ends of the collar 37. The outer shield portion 45 has spaced-apart longitudinal edges 48 with a space therebetween which is wider than the space 47 but centered therewith. These spaces provide access to the wires and their connections.

The fixed contact strap 20 should have a much higher resonant frequency than that of the

tynes

17 and 18 for reducing the hold region, and in somecases, the length and stiifness of the strip 20 may prevent its resonant frequency from being as high as it should. In such cases, an additional, much shorter strap 50 of resilient metal is cantilever attached to the strap 20, and its free end is opposite and normally spaced from the contact 19 on the tyne 17.

In the operation of FIGS. 1-3, A.C. at the resonant frequency of the

tynes

17 and 18 is applied through the wires 32 to the ends of the winding of the coil 25, producing an alternating magnetic field at the inner end of the magnet 36 acting as the polepiece of the coil, causing the free ends 0c the tynes to be attracted towards and repelled away from the magnet. At the end of its inward swing during each half-cycle, the tyne 17 moves its contact 19 against the fixed contact 22, closing a circuit which is not shown, in which the contacts are connected. The operation of FIG. 4 would be the same except that the contact 19 at the end of the inward swing of the tyne 17 would touch the free end of the contact strip 50.

What is claimed, is:

l. Atuning fork type relay comprising a frame, a tuning fork having its base attached to one end of said frame and having its tynes extending towards the other end of said frame, a coil of an electromagnet attached to said other end of said frame opposite and spaced from the free ends of said tynes, said coil having a parmanent magnet polepiece with one end extending midway between said free ends, a contact surface on the inner surface of one of said tynes, and a fixed contact strip of resilient metal insulatedly attached at one end to said frame between said tynes and having a contact surface at its other end extending into the space between said tynes opposite and normally spaced from said first mentioned contact surface.

2. A tuning fork type relay comprising a frame, a tuning fork having its base attached to one end of said frame and having its tynes extending towards the other end of said frame, said other end ofsaid frame having a flange thereon, a plastic disc cemented to said flange, a coil of an electromagnet supported by said disc, said coil having a polepiece with one end extending midway between the free ends of said tynes, a contact surface on the inner surface of one of said tynes, and a fixed contact strip of resilient metal insulatedly attached at one end to said frame between said tynes and having a contact surface at its other end opposite and normally spaced from said first mentioned surface.

3. A tuning fork type relay comprising a frame having a flange at one end, a tuning fork having its base attached to the other end of said frame and having its tynes ex tending towards said one end, a circular, plastic disc cemented to said flange, a cylindrical coil of an electromagnet supported by said disc, said coil having a polepiece with one end extending through said disc and flange midway between the free ends of said tynes, a contact i strip surface on the inner surface of one of said tynes, a fixed contact of resilient metal insulatedly attached at one end to said frame bet-ween said tynes and having a contact surface at its other end opposite and normally spaced from said first mentioned surfaces, a circular base having contact pins connected to said frame, said fixed contact and to the ends of the winding of said coil, at the other end of said coil, and a collar around said coil in contact with said disc and base.

4. A tuning fork type relay as claimed in claim 3.,in which said collar has an outer diameter the same as that of said disc, in which said "base has a recessed inner edge having the same diameter as that of said disc, and in which a shield can is provided which has an outer portion in contact with said disc, said collar and said recessed edge of said base.

' 5. A tuning fork type relay as claimed in claim 4 in which said can has an inner portion with an end which contacts the side of said disc which is cemented to said flange.

References Cited in the file of this patent UNITED STATES PATENTS Eannarino Nov. 1, 1949

Claims

1. A TUNING FORK TYPE RELAY COMPRISING A FRAME, A TUNING FORK HAVING ITS BASE ATTACHED TO ONE END OF SAID FRAME AND HAVING ITS TYNES EXTENDING TOWARDS THE OTHER END OF SAID FRAME, A COIL OF AN ELECTROMAGNET ATTACHED TO SAID OTHER END OF SAID FRAME OPPOSITE AND SPACED FROM THE FREE ENDS OF SAID TYNES, SAID COIL HAVING A PARMANENT MAGNET POLEPIECE WITH ONE END EXTENDING MIDWAY BETWEEN SAID FREE ENDS, A CONTACT SURFACE ON THE INNER SURFACE OF ONE OF SAID TYNES, AND A FIXED CONTACT STRIP OF RESILIENT METAL INSULATEDLY ATTACHED AT ONE END TO SAID