US3872415A

US3872415A - Relay

Info

Publication number: US3872415A
Application number: US351750A
Authority: US
Inventors: David E Clarke
Original assignee: Texas Instruments Inc
Current assignee: Texas Instruments Inc
Priority date: 1973-04-16
Filing date: 1973-04-16
Publication date: 1975-03-18
Anticipated expiration: 1992-03-18
Also published as: GB1470332A; DE2418351A1; FR2225567B1; FR2225567A1; CA1021659A

Abstract

A relay which is operable at very low power levels and which is highly versatile in its applications is shown to be characterized by high gain and high reliability and by simplicity of structure. The relay comprises a first terminal mounted on a base of electrically insulating material and a second electrically conductive member having a terminal portion secured to the base, having a contact arm movable between an open circuit position spaced from the first terminal and a closed circuit position engaging the first terminal, and having integral spring portions connecting the contact arm and terminal portion of the second member for normally biasing the contact arm to one of the noted circuit positions. The relay also includes an actuator wire secured between the base and the contact arm of the second member. The actuator wire is formed of a nickel-titanium alloy and is adapted to be deformed from an original length to a second length as the contact arm is moved to the one circuit position in response to the noted spring bias while the wire material displays a relatively low modulus of elasticity below a transition temperature. The actuator wire is also adapted to abruptly return to its original length and to display a relatively higher modulus of elasticity to move the contact arm to the other circuit position against the spring bias when the wire material is heated above its transition temperature. Means are provided for electrically self-heating the actuator wire to its transition temperature when relay operation is desired.

Description

United States Patent 1191 Clarke 1 RELAY [75] Inventor: David E. Clarke, Attleboro, Mass.

[73] Assignee: Texas Instruments Incorporated,

Dallas, Tex.

22 Filed: Apr. 16, 1973 211 Appl. No.: 351,750

[52] U.S. Cl 337/140, 337/l3l, 337/395 [51] Int. Cl. H0lh 61/06 [58] Field of Search 337/140, 145, 41, 123,

337/124,125,126,127,128,129,l30,131, 132,133,l35,l36,138,139, 140,382, 393,

[56] References Cited UNlTED STATESPATENTS 2,761,931 9/1956 Schmidinger 337/135 2,838,645 6/1958 Welch 337/41 X 3,037,102 5/1962 Schmidinger... 337/140 X 3,111,566 11/1963 Jaidinger 337/140 X 3,180,954 4/1965 Collette et al. 337/137 3,405,380 10/1968 Riebs 337/41 X 3,461,424 8/1969 Kayuha, Jr 337/140 X 3,516,082 6/1970 Cooper 337/140 UX 3,634,803 l/l972 Wilson et al.... 337/140 X 3,652,969 3/1972 Willson 337/140 3,676,815 7/1972 Du Rocher 337/140 3.739314 6/1973 Rouvre et a1. 337/140 Primary Examiner-Arthur T. Grimley Attorney-Agent, 0r Firm-Harold Levine; John A. Haug; James P. McAndrews 1 1 Mar. 18, 1975 [57] ABSTRACT A relay which is operable at very low power levels and which is highly versatile in its applications is shown to be characterized by high gain and high reliability and by simplicity of structure. The relay comprises a first terminal mounted on a base of electrically insulating material and a second electrically conductive member having a terminal portion secured to the base, having a contact arm movable between an open circuit position spaced from the first terminal and a closed circuit position engaging the first terminal, and having integral spring portions connecting the contact arm and terminal portion of the second member for normally biasing the contact arm to one of the noted circuit positions. The relay also includes an actuator wire secured between the base and the contact arm of the second member. The actuator wire is formed of a nickel-titanium alloy and is adapted to be deformed from an original length toa second length as the contact arm is moved to the one circuit position in response to the noted spring bias while the wire material displays a relatively low modulus of elasticity below a transition temperature. The actuator wire is also adapted to abruptly return to its original length and to display a relatively higher modulus of elasticity to move the contact arm to the other circuit position against the spring bias when the wire material is heated above its transition temperature. Means are provided for electrically self-heating the actuator wire to its transition temperature when relay operation is desired.

7 Claims, 8 Drawing Figures l Ll/// .pmgmggmlams 872 415 sum 1 or 3 I as I //0 4 2 I 30 1 4/8 4 in I v I /6.7 14

PATENTEM 3,872,415

sum 2 mg 3 PHEMED R 1 8575 3,872, 11 5 SHEU 3 95 3 5 M81; g; 60 @2/ W jg 66 A? 56.. 7/624 .56

' Z0 I I 1 /4 M 52 1 RELAY With the development of increasingly more compact and inexpensive control systems which are operable at very low power levels, it becomes possible to incorporate an increasing number of control functions within the control system while still retaining reasonable system costs. However, for these control system advantages to be achieved in practice, the systems must be utilized with improved relays which are capable of operating at low power levels, which provide the high gain necessary for performing various individual control functions, and which are of compact, reliable and inexpensive construction.

It is an object of this invention to provide novel and improved electrical relays; to provide suchrelays which are operable at very low power levels; to provide such relays which display very high gain; and to provide such relays which are of compact, reliable, versatile and inexpensive construction.

Other objects and advantages of the novel and improved relays of this invention appear in the following detailed description of preferred embodiments of this invention, the detailed description referring to the drawings in which:

FIG. 1 is a plan view of a preferred embodiment of the relay of this invention;

FIG. 2 is a front elevation view of the relay shown in FIG. 1;

FIG. 3 is an end elevation view of the relay shown in FIG. 1;

FIG. 4 is a section view along line 44 of FIG. 1;

FIG. 5 is a partial section view to enlarged scale along line 5-5 of FIG. 1;

FIG. 6 is a perspective view of a component of the relay of FIG. 1;

FIG. 7 is a section view similar to FIG. 4 illustrating an alternate embodiment of the relay of this invention; and

FIG. 8 is a section view similar to FIG. 4 illustrating another alternate embodiment of the relay of this invention.

Referring to FIGS. 1-5 of the drawing, 10 indicates v a preferred embodiment of the relay of this invention which is shown to include a base member 12 of a strong, rigid, electrically insulating material such as a phenolic resin. Preferably, as shown, the base has a flat, bottom portion 12.1 and a generally U-shaped wall portion formed by upstanding walls 12.2, 12.3 and 12.4, the end wall 12.3 preferably having an aperture 12.5 therein receiving an electrically conductive output terminal member 14. The terminal 14 is secured in the aperture 12.5 by a press fit or in other conventional manner and extends in cantilever relation over the base bottom to support a first, stationary, output electrical contact 16.

In accordance with this invention, the relay 10 also includes a second electrically conductive member 18, best shown in FIG. 6, which integrally incorporates an output terminal portion 18.1 including two leg portions 18.2 and 18.3, a contact arm portion 18.4, and a pair of spring portions 18.5 and 18.6 which connect the contact arm 18.4 to the respective legs 18.2 and 18.3 of the terminal portion of the second conductive member. In a particularly inexpensive embodiment of this invention, the second conductive member 18 also includes an integral tang portion 18.7 upstanding from the contact arm, the tang preferably having reentrant surfaces thereon as indicated at 18.8 in FIG. 6.

In accordance with this invention, the second conductive member 18 is formed of beryllium copper or phosphor bronze or other electrically conductive spring material and carries a second output contact 20 at the distal end of the contact arm 18.4. The conductive member 18 is secured to the base 12 by cementing or in other conventional manner for disposing the contact 20 over the contact 16 as is best shown in FIG. 4. In this arrangement, the tang 18.7 and the contact arm 18.4 form a bell-crank element which is pivotably movable around an axis (indicated by the broken line 22 in FIG. 1) formed by the spring portions 18.5 and 18.6 of the conductive member. The contact arm 18.4 is normally disposed out of the general plane of the second conductive member 18 by deforming of the spring portions 18.5 and 18.6 as is best illustrated in FIG. 5. Accordingly, the contact arm 18.4 is normally biased to the open circuit position illustrated in FIG. 4 so that the contact 20 carried by the contact arm is normally separated or disengaged from the mating output contact 16'. However, the contact arm 18.4 is adapted to be moved to a closed circuit position wherein the contact 20 engages the contact 16 with selected contact pressure. In this regard, where the tang 18.7 of the second conductive member is relatively shorter than the contact arm 18.4, rotational movement of the bell-crank element formed by the tang and arm around the axis 22 requires relatively limited linear movement of the tang to provide fairly substantial movement of the movable output contact 20. As will be understood, the terminal 14 and the terminal portion 18.1 of the second conductive member are adapted to be connected to a device diagrammatically indicated in FIG. 1 by the terminals 24 and 26 so that the device is energized when the output circuit formed by the terminal 14 and the conductive member 18 is closed by engagement of the

contacts

16 and 20.

In -a preferred embodiment of this invention, a second base component 28, also preferably formed of phenolic resin or other electrically insulating material and also of generally U-shaped configuration, is then secured to the other side of the conductive member 18. Two relay control terminals 30, preferably comprising screws threadedly engaged with the base component 28, are then preferably recessed into grooves 28.1 in the second base component. An actuator wire 32 is then secured in electrically conductive relation between the control terminals 30 to extend around the tang 18.7 of the second conductive member 18. Preferably a length of electrically insulating tubing 34 is fitted over the actuator wire 32 as shown for electrically insulating the actuator wire from the second conductive member. In this way, the control terminals 30 are adapted to be connected to a control system, indicated in FIG. 1 by the terminals 36 and 38, for selectively directing electrical current through the metal actuator wire 32 when desired.

In accordance with this invention, the actuator wire 32 is preferably formed of a selected nickel-titanium alloy commonly called Nitinol having a composition, by weight, of from about 54 to 56 percent nickel and the balance titanium. As this metal alloy is well known, the alloy is not further described herein and it will be understood that the alloy is adapted to display a relatively low modulus of elasticity below a characteristic transitiontemperature and to display a relatively much higher modulus of elasticity when the wire material is heated above the noted transition temperature, this change in properties being reversible as the wire material is cooled below the transition temperature. When properly conditioned in well known manner, the noted alloy is also adapted to display remarkable shape memory properties. That is, when the material of the wire 32 is deformed while below its transition temperature as by stret'ching'the wire to increase the-wire length up to about 8- p'ercent, the wireis adapted to shorten abruptly and to return to its original length when the wire is heated above its transition temperature. After cooling, the wire is againadapted to be deformed to again prepare the wire for displaying its shape memory. Typically, for example, the wire 32 is formed of a nickel-titanium alloy comprising about 55 percent nickel, by weight, and the balance titanium, this alloy having a transition temperature at about 60C. and having alternately, the wire 32 is formed of other known metal alloys-capable of displaying similar shape memory and modulus of elasticity properties.

lnthe relay 10 of this invention, the spring proper ties of the conductive member l8are selected so that, with the material of the actuator wire 32 below its transition temperature, the spring portions 185 and 18.6 of'the second conductive member apply sufficient force to the wire [32 to deform the wire to increase the wire length, preferably by at least about 4 percent, and to normally bias the contact arm 18.4 to the open circuit position shown in FIG. 4 to hold the contact disen-' gaged from the'contact 16. However, when electrical current is selectively directed through the wire 32 between the relay control terminals for electrically self-heating the material of the wire above its transition temperature, the wireis sharply or abruptly shortened injlength returning to its original configuration and is sharply increased in modulus of elasticity for moving the contact arm 18.4 to its closed circuit position against the bias ofthe spring portions 18.5 and 18.6 to engage the contact 20 with its mating contact 16 for closing the output circuit of the relay. When the wire 321is thereafter. permitted to cool below its transition temperature,'whereby the modulus of elasticity of the wire material returns to its low initial level, the spring portions 18.5 and 18.6 again deform the wire to increase i'ts length and again return the contact arm 18.4 to its open circuit position. As will be understood, the spring portion 18.5 and 18.6 of the second conductive member are initially deformed to a selectedex'tent as illustrated in FIG. 5 for adjusting the tension the spring portions apply to the wire 32 and for adjusting the contact pressure between the

contacts

20 and 16 when Preferably the wire has a cross-sectionalarea less than about 1.5 X 10 square inches and typically the wire has a diameter of about 0.002inc'hes and a length of about 2 inches. As a result, the wire is adapted to be heated from room temperature to its transition temperature with very low input of electrical energy at low current levels but is adapted to provide significant movement of the contact arm 18.4 and to apply substantial contact pressure between the

contacts

20 and 16 so that the relay can switch substantial currents. Thus, the relay is operable at very low power levels but provides very high gain. Typically, for example, where the wire has a diameter of 0.002 inches and a length of 2 inches, the relay l0 is operable at a power level below 2 watts and preferably below 0.5 watts but displays a very high gain, preferably greater than about 500 to l and preferably on the order of 10,000 to. l, and can switch 50 amperes at I20 volts across the

contacts

20 and 16. The relay 10 is also of compact, reliable and very inexpensive construction. In addition, the relay is very versatile in its applications. Note that, as illustrated by the broken lines 40 in FIG. 2, a plurality of the relays 10 are adapted to be stacked together in a very compact package. I

Further, various alternate embodiments of the relay 10 are also included within the scope of this invention as is illustrated in FIGS. 7 and 8. That is, referring to FIG. 7 wherein components of the relay 42 shown therein which are comparable to components of the relay l0 ae identified with corresponding reference numerals, the relay 42 is shown to include'a base 12 supporting a first output terminal 14 to carry a contact 16 as in the relay '10. In addition, howeventhe second base element 28 is also provided with an aperture 28.2

and a second output terminal 44 is mounted in this aperture to support another output contact 46. The second conductive member '18 is then provided withan additional contact 48 as shown. Preferably, the tang 18.7 of the conductive member- 18' previously 'described, is-also replaced by a bell-crank arm member 50 of electrically insulating material which is secured to the contact arm 18.4 by a screw 52 or the like and which carries aboss 54, also preferably comprising a screw threadedly engaged with the bell-crank'arm 50, around which the actuator wire 32 extends. In the relay 42, the

contacts

46 and 48 are normally engaged for closing a first output circuit of the relay while the

contacts

20 and 16 are disengaged leaving a second output circuit of the relay open. However, when the acturator wire 32 is heated above its transition temperature by directing electrical current through the wire, the contact arm 18.4 moves as in the relay 10 to engage the

contacts

16 and 20 for closing the second output circuit and to open the first output circuit of the relay.

Referring now to FIG. 8, wherein corresponding reference numerals are again used, the relay 56'illustrated in this drawing figure as shown to include a base member 12 supporting a first output terminal 14 carrying a contact 16. A first conductive member I8 is then secured to the base 12 as in relay 10. Another base element 58 having an aperture 58.1 receiving a second output terminal 60 carrying a contact 62 is then mounted on the conductive member 18, the contact 62 being oriented upwardly as shown in FIG. 8. An additional conductive member 18 is then mounted on the second base element 58 for disposing its contact 20 to A be engaged with the output contact 62. A base element 28 is then secured on top of this additional conductive member 18 as shown in H0. 8. Neither of the conductive members 18 embodied in the relay 56 is provided with a tang 18.7 but bell-

crank arm elements

64 and 66 are secured to the conductive members 18 by a screw 52 and by a pin 68 so that the two contact arms 18.4 are arranged to move together. The actuator wire 32 is then extended around a screw boss 54 as in the relay 42. In this arrangement, two relay output circuits are normally open. However, when the actuator wire 32 is heated above its transition temperature, the wire shortens in length to move both contact arms 18.4 to engage one of the contacts 20 with the contact 16 and to engage the other circuit 20 with the contact 62 for closing two output circuits of the relay.

Of course other modifications and equivalents of the described relays 10, 42 and 56 are also within the scope of this invention. For example, the terminal 14, the

, conductive member 18 and the control terminals 30 of the relay could all be mounted on a single base element having the general configuration of the end wall 12.3 of the base described with reference to relay 10 for significantly reducing the size and weight of the relay. Other such modifications would be recognized by persons skilled in the art. It should be understood that this invention includes all modifications and equivalents of the disclosed embodiments falling within the scope of the appended claims.

I claim:

1. A relay comprising electrically insulating base means. a first conductive member mounted on said base means. a second conductive member formed of a single sheet of electrically conductive sheet material having a pair of spaced first portions secured to said base means, having a contact arm portion extending in cantilever relation from the remainder of said second member between said first portions of said second member and movable at its distal end between an open circuit position spaced from said first conductive member and a closed circuit position engaging said first conductive member, and having spring means integrally formed in said sheet material-respectively connecting said first member portions with an opposite end of said contact arm portion of said second conductive member and normally biasing said contact arm portion to one of said circuit positions, and an actuator wire element secured between said opposite end of said contact arm portion and said base means, said actuator element being formed of a metal alloy adapted to be deformed from an original configuration to a second configuration as said contact arm portion is moved to said one circuit position by said spring bias while said metal alloy displays a relatively low modulus of elasticity below a transition temperature and to abruptly return to said original configuration and to display a relatively higher of elasticity to move said contact arm portion to the other of said circuit positions against said spring bias when said metal alloy is heated above said transition temperature.

2. A relay as set forth in claim 1 wherein said actuator element is formed of a nickel-titanium alloy.

3. A relay as set forth in claim 2 wherein said nickeltitanium alloy has a composition, by weight, of from about 54 to 56 percent nickel and the balance titanium.

4. A relay as set forth in claim 3 wherein said actuator element comprises a wire of said nickel-titanium alloy having a cross-sectional area of less than about 1.5 X 10 square inches.

5. A relay comprising a base means of electrically insulating material having a bottom and having a pair of upstanding side walls and an end wall forming a base wall portion of generally U-shaped configuration, a first electrically conductive terminal member cantilever mounted on said end wall and mounting a first electrical contact at the distal end thereof over said bottom of said base means, a second member formed of a single sheet of electrically conductive spring material having a terminal portion including two leg portions thereof secured to said side walls of said base means, having a contact arm portion extending in cantilever relation from the remainder of said second member and mounting a second electrical contact means thereon at the distal end of said-contact arm portion for movement between an open circuit position spaced from said first contact and a closed circuit position engaging said first contact, and having spring portions integrally formed from said sheet material extending between respective leg portions and an opposite end of said contact arm portion of said second conductive member over said bottom of said base means and normally biasing said contact arm portion to said open circuit position, a bell-crank arm secured to said opposite end of said contact arm portion and rotatable with said contact arm portion around an axis extending through said spring portions, control terminals secured to said base means, and a metal actuator wire connected between said control terminals and secured in electrically conductive relation to said bellcrank arm, said wire being formed of a nickel-titanium alloy adapted to be deformed from an original length to a greater length as said contact arm portion is moved to said open circuit position in response to said spring bias while said alloy .displays a relatively low modulus of elasticity below a transition temperature and to abruptly return to its original length and to display a relatively higher modulus of elasticity to rotate said contact arm and bellcrank-arm on said axis to move said contact arm portion to said closed circuit position against said spring bias when said alloy is heated above said transition temperature by directing electrical current through said wire between said control terminals.

6. A relay as set forth in claim 5 having an additional electrically conductive terminal member cantilever mounted on said base means and mounting an additional electrical contact at the distal end thereof to normally engage said second contact means and to be disengaged from said second means when said actuator wire is heated to said transition temperature.

7. A relay as set forth in claim 5 having a plurality of said conductive terminal members mounting respective electrical contacts and mounted on said base means, having a plurality of said members of electrically conductive spring material mounted on said base means and having respective contacts mounted on the contact arm portions thereof, and having means for connecting said contact arm portions of said spring members together for common movement to engage respective spring member contacts with respective contacts mounted on said terminal members.

Claims

1. A relay comprising electrically insulating base means, a first conductive member mounted on said base means, a second conductive member formed of a single sheet of electrically conductive sheet material having a pair of spaced first portions secured to said base means, having a contact arm portion extending in cantilever relation from the remainder of said second member between said first portions of said second member and movable at its distal end between an open circuit position spaced from said first conductive member and a closed circuit position engaging said first conductive member, and having spring means integrally formed in said sheet material respectively connecting said first member portions with an opposite end of said contact arm portion of said second conductive member and normally biasing said contact arm portion to one of said circuit positions, and an actuator wire element secured between said opposite end of said contact arm portion and said base means, said actuator element being formed of a metal alloy adapted to be deformed from an original configuration to a second configuration as said contact arm portion is moved to said one circuit position by said spring bias while said metal alloy displays a relatively low modulus of elasticity below a transition temperature and to abruptly return to said original configuration and to display a relatively higher of elasticity to move said contact arm portion to the other of said circuit positions against said spring bias when said metal alloy is heated above said transition temperature.

3. A relay as set forth in claim 2 wherein said nickel-titanium alloy has a composition, by weight, of from about 54 to 56 percent nickel and the balance titanium.

4. A relay as set forth in claim 3 wherein said actuator element comprises a wire of said nickel-titanium alloy having a cross-sectional area of less than about 1.5 X 10 5 square inches.

5. A relay comprising a base means of electrically insulating matErial having a bottom and having a pair of upstanding side walls and an end wall forming a base wall portion of generally U-shaped configuration, a first electrically conductive terminal member cantilever mounted on said end wall and mounting a first electrical contact at the distal end thereof over said bottom of said base means, a second member formed of a single sheet of electrically conductive spring material having a terminal portion including two leg portions thereof secured to said side walls of said base means, having a contact arm portion extending in cantilever relation from the remainder of said second member and mounting a second electrical contact means thereon at the distal end of said contact arm portion for movement between an open circuit position spaced from said first contact and a closed circuit position engaging said first contact, and having spring portions integrally formed from said sheet material extending between respective leg portions and an opposite end of said contact arm portion of said second conductive member over said bottom of said base means and normally biasing said contact arm portion to said open circuit position, a bell-crank arm secured to said opposite end of said contact arm portion and rotatable with said contact arm portion around an axis extending through said spring portions, control terminals secured to said base means, and a metal actuator wire connected between said control terminals and secured in electrically conductive relation to said bell-crank arm, said wire being formed of a nickel-titanium alloy adapted to be deformed from an original length to a greater length as said contact arm portion is moved to said open circuit position in response to said spring bias while said alloy displays a relatively low modulus of elasticity below a transition temperature and to abruptly return to its original length and to display a relatively higher modulus of elasticity to rotate said contact arm and bell-crank arm on said axis to move said contact arm portion to said closed circuit position against said spring bias when said alloy is heated above said transition temperature by directing electrical current through said wire between said control terminals.