US3258559A

US3258559A - Vacuum relay

Info

Publication number: US3258559A
Application number: US456148A
Authority: US
Inventors: Lucia Victor E De
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-05-17
Filing date: 1965-05-17
Publication date: 1966-06-28
Anticipated expiration: 1983-06-28

Description

June 28, 1966 v 5 DE uc 3,258,559

VACUUM RELAY Filed May 1.7, 1965 Non-magnetic Disc 60 F lg.

Energizing Coil 58 Terminals 60 Victor E. De Lucio,

INVENTOR.

My, M

ATTORNEY.

United States Patent 3,258,559 VACUUM RELAY Victor E. De Lucia, 927 Euclid Ave., Santa Monica, Calif. Filed May 17, 1965, Ser. No. 456,148 6 Claims. (Cl. 200-87) The present invention relates to vacuum relays of the solenoid-operated type, and it relates more particularly to an improved vacuum relay of the type in which the pole pieces of the magnetic circuit thereof extend into the interior of the evacuated chamber for controlling the operation of the movable internal parts of the relay.

Vacuum relays are in general known to the relay and switching art. These relays are particularly advantageous in that they are capable of relatively high voltage operation and of relatively high current carrying capabilities without suffering contact erosion or the like.

The vacuum relay is also advantageous because it is generally unaffected by changes in atmospheric pressure or humidity. In addition, vacuum relays may be constructed to the substantially immune from vibration effects and to be able to withstand relatively high accelerations without affecting its switching capabilities.

The general type of vacuum relay with which the pres- 'ent invention is concerned includes a envelope formed of glass, or other vitreous or di-electric material. The envelope of this general .type of vacuum relay has a metallic end wall of non-magnetic material through which the magnetic core of the magnetic circuit of the relay extends, and the end wall is sealed to the envelope to form therewith an evacuated chamber.

The armature of .the type of relay with which the invention is concerned is pivotally mounted Within the chamber for movement towards and away from the end of the aforementioned core. A spring biasing means urges the armature away from the end of the core, and when the relay is energized, the armature is drawn down in a pivotal manner towards the end of the core. A movable contact is mounted on the armature, and this movable contact is caused selectively to engage fixed contacts in the evacuated chamber as the relay is energized and de-energized.

The present invention is particularly concerned with the structural composition of the magnetic circuit and energizing coil of the vacuum relay. In accordance with the concepts of one of the aspects of the invention, one end of .the glass envelope of the vacuum chamber is initially open, and an annular flange is sealed into the peripheral edge of the vitreous envelope in position to surround the open end. This flange may be formed of a suitable non-magnetic metal or alloy, which exhibits a coeflicien-t of expansion closely matching the coeflicient of expansion of the glass envelope. A suitable alloy for this purpose, for example, is Kovar.

The flanged open end of the envelope of the vacuum relay to be described is closed by a composite disc-like Wall assembly. The composite wall has an outer ringshaped member formed, for example, of Kovar, and this member is welded to the above-mentioned flange, for example, by a heliarc weld. A ring-shaped or annular pole piece composed of magnetizable material, such as iron,' is positioned concentrically within the outer ring shaped member of the composite wall, and this pole piece is brazed to the ring-shaped member, for example, by a copper braze.

The composite end wall of the vacuum relay to be described also includes a further ring-shaped member which is composed of a non-magnetic material such as, for example, a copper-nickel alloy. This latter ringshaped member is mounted in nested concentric relationship with the above-mentioned ring-shaped pole piece,

and it is brazed to the pole piece, for example, by a copper braze.

Finally, the composite end wall of the vacuum relay to be described is completed by a central pole piece composed of magnetizable material, such as iron. The central pole piece is brazed to the aforementioned nonmagnetic ring-shaped member by, for example, a copper braze. It will be appreciated that the composite end Wall assembly closes the open end of the vitreous envelope, and that the composite end Wall and the envelope together define the evacuated chamber for the vacuum relay.

The above-mentioned construction in accordance with the teachings of the invention is advantageous in that it enables the magnetic circuit of the relay to project into the evacuated chamber, and yet it provides for a minmum of mass of magnetic core structure in the chamber itself. This simplifies the fabrication of the relay from an out-gassing and evacuating standpoint. This improved construction also reduces the required amount of high purity iron, compatible with the vacuum environment, to .a minimum, as compared with the prior art relays of this general type.

The energizing coil for the relay to be described herein, and the magnetic core structure associated with the energizing coil, is formed as a separate energizing unit. This separate energizing unit is adapted to be mounted on the external surfaces of the aforementoned ringshaped and central pole pieces.

The energizing unit of the embodiment of the invention to be described has a central core which contacts the external surface of the central pole piece when the energizing unit is mounted in place, and the energizing unit also includes a cylindrical-shaped housing of magnetizable material, such as iron, the ring-shaped upper peripheral edge of which contacts the outer surface of the ring-shaped pole piece, when the energizing unit is mounted in place.

The energizing coil is mounted on the central core of the energizing unit within the cylindrical housing. The end wall of the energizing unit remote from the relay chamber is composed of magnetizable material, and suitable terminals for the energizing coil extend through the end Wall.

It is, accordingly, an object of the present invention to provide an improved vacuum relay in which the evacuated chamber is formed in a novel and improved manner, and in which the major portion of the magnetic core structure of the relay is positioned outside the evacuated chamber and as a unit separate from the components of the evacuated chamber.

A further object is to provide such an improved vacuum relay in which the mass of magnetic structure actually Within the evacuated chamber is, accordingly, reduced to a minimum.

Another object of the invention is to provide such an improved vacuum relay which is relatively simple and economical to manufacture, in that the evacuated chamber and the internal moving parts can be assembled and tested as a separate unit, prior to the inclusion of the energizing unit into the relay assembly.

Yet another object of the invention is to provide such an improved vacuum relay which is relatively easy to service and repair, in that the energizing unit may be easily and simply removed from the relay structure without alfecting in any manner the internal components of the relay, or the evacuated state of the evacuated chamber.

Another object is to provide such an improved vacuum relay in which the movable contact thereof is mounted in an improved manner so as to perform its circuit making or breaking function effectively and efliciently.

Other features, objects and advantages of the invention will became apparent from a consideration of the following description, when the description is considered in conjunction with the accompanying drawing, in which:

FIGURE 1 is a side sectional view of a vacuum relay constructed in accordance with the concepts of one embodiment of the invention;

FIGURE 2 is a cross-sectional view of the relay of FIGURE 1 taken substantially on the line 2-2 of FIG- URE l, and particularly showing the manner in which the movable contact of the relay selectively engages certain fixed contacts thereof;

FIGURE 3 is a bottom view, substantially on the line 3-3 of FIGURE 1, of the vacuum chamber portion of the relay;

FIGURE 4 is a cross-sectional view, like FIGURE 2, but showing a modified construction;

FIGURE 5 is a perspective View of the movable contact of the relay of FIGURE 1 and the manner in which .it is mounted in the relay; and

FIGURE 6 is a side elevation of the movable contact.

The vacuum relay shown in FIGURES 1 and 2 includes an envelope 10 formed of glass, for example, or other vitreous material. In the embodiment under consideration, the envelope 10 has a generally cylindrical configuration, and it is closed at one end and open at the other.

A flanged member 12 is sealed into the peripheral edge of the vitreous envelope 10, and the flange member surrounds the open end of the envelope. This flange member, as mentioned above, may be formed of Kovar, or other metal or alloy having a coefficient of expansion matching that of the envelope 10.

The open end of the vitreous envelope 10 is closed by a composite metallic end wall having a disc-shaped configuration. This end wall includes an outer metallic ringshaped member 14. The ring-shaped member 14 is also formed of a low expansion metal or alloy such as Kovar, and this ring is attached to the flange member 12 by, for example, a heliarc weld. As annular pole piece 16 is brazed, for example, to the member 14. The annular pole piece 16 is composed of a magnetizable material, such as iron.

The end Wall also includes a central pole piece 18, composed of a magnetizable material such as iron. An annular-shaped member of non-magnetic material, such as copper-nickel alloy, for example, is interposed between the annular pole piece 16 and the central pole piece 18. The member 20 is brazed to the

pole pieces

16 and 18, so that the

members

14, 16, 18 and 20 combine to form a composite metallic end wall for the vitreous envelope 10. The various members which form the end wall are sealed to one another, for example, by welding, as mentioned above; and the ring-shaped member 14 is sealed to the flange 12, so that the composite end Wall, in conjunction with the vitreous envelope 10, forms an evacuated chamber for the vacuum relay.

An armature 22, composed of magnetizable material :such as iron, is pivotally mounted in the evacuated chamber adjacent the central pole piece 18. A resilient coil :spring 23 is positioned between the annular member 20 :and the under side of the armature 22, so that the armature is normally biased in a clockwise direction away from the central pole piece 18. However, when the relay is energized, the armature is drawn in a counterclockwise direction pivotally down onto the pole piece 18.

A rod 24 of insulating material, such as sapphire, for example, is mounted on the armature 22 by means of a clip 26. The rod 24 extends essentially perpendicularly to the upper surface of the armature 22.

A plurality of rigid conductive contact pins 28, 30 and 32 extend through the envelope 10 and into the evacuated chamber in positions illustrated in FIGURE 2. These pins constitute'the fixed contacts of the relays, and

appropriate terminals

28a, 30a and 32a are provided for receiving connections to the respective pins.

The end of the inner end of the contact pin 32 is slotted, and a conductive leaf-shaped movable contact 34 is pivotally mounted in the end slot of the pin 32. This leaf-like movable contact is also rotatably mounted on the end of the rod 24 by means of a clip 35 (FIGURES 5 and 6). The clip 35 may be composed, for example, of a suitable material such as molybdenum or iron. The leaf contact 34 may appropriately be made of tungsten. The contact 34 is silver or copper brazed, for example, to the clip 35. When tungsten is used for the contact, its surface may be brought to a high polish, and this reduces the chances of contact arcing due to high fields around the contacts.

The arrangement is such that when the armature 22 is drawn down onto the pole piece 18, the movable contact leaf 34 is caused to break its connection with the inner end of the pin 30, and to make connection with the inner end of the pin 28. The pin 32, therefore, forms the common pole of the relay, and it selectively breaks contact with the pin 30 and makes contact with the pin 28, when the relay is energized.

The rod 24 is preferably coated with silver, or other suitable material. The resulting silver-iron contacting surfaces, between the coated rod and the clip 35, have a low coeflicient of friction. This is because the silver acts as a lubricant in high vacuum and thereby provides for a minimum of galling and low coefficient of friction.

In accordance with the concepts of the invention, and as mentioned briefly above, a separate energizing unit 50 is provided. This energizing unit includes a cylindricalshaped outer housing 52 composed of magnetizable material, such as iron. One end of the housing is enclosed by an end wall 54 which also is composed of a magnetizable material, such as iron. A central core 56 extends along the longitudinal axis of the energizing unit from the end wall 54 along the length of the unit. A threaded stud 57 extends from the end of the core 56, and this stud is received by a threaded aperture in the outer surface of the pole piece 18, so that the energizing unit 50 may be conveniently mounted on the external surface of the composite end wall of the vacuum chamber of the relay.

When the energizing unit 58 is mounted on the end wall, the end of the core 56 is in contact with the outer surface of the pole piece 18, and the peripheral edge of the housing 52 is in contact with the annular pole piece 16. A magnetic circuit is formed, therefore, from the pole piece 18 through the central core 56, through the housing 52, to the annular pole piece 16 and to the armature 22.

An energizing coil 58 is mounted on an insulating bobbin 60, which bobbin may be relatively thin, to permit close magnetic coupling between the coil and the magnetic circuit. Terminals 60 for the energizing coil 58 extend through the end wall 54, and are insulated from the end wall.

The embodiment shown in FIGURE 4 is a single normally-open contact configuration. In this latter embodiment, the movable contact 34 is normally spring biased against an insulating projection 60 by means of a spring 24. In this embodiment the contact 34 rests against the edge of the contact pin 32 instead of in the slot, as' in FIGURE 2. When the relay is energized, the movable contact is drawn against the contact pin 28 to establish contact between the pin 32 and the pin 28.

It is desirable to remove residual gases and water vapor from the evacuated interior of the envelope 10 prior to using the relay. However, the usual flush type chemical getters have a tendency to create conductive short-circuiting films on the interior surface of the envelope.

To achieve gettering action in the embodiment of the invention under consideration, without adverse effects, a coating of gettering material 62 may be placed on the internal surface of the flange member 12 and/or on the internal surface of the ring-shaped member 14.

The gettering material may be an alloy of cerium known to the trade as CerAlloy 400, and composed of thorium, aluminum and cerium. This alloy is most effective in reducing hydrogen, carbon monoxide, methane, water vapor, oxygen and carbon dioxide, etc., during normal operating temperatures of the relay and without any adverse or deleterious effects. About 12% titanium can be added to increase the absorbing effectiveness of the alloy with respect to hydrogen.

The coating 62 of gettering material can be placed on the rear surface of the contact 34, as shown in FIGURE 6. A relatively high current can be passed through the relay to heat the contact and increase the effectiveness of the gettering action. If desired, the gettering material may be coated on a separate strip which, in turn, is spot welded or otherwise affixed to the rear surface of the contact.

A description of the gettering action of CerAlloy 400 is contained, for example, in ASD Technical Report 61- 268, entitled Ceramic Receiving Tube Refinement Program by Bruce E. Barnaby, released to the Ofiice of Technical Services, United States Department of Commerce, for sale to the public.

The invention provides, therefore, an improved vacuum relay which is relatively simple to construct and test; and one which is conceived to have a minimum of magnetic parts and surface area in the evacuated chamber itself.

While particular embodiments of the invention have been shown and described, modifications may be made, and it is intended in the claims to cover all such modifications as fall within the spirit and scope of the invention.

What is claimed is:

1. A vacuum relay including: an envelope having a discontinuous end portion; a composite wall including a central pole piece of magnetizable material, an annular pole piece of magnetizable material surrounding said central pole piece in concentric relationship therewith and spaced radially therefrom, and an annular member of non-magnetic material interposed between said central pole piece and said annular pole piece; means for sealing said composite wall to said envelope to enclose said end portion thereof and to constitute therewith a vacuum chamber; an armature mounted within said vacuum chamber adjacent said central pole piece; resilient means for normally biasing said armature away from said central pole piece; fixed contact means mounted on said envelope and extending into said vacuum chamber; movable contact means mounted on said armature for selectively engaging said fixed contact means; an energizing unit mounted externally of said vacuum chamber and including a central core member of magnetizable material in magnetic contact with the external surface of said central pole piece and further including a housing of magnetizable material in magnetic contact with the outer surface of said annular pole piece; and said energizing unit including an energizing coil mounted on said central core member and positioned in said housing.

2. The relay defined in claim 1 and which includes a metallic flange member sealed to said envelope and surrounding said end portion thereof, and an outer annular metallic member included in said composite wall sealed to said annular pole piece and to said flange member for mounting said composite wall on said envelope.

3. The relay defined in claim 1 in which said central pole piece has a threaded aperture in the external surface thereof, and which includes a threaded stud extending outwardly from said central core member of said energizing unit to be received in said threaded aperture in said central pole piece to mount said energizing unit on the external surface of said composite end wall.

4. The relay defined in claim 1 in which said housing of said energizing unit has a cylindrical configuration, and said housing includes an end wall of magnetizable material enclosing the end thereof remote from said composite end wall, and said central core member extends along the longitudinal axis of said energizing unit from said end wall thereof.

5. A vacuum relay including: an envelope having a discontinuous portion; an essentially uniplanar composite wall including a central pole piece of magnetizable material, an annular pole piece of magnetizable material surrounding said central pole piece in spaced concentric relationship therewith, and an annular member of non-magnetic material interposed between said central pole piece and said annular pole piece; a metallic flange member sealed to said envelope and surrounding :said discontinuous portion thereof; and an outer annular metallic member included in said composite wall and sealed to said annular pole piece and to said flange member for mounting said composite wall on said envelope.

6. A vacuum relay including: a vitreous envelope having a discontinuous portion; an essentially uniplanar composite wall including a central pole piece of magnetizable material and including an external threaded portion for receiving a mating pole piece of an external energizing coil assembly, an annular pole piece of magnetizable material surrounding said central pole piece in spaced concentric relationship therewith and having an external surface for receiving a mating annular pole piece of said external coil assembly, and an annular member of non-magnetic material interposed between said central pole piece and said annular pole piece; a metallic flange member sealed to said envelope and surrounding said discontinuous portion thereof; and an outer annular metallic member included in said composite wall and sealed to said annular pole piece and to said flange member for mounting said composite wall on said envelope.

References Cited by the Examiner UNITED STATES PATENTS 11/1959 Jennings 200-87 9/1961 Racz et a1. 200l44

Claims

5. A VACCUM RELAY INCLUDING: AN ENVELOPE HAVING A DISCONTINUOUS PORTION; AN ESSENTIALLY UNIPLANAR COMPOSITE WALL INCLUDING A CENTRAL POLE PIECE OF MAGNETIZABLE MATERIAL, AN ANNULAR POLE PIECE OF MAGNETIZABLE MATERIAL SURROUNDING SAID CENTRAL POLE PIECE IN SPACED CONCENTRIC RELATIONSHIP THEREWITH, AND AN ANNULAR MEMBER OF NON-MAGNETIC MATERIAL INTERPOSED BETWEEN SAID CENTRAL POLE PIECE AND SAID ANNULAR POLE PIECE; A METALLIC FLANGE MEMBER SEALED TO SAID ENVELOPE AND SURROUNDING SAID DISCONTINUOUS PORTION THEREOF; AND AN OUTER ANNULAR METALLIC MEMBER INCLUDING IN SAID COMPOSITE WALL AND SEALED TO SAID ANNULAR POLE PIECE AND TO SAID FLANGE MEMBER FOR MOUNTING SAID COMPOSITE WALL ON SAID ENVELOPE.