US3441882A - Vacuum relay - Google Patents

Description

April 9, 1969 v. E. DE LUCIA 3,441,882

VACUUM RELAY Filed June 26. 1967 y m x a/vrae Mc/ar 6: .06! 1/6/14 xrraen/ar 3,441,882 VACUUM RELAY Victor E. De Lucia, Santa Monica, Calitl, assignor to Torr Laboratories Inc., Los Angeles, Calif., a corporation of California Filed June 26, 1967, Ser. No. 648,697 lint. Cl. Hillh 1/66 US. Cl. 335154 9 Claims ABSTRACT OF THE DISCLOSURE A vacuum relay is described in the specification, in which the switching components of the relay operate in an evacuated envelope, The relay uses magnetizable members within the envelope, not only to provide a movable armature and to complete a magnetic path through the envelope, but also to serve as the stationary and movable electrical contacts of the relay. These members are constructed, as will be described, so as to provide a miniature relay which is capable of high voltage and high current operation and which is extremely sensitive but immune to external shocks and vibrations.

Background of the invention Vacuum relays of the general type with which the present invention is concerned, in Which the relay contacts operate in an evacuated envelope, are presently in widespread use and have many applications. These applications include, for example, the electrical control circuits of missiles, capsules, and other space vehicles; since such control circuits require miniature relays of high current carrying capacities, and high voltage capabilities, and which are able to withstand high acceleration forces, and external shocks and vibrations, without spurious contact operation, and without damage of any nature to the relay.

The vacuum relay to be described herein exhibits high current carrying capabilities, and is able to Withstand high voltages. The vacuum relay of the invention is also immune to high acceleration forces and external shocks and vibrations. The relay of the invention is also advantageous in that it is able to operate for long periods of time without oxidation or general deterioration of its contacts.

The relay of the invention, in the embodiment to be described, includes a movable magnetizable member positioned within an evacuated envelope, and it also includes a pair of stationary magneizable members Within the envelope. The internal movable magnetizable member constitutes a low mass armature for the relay, the low mass of which provides immunity in the relay against spurious operation due to acceleration and vibrational forces. Other force absorbing means are also used, as will be described further to protect the relay against such forces, and further to enhance its immunity to spurious operations in the presence of such forces. This latter member also serves as a movable electrical contact for the relay, which will also be described.

The pair of stationary magnetizable members within the envelope of the relay of the invention provides, in conjunction with the low mass armature, a desired low reluctance path for the actuating magnetic flux from an external energizing magnetic assembly for the relay The movable magnetizable member is resiliently mounted Within the envelope in bridging relationship with the two stationary magneiizable members. One of the two stationary members also serves as a fixed electrical contact for the relay, as will be described.

To prevent free vibration in the envelope of the resiliently mounted armature and movable contact, an integral protruding member is provided on the internal surface of States Patent the envelope which bears against the movable magnetizable member. This protruding portion biases the armature towards the stationary magnetizable members and against the tension of its resilient supporting member. By this means, the resiliently supported armature is held against vibration, both during the energized and de-energized condition of the relay.

Additional pole pieces are mounted on the stationary magnetizable members further to reduce the magnetic reluctance path through the relay. The relay of the invention uses the stationary and movable magnetizable members described above, not only to form the armature and low reluctance path, but also to provide the movable and fixed electric contacts for the relay. To this end, and in accordance with the teaching of the invention, appropriate electric contacts are affixed to the armature and to one of the stationary magnetizable members, and these electrical contacts are caused to engage one another when the relay is energized.

The electrical contacts are in the form of thin electrical contact buttons of refractory material, and they are bonded to the respective magnetizable members, for example, by a silver or gold bond. These contact buttons are made extremely thin, so that the magnetic path between the armature and the stationary magnetizable members is not interrupted to any appreciable extent by the operation of the relay. For example, these contact buttons have a thickness of the order of 2 mils. That is, these thin contacts assure that a low reluctance magnetic path is preserved through the interior of the envelope The gold or silver bonding of the contact buttons to their respective magnetizable members provides for a good heat transfer, so that there is no tendency for hot spots to develop in the relay, and there is no likelihood of welding of the contacts.

Summary of the invention The invention provides an improved vacuum relay Wh'ch is small in size and light in Weight, and yet which is capable of withstanding high voltages and of carrying high currents. The improved relay of the invention is relatively simple in its construction, and may be marketed at a relatively low price. The relay is also immune to external shocks or vibrations, as pointed out previously herein.

The relay of the present invention includes three magnetizable members disposed in an evacuated envelope, which are constructed as will be described, so as to form a low reluctance path for the magnetic core of an external magnetic energizing unit for the relay. Two of the three internal magnetizable members in the vacuum relay of the invention are mounted to be stationary within the evacuated envelopes, and the third is resiliently held in bridging relationship with the two stationary members and is movable with respect thereto, as will be described.

The internal movable magnetizable member constitutes a low mass magnetic armature for the relay, and it also constitutes movable electrical contact for the relay. This member is light and is supported in a manner such as to provide immunity in the relay against spurious operation due to external shocks, accelerations or vibrational forces. The inclusion of the two stationary magnetizable members in the envelope, not only forms the desired low reluctance magnetic path for the actuating magnetic flux from the external energizing unit, but as mentioned above, they also serve as stationary electrical contacts for the relay.

As mentioned above, the two stationary magnetizable members are formed so as to provide a low reluctance path for the magnetic circuit of the relay and, to that end, additional pole pieces are mounted on the members, or formed integral therewith, as will be described.

Moreover, to render the relay immune against external forces and vibrations, a resilient mount is provided hetween the relay and the external magnetizing coil, and a protective external casing is provided in which the relay assembly, together with its external energizing coll, are

potted, for example, with an appropriate epoxy resin.

In addition to the magnetic features of the relay described above, the embodiment of the invention to be described also includes an integral portion of the envelope which protrudes inwardly from the wall of the evacuated envelope to bear against the movable magnetizable member. This protruding envelope portion biases the movable magnetizable member towards the two stationary magnetizable members and against the tension of its resilient supporting wire. The protruding envelope portion, therefore, serves to eliminate any free vibratory motion of the movable magnetizable member, as would render the relay susceptible to spurous operation from external shocks, accelerations, or vibrational forces. In this way, the movable magnetizable member is positively held against vibration during its de-energized conditions of the relay, when such vibrations have a tendency to occur.

Brief description of the drawings FIGURE 1 is an end perspective view of one embodiment of the relay invention, with its energizing coil and removed from its protective outer casing;

FIGURE 2 is a side sectional view of the relay of FIG- URE 1 along the line 22, on an enlarged scale, and illustrating particularly the internal components of the relay and the structural components of its magnetic energizing coil;

FIGURE 3 is a fragmentary perspective view of certain of the components of the assembly of FIGURE 2; and

FIGURE 4 is a perspective view of the relay of FIG- URE l, on a reduced scale, potted in its outer casing, and ready for installation in appropriate equipment.

Detailed description of the illustrated embodiment The improved vacuum relay to be described uses the magnetizable members in the evacuated envelope, as mentioned above, not only to form the armature and low reluctance magnetic path, but also to provide electrical contacts and electrical paths for the relay. To this end, appropriate electric contact buttons are afiixed to the movable magnetizable member and to one of the stationary magnetizable members, and the electrical contact buttons are caused to engage one another when the relay is energized. An electric circuit is established through the two magnetizable members of the relay when the contact buttons so engage one another. As mentioned above, these contact buttons are made extremely thin (of the order of 2 mils), so as to preserve the low reluctance magnetic path provided by the stationary and movable magnetizable members in the relay envelope.

The movable magnetizable member in the embodiment to be described is supported by a resilient wire which extends from one end of the envelope. The resilient wire supports the movable member so that it bears against the aforementioned protruding portion of the envelope when the relay is de-energized and is spaced from the two stationary magnetizable members. The movable member is drawn against the two stationary magnetizable members in the envelope when the relay is energized so that it engages first one and then the other of the stationary members. The armature is, therefore, normally in bridging relationship with the two stationary members. The actual mass and size of the movable member in the relay may therefore be reduced to an absolute minimum, for optimum immunity of the relay to the effects of external shocks, vibrations and the like. The resilient wire supporting the movable member is formed of electrically conductive material, such as tungsten, so that an electrical connection may be established through the movable member to the electric contact button afiixed thereto.

The vacuum relay of the invention, in the illustrated embodiment, includes an elongated tubular envelope which is formed of glass, or other suitable vitreous or other material. A pair of rigid electrically conductive terminal pins 12 and 14 extend through opposite ends of the envelope 1t) and are sealed thereto. These terminal pins extend into the envelope in axial alignment with one another, and they are spaced axially from one another. The terminal pins 12 and 14 are formed of electrically conductive material, such as tungsten.

A pair of fiat elongated stationary magnetizable members 16 and 18 are welded, or otherwise affixed to the respective inner ends of the terminal pins 12 and 14. The stationary members 16 and 18 may be formed of iron, or other magnetizable material. These members are disposed in the envelope 10 in axial alignment with one another, and they are spaced axially in the envelope from one another, as shown. The flat stationary members 16 and 18 are electrically conductive, and they are in electrical contact with the terminal pins 12 and 14.

The illustrated vacuum relay of the invention also includes a flat movable magnetizable member 20, which is formed of iron or other suitable magnetizable material, and which serves as the armature and movable electrical contact of the relay. The movable member 20 is in the form of a fiat strip of the magnetizable material, and it is held by a resilient wire 22 in bridging relationship across the space between the ends of the axially aligned flat members 16 and 18. The resilient wire 22 is electrically conductive and it is welded, or otherwise aflixed and electrically connected to the armature 20 and to the terminal pin 14. The resilient wire 22, in addition to supporting the armature 20, serves as an electrical connection between the armature and the terminal pin 14. The resilient wire 22 may appropriately be formed of tungsten.

A pair of pole pieces 17 and 19 are mounted respectively on the stationary members 16 and 18, or these may be formed integrally therewith. These pole pieces may, likewise, be formed of iron, or other appropriate magnetizable material. They extend from the planes of the respective stationary members to the edge of the encapsulating envelope 10, as shown in FIGURE 2, so as to provide a low reluctance path through the envelope from an external magnetic energizing circuit which will be described. The pole piece 19 is slotted to receive the wire 22, as best shown in FIGURE 3.

An integral projection or protruding portion 24 is formed on the inner surface of the envelope 10. This projection 24 bears against the movable member 20, and it biases the movable member in the direction of the stationary members 16 and 18 against the tension of the resilient supporting wire 22. The projection 24 loads the movable member 20 and, thereby, obviates any tendency for the movable member to vibrate freely when the relay is in de-energized condition. This loading, in conjunction with the low size and mass of the armature, serves to prevent false closing of the movable member with the stationary members 16 and 18 due to external shocks or vibration forces.

An electrical contact button 26 is atfixed to the movable member 20 in electrical connection therewith, and an electrical contact button 28 is affixed to the stationary member 16 in electrical contact with the member 16. These contacts may be formed, for example, of tungsten or other suitable electrically conductive refractory material. They are extremely thin, as mentioned above, having a thickness of the order of 2 mils, for example, so as to preserve the low reluctance magnetic path through the relay.

The contact buttons 26 and 28 are bonded to the armature 20 and to the stationary member 16 respectively, by gold or silver bonding, so as to provide a high heat conductive path away from the contact buttons and thereby to prevent hot spots and contact welding. The magnetizable members 16, 18 and 20 may be coated, for example, by nickel or gold, if so desired, so as to enhance their electrical conductive characteristics without detracting from their magnetic characteristics.

The energizing unit 50 for the relay inludes, as shown in FIGURE 2, a housing having an outer tubular wall 51 which is formed of magnetizable material such as iron. An inner tubular wall 52 is also provided for the housing, and this inner tubular wall is formed of appropriate nonmagnetic material, such as brass. The inner tubular wall is separated from the envelope by resilient means 53, which, for example, may be in the form of axially spaced layers of rubberized tape. This resilient means serves to support the envelope 10 resiliently within the unit 50, further to protect the unit from external vibrations, shocks and accelerations, and to prevent spurious operation of the relay in response to such external disturbances.

A pair of disc-shaped end walls 5 4 and 56 form the opposite ends of the housing 50. These end walls are made of appropriate magnetizable material, such as iron. The end wall 56 is made to have a larger diameter than the end wall 54, and the end wall 56 bears aginst a shoulder 58 which is formed on the inner surface of the outer tubular walls 51, and which extends around the periphery of the housing adjacent the right hand end in FIGURE 2. The edge of the outer tubular wall 51 is rolled over as at 60 so as to hold the housing 50 in an assembled condition.

An energizing coil 62 is disposed in the housing 50 on a bobbin 6 4 of insulating material. The bobbin 64 is mounted on the inner tubular wall 52 of the unit 50 in coaxial relationship therewith. A pair of electric terminals 66 are provided for the energizing coil 62, and these extend through the end walls 54.

When the illustrated vacuum relay of the invention is de-energized, the movable member is positively biased in a spring-loaded condition against the protruding protion 24 of the envelope 10, this by means of the resilinet Wire 22. This condition of the relay is shown in FIGURE 2 which illustrates the relay in its de-energized state. It will be appreciated, therefore, that in its de-energized state, and for the reasons expressed above, there is no appreciable vibration of the movable member 20.

Upon the energization of the relay, the energizing coil 62, and its associated magnetic circuit, including the outer tubular wall 50 and the disc-shaped end walls 54 and 56, establish a magnetic field in the interior of the envelope 10. This magnetic field is carried through the low reluctance path established by the pole pieces 17 and 19 and the stationary magnetizable members 16 and 18, as well as by the movable magnetizable member 20. The magnetic field causes the member 20 to be positively drawn against the stationary members 16 and 18.

When the movable member 20 is drawn against the stationary members 16 and 18, due to the energization of the relay, the contact buttons 26 and 28 establish electrical connection with one another, so that electrical contact is established between the terminal pins 12 and 14 by way of the member 16, the contact buttons 26 and 28, the member 20 and the resilient Wire 22. The action of the relay is such that movable member 20 causes the contact buttons 26 and 28 to establish electrical connection with one another before any contact is established between the other end of the movable member and the stationary member 18. Likewise, upon the de-energizing of the relay, the contact buttons 26 and 28 break after the armature 20 breaks its connection with the stationary member 18. This action means that all circuit connections are made and broken between the contact buttons 26 and 28, rather than between the movable member 20 and the stationary member 18, so that any arcing or welding tendency between the movable member and the stationary member 20 is prevented.

If so desired, an insulating oxide coating may be formed on the surfaces of the movable member 20 and the stationary member 18 at their areas of contact, so as to prevent the gassage of any electric current through these members.

As noted above, the contact buttons 26 and 28 may be formed of tungsten or other appropriate refactory material. These contacts, as mentioned, are preferably gold or silver bonded to the armature 20 and to the stationary member 18 respectively, and they are extremely thin so that the magnetic path between the armature and the stationary member 18 is not interrupted to any appreciable extent. The gold or silver bonding of the contact buttons 26 and 28 to their respective members 20 and 16 provides a good heat transfer between the contact buttons and their respective members, so that there is no tendency for hot spots to develop and, therefore, there is no likelihood of welding of the contacts during operation of the relay.

As noted above, the movable member 20 and the stationary member 16 are both used to carry electric current to the relay. The electrical conductivity of these members may be enhanced, without deteriorating its magnetic characteristic, providing (for example) a nickel and gold plated outer surface.

To form such an assembly, the member 20 and the stationary member 16 are first fired in a hydrogen oven to clean the members, and for example, a nickel coating is electroplated over the members by any appropriate known plating process. The nickel coating is deposited, for example, to a thickness of one mil. The coated members 16 and 18 are then fired again in hydrogen to bond the nickel coating securely to the surfaces of the members and to clean their surfaces.

A gold coating may then be plated on the members to a thickness for example of one mil by any suitable plating process. The contact buttons 26 and 28 are initially tacked on their respective members 16 and 20, for example, by spot welding, and the assemblies are again fired in a hydrogen oven to melt the gold (or silver), and to cause the contacts 26 and 28 to be bonded in intimate contact with'the respective members 16 and 20.

The rubbzerized tape is then wound over the envelope 10, as spaced axial positions, to provide the resilient support for the magnetic assembly 50, and the assembly 50 is slipped into place to form the unit of FIGURE 1. Appropriate leads are soldered to the terminals 12 and 14, as well as to the energizing terminal 66, and the unit is placed in an outer casing (FIGURE 4). The unit is potted in the outer casing by a suitable epoxy 82, for example, and the leads may be brought the respective ends of the completed unit, these leads being designated 84 and 86.

The invention provides, therefore, an improved vacuum relay assembly which is relatively simple and inexpensive to construct. The vacuum relay of the invention is advantageous because of its low mass, and because of its immunity to spurious operation, malfunction or damage, in the presence of high external forces. The relay is also advantageous because of its high sensitivity, and because of its capabilities of carrying high currents and operating under high voltage conditions.

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

What is claimed is:

1. A vacuum relay assembly including: an evacuated housing: a pair of elongated electrically conductive terminal pins extending into said housing in substantial axial alignment with one another and axially snaced from one another; a pair of axially spaced, axially aligned first and second stationary elongated members of mag etizable material positioned Within said housing and affixed to respective ones of said pins to be supported thereby in respective electrical contact with corresponding ones of said pins; first and second pole pieces of magne izable material positioned on respective ones of said s ationary members and extending out of the plane thereof towards the inner surface of said housing; an armature composed of a movable member of magnetizable material; a resilient electrically conductive wire-like member afiixed to one of said terminal pins in electrical contact therewith and to said armature in electrical contact therewith for resiliently supporting said armature in bridging essentially parallel relationship with said first and second stationary magnetizable members and is normally displaced therefiom; a first relatively thin electric contact button formed of an electrically conductive material afiixed tosaid armature; a second relatively thin electric contact button formed of an electrically conductive material afiixed to said first magnetizable member in facing relationship with said first contact button, the thickness of said first and second contact buttons being insufiicient to interrupt the magnetic path through said armature and through said first magnetizable member to any appreciable extent.

2. The assembly defined in claim 1 and which includes projecting means formed integrally with the inner surface of the wall of said housing and extending radially inwardly therefrom to bear against said armature and bias said armature against the tension of said wire-like member in the direction of said stationary members.

3. The assembly defined in claim 1 and which includes magnetic energizing means positioned externally of said evacuated housing in coaxial relationship with said armature and said stationary members to establish a magnetic flux in said stationary members and in said armature to draw said armature into contact with said stationary members against the tension of said resilient wire-like member so as to cause said contact buttons to engage one another.

4. The assembly defined in claim 3 in which said contact buttons are formed of a refractory material, and which include metallic bonds of relatively high heat conductivity material respectively interposed between said 8 first contact button and said armature and between said second contact button and said first magnetizable member to obviate any tendency for hot spots and resulting welding of said contact buttons to occur.

5. The assembly defined in claim 4 in which said contact buttons are formed of tungsten, and which said metallic bonds are formed of gold.

6. The assemby defined in claim 1, and which includes coatings of high electrical conductivity on said armature and on said first magnetizable member.

7. The assembly defined in claim 6 in which said Coatings are formed of nickel and gold.

8. The assembly defined in claim 3 in which said magnetic energizing means includes a tubular inner wall for receiving said evacuated housing, and which includes resilient means positioned on said housing between said housing and said tubular inner wall of said magnetic energizing means.

9. The assembly defined in claim 3 in which said housing and said magnetic energizing means are enclosed is n an outer tubular envelope, and which are potted in said outer envelope by an epoxy resin material.

References Cited UNITED STATES PATENTS 3/1965 Zi-mmer 335--154 X 6/1967 Bongard et al 335--154

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