US3697907A - Vacuum relay - Google Patents

Abstract

An improved high voltage vacuum relay is provided which includes internal shielding means which serves to prevent ionic discharge within the relay from the high voltage contacts thereof to its grounded magnetic actuating circuit, and which also serves to strengthen the bulb and to make the unit less susceptible to breakage.

Description

United States Patent De Lucia 1 Oct. 10, 1972 [54] VACUUM RELAY 2,966,569 12/1960 Jennings ..200/ 144 B [72] Inventor: gicltgu' E. De Lucia, Los Angeles, FOREIGN PATENTS OR APPLICATIONS a1 206,663 2/1968 U.S.S.R ..200/144 B Ass1gnee= Torr Laboratories,- a Los 106,773 12/1963 Netherlands ..,..200/144 B geles, Calif.

Primary Examiner-Harold Broome [22] Flled' 1970 Attorney-Jessup & Beecher [21] Appl. No.: 103,153

[57] ABSTRACT 52 us. Cl. ..335/201, 200/144 B An mp e high voltage vacuum relay is provided [51] Int. Cl. ..HOlh 9/32 which includes internal Shielding means which Serves [58] Field of Search 5 /20 1, 200/144 3 to prevent ionic discharge within the relay from the high voltage contacts thereof to its grounded magnetic actuating circuit, and which also serves to strengthen [56] References Clted the bulb and to make the unit less susceptible to UNlTED STATES PATENTS breakag 3,154,655 10/ 1964 Hawkins ..200/144 B 2 Claims, 2 Drawing Figures A1 zfii x/a- Z8 Z3; 3 if :521" axe 32 O h7g4 Va/Iage fflfll/d/l fllq #M-zaa0 56 (Ila/'32 2 1- 34 +2 aaza za I rama? 10 I 5 M 22 azmz PATENTEDum 10 I972 3 6 9 07 VACUUM RELAY BACKGROUND OF THE INVENTION High voltage vacuum switches, or relays, are known to the art which include relay switching contacts enclosed in an evacuated envelope. Such a construction minimizes contact deterioration, and such relays may be operated to switch high voltages over long operational periods without excessive maintenance requirements.

However, during the switching cycle of a high voltage vacuum relay, arcing does occur between the contacts. The resulting arc consists of ionized metallic and gas particles, these ionized particles being liberated from the relay contacts by the high temperature of the arc. The intensity of the ions so liberated is a function of the power being switched by the relay, and also of the gas embedded in the contacts and of the electron work function of the contacts.

In the prior art vacuum relay units, ionic discharge occurs between the high voltage contacts and the magnetic actuating members which are usually established at ground potential, the latter being included within the envelope to increase the magnetic sensitivity of the actuating armature. Such an ionic discharge can become sufficiently high so as to create short circuits in the electrical circuitry associated with the relay. The ionic discharge is caused by the positive ions released during the arcing action colliding with the few remaining gas molecules still present within the evacuated envelope of the relay.

The vacuum relay of the present invention is constructed to incorporate an internal shield and metallic baffle, as will be described, so that the ions and electrons which are developed during the arcing of the relay contacts are not attracted and accelerated towards the grounded magnetic actuating members, but are maintained in the upper portion of the envelope and neutralized when they collide with the shield and baffle. With such a construction, no sustained discharge to the grounded magnetic members is possible.

The structure of the present invention renders it possible for the relay to operate in conjunction with higher voltages than possible with prior art relays of the same size and electrical construction.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side section of a vacuum relay constructed to incorporate the concepts of the present invention; and

FIG. 2 is a cross-sectional view of the relay of FIG. 1, taken along the line 2-2 of FIG. 1.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT The relay shown in FIGS. 1 and 2 includes, for example, an envelope formed of glass, or other vitreous or ceramic material. The envelope 10 is formed in known manner, and its open lower end is enclosed by a magnetic actuating unit 12. The magnetic actuating unit 12 includes a central core 14 on which an electric actuating coil 16 is wound. The coil is surrounded by a magnetic housing 18, and the magnetic circuit is completed by a lower cover plate 20, also formed of magnetic material. The magnetic actuating unit 12 is normally maintained at ground potential, as indicated by the ground symbol.

A magnetic armature 22 is hinged to the upper end of the magnetic unit 12, and extends across the central core 16. A spring 24 normally biases the armature 22 to its illustrated inclined position. However, when the actuating coil 16 is energized, the armature is turned down to an essentially horizontal position.

An insulating rod 26 is mounted on the armature 22, and the rod extends upwardly to a movable contact 28. The movable contact 28 is pivotally mounted, for example, in a first high voltage contact terminal pin 30, the terminal pin 30 extending through the wall of the envelope 10. When the armature 22 is actuated in the manner described above, the movable contact 28 is brought into selective contact with a second high voltage terminal pin 32 which, likewise, extends through the envelope 10.

The relay components, as thus far described, are know to the art. As mentioned above, such a relay is capable of switching relatively high voltages between the high voltage terminal pins 30 and 32 with a minimum of deterioration of the relay contacts. However, the voltages which may be handled by such a prior art relay are limited, due to the fact that there is a tendency for an ionic discharge to occur between the high voltage contacts 32 and the grounded magnetic members forming the magnetic unit 12 at the bottom of the relay.

Such a discharge is prevented in the construction of the present invention by providing a glass or ceramic shield 34 midway down the envelope 10 and extending across the envelope, as shown in FIGS. 1 and 2. The shield 34 may be integral with the envelope 10. A central opening 36 is provided in the shield 34, and the insulating rod 26 extends through the opening. In addition, a metallic baffle 40 is mounted on the rod 26 directly under the opening 36. As mentioned above, the shield 34 also adds strength to the envelope 10. The shield also serves to extend the path on which a short circuiting metal film could be formed, thereby militating against the formation of such a path.

With the illustrated construction, the electrostatic field within the envelope 10 is minimized, so that there is no tendency for an ionic discharge to occur between the high voltage contacts 28, 30, 32 and the grounded magnetic unit 12. Instead, the ions are maintained in the upper part of the envelope l0, and are neutralized as they contact the shield 34 or the baffle 40. Therefore, the relay of the present invention by means of a simple expedient is capable of highly efficient operation, and of handling higher voltages than similar relays of the prior art.

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

What is claimed is:

1. In a vacuum relay which comprises an evacuated envelope formed of vitreous material and having an open end, a magnetic actuating unit mounted at said open end of said envelope and enclosing said open end, and high voltage relay switching contacts mounted at relay switching contacts; and a baffle mounted on said rod adjacent said opening and disposed on the side of said opening remote from said relay contacts, said baffle extending beyond the peripheral edge of said openmg.

2. The vacuum relay of claim 1, in which said baffle is composed of a metallic material.

Claims (2)

1. In a vacuum relay which comprises an evacuated envelope formed of vitreous material and having an open end, a magnetic actuating unit mounted at said open end of said envelope and enclosing said open end, and high voltage relay switching contacts mounted at the end of said envelope remote from said magnetic actuating unit; a vitreous shield integral with said envelope and extending across said envelope between said magnetic actuating unit and said switching contacts to strengthen said envelope and to inhibit ionic discharge within said envelope between said contacts and said magnetic unit, said vitreous shield having an opening therein; an insulating rod extending from said magnetic actuating unit through said opening to said relay switching contacts; and a baffle mounted on said rod adjacent said opening and disposed on the side of said opening remote from said relay contacts, said baffle extending beyond the peripheral edge of said opening.

2. The vacuum relay of claim 1, in which said baffle is composed of a metallic material.

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