US3177328A - Sealed-in contact structure with extended glow discharge surfaces - Google Patents

Sealed-in contact structure with extended glow discharge surfaces Download PDF

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Publication number
US3177328A
US3177328A US44195A US4419560A US3177328A US 3177328 A US3177328 A US 3177328A US 44195 A US44195 A US 44195A US 4419560 A US4419560 A US 4419560A US 3177328 A US3177328 A US 3177328A
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US
United States
Prior art keywords
contact
area
glow discharge
areas
making
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US44195A
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English (en)
Inventor
Borchert Lothar
Huber Christian
Rau Karl-Ludwig
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens and Halske AG
Siemens Corp
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Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
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Application granted granted Critical
Publication of US3177328A publication Critical patent/US3177328A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/38—Cold-cathode tubes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/02—Contacts characterised by the material thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/02—Contacts characterised by the material thereof
    • H01H1/0201—Materials for reed contacts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/64—Protective enclosures, baffle plates, or screens for contacts
    • H01H1/66—Contacts sealed in an evacuated or gas-filled envelope, e.g. magnetic dry-reed contacts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/02—Contacts characterised by the material thereof
    • H01H2001/0208—Contacts characterised by the material thereof containing rhenium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2893/00—Discharge tubes and lamps
    • H01J2893/0064—Tubes with cold main electrodes (including cold cathodes)
    • H01J2893/0065—Electrode systems

Definitions

  • a sealed-in contact structure comprises magnetizable contact springs disposed within a glass tube which is hermetically fused at its ends.
  • the glass tube may be filled with a protective gas, for example, a mixture of nitrogen and hydrogen, to prevent corrosion of the contacts.
  • a protective gas for example, a mixture of nitrogen and hydrogen
  • the same effect is obtained by filling the giass tube with a noble gas, for example, argon. Accordingly, such a structure constitutes in principle a contact arrangement disposed within a hermetically sealed chamber which is filled with a protective gas or a noble gas.
  • the object of the present invention is to considerably increase the life of such contact structures.
  • this object is realized by the provision of means, at the areas of the contacts over which a glow discharge extends upon contact actuation, forming a surface of a highmelting metal, for example, molybdenum, tungsten, tantalum, acting in the manner of a pure metal cathode.
  • the invention is based upon recognition of the following observations:
  • the contact springs of a contact structure may be compared with the electrodes of a gas discharge tube. Accordingly, a glow discharge will occur between the electrodes during the opening operation thereof in the presence of a voltage thereon which exceeds the firing voltage. This occurs especially when an inductive load, for example, a relay, is to be switched by means of such a contact structure. In such a case, the spontaneous current interruption elfects induction of a voltage peak appearing directly at the contact gap and thereby firing the glow discharge.
  • metals with relatively high melting point for example, molybdenum, tungsten or tantalum, which oifer a very high resistance to the cathode vaporization occurring incident to glow discharges.
  • Such metals have already been used in cathode tubes in connection with so-called pure metal cathodes.
  • these metals appeared until now unsuitable for contact materials because experience with such contacts, operated in air, for example, tungsten contacts, showed that these materials tend, especially with weak loading, toward formation of high resistance layers and even insulating layers.
  • the contact springs of sealedin contact devices therefore have usually been provided with a noble metal layer or coating, for example, gold, which is however less resistant against cathode vaporization.
  • highmelting metals such, for example, as molybdenum, tantalum or tungsten, employed as surface materials of contact springs disposed in a hermetically sealed chamber or space filled with a protective gas or noble gas, make it possible to practically eliminate the 3,177,328 Patented Apr. 6, 1965 detrimental cathode vaporization; the otherwise observed tendency of such metals, to form high resistance layers or coatings being thereby prevented by the protective gas or noble gas.
  • the above described measures taken in accordance with the invention result in long life of the contacts since undesired alteration thereof, due to glow discharge, is largely eliminated. This also results in an improvement with respect to the time constants of the electric and magnetic characteristics.
  • the highmelting metal is provided upon the contact springs in the form of foils.
  • FIG. 1 shows an embodiment of a sealed-in contact device or structure according to the invention with the highmelting metal secured to the contact spring in the manner of foils;
  • FIGS. 2 and 3 illustrate an embodiment in which the highmelting metal is riveted to a contact spring.
  • FIG. 1 numeral it indicates the sealing or protective tube containing the contact springs 2 and 3.
  • the tube 1 is made of glass and is fused at its ends about the contact springs 2 and 3.
  • the contact springs 2 and 3 are within the contact points or areas thereof provided each with a foil 4 consisting of a highmelting metal, for example, molybdenum.
  • the foil 4- is drawn about the respective contact springs 2 and 3 so as to produce relatively large areas which are adapted to otter a correspondingly high resistance against cathode vaporization incident to a glow discharge occurring in operation of the structure.
  • the rivet 5 has a dish-shaped part disposed on a spring such as indicated at 7, facing in the direction of the other spring (not shown) cooperating therewith.
  • the stem 6 of the rivet extends through the contact spring 7 and is riveted over on the other side of the contact spring as shown.
  • Both contact parts belonging to a contact structure are advantageously provided with a highmelting metal.
  • Such a contact structure can be connected in a circuit regardless of the direction of the current to be controlled while at the same time considerably reducing the so-called finemigration emanating from the contact spring representing the cathode.
  • the operative effect of the above described measures may be supported or enhanced by filling the hermetically sealed space, containing the contacts, with a gas at a pressure which is as compared with the atmospheric pressure reduced to such extent that a glow discharge will extend with its cathodic coverage over an area which is considerably larger than the contact area belonging to the contact points, so that the cathode vaporization caused by the glow discharge is preponderantly distributed over areas which do not partake in the contact operation proper.
  • the pressure in the hermetically sealed chamber can be reduced with respect to the atmospheric pressure so as to produce a cathodic coverage which involves the contacts to the extent to which they are provided with the highmeltingmetal. There would in such case result a cathodic coverage corresponding to the extent of the contact areas 4 in FIG. 1. It is, however, also possible, by the use of appropriate pressure, to achieve a cathodic coverage extending beyond the highmelting metal. There will result in this case a still lower current density requiring, however, toleration of some residual cathode vaporization at areas which are not provided with highmelting metal. This is however immaterial because the resultant cathode vaporization is of little importance due to the low specific total current loading.
  • a contact arrangement comprising two mutually cooperating contact members disposed within a hermetically sealed chamber which contains a protective gas, said contact members having respective engageable contactmaking areas, a thin sheet of a high melting-metal, selected from the class of metals consisting of molybdenum, tantalum and tungsten, applied to the contact-making area of each contact member, each sheet having an area considerably greater than the contact-making area of the associated contact member, the inert gas filling having a pressure which is with respect to the atmospheric pressure reduced so that the cathodic coverage of a glow discharge extends over an area which is considerably greater than the contact-making area occupied by the contacting surfaces of said contact member, each of said thin sheets having an area of a size to accommodate the extended glow discharge, the cathode vaporization caused by the glow discharge being thereby shifted predominately to areas of said highmelting metal sheets which do not form the actual contact-making areas of the contact members.
  • a thin sheet of a high melting-metal selected from the class of metals

Landscapes

  • High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
  • Contacts (AREA)
US44195A 1959-08-06 1960-07-20 Sealed-in contact structure with extended glow discharge surfaces Expired - Lifetime US3177328A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES64319A DE1112161B (de) 1959-08-06 1959-08-06 Kontaktanordnung, die in einem hermetisch abgeschlossenen Raum untergebracht ist

Publications (1)

Publication Number Publication Date
US3177328A true US3177328A (en) 1965-04-06

Family

ID=7497093

Family Applications (1)

Application Number Title Priority Date Filing Date
US44195A Expired - Lifetime US3177328A (en) 1959-08-06 1960-07-20 Sealed-in contact structure with extended glow discharge surfaces

Country Status (5)

Country Link
US (1) US3177328A (en, 2012)
CH (1) CH387739A (en, 2012)
DE (1) DE1112161B (en, 2012)
GB (1) GB948931A (en, 2012)
NL (1) NL254443A (en, 2012)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1089907A (en) * 1912-03-20 1914-03-10 Gen Electric Electrical contact.
US1900256A (en) * 1932-02-26 1933-03-07 Gen Plate Co Electrical contact and the manufacture thereof
US2200443A (en) * 1938-11-29 1940-05-14 Westinghouse Electric & Mfg Co Discharge lamp circuit
US2321910A (en) * 1941-10-23 1943-06-15 Westinghouse Electric & Mfg Co Time delay glow switch
US2323702A (en) * 1940-08-02 1943-07-06 Westinghouse Electric & Mfg Co Voltage responsive switch
US2506414A (en) * 1947-12-05 1950-05-02 Bell Telephone Labor Inc Sealed wire contact device
US2625622A (en) * 1950-05-25 1953-01-13 Westinghouse Electric Corp Lamp starter
US3007855A (en) * 1958-12-29 1961-11-07 Bell Telephone Labor Inc Rhodium plating

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE407725C (de) * 1923-08-30 1925-01-02 Franz Joseph Koch Vakuumunterbrecher
DE705358C (de) * 1936-10-24 1941-04-25 Siemens & Halske Akt Ges Vakuumschalter
DE966816C (de) * 1950-03-04 1957-09-12 Siemens Ag Verfahren zur Herstellung von Federkontakten mit plattiertem Kontaktniet fuer elektrische Apparate

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1089907A (en) * 1912-03-20 1914-03-10 Gen Electric Electrical contact.
US1900256A (en) * 1932-02-26 1933-03-07 Gen Plate Co Electrical contact and the manufacture thereof
US2200443A (en) * 1938-11-29 1940-05-14 Westinghouse Electric & Mfg Co Discharge lamp circuit
US2323702A (en) * 1940-08-02 1943-07-06 Westinghouse Electric & Mfg Co Voltage responsive switch
US2321910A (en) * 1941-10-23 1943-06-15 Westinghouse Electric & Mfg Co Time delay glow switch
US2506414A (en) * 1947-12-05 1950-05-02 Bell Telephone Labor Inc Sealed wire contact device
US2625622A (en) * 1950-05-25 1953-01-13 Westinghouse Electric Corp Lamp starter
US3007855A (en) * 1958-12-29 1961-11-07 Bell Telephone Labor Inc Rhodium plating

Also Published As

Publication number Publication date
NL254443A (en, 2012)
GB948931A (en) 1964-02-05
DE1112161B (de) 1961-08-03
CH387739A (de) 1965-02-15

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