US3128418A - Magnetically latched switch operator - Google Patents

Magnetically latched switch operator Download PDF

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Publication number
US3128418A
US3128418A US42678A US4267860A US3128418A US 3128418 A US3128418 A US 3128418A US 42678 A US42678 A US 42678A US 4267860 A US4267860 A US 4267860A US 3128418 A US3128418 A US 3128418A
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Prior art keywords
core
oersteds
switch operator
magnetic
gausses
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US42678A
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Frank A Zupa
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AT&T Corp
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Bell Telephone Laboratories Inc
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Priority to NL266598D priority Critical patent/NL266598A/xx
Priority to NL126658D priority patent/NL126658C/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US42678A priority patent/US3128418A/en
Priority to FR865357A priority patent/FR1292616A/en
Priority to GB22629/61A priority patent/GB928119A/en
Priority to DEW30260A priority patent/DE1224051B/en
Priority to BE605899A priority patent/BE605899A/en
Application granted granted Critical
Publication of US3128418A publication Critical patent/US3128418A/en
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H51/00—Electromagnetic relays
    • H01H51/01—Relays in which the armature is maintained in one position by a permanent magnet and freed by energisation of a coil producing an opposing magnetic field
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest

Definitions

  • a material that is magnetically hard for example, high carbon permanent magnet material, has high retentivity but requires a relatively large force to magnetize it.
  • a soft magnetic material for example, annealed low carbon steel, is easy to magnetize but has very little ability to retain its magnetism.
  • An object of the present invention is to improve switch operating electromagnets by retaining good operating capability and, at the same time, increasing their magnetic latching ability.
  • a more specific object is to facilitate the operation of magnetically latchable electromagnetic switches by improving the magnetic properties of the core material.
  • a feature of this invention resides in an electromagnetic switch having high holding power at no current coupled with adequate force for a moderate expenditure of power during operation. More particularly, the noted feature involves an electromagnetic switch having a core with high magnetic retentivity and relatively high permeability.
  • An exemplary embodiment of this invention comprises a latching switch having a magnetic core, a coil for energizing the core, an armature to be attracted by the coilenergized core and held in attracted position by the residual magnetism of the core when the coil energization ceases.
  • the core has a high magnetic retentivity and high permeability with a coercive force (H,,) of 23.5 oersteds and a residual flux density or induction (13,) of 13,300 gausses for an applied magnetic force (H or 143 oersteds, and a saturation induction (B of 16,300 gausses, the maximum permeability (u being 320. Allowable deviations from the magnetic characteristics of this exemplary embodiment will be considered in the ensuing description of the invention.
  • FIG. 1 is an elevational view, partly in section, of a switch operator illustrative of a device incorporating this invention.
  • FIG. 2 is a plot showing an initial magnetization curve and a hysteresis loop of a core material particularly suitable for the purposes of this invention.
  • the switch operator comprise a frame 11 to which is secured a core 12 and an operating coil 13.
  • An armature 14 pivoted to the frame 11 includes a contact operating portion 15 for deflecting a multiplicity of contacts represented diagrammatically at 16.
  • a portion of the frame 11 and of the armature 14 are shown in section to indicate that there is an extension of the armature and the cooperating portion of the frame for the operation of other contacts or groups of 3,128,418 Patented Apr. 7, 1964 contacts; for example, the magnets for vertical row operation in a cross-bar switch as in Patent 2,021,329 to J. N. Reynolds, issued November 19, 1935.
  • the core 12 has a rounded end 17 facing the armature 14.
  • This end may comprise a spherical surface having a suitable radius.
  • the area of the armature-pole face contact will be substantially constant and yield a stronger concentration of flux and thereby a stronger latching force, notwithstanding slight tilting of the armature or longitudinal displacement of the core.
  • a 3.5 inch core of 0.375 inch diameter advantageously would have a spherical end surface of a radius between 7 and 9 inches.
  • the ability of the switch operator of this invention to hold the armature in the absence of applied power and also to pick it up at moderate power lies in the novel magnetic characteristics of the core.
  • a core having the magnetic characteristics previously noted for an exemplary embodiment may be made by a proper selection of high carbon steel and correct heat treatments of such steel.
  • a suitable steel is 1.2% carbon tool steel which may typically contain 1.2% carbon, 0.3% manganese, 0.22% silicon, 0.10% vanadium, 0.025% sulfur and phosphorus, and the remainder iron.
  • Such a steel heated at 1475 F.i25 F. for 30 minutes, quenched in water, and then reheated for 30 minutes at from 850 F. to 950 F., and cooled in air has particularly advantageous magnetic properties. It may be noted here that satisfactory magnetic properties may be obtained with properly heat treated steels having lower or higher carbon content, with or without other alloying elements which are known to promote the hardening process.
  • a desirable way to designate a suitable core steel is to use the hardness indications.
  • Those of the Rockwell 30-N scale are quite suitable. Using this scale, investigations of steel and heat treatments to produce hardness in a range of about 35 to were used to find a suitable material. It was found that if the hardness was within the range 54 to 64 on the noted 30-N scale, both the residual induction B and the coercive force H were particularly satisfactory. The results were outstandingly good with the material having a hardness designated as 60. Because the effectiveness of the heat treatment, particularly the quenching stage, is a function of the size of the bore piece, the hardness number was found to be a more satisfactory indication of the desired magnetic properties than the designation of a specific heat treatment. In other words, the heat treatment should, within the suitable range, be tailored to the size of the piece under treatment to result in a Rockwell 30-N hardness between 54 and 64.
  • FIG. 2 A hysteresis curve of the magnetic characteristics of the noted 60 hardness material is shown in FIG. 2.
  • the data for this plot was taken after the application of a maximum magnetizing force H of 143 oersteds, which gave a saturation induction B of 16,300 gausses.
  • H the residual induction B
  • H the magnetizing force
  • H the magnetizing force
  • the maximum permeability (,u is 320 for this material and treatment.
  • the same steel, heat treated to have a Rockwell hardness number of 35 has under like circumstances of test a B of about 10,000 gausses, an H of about 9 oersteds, and a ,u of about 500.
  • the same steel with a hardness number of 81 has a B of about 7,500 gausses, an H of about 44 oersteds, and a ,u of 113.
  • a magnetically latcliable Switch Operator comprising a magnetic core of about 1% carbon steel, a coil for ener izing the core, an armature associated with the core and for controlling contacts, said core having a Rockwell 30-N scale hardness of 54 to 64, and a high retentivity coupled with a high permeability, the coercive force of the core being from 20 to 27 oerst'eds and the residual flux density from 10,000 to 13,500 gausses based on an applied magnetizing force of at least 70 oersteds.
  • An electromagnetic operator for switch means comprising a core of magnetic material, a coil for energizing the core, and an armature associated with the core for actuation thereby, said core material comprising a relatively hard steel containing 1.2% carbon and heat treated induction of 13,300 gausses due to an applied magnetizing force of 143 oersteds resulting in a saturation induction of 16,300 gausses.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Materials Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Power Engineering (AREA)
  • Electromagnetism (AREA)
  • Heat Treatment Of Articles (AREA)
  • Soft Magnetic Materials (AREA)
  • Electromagnets (AREA)

Description

April 7, 1964 F. A. ZUPA MAGNETICALLY LATCHED SWITCH OPERATOR Filed July 13, 1960 (B5 lqaoo) |4,ooo (9,- 0,300)
Ill
l I l [43 6O 5O 4O 30 20 l0 0 IO 20 3O 4O 5O 6O 70 M3 OERS T505 4- //v VENTOR F. A. ZUPA ATTORNEV United States Patent 3,128,418 MAGNETICALLY LATCHED SWITCH OPERATOR Frank A. Zupa, New York, N.Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N.Y., a corporation of New York Filed July 13, 1960, Ser. No. 42,678 2 Claims. (Cl. 317-165) This invention relates to electromagnetically operated switches, relays, and similar devices, and more particularly to magnetically latched operating means for such devices.
It has been known for some time that the core of an electromagnetic switch operator could be made of a material having sufficient magnetic retentivity to latch or hold the switch after the coil of the electromagnet had been deenergized. One problem with such devices has arisen because of the difliculty in obtaining a core material having both high residual magnetic strength and low operating power requirements.
A material that is magnetically hard, for example, high carbon permanent magnet material, has high retentivity but requires a relatively large force to magnetize it. On the other hand, a soft magnetic material, for example, annealed low carbon steel, is easy to magnetize but has very little ability to retain its magnetism.
An object of the present invention is to improve switch operating electromagnets by retaining good operating capability and, at the same time, increasing their magnetic latching ability.
A more specific object is to facilitate the operation of magnetically latchable electromagnetic switches by improving the magnetic properties of the core material.
A feature of this invention resides in an electromagnetic switch having high holding power at no current coupled with adequate force for a moderate expenditure of power during operation. More particularly, the noted feature involves an electromagnetic switch having a core with high magnetic retentivity and relatively high permeability.
An exemplary embodiment of this invention comprises a latching switch having a magnetic core, a coil for energizing the core, an armature to be attracted by the coilenergized core and held in attracted position by the residual magnetism of the core when the coil energization ceases. The core has a high magnetic retentivity and high permeability with a coercive force (H,,) of 23.5 oersteds and a residual flux density or induction (13,) of 13,300 gausses for an applied magnetic force (H or 143 oersteds, and a saturation induction (B of 16,300 gausses, the maximum permeability (u being 320. Allowable deviations from the magnetic characteristics of this exemplary embodiment will be considered in the ensuing description of the invention.
Other and further objects and features of this invention will appear more fully and clearly from the following pertinent description and the appended drawings, in which:
FIG. 1 is an elevational view, partly in section, of a switch operator illustrative of a device incorporating this invention; and
FIG. 2 is a plot showing an initial magnetization curve and a hysteresis loop of a core material particularly suitable for the purposes of this invention.
As may be seen in FIG. 1, the switch operator comprise a frame 11 to which is secured a core 12 and an operating coil 13. An armature 14 pivoted to the frame 11 includes a contact operating portion 15 for deflecting a multiplicity of contacts represented diagrammatically at 16. A portion of the frame 11 and of the armature 14 are shown in section to indicate that there is an extension of the armature and the cooperating portion of the frame for the operation of other contacts or groups of 3,128,418 Patented Apr. 7, 1964 contacts; for example, the magnets for vertical row operation in a cross-bar switch as in Patent 2,021,329 to J. N. Reynolds, issued November 19, 1935.
The core 12 has a rounded end 17 facing the armature 14. This end may comprise a spherical surface having a suitable radius. With such an arrangement, the area of the armature-pole face contact will be substantially constant and yield a stronger concentration of flux and thereby a stronger latching force, notwithstanding slight tilting of the armature or longitudinal displacement of the core. For example, a 3.5 inch core of 0.375 inch diameter advantageously would have a spherical end surface of a radius between 7 and 9 inches.
As has been indicated, the ability of the switch operator of this invention to hold the armature in the absence of applied power and also to pick it up at moderate power lies in the novel magnetic characteristics of the core.
Applicant has discovered that a core having the magnetic characteristics previously noted for an exemplary embodiment may be made by a proper selection of high carbon steel and correct heat treatments of such steel. A suitable steel is 1.2% carbon tool steel which may typically contain 1.2% carbon, 0.3% manganese, 0.22% silicon, 0.10% vanadium, 0.025% sulfur and phosphorus, and the remainder iron. Such a steel heated at 1475 F.i25 F. for 30 minutes, quenched in water, and then reheated for 30 minutes at from 850 F. to 950 F., and cooled in air has particularly advantageous magnetic properties. It may be noted here that satisfactory magnetic properties may be obtained with properly heat treated steels having lower or higher carbon content, with or without other alloying elements which are known to promote the hardening process.
A desirable way to designate a suitable core steel is to use the hardness indications. Those of the Rockwell 30-N scale are quite suitable. Using this scale, investigations of steel and heat treatments to produce hardness in a range of about 35 to were used to find a suitable material. It was found that if the hardness was within the range 54 to 64 on the noted 30-N scale, both the residual induction B and the coercive force H were particularly satisfactory. The results were outstandingly good with the material having a hardness designated as 60. Because the effectiveness of the heat treatment, particularly the quenching stage, is a function of the size of the bore piece, the hardness number was found to be a more satisfactory indication of the desired magnetic properties than the designation of a specific heat treatment. In other words, the heat treatment should, within the suitable range, be tailored to the size of the piece under treatment to result in a Rockwell 30-N hardness between 54 and 64.
A hysteresis curve of the magnetic characteristics of the noted 60 hardness material is shown in FIG. 2. The data for this plot was taken after the application of a maximum magnetizing force H of 143 oersteds, which gave a saturation induction B of 16,300 gausses. As may be seen, the residual induction B,, when the magnetizing force is reduced to Zero (H is 13,300 gausses. Moreover, the reverse magnetization to produce zero induction is 23.5 oersteds, namely, the coercive force H The maximum permeability (,u is 320 for this material and treatment.
It may be noted that the same steel, heat treated to have a Rockwell hardness number of 35, has under like circumstances of test a B of about 10,000 gausses, an H of about 9 oersteds, and a ,u of about 500. On the other hand, the same steel with a hardness number of 81 has a B of about 7,500 gausses, an H of about 44 oersteds, and a ,u of 113.
By staying within the optimum hardness range of 54 to 64 on the noted Rockwell scale, it is possible to obtain good Cores by magnetizing at a force of over 70 oersteds. Such cores will have a coercive force H between 20 and 27 oersteds and a residual flux density B of 10,000 to 13,500 gausses.
What is claimed is':'
1. A magnetically latcliable Switch Operator comprising a magnetic core of about 1% carbon steel, a coil for ener izing the core, an armature associated with the core and for controlling contacts, said core having a Rockwell 30-N scale hardness of 54 to 64, and a high retentivity coupled with a high permeability, the coercive force of the core being from 20 to 27 oerst'eds and the residual flux density from 10,000 to 13,500 gausses based on an applied magnetizing force of at least 70 oersteds.
2. An electromagnetic operator for switch means comprising a core of magnetic material, a coil for energizing the core, and an armature associated with the core for actuation thereby, said core material comprising a relatively hard steel containing 1.2% carbon and heat treated induction of 13,300 gausses due to an applied magnetizing force of 143 oersteds resulting in a saturation induction of 16,300 gausses.
References Cited in the file of this patent UNITED STATES PATENTS 2,397,116 Armstrong Mar. 26, 1946 2,735,967 Lewis Feb. 21, 1956 2,885,606 Clements May 5, 1959 2,894,181 Brewer July 7, 1959 2,928,917 Crain Mar. 15, 1960 2,932,704 Dennison et a1. Apr. 20, 1960 2,935,656 Baker May 3, 1960 OTHER REFERENCES Vanadium, Vanadium Corp. of America, New York, NY. (pages 114118 relied on).
Ferrornagnetism (Bozorth), published by V. Van Nostrand C0,, Princeton, N1, 1959 (pages 39, 364-371 to have a coercive force of 23.5 oersteds and a residual 20 relied

Claims (1)

1. A MAGNETICALLY LATCHABLE SWITCH OPERATOR COMPRISING A MAGNETIC CORE OF ABOUT 1% CARBON STEEL, A COIL FOR ENERGIZING THE CORE, AN ARMATURE ASSOCIATED WITH THE CORE AND FOR CONTROLLING CONTACTS, SAID CORE HAVING A ROCKWELL 30-N SCALE HARDNESS OF 54 TO 64, AND A HIGH RETENTIVITY COUPLED WITH A HIGH PERMEABILITY, THE COERCIVE FORCE OF THE CORE BEING FROM 20 TO 27 OERSTEDS AND THE RESIDUAL FLUX DENSITY FROM 10,000 TO 13,500 GAUSSES BASED ON AN APPLIED MAGNETIZING FORCE OF AT LEAST 70 OERSTEDS.
US42678A 1960-07-13 1960-07-13 Magnetically latched switch operator Expired - Lifetime US3128418A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
NL266598D NL266598A (en) 1960-07-13
NL126658D NL126658C (en) 1960-07-13
US42678A US3128418A (en) 1960-07-13 1960-07-13 Magnetically latched switch operator
FR865357A FR1292616A (en) 1960-07-13 1961-06-19 Magnetic bonding contactor
GB22629/61A GB928119A (en) 1960-07-13 1961-06-22 Improvements in or relating to electromagnetic switches retained set by remanent magnetism
DEW30260A DE1224051B (en) 1960-07-13 1961-06-29 Use of a carbon steel as the material for the magnetic core of electromagnetically latched switches
BE605899A BE605899A (en) 1960-07-13 1961-07-07 Electromagnetically Actuated Latch Switches

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US42678A US3128418A (en) 1960-07-13 1960-07-13 Magnetically latched switch operator

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US3128418A true US3128418A (en) 1964-04-07

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DE (1) DE1224051B (en)
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NL (2) NL126658C (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3271707A (en) * 1963-11-15 1966-09-06 Chauvin Arnoux Et Cie Soc Electromagnetic relay of the bistable type
US3364449A (en) * 1963-12-18 1968-01-16 Bell Telephone Labor Inc Magnetically actuated switching devices
US3486138A (en) * 1965-04-30 1969-12-23 Modern Precision Eng Finchley Electromagnetic switches utilizing remanent magnetic material
FR2371766A1 (en) * 1976-11-23 1978-06-16 Metalimphy Polarised relay system for circuit breakers - has alloyed permanent magnet with reversible relative permeability and coercive force between
EP0974997A2 (en) * 1998-07-21 2000-01-26 Eaton Corporation Fault current tolerable contactor

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2397116A (en) * 1944-08-15 1946-03-26 Westinghouse Electric Corp Control system
US2735967A (en) * 1956-02-21 Electromagnetic relays
US2885606A (en) * 1956-10-19 1959-05-05 Warner W Clements Impulse type electromotive device
US2894181A (en) * 1957-03-08 1959-07-07 Internat Typographical Union O Electromechanical device and improved armature therefor
US2928917A (en) * 1958-05-21 1960-03-15 Harry M Crain Self de-energizing relay
US2932704A (en) * 1958-03-18 1960-04-12 Cutler Hammer Inc Electromagnetic device
US2935656A (en) * 1956-05-15 1960-05-03 Gen Dynamics Corp Annunciator device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1823772U (en) * 1959-07-31 1960-12-22 Magnetschultz Spezialfabrik Fu ELECTRICALLY SWITCHED DC MAGNET.

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2735967A (en) * 1956-02-21 Electromagnetic relays
US2397116A (en) * 1944-08-15 1946-03-26 Westinghouse Electric Corp Control system
US2935656A (en) * 1956-05-15 1960-05-03 Gen Dynamics Corp Annunciator device
US2885606A (en) * 1956-10-19 1959-05-05 Warner W Clements Impulse type electromotive device
US2894181A (en) * 1957-03-08 1959-07-07 Internat Typographical Union O Electromechanical device and improved armature therefor
US2932704A (en) * 1958-03-18 1960-04-12 Cutler Hammer Inc Electromagnetic device
US2928917A (en) * 1958-05-21 1960-03-15 Harry M Crain Self de-energizing relay

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3271707A (en) * 1963-11-15 1966-09-06 Chauvin Arnoux Et Cie Soc Electromagnetic relay of the bistable type
US3364449A (en) * 1963-12-18 1968-01-16 Bell Telephone Labor Inc Magnetically actuated switching devices
US3486138A (en) * 1965-04-30 1969-12-23 Modern Precision Eng Finchley Electromagnetic switches utilizing remanent magnetic material
FR2371766A1 (en) * 1976-11-23 1978-06-16 Metalimphy Polarised relay system for circuit breakers - has alloyed permanent magnet with reversible relative permeability and coercive force between
EP0974997A2 (en) * 1998-07-21 2000-01-26 Eaton Corporation Fault current tolerable contactor
EP0974997A3 (en) * 1998-07-21 2000-08-16 Eaton Corporation Fault current tolerable contactor
EP1708223A2 (en) * 1998-07-21 2006-10-04 EATON Corporation Fault current tolerable contactor
CN100345238C (en) * 1998-07-21 2007-10-24 易通公司 Fault current tolerable contactor
EP1708223A3 (en) * 1998-07-21 2008-04-02 EATON Corporation Fault current tolerable contactor

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DE1224051B (en) 1966-09-01
NL266598A (en)
BE605899A (en) 1961-11-03
GB928119A (en) 1963-06-06

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