US3659238A - Permanent magnet electromagnetic actuator - Google Patents

Permanent magnet electromagnetic actuator Download PDF

Info

Publication number
US3659238A
US3659238A US51056A US3659238DA US3659238A US 3659238 A US3659238 A US 3659238A US 51056 A US51056 A US 51056A US 3659238D A US3659238D A US 3659238DA US 3659238 A US3659238 A US 3659238A
Authority
US
United States
Prior art keywords
flux
magnetic
path
force
permanent magnet
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
US51056A
Other languages
English (en)
Inventor
Brandt M Griffing
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.)
International Business Machines Corp
Original Assignee
International Business Machines Corp
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
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Application granted granted Critical
Publication of US3659238A publication Critical patent/US3659238A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J9/00—Hammer-impression mechanisms
    • B41J9/26—Means for operating hammers to effect impression
    • B41J9/36—Means for operating hammers to effect impression in which mechanical power is applied under electromagnetic control
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/14—Pivoting armatures
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K33/00—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system

Definitions

  • ABSTRACT Two essentially parallel magnetic flux paths are arranged so as to share a permanent magnet.
  • a movable armature in one flux path functions as a mechanical actuator by means of a selectively actuated magnetic opposing coil for effectively cancelling the flux in that path.
  • the other of the parallel magnetic flux paths is constructed and arranged for providing a shunt for sufi'icient additional magnetic flux during actuation of the opposing coil so as to prevent the shifting of the magnetic properties of the permanent magnet beyond the point of recovery to the original operating point upon deactuation of the coil.
  • the mechanical arrangement is such that the movable armature is retrieved by the magnetic circuit when the coil is deenergized.
  • This invention relates to electromechanical actuators. More particularly, this invention relates to devices for imparting mechanical motion to movable components by means of introducing and removing energizing pulses to control coils which operate in conjunction with magnetic flux circuits.
  • a particular utility for the present invention resides in its application to print hammer actuators, especially wherever high reliability, maintainability and minimum space arrangement of multiple actuators are involved.
  • Electromechanical actuators in the past wherein AC magnetic flux operations are involved have not employed permanent magnets for providing the static holding force since this static holding force must be reduced substantially to zero upon actuation of the device. Typically, this is effected by a so-called bucking coil which reduces the magnetic flux to substantially zero by an appropriate design of ampere turns.
  • the Brown et al. U.S. Pat. No. 3,460,469 shows such an arrangement and, in apparatus such as is there shown, the use of a permanent magnet for normal or static biasing is not possible since the reduction of the magnetic flux to zero would result in sufficient demagnetization of the permanent magnet so that it would not return to its normal static operating point with sufficient strength to effect retrieval of the movable armature. Therefore, the prior art devices have relied upon the use of additional holding coils for recreating the magnetic flux that provides the static holding force.
  • This invention is an electromechanical actuator particularly well suited for operations such as a print hammer actuator or a punch control or the like.
  • the apparatus includes a pair of magnetic flux paths which are arranged so that a permanent magnet provides a common magnetomotive force.
  • One flux path includes a movable magnetic portion or armature which is normally biased so as to provide a force in the direction that the desired mechanical motion is to occur. The strength of the magnetic field in that flux path is sufficient to retrieve the actuator portion at its maximum movement position notwithstanding this biasing force.
  • This actuator magnetic flux path also includes means for introducing an opposing magnetic flux to the flux generated by the permanent magnet, this typically being effected by a so-called bucking coil.
  • the invention includes a shunt magnetic path which is separate from the actuator path except for a common leg including the aforementioned permanent magnet.
  • This shunt path is constructed and arranged so as to absorb a sufficient amount of the magnetic flux from the permanent magnet when the bucking coil is actuated so as to permit the permanent magnet to operate within a range of its B-H curve in such a manner that removal of the opposing magnetic field will result in the permanent magnet substantially returning to its original or static point on the 3-H curve.
  • This shunt path would normally include an arrangement of magnetic reluctance such as an air gap.
  • Another object of this invention is to provide an electromechanical actuator which requires only the input for the bucking coil to cause operation.
  • Still another object of the present invention is to provide an electromechanical actuator which can be combined with a multiplicity of other actuators in a compact arrangement such that reliability and serviceability are markedly enhanced.
  • Yet another object of this invention is to provide an electromechanical actuator which utilizes a permanent magnet shared by an actuator magnetic flux path and a shunt magnetic flux path.
  • a still further object of the present invention is to provide an electromechanical actuator capable of AC magnetic operation while using a permanent magnet in such a manner that energization and deenergization of an actuating operation will not result in demagnetization of the permanent magnet.
  • FIG. 1 illustrates a preferred embodiment of the present invention particularly adapted for print hammer actuation.
  • FIG. 2 presents a view of the part of the actuator components as would be seen from the right side of the FIG. 1 embodiment.
  • FIG. 3 is an upper view of the FIG. 1 embodiment.
  • FIG. 4 shows a typical BH curve portion that might be applicable to one type of material useful for the permanent magnet employed in the FIG. 1 apparatus.
  • permanent magnets have not been generally favored for use in electromechanical actuators since they have generally been considered not to be adaptable to AC magnetic operations. They have been predominately employed for DC magnetic functioning. Devices which have attempted to utilize the permanent magnet for electromechanical actuators have involved acceptance of certain undesirable features such as movable coils, the requirement for flux reversal instead of merely reducing the flux to zero and the like.
  • the major objection to the use of a permanent magnet in an AC magnetic operation of an electromechanical device is that the normal physical state of a permanent magnet tends to be reduced to one of less energy content when the magnetic field is reduced to zero.
  • FIG. 1 apparatus illustrates one form of the present invention which maintains a nearly constant flux level in the permanent magnet while allowing the flux level in the movable portion or armature to be reduced to zero to fire a print hammer.
  • the present invention reduces the ampere turns required to fire the hammer to a minimum.
  • the apparatus illustrated in FIG. 1 includes two flux paths which have a common leg that includes a permanent magnet 10.
  • the first flux path shown generally as 01 provides the necessary flux to retrieve and retain movable armature element 16 into theenergized position against the upper magnetic core portion 14.
  • the other magnetic flux path is shown generally as 02 withthis path providing the shunt with magnetic mix which, mien 55m fiirough thegap 11, generates the necessary magnetomotive force in the lower portion 12 to drive 01. It can be seen from the following description that. the larger the ratio of QZ to 01, the smaller the flux change will be in the magnet and the lower the ampere turns required in the buck coil 15 to fire the hammer 18.
  • a C-shaped magnetic path portion composed of lower portion or arm 12 and upper portion or arm 14 (including the extension through bucking coil 15 ending in face 23) are held in place by cover plate 22. Magnet and column 13 are bonded together and to plate 22.
  • the C-shaped path could be cast in one piece from magnetic material (typically iron) which could include upper and lower arms 14 and 12 as well as the upper extension ending in face 23.
  • the portion of upper arm 14 ending in face 23 could be bolt mounted as shown to permit some movement to accommodate adjustment of the interfacing between 23 and armature 16.
  • the flux density in the upper path loop is low everywhere except in the vicinity of the armature 16 so that the potential difference I-IL of permanent magnet 10 drives flux in two parallel paths, armature path 01 and gap path 02.
  • H L refers to the coercive force H and the magnet length L.
  • the magnet is driven to positive saturation and returns to the quiescent operating point P in FIG. 4.
  • the bucking coil 15 is energized by introducing an appropriate pulse to leads 24, the flux 01 is driven to Zero. This is accompanied by a shift in the operating point of magnet 10 to point T on FIG. 4 as it attempts to drive 01 through the gap 11 in addition to the static 02. Since all permanent magnets have some degree of slope on their B-H curves as is shown in FIG. 4, not all of 0
  • ampere turns (NI) required for bucking coil 15 can be determined from the following equation:
  • K is the slope of the B-H curve at P
  • A is the area of the magnet
  • 11, is the coercive force generated by the magnet as shown in the FIG. 4 curve
  • L is the magnet length.
  • K and H are taken as positive quantities and 0 is a measure of the induced flux.
  • the actuator path includes a permanent magnet 10, the upper portion of column 13 including post 17, magnetic actuator or armature portion 16 which is movable relative to both the face 23 and the post 17, the upper arm ending in face 23, and arm 14.
  • the shunt path includes lower portion 12, gap 11 which might typically be an air gap, the lower portion of column 13 and permanent magnet 10.
  • the print hammer is mechanically actuated by the face 18 of lever arm 21 which is attached to the apparatus by bolts 20. Fulcrum 19 might be included for mechanical leaverage purposes substantially for the same reasons as is shown and described in the Brown et al. patent.
  • FIG. 4 B-H' curve is illustrated as might be typically encountered for a permanent magnet composed of the Alnico 5 materials with a magnetic flux density of nearly 13,000 gauss at point P and only slightly less at point T.
  • the present invention is particularly well adapted for arrangements of multiple electromechanical actuating devices similar to those shown in FIG. 2 of Brown et al. U.S. Pat. No. 3,460,469.
  • the use of the present invention clearly makes it possible to place many devices side by side in a relatively compact environment wherein there is little or no air space to permit flux leakage around the actuator.
  • electromechanical actuators such as the present invention can be replaced with relative ease from that compact environment since no intervening holding coil is required.
  • the armature 16 does not need to be fixed to the flux path in the manner shown. It need only be biased sufficiently to move it away from the flux path so as to perform the particular mechanical function desired but not be biased enough so that it cannot be retrieved by the magnetomotive force when the buck coil is not energized. If desired, the length of mechanical thrust available for armature 16 could be extended by utilizing some additional means for returning armature 16 to sufficient proximity with face 23 so that the magnetic flux in the armature path will retrieve and/or hold armature 16 in the ready position.
  • Alnico material primarily is that it has been available for a considerable length of time such that it is now consistently manufactured within acceptable tolerances such as 5 percent and is readily available in the commercial market.
  • An electromechanical actuator comprising a permanent magnet
  • said second path being constructed and arranged for absorbing sufficient magnetic flux whensaid flux reducing means is actuated so that said permanent magnet can substantially recover its magnetic strength when said flux reducing means is deactivated and said movable means is returned in magnetic circuit with said first flux path.
  • said first flux path generates a sufficient magnetic force for overcoming the force from said biasing means and for retrieving said movable means back in magnetic circuit with said first flux path upon deactuation of said flux reducing means.
  • said second flux path includes a magnetic reluctance portion for maintaining the magnetomotive force demands upon said magnet when said flux reducing means is actuated within the range of the 8-H curve of said magnets which will permit substantial recovery of said magnet to its magnetic strength prior to actuation of said flux reducing means after deactuation thereof.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Electromagnets (AREA)
  • Impact Printers (AREA)
US51056A 1970-06-30 1970-06-30 Permanent magnet electromagnetic actuator Expired - Lifetime US3659238A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US5105670A 1970-06-30 1970-06-30

Publications (1)

Publication Number Publication Date
US3659238A true US3659238A (en) 1972-04-25

Family

ID=21969074

Family Applications (1)

Application Number Title Priority Date Filing Date
US51056A Expired - Lifetime US3659238A (en) 1970-06-30 1970-06-30 Permanent magnet electromagnetic actuator

Country Status (8)

Country Link
US (1) US3659238A (de)
CA (1) CA931202A (de)
CH (1) CH528370A (de)
DE (1) DE2132354A1 (de)
FR (1) FR2095553A5 (de)
GB (1) GB1326970A (de)
NL (1) NL7108615A (de)
SE (1) SE360194B (de)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3834305A (en) * 1972-08-23 1974-09-10 Suwa Seikosha Kk Printer
DE2504566A1 (de) * 1974-02-04 1975-08-14 Canon Kk Reflexkamera
US4033255A (en) * 1975-11-13 1977-07-05 Printronix, Inc. Print hammer actuator for dot matrix printers
US4044668A (en) * 1975-05-16 1977-08-30 Printronix, Inc. Print hammer mechanism
DE2920732A1 (de) * 1978-06-02 1979-12-06 Printronix Inc Druckhammermechanismus fuer einen punktmatrix-drucker
EP0012812A1 (de) * 1978-12-29 1980-07-09 International Business Machines Corporation Magnetische Betätigungsvorrichtung mit Flussmodulation
US4225250A (en) * 1978-10-10 1980-09-30 Tally Corporation Segmented-ring magnet print head
DE3135957A1 (de) * 1980-09-11 1982-05-27 Nippon Electric Co., Ltd., Tokyo "druckkopf fuer punktmatrixdrucker"
US4377348A (en) * 1980-03-27 1983-03-22 Oki Electric Industry Co., Ltd. Printer head for serial dot printer
US4461207A (en) * 1980-11-17 1984-07-24 International Business Machines Corporation Actuator mechanism for a printer or the like using dual magnets
US4591280A (en) * 1985-01-22 1986-05-27 Mannesmann Tally Corporation Permanent magnet, stored energy, print head
AU623964B2 (en) * 1989-01-03 1992-05-28 Holec Holland N.V. Trip device for an electrical switch and an electrical switch with this trip device

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2888290A (en) * 1956-02-27 1959-05-26 William C Pierce Door with magnetic catch
US3282203A (en) * 1964-04-16 1966-11-01 Burroughs Corp Magnetically operated print hammers in high speed printers
US3285166A (en) * 1964-12-18 1966-11-15 Data Products Corp High speed print hammer and bar magnet means
US3441883A (en) * 1966-03-22 1969-04-29 L Ind Electr De La Seine Sensitive electro-magnetic tripping device of the re-setting type
US3449639A (en) * 1966-12-30 1969-06-10 Ibm Actuator driver circuit

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2888290A (en) * 1956-02-27 1959-05-26 William C Pierce Door with magnetic catch
US3282203A (en) * 1964-04-16 1966-11-01 Burroughs Corp Magnetically operated print hammers in high speed printers
US3285166A (en) * 1964-12-18 1966-11-15 Data Products Corp High speed print hammer and bar magnet means
US3441883A (en) * 1966-03-22 1969-04-29 L Ind Electr De La Seine Sensitive electro-magnetic tripping device of the re-setting type
US3449639A (en) * 1966-12-30 1969-06-10 Ibm Actuator driver circuit

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3834305A (en) * 1972-08-23 1974-09-10 Suwa Seikosha Kk Printer
DE2504566A1 (de) * 1974-02-04 1975-08-14 Canon Kk Reflexkamera
US4044668A (en) * 1975-05-16 1977-08-30 Printronix, Inc. Print hammer mechanism
US4033255A (en) * 1975-11-13 1977-07-05 Printronix, Inc. Print hammer actuator for dot matrix printers
DE2920732A1 (de) * 1978-06-02 1979-12-06 Printronix Inc Druckhammermechanismus fuer einen punktmatrix-drucker
US4225250A (en) * 1978-10-10 1980-09-30 Tally Corporation Segmented-ring magnet print head
EP0012812A1 (de) * 1978-12-29 1980-07-09 International Business Machines Corporation Magnetische Betätigungsvorrichtung mit Flussmodulation
US4377348A (en) * 1980-03-27 1983-03-22 Oki Electric Industry Co., Ltd. Printer head for serial dot printer
DE3135957A1 (de) * 1980-09-11 1982-05-27 Nippon Electric Co., Ltd., Tokyo "druckkopf fuer punktmatrixdrucker"
US4461207A (en) * 1980-11-17 1984-07-24 International Business Machines Corporation Actuator mechanism for a printer or the like using dual magnets
US4591280A (en) * 1985-01-22 1986-05-27 Mannesmann Tally Corporation Permanent magnet, stored energy, print head
AU623964B2 (en) * 1989-01-03 1992-05-28 Holec Holland N.V. Trip device for an electrical switch and an electrical switch with this trip device

Also Published As

Publication number Publication date
GB1326970A (en) 1973-08-15
NL7108615A (de) 1972-01-03
DE2132354A1 (de) 1972-02-10
SE360194B (de) 1973-09-17
CA931202A (en) 1973-07-31
CH528370A (de) 1972-09-30
FR2095553A5 (de) 1972-02-11

Similar Documents

Publication Publication Date Title
US3659238A (en) Permanent magnet electromagnetic actuator
US4072918A (en) Bistable electromagnetic actuator
US3671893A (en) Magnetic latch and switch using cobalt-rare earth permanent magnets
US2436354A (en) Electromagnet with armature
TR199802325T2 (xx) Manyetik hareket tertibatl� �alter.
GB1199088A (en) Improvements in and relating to Solenoid or Electro-Magnet Apparatus
US3470510A (en) Magnetic latch relay
US3741113A (en) High energy print hammer unit with fast settle out
US4429553A (en) Cam-support carriage for a knitting machine
EP1417694B1 (de) Elektromagnetanordnung für einen schalter
GB1157552A (en) Electromagnetically Releasable Holding Magnet Arrangement.
GB2289374A (en) Electromagnetic actuators
US3673529A (en) Magnetic actuator
GB1207758A (en) Magnetodynamic actuator
US3609609A (en) High-speed electromagnet
US4290356A (en) Actuator mechanism for a print hammer or the like
US2491098A (en) Polar biased relay
US3569947A (en) Magnetic memory device
US2414583A (en) Polarized electromagnet
US3754199A (en) Magnetic mechanical amplifier
US3452253A (en) Electromagnetic actuator having a pair of electromagnets with an armature movable between them
GB1149699A (en) Electromagnetic actuator
GB1005920A (en) Electromagnetically operated rotary actuators
JPH04286103A (ja) 永久磁石可動型電磁石
JP3035864B2 (ja) 磁気吸着装置