EP1253226B1 - Structure of a linear electric motor, particularly for electromechanical actuators of weaving machines - Google Patents

Structure of a linear electric motor, particularly for electromechanical actuators of weaving machines Download PDF

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Publication number
EP1253226B1
EP1253226B1 EP20020008352 EP02008352A EP1253226B1 EP 1253226 B1 EP1253226 B1 EP 1253226B1 EP 20020008352 EP20020008352 EP 20020008352 EP 02008352 A EP02008352 A EP 02008352A EP 1253226 B1 EP1253226 B1 EP 1253226B1
Authority
EP
European Patent Office
Prior art keywords
driving shaft
electric motor
linear electric
core portions
core
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
EP20020008352
Other languages
German (de)
French (fr)
Other versions
EP1253226A1 (en
Inventor
Rosario Castelli
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.)
LGL Electronics SpA
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LGL Electronics SpA
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Filing date
Publication date
Application filed by LGL Electronics SpA filed Critical LGL Electronics SpA
Publication of EP1253226A1 publication Critical patent/EP1253226A1/en
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    • 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
    • H01F7/16—Rectilinearly-movable armatures
    • H01F7/1607—Armatures entering the winding
    • H01F7/1615—Armatures or stationary parts of magnetic circuit having permanent magnet
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
    • D03D47/34—Handling the weft between bulk storage and weft-inserting means
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
    • D03D47/34—Handling the weft between bulk storage and weft-inserting means
    • D03D47/36—Measuring and cutting the weft
    • D03D47/361—Drum-type weft feeding devices
    • D03D47/362—Drum-type weft feeding devices with yarn retaining devices, e.g. stopping pins
    • D03D47/363—Construction or control of the yarn retaining devices
    • 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
    • H01F7/121—Guiding or setting position of armatures, e.g. retaining armatures in their end position
    • H01F7/122—Guiding or setting position of armatures, e.g. retaining armatures in their end position by permanent magnets

Definitions

  • the present invention is concerned with an improved structure of a linear electric motor for electromechanical actuators of weaving machines, and more particularly of metering weft-suppliers for fluid jet looms.
  • the invention relates to linear electric motors comprising a driving shaft, usually made of a ceramic material, to which are coupled cylindrical, radial-polarity permanent magnets which form a movable core for the motor.
  • the core linearly slides within a cavity of a stator housing bearing excitation coils and guide/supporting bushes for said driving shaft.
  • US-A-3 870 931 discloses a solenoid servomechanism comprising a ferromagnetic casing, which receives solenoid coils controlled to effect an axial displacement of a ferromagnetic armature that is disposed within the coils.
  • the armature surrounds a shaft, to which is affixed by knurling, and the shaft is supported for axial movements, at its opposite ends, in sleeve bearings supported on the casing.
  • EP-A-0 363 938 describes an electromagnetic unit in weft feeders of fluid jet looms, which is adapted to block the yam unwinding from the weft feeder.
  • the electromagnetic unit comprises two coaxial, adjacent coils enveloped by a cylindrical, hollow casing.
  • a movable, elongated stem is axially slidable within the coils, and is guided in its axial motion by a hollow cylinder.
  • the central part of the stem is enveloped by a hollow cylinder of iron which is connected thereto.
  • the stem is provided with two spaced central collars.
  • the movable core in a linear motor as above moves at a high speed. Due to this circumstance, on the one hand, such motors are particularly suitable to operate as electromechanical actuators because of their quick action, but, on the other hand, because of the high accelerations and decelerations to which the core is subjected, the core suffers to high mechanical stresses, and the parts of the motor must therefore be oversized, with unfavorable dynamical and economical consequences, including a limitation of the life of the motor.
  • the invention is based on the innovative concept of providing the driving shaft with a central salient collar integral with the shaft and onto which the entire movable core of the motor is firmly crimped.
  • the movable core consists of two substantially cylindrical, identical core portions made of a non-magnetic material, provided with respective terminal flanges and mounted on the driving shaft on opposite sides of said collar, from which they are separated by means of at least one elastomeric ring. Said core portions have respective threaded areas which are screwed into corresponding threaded areas of a cylindrical central case.
  • the threaded engagement by deforming said elastomeric ring, pushes the terminal flanges of said core portions axially into abutment with corresponding, radial-polarity, magnetic rings, thereby locking said magnetic rings onto said driving shaft.
  • Fig. 1 shows a known linear motor 1 of a known kind, comprising a hollow stator 2 having at least two pole pieces 3, 4 and preferably a third pole piece 5 (intended to considerably improve the performance of the motor) and two excitation coils 6, 7.
  • a movable core of the motor, referenced generally as 8, is slidable with rectilinear motion within the stator cavity and is firmly crimped onto a driving shaft 9, typically of a ceramic material, and which is also slidable, being supported and guided by bushes 10 carried by stator 2.
  • driving shaft 9 is provided with a projecting central collar 9a integral with the shaft, onto which movable core 8 is firmly crimped.
  • core 8 consists of two identical, substantially cylindrical core portions 11a, 11b, made of a non-magnetic material such as aluminum, and provided with respective terminal flanges 110a, 110b. Said portions are mounted on driving shaft 9 on opposite sides of collar 9a, and they are separated from the collar by at least one elastomeric O-ring 12.
  • Core portions 11a, 11b have respective threaded areas 13-14 that are screwed into a correspondingly threaded cylindrical central case 15.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Textile Engineering (AREA)
  • Power Engineering (AREA)
  • Linear Motors (AREA)
  • Looms (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)

Description

  • The present invention is concerned with an improved structure of a linear electric motor for electromechanical actuators of weaving machines, and more particularly of metering weft-suppliers for fluid jet looms.
  • More precisely, the invention relates to linear electric motors comprising a driving shaft, usually made of a ceramic material, to which are coupled cylindrical, radial-polarity permanent magnets which form a movable core for the motor. The core linearly slides within a cavity of a stator housing bearing excitation coils and guide/supporting bushes for said driving shaft.
  • US-A-3 870 931 discloses a solenoid servomechanism comprising a ferromagnetic casing, which receives solenoid coils controlled to effect an axial displacement of a ferromagnetic armature that is disposed within the coils. The armature surrounds a shaft, to which is affixed by knurling, and the shaft is supported for axial movements, at its opposite ends, in sleeve bearings supported on the casing.
  • EP-A-0 363 938 describes an electromagnetic unit in weft feeders of fluid jet looms, which is adapted to block the yam unwinding from the weft feeder. The electromagnetic unit comprises two coaxial, adjacent coils enveloped by a cylindrical, hollow casing. A movable, elongated stem is axially slidable within the coils, and is guided in its axial motion by a hollow cylinder. The central part of the stem is enveloped by a hollow cylinder of iron which is connected thereto. The stem is provided with two spaced central collars.
  • As well known to persons skilled in the art, the movable core in a linear motor as above moves at a high speed. Due to this circumstance, on the one hand, such motors are particularly suitable to operate as electromechanical actuators because of their quick action, but, on the other hand, because of the high accelerations and decelerations to which the core is subjected, the core suffers to high mechanical stresses, and the parts of the motor must therefore be oversized, with unfavorable dynamical and economical consequences, including a limitation of the life of the motor.
  • It is the main object of this invention to overcome the above mentioned drawbacks of known linear motors and, more particularly, to provide a linear motor having a considerably improved structure, with a high mechanical resistance, with a simple and compact construction, with a limited mass and inertia, and free from welded and bonded joints and from moulded polymeric components, so that the structure will be easy to assemble and able to operate under severe conditions for a long time and at high frequencies, e. g. in the range of 1300 to 1600 cycles/minute.
  • According to the invention, the above and other objects, such as will appear from the following detailed description, are achieved by means of a structure of a linear electric motor having the features recited in the attached claims.
  • Substantially, the invention is based on the innovative concept of providing the driving shaft with a central salient collar integral with the shaft and onto which the entire movable core of the motor is firmly crimped. To such purpose, the movable core consists of two substantially cylindrical, identical core portions made of a non-magnetic material, provided with respective terminal flanges and mounted on the driving shaft on opposite sides of said collar, from which they are separated by means of at least one elastomeric ring. Said core portions have respective threaded areas which are screwed into corresponding threaded areas of a cylindrical central case. The threaded engagement, by deforming said elastomeric ring, pushes the terminal flanges of said core portions axially into abutment with corresponding, radial-polarity, magnetic rings, thereby locking said magnetic rings onto said driving shaft.
  • The features, purposes and advantages of the improved motor structure according to the present invention will appear from the following detailed description and with reference to the attached explicatory drawings, wherein:
  • Fig. 1 is an axial section of an improved linear electric motor according to the present invention,
  • Fig. 2 is a detail of the movable core of the motor shown in Fig. 1,
  • Fig. 3 is an exploded perspective view of the movable core of Fig. 2.
  • Fig. 1 shows a known linear motor 1 of a known kind, comprising a hollow stator 2 having at least two pole pieces 3, 4 and preferably a third pole piece 5 (intended to considerably improve the performance of the motor) and two excitation coils 6, 7. A movable core of the motor, referenced generally as 8, is slidable with rectilinear motion within the stator cavity and is firmly crimped onto a driving shaft 9, typically of a ceramic material, and which is also slidable, being supported and guided by bushes 10 carried by stator 2.
  • According to the invention, driving shaft 9 is provided with a projecting central collar 9a integral with the shaft, onto which movable core 8 is firmly crimped. To such purpose, core 8 consists of two identical, substantially cylindrical core portions 11a, 11b, made of a non-magnetic material such as aluminum, and provided with respective terminal flanges 110a, 110b. Said portions are mounted on driving shaft 9 on opposite sides of collar 9a, and they are separated from the collar by at least one elastomeric O-ring 12. Core portions 11a, 11b have respective threaded areas 13-14 that are screwed into a correspondingly threaded cylindrical central case 15. The threaded engagement, by deforming elastomeric ring 12, pushes terminal flanges 110a-b of said core portions axially into abutment with corresponding, radial-polarity, magnetic rings 16a, 16b, thereby locking said magnetic rings onto said driving shaft 9.

Claims (3)

  1. A structure of a linear electric motor (1), particularly for electromechanical actuators of weaving machines, comprising a driving shaft (9) provided with a projecting central collar (9a) integral with it, and an associated movable core (8) which is firmly crimped onto said central collar (9a) and is linearly movable within a corresponding cavity of a stator housing (2) bearing excitation coils (6-7) and guide/supporting bushes (10) for the driving shaft, characterized in that said movable core (8) consists of two core portions (11a, 11b), made of a non-magnetic material, provided with respective terminal flanges (110a, 110b) and mounted on the driving shaft (9) on opposite sides of the projecting collar (9a), from which they are separated by at least one elastomeric ring (12), and in that said core portions (11a, 11b) are substantially cylindrical and have respective threaded areas (13-14), engaging a corresponding threaded, cylindrical central case (15), the threaded engagement deforming said elastomeric ring (12) to axially push the terminal flanges (110a-b) of the core portions into abutment with corresponding, radial-polarity magnetic rings (16a, 16b), thereby locking said magnetic rings onto said driving shaft.
  2. The structure of a linear electric motor according to claim 1, characterized in that said driving shaft (9) is made of a ceramic material and said substantially cylindrical core portions (11a-11b) are made of aluminium.
  3. The structure of a linear electric motor according to claim 1 or 2, characterized in that said core portions (11a, 11b) are identical.
EP20020008352 2001-04-27 2002-04-12 Structure of a linear electric motor, particularly for electromechanical actuators of weaving machines Expired - Lifetime EP1253226B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO20010061 2001-04-27
ITTO20010061 ITTO20010061U1 (en) 2001-04-27 2001-04-27 IMPROVED STRUCTURE OF LINEAR ELECTRIC MOTOR PARTICULARLY FOR ELECTROMECHANICAL ACTUATORS OF TEXTILE MACHINES.

Publications (2)

Publication Number Publication Date
EP1253226A1 EP1253226A1 (en) 2002-10-30
EP1253226B1 true EP1253226B1 (en) 2005-06-15

Family

ID=11458440

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20020008352 Expired - Lifetime EP1253226B1 (en) 2001-04-27 2002-04-12 Structure of a linear electric motor, particularly for electromechanical actuators of weaving machines

Country Status (3)

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EP (1) EP1253226B1 (en)
DE (1) DE60204625T2 (en)
IT (1) ITTO20010061U1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3770174B2 (en) * 2002-02-15 2006-04-26 株式会社豊田自動織機 Electromagnetic drive for weft insertion control in looms
IT201700051526A1 (en) * 2017-05-12 2018-11-12 Roj S R L Electromagnetic weft stop device in weft feeder for textile machines and slider for this device

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3870931A (en) * 1974-02-04 1975-03-11 Sun Chemical Corp Solenoid servomechanism
IT1230561B (en) * 1988-10-14 1991-10-28 Roy Electrotex Spa ELECTROMAGNETIC STOP UNIT OF THE WEFT WIRE IN MI-SURATORI PORGITRAMA FOR JET TEXTILE FRAMES

Also Published As

Publication number Publication date
DE60204625D1 (en) 2005-07-21
DE60204625T2 (en) 2006-05-11
EP1253226A1 (en) 2002-10-30
ITTO20010061V0 (en) 2001-04-27
ITTO20010061U1 (en) 2002-10-28

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