WO2008147189A1 - Actuator - Google Patents

Actuator Download PDF

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Publication number
WO2008147189A1
WO2008147189A1 PCT/NL2008/050324 NL2008050324W WO2008147189A1 WO 2008147189 A1 WO2008147189 A1 WO 2008147189A1 NL 2008050324 W NL2008050324 W NL 2008050324W WO 2008147189 A1 WO2008147189 A1 WO 2008147189A1
Authority
WO
WIPO (PCT)
Prior art keywords
actuator
flux conductor
annular
static
coils
Prior art date
Application number
PCT/NL2008/050324
Other languages
French (fr)
Inventor
Johannes Adrianus Antonius Theodorus Dams
Lambertus Gerardus Cornelis Van Den Broek
Original Assignee
Magnetic Innovations Bv
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 Magnetic Innovations Bv filed Critical Magnetic Innovations Bv
Priority to EP08766747A priority Critical patent/EP2198436B1/en
Publication of WO2008147189A1 publication Critical patent/WO2008147189A1/en

Links

Classifications

    • 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
    • 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
    • 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
    • H01F2007/1692—Electromagnets or actuators with two coils
    • 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
    • H01F7/081—Magnetic constructions

Definitions

  • the invention relates to an actuator comprising an annular magnet displaceable in axial direction, two magnet-connected annular, displaceable flux conductors, one on either one of the two axial sides of the magnet, two annular coils at a distance surrounding the magnet, which are present at a mutual distance in axial direction, and an annular, static flux conductor surrounding the coils.
  • the static flux conductor is usually present at a short distance from the outside of the coils as a result of dimensional tolerances of the coils, but can obviously also be in contact with the coils.
  • actuators of mis type With actuators of this type it is desired for the axial force at a constant power level to be constant and independent of the displacement of the piston. In the known actuator this is not the case.
  • the actuator according to the invention is characterized in that the actuator further includes at least one additional annular, static flux conductor which is present in the gap between the coils. Through the agent of this additional flux conductor the reluctance forces are reduced. In powerless condition the magnet with the two flux conductors can be displaced axially over a relatively large distance relative to the static flux conductor as a result of this, while a slight changing force is experienced as a result of a changing reluctance of the magnetic circuit.
  • the outside surface of the additional annular, static flux conductor is in contact with the inside surface of the static flux conductor.
  • the additional flux conductor has an in essence trapezoidal cross section.
  • a further embodiment of the actuator according to the invention is characterized in that the inside of the additional flux conductor is hollow, seen in cross sectional view.
  • a still further embodiment of the actuator according to the invention is characterized in that the static flux conductor is laminated.
  • the layers can then rest on each other in radial, axial or tangential direction. It should be observed that application of a laminated static flux conductor in an actuator of the type defined in the opening paragraph is also possible irrespective of the application of the additional static flux conductor in the gap.
  • a still further embodiment of the actuator according to the invention is characterized in that the layers rest on each other in radial direction. As a result, the layers are fully capable of minimizing eddy currents. Needless to observe that when anisotropic ferrite plates are applied, the direction having the least magnetic reluctance should be parallel with the axial shaft of the actuator.
  • the static flux conductor is preferably formed by a wound metal band.
  • the layers are adjoining each other in axial direction.
  • the layers are not fully capable of minimizing eddy current losses.
  • the manufacture of such segments is simpler.
  • isotropic ferrite material is to be preferred in this case, because normally the direction having the smallest magnetic reluctance is the rolling direction of the plate material (and not the thickness direction of the plate).
  • the static flux conductor may be comprised of at least two segments.
  • the segments are preferably formed by subdividing into segments a metal band wound into an annular core.
  • Fig. 1 shows a longitudinal section of an embodiment of the actuator according to the invention
  • Fig.2 shows a cross section of the actuator represented in Fig. 1.
  • the actuator 1 has an annular magnet 3 which is displaceable in axial direction, with attached thereto on either one of the two sides annular, displaceable flux conductors S.
  • the actuator 1 further includes two annular coils 7 at a distance surrounding the magnet 3, with a gap 9 between these coils, and an annular, static flux conductor 11 surrounding the coils, which flux conductor 11 is in contact with or present at a small distance from the outside of the coils.
  • An additional annular, static, ferrite flux conductor 13 is present in the gap 9 between the coils, the outside surface of the flux conductor 13 being present in the proximity of the inside surface of the static flux conductor 11.
  • the dimensions of the additional flux conductor 13 are optimized in order to reduce the reluctance forces.
  • This additional flux conductor 13 has an in essence trapezoidal cross section with a hollow interior.
  • the static flux conductor 11 is laminated, the layers in radial direction resting on top of each other. As a result, for the present application the layers are fully capable of minimizing eddy current losses. When anisotropic ferrite material is used, the direction having the smallest magnetic reluctance should be parallel with the axial shaft of the actuator.
  • the static flux conductor 11 is comprised of four segments 1 la-d of a wound, ferrite metal band. The segments are formed by subdividing into segments an annular wound metal band (transformer plate).
  • the layers of the laminated static flux conductor may also be disposed against each other in axial direction.
  • the flux conductor is not fully capable of minimizing eddy current losses it is true, but the manufacture of such segments is much simpler.
  • isotropic ferrite material is in this case preferable, since the direction having the smallest magnetic reluctance is normally found in the rolling direction of the plate material and not in the thickness direction of the plate.
  • the static flux conductor it is also possible for the static flux conductor to be formed as one massive whole in lieu of being laminated.
  • the additional flux conductor may also have another shape than the trapezoidal cross section shown here and may be laminated and/or segmented. It is also possible for more than one additional flux conductors to be present in the gap between the coils.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Electromagnets (AREA)
  • Linear Motors (AREA)

Abstract

An actuator (1) has an annular magnet (3) displaceable in axial direction, with attached thereto on either one of the two sides annular, displaceable flux conductors (5). The actuator (1) further has two annular coils (7) surrounding the magnet at a distance with a gap (9) therebetween, and an annular, static flux conductor (11) surrounding the coils, which is in contact with the outside of the coils. The gap (9) accommodates an additional annular, static, ferritic flux conductor (13) whose outside surface is attached to the inside surface of the static flux conductor (11). The static flux conductor (11) is laminated with the layers resting on each other in radial direction.

Description

Actuator
DESCRIPTION
Field of the invention.
The invention relates to an actuator comprising an annular magnet displaceable in axial direction, two magnet-connected annular, displaceable flux conductors, one on either one of the two axial sides of the magnet, two annular coils at a distance surrounding the magnet, which are present at a mutual distance in axial direction, and an annular, static flux conductor surrounding the coils. The static flux conductor is usually present at a short distance from the outside of the coils as a result of dimensional tolerances of the coils, but can obviously also be in contact with the coils.
State of the art.
An actuator of mis type is generally known. With actuators of this type it is desired for the axial force at a constant power level to be constant and independent of the displacement of the piston. In the known actuator this is not the case.
Summary of the invention.
It is an object of the invention to provide an actuator of the type defined in the opening paragraph in which the axial force is less dependent on the displacement of the piston than with the known actuator. To this end the actuator according to the invention is characterized in that the actuator further includes at least one additional annular, static flux conductor which is present in the gap between the coils. Through the agent of this additional flux conductor the reluctance forces are reduced. In powerless condition the magnet with the two flux conductors can be displaced axially over a relatively large distance relative to the static flux conductor as a result of this, while a slight changing force is experienced as a result of a changing reluctance of the magnetic circuit. Preferably, the outside surface of the additional annular, static flux conductor is in contact with the inside surface of the static flux conductor. An embodiment of the actuator according to the invention is characterized in that the additional flux conductor has an in essence trapezoidal cross section.
A further embodiment of the actuator according to the invention is characterized in that the inside of the additional flux conductor is hollow, seen in cross sectional view.
In order to enhance the efficiency of the actuator according to the invention and/or reduce the cost price, a still further embodiment of the actuator according to the invention is characterized in that the static flux conductor is laminated. The layers can then rest on each other in radial, axial or tangential direction. It should be observed that application of a laminated static flux conductor in an actuator of the type defined in the opening paragraph is also possible irrespective of the application of the additional static flux conductor in the gap.
Yet a still further embodiment of the actuator according to the invention is characterized in that the layers rest on each other in radial direction. As a result, the layers are fully capable of minimizing eddy currents. Needless to observe that when anisotropic ferrite plates are applied, the direction having the least magnetic reluctance should be parallel with the axial shaft of the actuator.
The static flux conductor is preferably formed by a wound metal band. hi another embodiment of the actuator the layers are adjoining each other in axial direction. In this case the layers are not fully capable of minimizing eddy current losses. However, the manufacture of such segments is simpler. Application of isotropic ferrite material is to be preferred in this case, because normally the direction having the smallest magnetic reluctance is the rolling direction of the plate material (and not the thickness direction of the plate). For reasons of manufacturing technology the static flux conductor may be comprised of at least two segments.
The segments are preferably formed by subdividing into segments a metal band wound into an annular core.
Brief description of the drawings.
The invention will be described below in more detail based on an example of embodiment of the actuator according to the invention represented in the drawing figures, in which: Fig. 1 shows a longitudinal section of an embodiment of the actuator according to the invention; and
Fig.2 shows a cross section of the actuator represented in Fig. 1.
Detailed description of the drawings.
An embodiment of the actuator according to the invention is shown in Figs. 1 and 2 in longitudinal section and cross section respectively. The actuator 1 has an annular magnet 3 which is displaceable in axial direction, with attached thereto on either one of the two sides annular, displaceable flux conductors S. The actuator 1 further includes two annular coils 7 at a distance surrounding the magnet 3, with a gap 9 between these coils, and an annular, static flux conductor 11 surrounding the coils, which flux conductor 11 is in contact with or present at a small distance from the outside of the coils.
An additional annular, static, ferrite flux conductor 13 is present in the gap 9 between the coils, the outside surface of the flux conductor 13 being present in the proximity of the inside surface of the static flux conductor 11. The dimensions of the additional flux conductor 13 are optimized in order to reduce the reluctance forces. This additional flux conductor 13 has an in essence trapezoidal cross section with a hollow interior.
The static flux conductor 11 is laminated, the layers in radial direction resting on top of each other. As a result, for the present application the layers are fully capable of minimizing eddy current losses. When anisotropic ferrite material is used, the direction having the smallest magnetic reluctance should be parallel with the axial shaft of the actuator. The static flux conductor 11 is comprised of four segments 1 la-d of a wound, ferrite metal band. The segments are formed by subdividing into segments an annular wound metal band (transformer plate).
Albeit the invention has been described in the foregoing based on the drawing figures, it should be observed that the invention is not by any manner or means restricted to the embodiment shown in the drawing figures. The invention also extends to all embodiments deviating from the embodiment shown in the drawing figures within the spirit and scope defined by the claims.
For example, the layers of the laminated static flux conductor may also be disposed against each other in axial direction. As a result, the flux conductor is not fully capable of minimizing eddy current losses it is true, but the manufacture of such segments is much simpler. Application of isotropic ferrite material is in this case preferable, since the direction having the smallest magnetic reluctance is normally found in the rolling direction of the plate material and not in the thickness direction of the plate. It is also possible for the static flux conductor to be formed as one massive whole in lieu of being laminated.
Furthermore, the additional flux conductor may also have another shape than the trapezoidal cross section shown here and may be laminated and/or segmented. It is also possible for more than one additional flux conductors to be present in the gap between the coils.

Claims

CLAIMS:
1. An actuator comprising: an annular magnet displaceable in axial direction, two magnet-connected annular, displaceable flux conductors, which in axial direction are present at a mutual distance, two annular coils at a distance surrounding the magnet, which are present in axial direction at a mutual distance, and an annular, static flux conductor surrounding the coils, characterized in that the actuator further includes at least one additional annular, static flux conductor which is present in the gap between the coils.
2. An actuator as claimed in claim 1, characterized in that the outside surface of the additional annular, static flux conductor is in contact with the inside surface of the static flux conductor.
3. An actuator as claimed in claim 1 or 2, characterized in that the additional flux conductor has an in essence trapezoidal cross section.
4. An actuator as claimed in claim 1, 2 or 3, characterized in that the inside of the additional flux conductor is hollow, seen in a cross-sectional view.
5. An actuator as claimed in any one of the preceding claims, characterized in that the static flux conductor is laminated.
6. An actuator as claimed in claim 5, characterized in that the layers rest on each other in radial direction.
7. An actuator as claimed in claim 6, characterized in that the static flux conductor is formed by a wound metal band.
8. An actuator as claimed in claim S, characterized in that the layers are adjoining each other in axial direction.
9. An actuator as claimed in claim 5, 6, 7 or 8, characterized in that the static flux conductor is comprised of at least two segments.
10. An actuator as claimed in claims 7 and 9, characterized in that the segments are formed by subdividing into segments a metal band wound into an annular core.
PCT/NL2008/050324 2007-05-29 2008-05-28 Actuator WO2008147189A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP08766747A EP2198436B1 (en) 2007-05-29 2008-05-28 Actuator

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL2000666A NL2000666C1 (en) 2007-05-29 2007-05-29 Actuator.
NL2000666 2007-05-29

Publications (1)

Publication Number Publication Date
WO2008147189A1 true WO2008147189A1 (en) 2008-12-04

Family

ID=39672914

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NL2008/050324 WO2008147189A1 (en) 2007-05-29 2008-05-28 Actuator

Country Status (3)

Country Link
EP (1) EP2198436B1 (en)
NL (1) NL2000666C1 (en)
WO (1) WO2008147189A1 (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5896076A (en) * 1997-12-29 1999-04-20 Motran Ind Inc Force actuator with dual magnetic operation

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5896076A (en) * 1997-12-29 1999-04-20 Motran Ind Inc Force actuator with dual magnetic operation

Also Published As

Publication number Publication date
NL2000666C1 (en) 2008-12-02
EP2198436B1 (en) 2012-11-21
EP2198436A1 (en) 2010-06-23

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