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WO2008143492A1 - Linear motion device - Google Patents

Linear motion device Download PDF

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Publication number
WO2008143492A1
WO2008143492A1 PCT/MY2007/000033 MY2007000033W WO2008143492A1 WO 2008143492 A1 WO2008143492 A1 WO 2008143492A1 MY 2007000033 W MY2007000033 W MY 2007000033W WO 2008143492 A1 WO2008143492 A1 WO 2008143492A1
Authority
WO
WIPO (PCT)
Prior art keywords
magnetic field
core
field source
linear motion
motion device
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.)
Ceased
Application number
PCT/MY2007/000033
Other languages
French (fr)
Inventor
Chris Reijmer
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.)
Individual
Original Assignee
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
Application filed by Individual filed Critical Individual
Priority to PCT/MY2007/000033 priority Critical patent/WO2008143492A1/en
Publication of WO2008143492A1 publication Critical patent/WO2008143492A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K41/00—Propulsion systems in which a rigid body is moved along a path due to dynamo-electric interaction between the body and a magnetic field travelling along the path
    • H02K41/02—Linear motors; Sectional motors
    • H02K41/03—Synchronous motors; Motors moving step by step; Reluctance motors
    • H02K41/031—Synchronous motors; Motors moving step by step; Reluctance motors of the permanent magnet type
    • 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
    • H02K33/16—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system with polarised armatures moving in alternate directions by reversal or energisation of a single coil system
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/18—Structural association of electric generators with mechanical driving motors, e.g. with turbines
    • H02K7/1869—Linear generators; sectional generators
    • H02K7/1876—Linear generators; sectional generators with reciprocating, linearly oscillating or vibrating parts
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/12—Stationary parts of the magnetic circuit
    • H02K1/14—Stator cores with salient poles
    • H02K1/145—Stator cores with salient poles having an annular coil, e.g. of the claw-pole type
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/22—Rotating parts of the magnetic circuit
    • H02K1/27—Rotor cores with permanent magnets
    • H02K1/2706—Inner rotors
    • H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
    • H02K1/2726—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of a single magnet or two or more axially juxtaposed single magnets
    • H02K1/2733—Annular magnets
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K2207/00—Specific aspects not provided for in the other groups of this subclass relating to arrangements for handling mechanical energy
    • H02K2207/03—Tubular motors, i.e. rotary motors mounted inside a tube, e.g. for blinds

Definitions

  • the present invention relates to a linear motion device such as a motor device, generator device, and the like, for motive drive or electrical power generation.
  • U. S. Pat. No. 4,335,338 discloses a linear motor
  • U. S. Pat No. 4,675,563 discloses a reciprocating linear motor
  • U. S. Pat. No. 6,914,351 discloses a linear electrical machine that may function as an alternator or a motor.
  • the present invention is therefore specifically suited for but not limited to in-flow actuation of flow control valves for liquids and gases.
  • gas and liquid tight nature of the present invention is that it enables excellent bearing and cooling and thereby small footprint high power versions when used as a linear motor or generator.
  • a linear motion device adapted for motive drive.
  • the linear motion device comprises at least one core magnetic field source (1), at least one gap magnetic field source (2) and at least one magnetic core (3) made of low reluctance material.
  • the at least one gap magnetic field source (2) is movable in a linear direction parallel to the longitudinal axis of the at least one magnetic core (3).
  • the at least one magnetic core (3) is arranged in between the at least one core magnetic field source (1) and the at least one gap magnetic field source (2).
  • the linear motion device is further characterised in that the at least one core magnetic field source (1) has axial flux polarity when actuated, and the at least one gap magnetic field source (2) has axial flux polarity when actuated, and the at least one magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the at least one magnetic core (3), and wherein an interaction between the magnetic field of the actuated at least one core magnetic field source (1) and the magnetic field of the actuated at least one gap magnetic field source (2) around the at least one field concentration portion (4), produces a magnetic force that is exerted to the at least one gap magnetic field source (2) to move it in a linear direction parallel to the longitudinal axis of the at least one magnetic core (3).
  • the at least one core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
  • the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
  • the at least one field concentration portion (4) is a V-shaped indentation (4a) in the at least one magnetic core (3).
  • the at least one field concentration portion (4) is positioned within width (12) of the at least one core magnetic field source (1).
  • width (10) of the at least one field concentration portion (4) is similar to width (11) of the at least one gap magnetic field source (2).
  • the at least one core magnetic field source (1) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof.
  • the at least one gap magnetic field source (2) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof, or made of a non magnetised ferromagnetic material.
  • the at least one core magnetic field source (1), the at least one gap magnetic field source (2) and the at least one magnetic core (3) have tubular configuration.
  • the linear motion device is a motor device.
  • a linear motion device adapted for motive drive.
  • the linear motion device comprises at least one core magnetic field source (1), at least one gap magnetic field source (2) and at least one magnetic core (3) made of low reluctance material.
  • the at least one core magnetic field source (1) and the at least one magnetic core (3) are movable in a linear direction parallel to the longitudinal axis of the at least one gap magnetic field source (2).
  • the at least one magnetic core (3) is arranged in between the at least one core magnetic field source (1) and the at least one gap magnetic field source (2).
  • the linear motion device is further characterised in that the at least one core magnetic field source (1) has axial flux polarity when actuated, and the at least one gap magnetic field source (2) has axial flux polarity when actuated, and the at least one magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the at least one magnetic core (3), and wherein an interaction between the magnetic field of the actuated at least one core magnetic field source (1) and the magnetic field of the actuated at least one gap magnetic field source (2) around the at least one field concentration portion (4), produces a magnetic force that is exerted to at least one core magnetic field source (1) and the at least one magnetic core (3) to move them in a linear direction parallel to the longitudinal axis of the at least one gap magnetic field source (2).
  • the at least one core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
  • the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
  • the at least one field concentration portion (4) is a V-shaped indentation (4a) in the at least one magnetic core (3).
  • the at least one field concentration portion (4) is positioned within width (12) of the at least one core magnetic field source (1).
  • width (10) of the at least one field concentration portion (4) is similar to width (11) of the at least one gap magnetic field source (2).
  • the at least one core magnetic field source (1) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof.
  • the at least one gap magnetic field source (2) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof, or made of a non magnetised ferromagnetic material.
  • the at least one core magnetic field source (1), the at least one gap magnetic field source (2) and the at least one magnetic core (3) have tubular configuration.
  • the linear motion device is a motor device.
  • a linear motion device adapted for electrical power generation.
  • the linear motion device comprises at least one core magnetic field source (1), at least one gap magnetic field source (2) and at least one magnetic core (3) made of low reluctance material.
  • the at least one core magnetic field source (1) is a conductor adapted for carrying electrical current, and the at least one gap magnetic field source (2) is movable in a linear direction parallel to the longitudinal axis of the at least one magnetic core (3).
  • the at least one magnetic core (3) is arranged in between the at least one core magnetic field source (1) and the at least one gap magnetic field source (2).
  • the linear motion device is further characterised in that the at least one gap magnetic field source (2) has axial flux polarity when actuated, the at least one magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the at least one magnetic core (3), and wherein an electrical current is induced in the at least one core magnetic field source (1) when the actuated at least one gap magnetic field source (2) is in a relative motion to the at least one magnetic core (3).
  • the at least one core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
  • the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
  • the at least one field concentration portion (4) is a V-shaped indentation (4a) in the at least one magnetic core (3).
  • the at least one field concentration portion (4) is positioned within width (12) of the at least one core magnetic field source (1).
  • width (10) of the at least one field concentration portion (4) is similar to width (11) of the at least one gap magnetic field source (2).
  • the at least one gap magnetic field source (2) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof.
  • the at least one core magnetic field source (1), the at least one gap magnetic field source (2) and the at least one magnetic core (3) have tubular configuration.
  • the linear motion device is an electrical generator device.
  • a linear motion device adapted for electrical power generation.
  • the linear motion device comprises at least one core magnetic field source (1), at least one gap magnetic field source (2) and at least one magnetic core (3) made of low reluctance material.
  • the at least one core magnetic field source (1) is a conductor adapted for carrying electrical current, and the at least one core magnetic field source (1) and the at least one magnetic core (3) are movable in a linear direction parallel to the longitudinal axis of the at least one gap magnetic field source (2).
  • the at least one magnetic core (3) is arranged in between the at least one core magnetic field source (1) and the at least one gap magnetic field source (2).
  • the linear motion device is further characterised in that the at least one gap magnetic field source (2) has axial flux polarity when actuated, the at least one magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the at least one magnetic core (3), and wherein an electrical current is induced in the at least one core magnetic field source (1) when the at least one core magnetic field source (1) and the at least one magnetic core (3) are in a relative motion to the actuated at least one gap magnetic field source (2).
  • the at least one core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
  • the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
  • the at least one field concentration portion (4) is a V-shaped indentation (4a) in the at least one magnetic core (3).
  • the at least one field concentration portion (4) is positioned within width (12) of the at least one core magnetic field source (1).
  • width (10) of the at least one field concentration portion (4) is similar to width (11) of the at least one gap magnetic field source (2).
  • the at least one gap magnetic field source (2) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof.
  • the at least one core magnetic field source (1), the at least one gap magnetic field source (2) and the at least one magnetic core (3) have tubular configuration.
  • the linear motion device is an electrical generator.
  • FIG. 1 is an axial cross sectional view of a linear motion device in accordance with an embodiment of the present invention.
  • FIG. 2 is an axial cross sectional view of a core magnetic field source (1) encased within low reluctance material on all sides (3, 4, 5).
  • FIG. 3 shows an axial cross sectional view of a magnetic core (3) with a field concentration portion (4) of a linear motion device and includes graphs of cross sectional area of low reluctance material and flux density with respect to horizontal position.
  • FIG. 4 is an axial cross sectional view showing another method of construction of a magnetic core (3) with a field concentration portion (4).
  • FIG. 5 is an axial cross sectional view showing a relationship between a gap magnetic field source's width (11) and a field concentration portion's width (10) of the linear motion device as shown in FIG. 1.
  • FIG. 6 shows an axial cross sectional view of two tubular magnetic field sources having a same axial flux polarity, and a graph of the resultant centre fleeing force.
  • FIG. 7 shows an axial cross sectional view of two tubular magnetic field sources having an opposite magnetic axial flux polarity, and a graph of the resultant centre seeking force.
  • FIG. 8 is an axial cross sectional view of a linear motion device in accordance with another embodiment of the present invention.
  • FIG. 9 is an axial cross sectional view of a linear motion device in accordance with another embodiment of the present invention.
  • FIG. 1 shows a linear motion device in accordance with an embodiment of the present invention, adapted for motive drive or electrical power generation.
  • the linear motion device is a single phase motion device which includes a core magnetic field source (1) having axial flux polarity when actuated, two gap magnetic field sources (2) having axial flux polarity when actuated, fixed on a support (6), and a magnetic core (3) with a field concentration portion (4).
  • the magnetic core (3) is placed inside the core magnetic field source (1), and the gap magnetic field sources (2) are placed inside the magnetic core (3).
  • the two gap magnetic field sources (2) are positioned with alternating axial flux polarity, for instance, a first gap magnetic field source (2a) has North Pole region on a left side and South Pole region on a right side when actuated, whereas a second gap magnetic field source (2b) has South Pole region on a left side and North Pole region on a right side when actuated.
  • the linear motion device is configured with the gap magnetic field sources (2, 6) relatively movable in a linear direction parallel to the longitudinal axis of the magnetic core (3) during operation of the linear motion device.
  • the linear motion device can be configured with the core magnetic field source (1) and the magnetic core (3) relatively movable in a linear direction parallel to the longitudinal axis of the gap magnetic field source (2).
  • the core magnetic field source (1) has a suitably tubular configuration.
  • the core magnetic field source (1) can either be a permanent magnet, an annularly wound coil carrying a current, or a combination thereof.
  • the coil can be sourced by either a direct or an alternating current to provide a desired magnetic field.
  • the core magnetic field source (1) is preferably encased within low reluctance material on all sides (3, 4, 5a, 5b, 5c). This is to maximise flux within the magnetic core (3) which consequently maximises flux density and thus magnetic force or induced current.
  • the gap magnetic field source (2) has a suitably tubular configuration.
  • the gap magnetic field source (2) can be a permanent magnet, a wound coil carrying an either direct or alternating current, or a combination thereof, or - when the linear motion device is adapted for motive drive - made of a non magnetised ferromagnetic material.
  • the gap magnetic field source (2) is made of a non magnetised ferromagnetic material it is actuated through magnetic induction by the magnetic field of the actuated core magnetic field source (1), and as a result the gap magnetic field source (2) and the core magnetic field source(l) have opposite axial flux polarity.
  • Magnetic induction of the gap magnetic field source (2) occurs when the horizontal positions of the gap magnetic field source (2) and the field concentration portion (4) overlap, because the gap magnetic field source (2) then becomes part of a path of least reluctance (2, 3, 4, 5).
  • the magnetic core (3) is made of low reluctance magnetically soft material to provide a low reluctance flux path for the fields of the actuated core magnetic field source (1) and the actuated gap magnetic field source (2), and has a suitably tubular configuration.
  • the magnetic core (3) is suitably either made of laminated low reluctance magnetically soft material or made of Soft Magnetic Composite (SMC), in order to manage eddy current losses.
  • SMC Soft Magnetic Composite
  • the magnetic core (3) can be made of any suitable low reluctance magnetically soft material in case the linear motion device operates as a direct current linear motor.
  • the magnetic core (3) in the figure includes one field concentration portion (4).
  • the field concentration portion (4) is achieved by reducing the cross sectional area of low reluctance material in the field concentration portion (4) compared to the minimum cross sectional area of low reluctance material in the magnetic core (3).
  • One method of implementing the field concentration portion (4) is shown in FIG. 3, where the field concentration portion (4) is a V-shaped indentation (4a) in the magnetic core (3). It should be noted that any method or shape that results in a smaller cross sectional area of low reluctance material in the field concentration portion (4) than the minimum cross sectional area of low reluctance material in the rest of the magnetic core (3) achieves a field concentration portion (4).
  • flux density is defined as flux per cross sectional area
  • the effect of the field concentration portion (4) is that the flux density in the field concentration portion (4) progressively increases and reaches saturation level.
  • FIG. 3 also shows a graph of cross sectional area of low reluctance material with respect to a horizontal position in the magnetic core (3) and the field concentration portion (4).
  • the graph shows that cross sectional area of low reluctance material decreases starting from a position indicated as DO, which is the boundary between the magnetic core (3) and the field concentration portion (4).
  • the cross sectional area of low reluctance material decreases until it bottoms at a middle horizontal position (indicated as Dl) of the field concentration portion (4).
  • Dl middle horizontal position
  • the 3 also indicates the relationship of flux density with respect to a horizontal position in the magnetic core (3).
  • the flux density increases starting from the position indicated as DO.
  • the flux density peaks at the position indicated as Dl and thereon, decreases until it reaches to the position indicated as D2 in the magnetic core (3).
  • FIG. 4 shows another method of implementing a field concentration portion (4) in the magnetic core (3).
  • the figure shows how a field concentration portion (4) is achieved by bonding two individual magnetic cores (3a, 3b) together with a non magnetic (high reluctance) agent (4a).
  • width (10) of the field concentration portion (4) is equal to width (11) of the gap magnetic field source (2).
  • the field concentration portion (4) is suitably positioned within width (12) of the core magnetic field source (1).
  • linear motion device adapted for motive drive such as linear motor.
  • the linear motion device adapted for motive drive is operated based upon an interaction between the magnetic field of the actuated gap magnetic field source (2) and the magnetic field of the actuated core magnetic field source (1) around the field concentration portion (4) in the magnetic core (3).
  • both the core magnetic field source (1) and the gap magnetic field source (2) are actuated.
  • the magnetic core (3) carries the magnetic fields of the actuated core magnetic field source (1) and the actuated gap magnetic field source (2) which causes the flux density in part of the field concentration portion (4) to reach saturation levels.
  • the magnetic permeability of the saturated part of the field concentration portion (4) approaches the magnetic permeability of free space. This causes the saturated part of the field concentration portion (4) to act like a dynamic air gap with two dynamic magnetic poles.
  • An actuated gap magnetic field source (2) only experiences a significant net force component in a linear direction parallel to the longitudinal axis of the magnetic core (3) when the horizontal positions of the gap magnetic field source (2) and the field concentration portion (4) are different but overlapping, and the core magnetic field source (1) is actuated. This is caused by the fact that in that case the flux loop of the gap magnetic field source (2) asymmetrically influences the flux density distribution in the field concentration portion (4), as a result of which the dynamic air gap in the field concentration portion (4) shifts position. As the flux loop of the gap magnetic field source (2) closes in a path of least reluctance, the gap magnetic field source (2) will experience a force either towards or away from the centre of the dynamic air gap. This means the interaction of the magnetic fields around the dynamic air gap in the field concentration portion (4) results in either a centre fleeing force (F C F) or a centre seeking force (F CP ).
  • F C F centre fleeing force
  • F CP centre seeking force
  • FIG. 6 a tubular magnetic field source (21) is inserted in the hollow centre of stationary tubular magnetic field source (20), both magnetic field sources having a same axial flux polarity when actuated.
  • the figure shows that the inside flux path of actuated magnetic field source (20) and the outside flux path of actuated magnetic field source (21) are in opposite directions (one clockwise and the other counter clockwise), as a result of which they physically can not merge and produce a repulsive force between the magnetic field sources in a linear direction parallel to the longitudinal axis of the magnetic field source (20).
  • the graph in FIG. 6 shows that displacement of the centre of magnetic field source (21) relative to the centre of magnetic field source (20) results in a force that accelerates magnetic field source (21) in the direction of the displacement.
  • This centre fleeing force accelerates the centres of the two magnetic field sources away from each other. Therefore, if the actuated gap magnetic field source (2) and the actuated core magnetic field source (1) have the same axial flux polarity, then a centre fleeing force is produced that accelerates the centres of the gap magnetic field source (2) and the field concentration portion (4) away from each other in a linear direction parallel to the longitudinal axis of the magnetic core (3).
  • FIG. 7 a tubular magnetic field source (22) is inserted in the hollow centre of stationary tubular magnetic field source (20), both magnetic field sources having an opposite axial flux polarity when actuated.
  • the figure shows that the inside flux path of actuated magnetic field source (20) and the outside flux path of actuated magnetic field source (22) are in the same direction (both clockwise or both counter clockwise), as a result of which they merge and produce an attractive force between the magnetic field sources in a linear direction parallel to the longitudinal axis of the magnetic field source (20).
  • the graph in FIG. 7 shows that displacement of the centre of magnetic field source (22) relative to the centre of magnetic field source (20) results in a force that accelerates magnetic field source (22) in the opposite direction of the displacement. This centre seeking force accelerates the centres of the two magnetic field sources towards each other.
  • actuated gap magnetic field source (2) and the actuated core magnetic field source (1) have opposite axial flux polarity, then a centre seeking force is produced that accelerates the centres of the gap magnetic field source (2) and the field concentration portion (4) towards each other in a linear direction parallel to the longitudinal axis of the magnetic core (3).
  • the total force exerted to a movable member which could be either the core magnetic field source (1) and the magnetic core (3) or the gap magnetic field source (2), is the vector sum of the forces between the individual magnetic fields.
  • the total force exerted to the combined actuated gap magnetic field sources (2, 6) is the vector sum of the force experienced by the first actuated gap magnetic field source (2a) and the force experienced by the second actuated gap magnetic field source (2b).
  • total force is the vector sum of a centre seeking force and a centre fleeing force.
  • Magnetic force as a consequence of flux interaction is proportional to the flux density involved, so the magnetic force increases as the flux density in the field concentration portion (4) increases.
  • the magnitude of the magnetic force is a function of the magneto motive force of the individual magnetic field sources (1, 2), the total reluctance of the path of least reluctance (2, 3, 4, 5), flux density in the field concentration portion (4) and the relative position of the field concentration portion (4) and the gap magnetic field sources (2) with respect to each other.
  • length of displacement of the movable member which could either be the core magnetic field source (1) and the magnetic core (3) or the gap magnetic field source (2) depends on the width (11), relative pitch and axial flux polarity of the actuated gap magnetic field source (2), position of the actuated gap magnetic field source (2) relative to the position of the field concentration portion (4), the width (10) and relative pitch of the field concentration portion (4), and actuation of the core magnetic field source (1).
  • the core magnetic field source (1) is an annularly wound coil connected to an electrical load
  • the gap magnetic field sources (2) are permanent magnets fixed on a support
  • the gap magnetic field sources (2, 6) are motioned in a linear direction parallel to the longitudinal axis of the magnetic core (3). This generates a time-varying flux in the magnetic core (3) that induces a current in the core magnetic field source (1).
  • the core magnetic field source (1) is an annularly wound coil connected to an electrical load
  • the gap magnetic field sources (2) are permanent magnets fixed on a support (6)
  • the core magnetic field source (1) and the magnetic core (3) are motioned in a linear direction parallel to the longitudinal axis of the gap magnetic field sources (2). This generates a time-varying flux in the magnetic core (3) that induces a current in the core magnetic field source (1).
  • FIG. 8 shows a three-phase linear motion device in accordance with another embodiment of the present invention, which includes three core magnetic field sources (1) having axial flux polarity when actuated, twelve gap magnetic field sources (2) having axial flux polarity when actuated, fixed on a support (6) and a magnetic core (3) with three field concentration portions (4).
  • each core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
  • the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
  • the magnetic core (3) is placed inside the core magnetic field sources (1), and the gap magnetic field sources (2) are placed inside the magnetic core (3).
  • FIG. 9 shows a three-phase linear motion device in accordance with another embodiment of the present invention, which includes three core magnetic field sources (1) having axial flux polarity when actuated, twelve gap magnetic field sources (2) having axial flux polarity when actuated, fixed in a support (6) and a magnetic core (3) with three field concentration portions (4).
  • each core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
  • the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
  • the magnetic core (3) is placed inside the gap magnetic field sources (2), and the core magnetic field sources (1) are placed inside the magnetic core (3).
  • the present invention offers specific advantages over other types of linear motion devices.
  • the magnetic core (3) can be suitably made of a tubular configuration with a number of (integrated or attached) rings (5a, 5b), and a number of V-shaped indentations (4a) as field concentration portions (4) and thus, it can be easily turned on a lathe out of electrical steel, moulded in electrical steel or injection moulded with a suitable Soft Magnetic Composite (SMC).
  • SMC Soft Magnetic Composite
  • coils that are used as core magnetic field source (1) can be directly wound around the magnetic core (3).
  • the gap magnetic field source (2) can be made out of non magnetised ferromagnetic material or a coil directly wound around a central support (6). If the gap magnetic field source (2) is a permanent magnet, axially magnetised permanent magnet rings or cylinders can be suitably used, without a need for radially magnetised magnet rings which are difficult to manufacture and higher in cost to manufacture.
  • Another advantage of the present invention is that it eliminates back iron requirement for permanent magnet gap magnetic field sources (2). This is because the axial flux loop of the actuated gap magnetic field sources (2) closes through the magnetic core (3).
  • Another advantage of the present invention is that it reduces cogging torque when operated as a linear motor, as the magnetic core (3) and the field concentration portion (4) are then designed in such a way that the axial magnetic field of the actuated individual gap magnetic field sources (2) do not saturate the magnetic core (3) in the field concentration portion (4).
  • Another advantage of the present invention is that the magnetic core (3) can be suitably designed without any seams or joints. Thus, rolling bearings or lubricants can be suitably provided in between the moving parts to reduce friction.
  • the present invention is specifically suited for in-flow actuation of flow control valves for liquids and gases.
  • One possible implementation of such a valve is to use the configuration of FIG. 1, wherein the gap magnetic field sources (2) are fixed on a hollow support (6) connected to a seal / seal seat combination upstream or downstream.
  • the gas or liquid, of which the flow is to be controlled flows through the magnetic core (3) which is gas and liquid tight and suitably without any seams or joints. This would allow the valve to be an integral part of the gas or liquid tubing, and thus integrate valve control with the actual valve itself, without the need for an external perpendicular valve control mechanism.
  • Another advantage of the present invention is that it provides excellent cooling possibilities whereby it enables the use of an internal coolant when adapted as a linear motor and thereby facilitating small footprint high power versions.
  • it When it is adapted for electrical power generation, it provides a compact design whereby magnetic field strength can be increased due to the excellent cooling possibilities, and thereby induced voltage can be increased.
  • linear motion device can be implemented for other applications such as power tools (i.e. hammers and pullers), electromagnetic guns, electromagnetic toys and any other devices that require linear movement.
  • power tools i.e. hammers and pullers
  • electromagnetic guns electromagnetic toys
  • any other devices that require linear movement i.e. hammers and pullers

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  • Linear Motors (AREA)

Abstract

The present invention relates to a linear motion device adapted for motive drive or electrical power generation. The linear motion device comprises at least one core magnetic field source (1) having axial flux polarity when actuated, at least one gap magnetic field source (2) having axial flux polarity when actuated, fixed on a support (6), and at least one magnetic core (3) made of low reluctance material. The gap magnetic field source (2, 6) is movable in a linear direction parallel to the longitudinal axis of the magnetic core (3). The magnetic core (3) is arranged in between the core magnetic field source (1) and the gap magnetic field source (2). The magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the magnetic core (3). The magnetic fields of the actuated magnetic field sources (1, 2) flow in a path of least reluctance (2, 3, 4, 5), and concentrate in the field concentration portion (4) passing through it. As a result, a magnetic force is exerted to the gap magnetic field source (2, 6) to move it in a linear direction parallel to the longitudinal axis of the magnetic core (3).

Description

LINEAR MOTION DEVICE
FIELD OF INVENTION
The present invention relates to a linear motion device such as a motor device, generator device, and the like, for motive drive or electrical power generation.
BACKGROUND OFTHE INVENTION
As is well known in the art, various linear motion devices exist for electrical power generation and motive drive. For example, U. S. Pat. No. 4,335,338 discloses a linear motor, in another example, U. S. Pat No. 4,675,563 discloses a reciprocating linear motor and in another example, U. S. Pat. No. 6,914,351 discloses a linear electrical machine that may function as an alternator or a motor.
Herein disclosed is the design of a linear motion device around a tubular magnetic core that can be made out of a continuous piece of low reluctance material without any seams or joints. Gas and liquid tight by nature, the present invention is therefore specifically suited for but not limited to in-flow actuation of flow control valves for liquids and gases.
Another benefit of the gas and liquid tight nature of the present invention is that it enables excellent bearing and cooling and thereby small footprint high power versions when used as a linear motor or generator.
SUMMARY OF INVENTION
Accordingly, it is an object of the present invention to provide a linear motion device with a gas and liquid tight low reluctance magnetic core.
It is another object of the present invention to provide a linear motion device that enables the use of an internal coolant and thereby facilitates small footprint high power versions. It is another object of the present invention to provide a linear motion device with minimal cogging torque.
It is another object of the present invention to provide simple and cheap construction of a linear motion device.
In accordance with a first aspect of the present invention, a linear motion device adapted for motive drive is provided. The linear motion device comprises at least one core magnetic field source (1), at least one gap magnetic field source (2) and at least one magnetic core (3) made of low reluctance material. The at least one gap magnetic field source (2) is movable in a linear direction parallel to the longitudinal axis of the at least one magnetic core (3). The at least one magnetic core (3) is arranged in between the at least one core magnetic field source (1) and the at least one gap magnetic field source (2). The linear motion device is further characterised in that the at least one core magnetic field source (1) has axial flux polarity when actuated, and the at least one gap magnetic field source (2) has axial flux polarity when actuated, and the at least one magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the at least one magnetic core (3), and wherein an interaction between the magnetic field of the actuated at least one core magnetic field source (1) and the magnetic field of the actuated at least one gap magnetic field source (2) around the at least one field concentration portion (4), produces a magnetic force that is exerted to the at least one gap magnetic field source (2) to move it in a linear direction parallel to the longitudinal axis of the at least one magnetic core (3).
Preferably, the at least one core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
Preferably, the gap magnetic field sources (2) are positioned with alternating axial flux polarity. Preferably, the at least one field concentration portion (4) is a V-shaped indentation (4a) in the at least one magnetic core (3).
Preferably, the at least one field concentration portion (4) is positioned within width (12) of the at least one core magnetic field source (1).
Preferably, width (10) of the at least one field concentration portion (4) is similar to width (11) of the at least one gap magnetic field source (2).
Preferably, the at least one core magnetic field source (1) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof.
Preferably, the at least one gap magnetic field source (2) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof, or made of a non magnetised ferromagnetic material.
Preferably, the at least one core magnetic field source (1), the at least one gap magnetic field source (2) and the at least one magnetic core (3) have tubular configuration.
Preferably, the linear motion device is a motor device.
In accordance with a second aspect of the present invention, a linear motion device adapted for motive drive is provided. The linear motion device comprises at least one core magnetic field source (1), at least one gap magnetic field source (2) and at least one magnetic core (3) made of low reluctance material. The at least one core magnetic field source (1) and the at least one magnetic core (3) are movable in a linear direction parallel to the longitudinal axis of the at least one gap magnetic field source (2). The at least one magnetic core (3) is arranged in between the at least one core magnetic field source (1) and the at least one gap magnetic field source (2). The linear motion device is further characterised in that the at least one core magnetic field source (1) has axial flux polarity when actuated, and the at least one gap magnetic field source (2) has axial flux polarity when actuated, and the at least one magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the at least one magnetic core (3), and wherein an interaction between the magnetic field of the actuated at least one core magnetic field source (1) and the magnetic field of the actuated at least one gap magnetic field source (2) around the at least one field concentration portion (4), produces a magnetic force that is exerted to at least one core magnetic field source (1) and the at least one magnetic core (3) to move them in a linear direction parallel to the longitudinal axis of the at least one gap magnetic field source (2).
Preferably, the at least one core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
Preferably, the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
Preferably, the at least one field concentration portion (4) is a V-shaped indentation (4a) in the at least one magnetic core (3).
Preferably, the at least one field concentration portion (4) is positioned within width (12) of the at least one core magnetic field source (1).
Preferably, width (10) of the at least one field concentration portion (4) is similar to width (11) of the at least one gap magnetic field source (2).
Preferably, the at least one core magnetic field source (1) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof.
Preferably, the at least one gap magnetic field source (2) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof, or made of a non magnetised ferromagnetic material. Preferably, the at least one core magnetic field source (1), the at least one gap magnetic field source (2) and the at least one magnetic core (3) have tubular configuration.
Preferably, the linear motion device is a motor device.
In accordance with a third aspect of the present invention, a linear motion device adapted for electrical power generation is provided. The linear motion device comprises at least one core magnetic field source (1), at least one gap magnetic field source (2) and at least one magnetic core (3) made of low reluctance material. The at least one core magnetic field source (1) is a conductor adapted for carrying electrical current, and the at least one gap magnetic field source (2) is movable in a linear direction parallel to the longitudinal axis of the at least one magnetic core (3). The at least one magnetic core (3) is arranged in between the at least one core magnetic field source (1) and the at least one gap magnetic field source (2). The linear motion device is further characterised in that the at least one gap magnetic field source (2) has axial flux polarity when actuated, the at least one magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the at least one magnetic core (3), and wherein an electrical current is induced in the at least one core magnetic field source (1) when the actuated at least one gap magnetic field source (2) is in a relative motion to the at least one magnetic core (3).
Preferably, the at least one core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
Preferably, the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
Preferably, the at least one field concentration portion (4) is a V-shaped indentation (4a) in the at least one magnetic core (3). Preferably, the at least one field concentration portion (4) is positioned within width (12) of the at least one core magnetic field source (1).
Preferably, width (10) of the at least one field concentration portion (4) is similar to width (11) of the at least one gap magnetic field source (2).
Preferably, the at least one gap magnetic field source (2) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof.
Preferably, the at least one core magnetic field source (1), the at least one gap magnetic field source (2) and the at least one magnetic core (3) have tubular configuration.
Preferably, the linear motion device is an electrical generator device.
In accordance with a fourth aspect of the present invention, a linear motion device adapted for electrical power generation is provided. The linear motion device comprises at least one core magnetic field source (1), at least one gap magnetic field source (2) and at least one magnetic core (3) made of low reluctance material. The at least one core magnetic field source (1) is a conductor adapted for carrying electrical current, and the at least one core magnetic field source (1) and the at least one magnetic core (3) are movable in a linear direction parallel to the longitudinal axis of the at least one gap magnetic field source (2). The at least one magnetic core (3) is arranged in between the at least one core magnetic field source (1) and the at least one gap magnetic field source (2). The linear motion device is further characterised in that the at least one gap magnetic field source (2) has axial flux polarity when actuated, the at least one magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the at least one magnetic core (3), and wherein an electrical current is induced in the at least one core magnetic field source (1) when the at least one core magnetic field source (1) and the at least one magnetic core (3) are in a relative motion to the actuated at least one gap magnetic field source (2). Preferably, the at least one core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
Preferably, the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
Preferably, the at least one field concentration portion (4) is a V-shaped indentation (4a) in the at least one magnetic core (3).
Preferably, the at least one field concentration portion (4) is positioned within width (12) of the at least one core magnetic field source (1).
Preferably, width (10) of the at least one field concentration portion (4) is similar to width (11) of the at least one gap magnetic field source (2).
Preferably, the at least one gap magnetic field source (2) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof.
Preferably, the at least one core magnetic field source (1), the at least one gap magnetic field source (2) and the at least one magnetic core (3) have tubular configuration.
Preferably, the linear motion device is an electrical generator.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an axial cross sectional view of a linear motion device in accordance with an embodiment of the present invention.
FIG. 2 is an axial cross sectional view of a core magnetic field source (1) encased within low reluctance material on all sides (3, 4, 5).
FIG. 3 shows an axial cross sectional view of a magnetic core (3) with a field concentration portion (4) of a linear motion device and includes graphs of cross sectional area of low reluctance material and flux density with respect to horizontal position.
FIG. 4 is an axial cross sectional view showing another method of construction of a magnetic core (3) with a field concentration portion (4).
FIG. 5 is an axial cross sectional view showing a relationship between a gap magnetic field source's width (11) and a field concentration portion's width (10) of the linear motion device as shown in FIG. 1.
FIG. 6 shows an axial cross sectional view of two tubular magnetic field sources having a same axial flux polarity, and a graph of the resultant centre fleeing force.
FIG. 7 shows an axial cross sectional view of two tubular magnetic field sources having an opposite magnetic axial flux polarity, and a graph of the resultant centre seeking force.
FIG. 8 is an axial cross sectional view of a linear motion device in accordance with another embodiment of the present invention.
FIG. 9 is an axial cross sectional view of a linear motion device in accordance with another embodiment of the present invention.
DETAILED DESCRIPTION
FIG. 1 shows a linear motion device in accordance with an embodiment of the present invention, adapted for motive drive or electrical power generation. The linear motion device is a single phase motion device which includes a core magnetic field source (1) having axial flux polarity when actuated, two gap magnetic field sources (2) having axial flux polarity when actuated, fixed on a support (6), and a magnetic core (3) with a field concentration portion (4). The magnetic core (3) is placed inside the core magnetic field source (1), and the gap magnetic field sources (2) are placed inside the magnetic core (3). The two gap magnetic field sources (2) are positioned with alternating axial flux polarity, for instance, a first gap magnetic field source (2a) has North Pole region on a left side and South Pole region on a right side when actuated, whereas a second gap magnetic field source (2b) has South Pole region on a left side and North Pole region on a right side when actuated.
The linear motion device is configured with the gap magnetic field sources (2, 6) relatively movable in a linear direction parallel to the longitudinal axis of the magnetic core (3) during operation of the linear motion device. Alternatively, the linear motion device can be configured with the core magnetic field source (1) and the magnetic core (3) relatively movable in a linear direction parallel to the longitudinal axis of the gap magnetic field source (2).
The core magnetic field source (1) has a suitably tubular configuration.
Moreover, the core magnetic field source (1) can either be a permanent magnet, an annularly wound coil carrying a current, or a combination thereof. In a case whereby the core magnetic field source (1) is a wound coil, the coil can be sourced by either a direct or an alternating current to provide a desired magnetic field.
As shown in FIG. 2, the core magnetic field source (1) is preferably encased within low reluctance material on all sides (3, 4, 5a, 5b, 5c). This is to maximise flux within the magnetic core (3) which consequently maximises flux density and thus magnetic force or induced current.
The gap magnetic field source (2) has a suitably tubular configuration. The gap magnetic field source (2) can be a permanent magnet, a wound coil carrying an either direct or alternating current, or a combination thereof, or - when the linear motion device is adapted for motive drive - made of a non magnetised ferromagnetic material.
In case the gap magnetic field source (2) is made of a non magnetised ferromagnetic material it is actuated through magnetic induction by the magnetic field of the actuated core magnetic field source (1), and as a result the gap magnetic field source (2) and the core magnetic field source(l) have opposite axial flux polarity. Magnetic induction of the gap magnetic field source (2) occurs when the horizontal positions of the gap magnetic field source (2) and the field concentration portion (4) overlap, because the gap magnetic field source (2) then becomes part of a path of least reluctance (2, 3, 4, 5).
The magnetic core (3) is made of low reluctance magnetically soft material to provide a low reluctance flux path for the fields of the actuated core magnetic field source (1) and the actuated gap magnetic field source (2), and has a suitably tubular configuration. In case the linear motion device operates as a generator or as an alternating current linear motor, the magnetic core (3) is suitably either made of laminated low reluctance magnetically soft material or made of Soft Magnetic Composite (SMC), in order to manage eddy current losses. The magnetic core (3) can be made of any suitable low reluctance magnetically soft material in case the linear motion device operates as a direct current linear motor. The magnetic core (3) in the figure includes one field concentration portion (4).
The field concentration portion (4) is achieved by reducing the cross sectional area of low reluctance material in the field concentration portion (4) compared to the minimum cross sectional area of low reluctance material in the magnetic core (3). One method of implementing the field concentration portion (4) is shown in FIG. 3, where the field concentration portion (4) is a V-shaped indentation (4a) in the magnetic core (3). It should be noted that any method or shape that results in a smaller cross sectional area of low reluctance material in the field concentration portion (4) than the minimum cross sectional area of low reluctance material in the rest of the magnetic core (3) achieves a field concentration portion (4). As flux density is defined as flux per cross sectional area, the effect of the field concentration portion (4) is that the flux density in the field concentration portion (4) progressively increases and reaches saturation level.
FIG. 3 also shows a graph of cross sectional area of low reluctance material with respect to a horizontal position in the magnetic core (3) and the field concentration portion (4). The graph shows that cross sectional area of low reluctance material decreases starting from a position indicated as DO, which is the boundary between the magnetic core (3) and the field concentration portion (4). The cross sectional area of low reluctance material decreases until it bottoms at a middle horizontal position (indicated as Dl) of the field concentration portion (4). Thereon, cross sectional area of low reluctance material in the field concentration portion (4) increases until it reaches to a boundary between the field concentration portion (4) and the magnetic core (3) indicated as D2. FIG. 3 also indicates the relationship of flux density with respect to a horizontal position in the magnetic core (3). The flux density increases starting from the position indicated as DO. The flux density peaks at the position indicated as Dl and thereon, decreases until it reaches to the position indicated as D2 in the magnetic core (3).
FIG. 4 shows another method of implementing a field concentration portion (4) in the magnetic core (3). The figure shows how a field concentration portion (4) is achieved by bonding two individual magnetic cores (3a, 3b) together with a non magnetic (high reluctance) agent (4a).
As shown in FIG. 5, preferably width (10) of the field concentration portion (4) is equal to width (11) of the gap magnetic field source (2). Moreover, the field concentration portion (4) is suitably positioned within width (12) of the core magnetic field source (1).
Herein below describes the linear motion device adapted for motive drive such as linear motor.
The linear motion device adapted for motive drive is operated based upon an interaction between the magnetic field of the actuated gap magnetic field source (2) and the magnetic field of the actuated core magnetic field source (1) around the field concentration portion (4) in the magnetic core (3).
During operation of the linear motion device for motive drive, both the core magnetic field source (1) and the gap magnetic field source (2) are actuated. Thus, the magnetic core (3) carries the magnetic fields of the actuated core magnetic field source (1) and the actuated gap magnetic field source (2) which causes the flux density in part of the field concentration portion (4) to reach saturation levels. As a result the magnetic permeability of the saturated part of the field concentration portion (4) approaches the magnetic permeability of free space. This causes the saturated part of the field concentration portion (4) to act like a dynamic air gap with two dynamic magnetic poles.
An actuated gap magnetic field source (2) only experiences a significant net force component in a linear direction parallel to the longitudinal axis of the magnetic core (3) when the horizontal positions of the gap magnetic field source (2) and the field concentration portion (4) are different but overlapping, and the core magnetic field source (1) is actuated. This is caused by the fact that in that case the flux loop of the gap magnetic field source (2) asymmetrically influences the flux density distribution in the field concentration portion (4), as a result of which the dynamic air gap in the field concentration portion (4) shifts position. As the flux loop of the gap magnetic field source (2) closes in a path of least reluctance, the gap magnetic field source (2) will experience a force either towards or away from the centre of the dynamic air gap. This means the interaction of the magnetic fields around the dynamic air gap in the field concentration portion (4) results in either a centre fleeing force (FCF) or a centre seeking force (FCP).
In FIG. 6, a tubular magnetic field source (21) is inserted in the hollow centre of stationary tubular magnetic field source (20), both magnetic field sources having a same axial flux polarity when actuated. The figure shows that the inside flux path of actuated magnetic field source (20) and the outside flux path of actuated magnetic field source (21) are in opposite directions (one clockwise and the other counter clockwise), as a result of which they physically can not merge and produce a repulsive force between the magnetic field sources in a linear direction parallel to the longitudinal axis of the magnetic field source (20). The graph in FIG. 6 shows that displacement of the centre of magnetic field source (21) relative to the centre of magnetic field source (20) results in a force that accelerates magnetic field source (21) in the direction of the displacement. This centre fleeing force accelerates the centres of the two magnetic field sources away from each other. Therefore, if the actuated gap magnetic field source (2) and the actuated core magnetic field source (1) have the same axial flux polarity, then a centre fleeing force is produced that accelerates the centres of the gap magnetic field source (2) and the field concentration portion (4) away from each other in a linear direction parallel to the longitudinal axis of the magnetic core (3).
In FIG. 7 a tubular magnetic field source (22) is inserted in the hollow centre of stationary tubular magnetic field source (20), both magnetic field sources having an opposite axial flux polarity when actuated. The figure shows that the inside flux path of actuated magnetic field source (20) and the outside flux path of actuated magnetic field source (22) are in the same direction (both clockwise or both counter clockwise), as a result of which they merge and produce an attractive force between the magnetic field sources in a linear direction parallel to the longitudinal axis of the magnetic field source (20). The graph in FIG. 7 shows that displacement of the centre of magnetic field source (22) relative to the centre of magnetic field source (20) results in a force that accelerates magnetic field source (22) in the opposite direction of the displacement. This centre seeking force accelerates the centres of the two magnetic field sources towards each other.
Therefore, if the actuated gap magnetic field source (2) and the actuated core magnetic field source (1) have opposite axial flux polarity, then a centre seeking force is produced that accelerates the centres of the gap magnetic field source (2) and the field concentration portion (4) towards each other in a linear direction parallel to the longitudinal axis of the magnetic core (3).
The total force exerted to a movable member, which could be either the core magnetic field source (1) and the magnetic core (3) or the gap magnetic field source (2), is the vector sum of the forces between the individual magnetic fields. For example, referring to FIG. 1, wherein the movable member is the combined gap magnetic field sources (2, 6), the total force exerted to the combined actuated gap magnetic field sources (2, 6) is the vector sum of the force experienced by the first actuated gap magnetic field source (2a) and the force experienced by the second actuated gap magnetic field source (2b). As the gap magnetic field sources in FIG. 1 are positioned with alternating axial flux polarity, total force is the vector sum of a centre seeking force and a centre fleeing force.
Magnetic force as a consequence of flux interaction is proportional to the flux density involved, so the magnetic force increases as the flux density in the field concentration portion (4) increases. Thus, the magnitude of the magnetic force is a function of the magneto motive force of the individual magnetic field sources (1, 2), the total reluctance of the path of least reluctance (2, 3, 4, 5), flux density in the field concentration portion (4) and the relative position of the field concentration portion (4) and the gap magnetic field sources (2) with respect to each other.
Furthermore, length of displacement of the movable member which could either be the core magnetic field source (1) and the magnetic core (3) or the gap magnetic field source (2) depends on the width (11), relative pitch and axial flux polarity of the actuated gap magnetic field source (2), position of the actuated gap magnetic field source (2) relative to the position of the field concentration portion (4), the width (10) and relative pitch of the field concentration portion (4), and actuation of the core magnetic field source (1).
Herein below describes the linear motion device adapted for electrical power generation.
When used as an electrical power generator, a relative motion of the magnetic core (3) and the gap magnetic field source (2) with respect to each other generates a time varying flux in the magnetic core (3) by the actuated gap magnetic field source (2). As a result, a current is induced in the core magnetic field source (1).
Referring to the linear motion device shown in FIG. 1, wherein the core magnetic field source (1) is an annularly wound coil connected to an electrical load, and the gap magnetic field sources (2) are permanent magnets fixed on a support
(6), the gap magnetic field sources (2, 6) are motioned in a linear direction parallel to the longitudinal axis of the magnetic core (3). This generates a time-varying flux in the magnetic core (3) that induces a current in the core magnetic field source (1).
Referring to the linear motion device shown in FIG. 1, wherein the core magnetic field source (1) is an annularly wound coil connected to an electrical load, and the gap magnetic field sources (2) are permanent magnets fixed on a support (6), the core magnetic field source (1) and the magnetic core (3) are motioned in a linear direction parallel to the longitudinal axis of the gap magnetic field sources (2). This generates a time-varying flux in the magnetic core (3) that induces a current in the core magnetic field source (1).
Other embodiments of the present invention operate according to the same principles described above for the linear motion device as shown in FIG. 1.
FIG. 8 shows a three-phase linear motion device in accordance with another embodiment of the present invention, which includes three core magnetic field sources (1) having axial flux polarity when actuated, twelve gap magnetic field sources (2) having axial flux polarity when actuated, fixed on a support (6) and a magnetic core (3) with three field concentration portions (4). Preferably, each core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5). Preferably, the gap magnetic field sources (2) are positioned with alternating axial flux polarity. The magnetic core (3) is placed inside the core magnetic field sources (1), and the gap magnetic field sources (2) are placed inside the magnetic core (3).
FIG. 9 shows a three-phase linear motion device in accordance with another embodiment of the present invention, which includes three core magnetic field sources (1) having axial flux polarity when actuated, twelve gap magnetic field sources (2) having axial flux polarity when actuated, fixed in a support (6) and a magnetic core (3) with three field concentration portions (4). Preferably, each core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5). Preferably, the gap magnetic field sources (2) are positioned with alternating axial flux polarity. The magnetic core (3) is placed inside the gap magnetic field sources (2), and the core magnetic field sources (1) are placed inside the magnetic core (3).
The present invention offers specific advantages over other types of linear motion devices.
One advantage of the present invention is that it provides a simple and cheap construction. This is because the magnetic core (3) can be suitably made of a tubular configuration with a number of (integrated or attached) rings (5a, 5b), and a number of V-shaped indentations (4a) as field concentration portions (4) and thus, it can be easily turned on a lathe out of electrical steel, moulded in electrical steel or injection moulded with a suitable Soft Magnetic Composite (SMC). Furthermore, coils that are used as core magnetic field source (1) can be directly wound around the magnetic core (3). The gap magnetic field source (2) can be made out of non magnetised ferromagnetic material or a coil directly wound around a central support (6). If the gap magnetic field source (2) is a permanent magnet, axially magnetised permanent magnet rings or cylinders can be suitably used, without a need for radially magnetised magnet rings which are difficult to manufacture and higher in cost to manufacture.
Another advantage of the present invention is that it eliminates back iron requirement for permanent magnet gap magnetic field sources (2). This is because the axial flux loop of the actuated gap magnetic field sources (2) closes through the magnetic core (3).
Another advantage of the present invention is that it reduces cogging torque when operated as a linear motor, as the magnetic core (3) and the field concentration portion (4) are then designed in such a way that the axial magnetic field of the actuated individual gap magnetic field sources (2) do not saturate the magnetic core (3) in the field concentration portion (4). Another advantage of the present invention is that the magnetic core (3) can be suitably designed without any seams or joints. Thus, rolling bearings or lubricants can be suitably provided in between the moving parts to reduce friction.
Furthermore, the present invention is specifically suited for in-flow actuation of flow control valves for liquids and gases. One possible implementation of such a valve is to use the configuration of FIG. 1, wherein the gap magnetic field sources (2) are fixed on a hollow support (6) connected to a seal / seal seat combination upstream or downstream. The gas or liquid, of which the flow is to be controlled, flows through the magnetic core (3) which is gas and liquid tight and suitably without any seams or joints. This would allow the valve to be an integral part of the gas or liquid tubing, and thus integrate valve control with the actual valve itself, without the need for an external perpendicular valve control mechanism.
Another advantage of the present invention is that it provides excellent cooling possibilities whereby it enables the use of an internal coolant when adapted as a linear motor and thereby facilitating small footprint high power versions. When it is adapted for electrical power generation, it provides a compact design whereby magnetic field strength can be increased due to the excellent cooling possibilities, and thereby induced voltage can be increased.
Moreover, the linear motion device can be implemented for other applications such as power tools (i.e. hammers and pullers), electromagnetic guns, electromagnetic toys and any other devices that require linear movement.
While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specifications are words of description rather than limitation and various changes may be made without departing from the scope of the invention.

Claims

1. A linear motion device adapted for motive drive comprising: at least one core magnetic field source (1); at least one gap magnetic field source (2); at least one magnetic core (3) made of low reluctance material; wherein the at least one gap magnetic field source (2) is movable in a linear direction parallel to the longitudinal axis of the at least one magnetic core (3); and the at least one magnetic core (3) is arranged in between the at least one core magnetic field source (1) and the at least one gap magnetic field source (2); characterised in that: the at least one core magnetic field source (1) has axial flux polarity when actuated, and the at least one gap magnetic field source (2) has axial flux polarity when actuated, and the at least one magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the at least one magnetic core (3) and wherein an interaction between the magnetic field of the actuated at least one core magnetic field source (1) and the magnetic field of the actuated at least one gap magnetic field source (2) around the at least one field concentration portion (4), produces a magnetic force that is exerted to the at least one gap magnetic field source (2) to move it in a linear direction parallel to the longitudinal axis of the at least one magnetic core (3).
2. The linear motion device as claimed in claim 1, wherein the at least one core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
3. The linear motion device as claimed in claim 1, wherein the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
4. The linear motion device as claimed in claim 1, wherein the at least one field concentration portion (4) is a V-shaped indentation (4a) in the magnetic core (3).
5. The linear motion device as claimed in claim 1, wherein the at least one field concentration portion (4) is positioned within width (12) of the at least one core magnetic field source (1).
6. The linear motion device as claimed in claim 1, wherein width (10) of the at least one field concentration portion (4) is similar to width (11) of the at least one gap magnetic field source (2).
7. The linear motion device as claimed in claim 1, wherein the at least one core magnetic field source (1) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof.
8. The linear motion device as claimed in claim 1, wherein the at least one gap magnetic field source (2) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof, or made of a non magnetised ferromagnetic material.
9. The linear motion device according to any of claims 1 to 8, wherein the at least one core magnetic field source (1), the at least one gap magnetic field source (2) and the at least one magnetic core (3) have tubular configuration.
10. The linear motion device according to any of claims 1 to 9, wherein the linear motion device is a motor device.
11. A linear motion device adapted for motive drive comprising: at least one core magnetic field source (1); at least one gap magnetic field source (2); at least one magnetic core (3) made of low reluctance material; wherein the at least one core magnetic field source (1) and the at least one magnetic core (3) are movable in a linear direction parallel to the longitudinal axis of the at least one gap magnetic field source (2); and the at least one magnetic core (3) is arranged in between the at least one core magnetic field source (1) and the at least one gap magnetic field source (2); characterised in that: the at least one core magnetic field source (1) has axial flux polarity when actuated, and the at least one gap magnetic field source (2) has axial flux polarity when actuated, and the at least one magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the at least one magnetic core (3), and wherein an interaction between the magnetic field of the actuated at least one core magnetic field source (1) and the magnetic field of the actuated at least one gap magnetic field source (2) around the at least one field concentration portion (4), produces a magnetic force that is exerted to at least one core magnetic field source (1) and the at least one magnetic core (3) to move them in a linear direction parallel to the longitudinal axis of the at least one gap magnetic field source (2).
12. The linear motion device as claimed in claim 11, wherein the at least one core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
13. The linear motion device as claimed in claim 11, wherein the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
14. The linear motion device as claimed in claim 11, wherein the at least one field 5 concentration portion (4) is a V-shaped indentation (4a) in the magnetic core (3).
15. The linear motion device as claimed in claim 11, wherein the at least one field concentration portion (4) is positioned within width (12) of the at least one
10 core magnetic field source (1).
16. The linear motion device as claimed in claim 11, wherein width (10) of the at least one field concentration portion (4) is similar to width (11) of the at least one gap magnetic field source (2).
15
17. The linear motion device as claimed in claim 11, wherein the at least one core magnetic field source (1) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof.
20 18. The linear motion device as claimed in claim 11, wherein the at least one gap magnetic field source (2) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof, or made of a non magnetised ferromagnetic material.
25 19. The linear motion device according to any of claims 11 to 18, wherein the at least one core magnetic field source (1), the at least one gap magnetic field source (2) and the at least one magnetic core (3) have tubular configuration.
20. The linear motion device according to any of claims 11 to 19, wherein the 30 linear motion device is a motor device.
21. A linear motion device adapted for electrical power generation comprising: at least one core magnetic field source (1); at least one gap magnetic field source (2); at least one magnetic core (3) made of low reluctance material; wherein the at least one core magnetic field source (1) is a conductor adapted for carrying electrical current; and the at least one gap magnetic field source (2) is movable in a linear direction parallel to the longitudinal axis of the at least one magnetic core (3); and the at least one magnetic core (3) is arranged in between the at least one core magnetic field source (1) and the at least one gap magnetic field source (2); characterised in that: the at least one gap magnetic field source (2) has axial flux polarity when actuated, and the at least one magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the at least one magnetic core (3), and wherein an electrical current is induced in the at least one core magnetic field source (1) when the actuated at least one gap magnetic field source (2) is in a relative motion to the at least one magnetic core (3).
22. The linear motion device as claimed in claim 21, wherein the at least one core magnetic field source (1) is encased within low reluctance material on all sides (3, 4, 5).
23. The linear motion device as claimed in claim 21, wherein the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
24. The linear motion device as claimed in claim 21, wherein the at least one field concentration portion (4) is a V-shaped indentation (4a) in the magnetic core (3).
25. The linear motion device as claimed in claim 21, wherein the at least one field concentration portion (4) is positioned within width (12) of the at least one core magnetic field source (1).
26. The linear motion device as claimed in claim 21, wherein width (10) of the at least one field concentration portion (4) is similar to width (11) of the at least one gap magnetic field source (2).
27. The linear motion device as claimed in claim 21, wherein the at least one gap magnetic field source (2) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof.
28. The linear motion device according to any of claims 21 to 27, wherein the at least one core magnetic field source (1), the at least one gap magnetic field source (2) and the at least one magnetic core (3) have tubular configuration.
29. The linear motion device according to any of claims 21 to 28, wherein the linear motion device is an electrical generator.
30. A linear motion device adapted for electrical power generation comprising: at least one core magnetic field source (1); at least one gap magnetic field source (2); at least one magnetic core (3) made of low reluctance material; wherein the at least one core magnetic field source (1) is a conductor adapted for carrying electrical current; and the at least one core magnetic field source (1) and the at least one magnetic core (3) are movable in a linear direction parallel to the longitudinal axis of the at least one gap magnetic field source (2); and the at least one magnetic core (3) is arranged in between the at least one core magnetic field source (1) and the at least one gap magnetic field source (2); characterised in that: the at least one gap magnetic field source (2) has axial flux polarity when actuated, and the at least one magnetic core (3) includes at least one field concentration portion (4) having smaller cross sectional area of low reluctance material than the minimum cross sectional area of low reluctance material in the rest of the at least one magnetic core (3), and wherein an electrical current is induced in the at least one core magnetic field source (1) when the at least one core magnetic field source (1) and the at least one magnetic core (3) are in a relative motion to the actuated at least one gap magnetic field source (2).
31. The linear motion device as claimed in claim 30, wherein the at least one core magnetic field source (1) is encased within a low magnetic reluctance material on all sides (3, 4, 5).
32. The linear motion device as claimed in claim 30, wherein the gap magnetic field sources (2) are positioned with alternating axial flux polarity.
33. The linear motion device as claimed in claim 30, wherein the at least one field concentration portion (4) is a V-shaped indentation (4a) in the magnetic core (3).
34. The linear motion device as claimed in claim 30, wherein the at least one field concentration portion (4) is positioned within width (12) of the at least one core magnetic field source (1).
35. The linear motion device as claimed in claim 30, wherein width (10) of the at least one field concentration portion (4) is similar to width (11) of the at least one gap magnetic field source (2).
36. The linear motion device as claimed in claim 30, wherein the at least one gap magnetic field source (2) is a permanent magnet or a coil adapted to carry electrical current or a combination thereof.
37. The linear motion device according to any of claims 30 to 36, wherein the at least one core magnetic field source (1), the at least one gap magnetic field source (2) and the at least one magnetic core (3) have tubular configuration.
38. The linear motion device according to any of claims 30 to 37, wherein the linear motion device is an electrical generator.
PCT/MY2007/000033 2007-05-24 2007-05-24 Linear motion device Ceased WO2008143492A1 (en)

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Cited By (4)

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ITBO20090118A1 (en) * 2009-02-27 2010-08-28 Ind Motori Elettri Ci S I M E L Soc TUBULAR ELECTRIC MOTOR
EP2566021A3 (en) * 2011-09-05 2017-01-11 Sanyo Denki Co., Ltd. Electric machine with linear mover
US11456655B2 (en) 2018-02-09 2022-09-27 Komp-Act Sa Linear motor with stacked electromagnets
EP3360239B1 (en) * 2015-10-05 2023-06-07 Langenstein & Schemann GmbH Forming machine, in particular a forging hammer

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US6265801B1 (en) * 1998-01-23 2001-07-24 Kabushiki Kaisha Toshiba Permanent magnet type electrical rotating machine
JP2004056972A (en) * 2002-07-23 2004-02-19 Shinko Electric Co Ltd Linear actuator
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US20060108878A1 (en) * 2004-11-22 2006-05-25 Lindberg Paul M Linear motor and stator core therefor

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US6265801B1 (en) * 1998-01-23 2001-07-24 Kabushiki Kaisha Toshiba Permanent magnet type electrical rotating machine
JP2004056972A (en) * 2002-07-23 2004-02-19 Shinko Electric Co Ltd Linear actuator
US20050001500A1 (en) * 2003-07-02 2005-01-06 Allan Chertok Linear electrical machine for electric power generation or motive drive
US20050211198A1 (en) * 2004-03-26 2005-09-29 Froeschle Thomas A Electromagnetic actuator and control
US20060108878A1 (en) * 2004-11-22 2006-05-25 Lindberg Paul M Linear motor and stator core therefor

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ITBO20090118A1 (en) * 2009-02-27 2010-08-28 Ind Motori Elettri Ci S I M E L Soc TUBULAR ELECTRIC MOTOR
EP2224581A3 (en) * 2009-02-27 2012-11-21 Societa' Industriale Motori Elettrici S.I.M.E.L. S.p.A. Tubular motor
EP2566021A3 (en) * 2011-09-05 2017-01-11 Sanyo Denki Co., Ltd. Electric machine with linear mover
EP3360239B1 (en) * 2015-10-05 2023-06-07 Langenstein & Schemann GmbH Forming machine, in particular a forging hammer
US11456655B2 (en) 2018-02-09 2022-09-27 Komp-Act Sa Linear motor with stacked electromagnets

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