JP2004521589A - Linear stepper motor, magnetizing device and method - Google Patents

Abstract

The present invention provides a method of magnetizing a shaft of a linear stepper motor, a magnetizing device (100), and a method of manufacturing the device. In one preferred embodiment, the linear stepper motor (20) includes a stator (32) and an axially extending cylindrical permanent magnet shaft (30) that magnetically interacts with the stator (32). The shaft (30) has a smooth surface along a portion of the shaft (30) on which axially alternating radial north and south poles (34, 36) are provided. Is provided. In another preferred embodiment of the present invention, there is provided a shaft (200) for a linear stepper motor that allows for rotational movement. In another preferred embodiment of the present invention, there is provided an "inside-out" motor (300) wherein the linearly moving member (314) is outside the stator (312).
[Selection diagram] Fig. 1

Description

【Technical field】
[0001]
The present invention relates generally to stepper motors, and more particularly, but not exclusively, to novel linear stepper motors, devices for magnetizing their shafts, and methods of use and manufacture. .
[Background Art]
[0002]
Some linear stepper motors convert rotary motion into linear motion by mechanical means such as the use of threaded nuts and lead screws. Conventional linear motors that directly convert electromagnetic energy at the stator poles into linear motion of the shaft typically use toothed structures or have relatively complex slide / stator arrangements. In any case, the manufacture of such motors is relatively expensive and typically involves a large number of parts.
[0003]
There is a problem in manufacturing a linear motor having a smooth shaft in which N poles and S poles are alternately arranged. One technique is to join cylindrical segments of N and S magnets together. However, said technique is time consuming and results in a slightly fragile structure. Another technique is to roll a cylinder of ferromagnetic material on a flat plate orthogonal to a series of alternating north and south magnetic strips. This technique has the disadvantage that it is a bit cumbersome and the magnetic strength of the resulting magnetized shaft is rather weak.
[0004]
Some conventional motors are described in the following patent documents.
[0005]
U.S. Pat. No. 6,064,067 issued to Chai et al. On Feb. 18, 1975, entitled "Variable Reluctance Linear Stepper Motor", describes a motor having a toothed structure in a coil and a linear member. The novelty of the patent appears to be the arrangement of the coils and the manner in which the coils are driven.
[Patent Document 1] US Pat. No. 3,867,676
The following patent, entitled "High-Performance Stepper Motor", issued to Matthias et al. On April 15, 1980, describes, in part, a variable reluctance linear stepper motor, which includes a stator. A non-magnetic material is arranged inside both the slider and the slider so as to reduce the leakage magnetic flux.
[Patent Document 2] US Pat. No. 4,198,582 [0007]
U.S. Pat. No. 6,064,067, issued to Langley on Aug. 25, 1981, entitled "Variable Magnetoresistive Stepper Motor", has a stator and slide structure with spirally toothed teeth, each of said teeth. A part of the motor whose width has a predetermined relationship is described.
[Patent Document 3] US Patent No. 4,286,180
U.S. Pat. No. 6,074,867 issued to Okamoto on Oct. 4, 1983, entitled "Linear Stepper Motor", describes a linear stepper motor having a toothed structure on a stator and slider. Winding salient poles are provided on the slider. The novelty of the patent appears to be the arrangement of the rollers and rails located between the stator and slider.
[Patent Document 4] US Patent No. 4,408,138
U.S. Pat. No. 5,093,867, issued to Conrad on Aug. 19, 1986, entitled "Linear and Rotary Actuator," describes a variable reluctance linear / rotary motor, wherein the motor is an armature. Has axial tooth steps radially spaced around its surface. The selective actuation of the stator windings provides for linear, rotational, or both linear and rotational movement of the armature.
[Patent Document 5] US Patent No. 4,607,197
U.S. Pat. No. 6,026,028, issued Nov. 11, 1986 to Barton, entitled "Read / Write Head Localization", has a toothed structure on opposing faces of a stator and an armature, wherein a coil is provided on the armature. A variable reluctance localization device arranged above is described.
[Patent Document 6] US Patent No. 4,622,609
U.S. Pat. No. 6,074,839 issued to Asano on September 22, 1987, entitled "VR Type Linear Stepper Motor", describes a motor having a toothed structure on a stator and a slider. Are located on the coil winding salient poles. The tooth structures have a predetermined relationship between the tooth structures.
[Patent Document 7] US Patent No. 4,695,777
U.S. Pat. No. 6,064,067 issued to Karidis on Dec. 8, 1987, entitled "Radial Polar Linear Magnetoresistive Motor", discloses a smooth double helical stator shaft with a radial pole stack and spacer stack. A motor having alternating smooth laminated armatures is described. This arrangement allows for a balanced flux path and utilizes the stator and armature surfaces as slider bearing surfaces.
[Patent Document 8] US Patent No. 4,712,027
U.S. Pat. No. 6,037,028 issued to Mar. 7, 1989 on Mar. 7, 1989, entitled "Linear Actuator with Multiple Closed-Loop Flux Paths Essentially Orthogonal to the Axis," A variable reluctance actuator similar to that is described.
[Patent Document 9] US Patent No. 4,810,914
U.S. Pat. No. 6,073,867, issued to Hinds on Jan. 18, 2000, entitled "Linear Stepper Motor", describes a variable reluctance stepper motor similar to the motor described in the '609 patent. The novelty of this patent appears to be the method of forming the teeth.
[Patent Document 10] US Patent No. 6,016,021 [Disclosure of the Invention]
[Problems to be solved by the invention]
[0015]
It is a primary object of the present invention to provide a permanent magnet shaft for a linear stepper motor having a smooth magnetized surface.
[0016]
It is a further object of the present invention to provide a linear stepper motor with a reduced number of parts, which is simple and economical to manufacture.
[0017]
It is a further object of the present invention to provide a quick and economical method of magnetizing a smooth shaft for a linear stepper motor.
[0018]
It is another object of the present invention to provide a smooth shaft magnetizer for a linear stepper motor.
[0019]
It is a further object of the present invention to provide a smooth shaft magnetizer for a linear stepper motor that can be manufactured economically.
[0020]
It is another object of the present invention to provide a stepper motor in which conventional coils are each easily wound around a bobbin.
[0021]
It is an object of the present invention to provide a stepper motor having a shaft rotatable at any position and at any time, regardless of whether the motor is powered on or whether the shaft is moving linearly. For another purpose.
[0022]
Other objects and individual features, members and their advantageous effects of the present invention will be described in the following description and accompanying drawings, or will be apparent from the following description and accompanying drawings.
[Means for Solving the Problems]
[0023]
SUMMARY OF THE INVENTION The present invention addresses the above-identified object in one preferred embodiment with a linear stepper motor comprising a stator and an axially extending cylindrical permanent magnet shaft that magnetically interacts with the stator. A linear stepper motor wherein the shaft has a smooth surface along a portion thereof and wherein axially alternating radial north and south poles are provided on the smooth surface. Achieved by. The present invention provides a method of magnetizing a shaft of such a motor, a magnetizing device, and a method of manufacturing the device. In another preferred embodiment of the present invention, there is provided a shaft for a linear stepper motor capable of rotational movement. In yet another preferred embodiment, there is provided an "inside-out" type motor wherein the linearly moving member is outside the stator.
BEST MODE FOR CARRYING OUT THE INVENTION
[0024]
Referring to the drawings, where identical or similar parts are numbered consistently throughout the several figures, reference to parentheses in the drawing numbers will direct the reader to the figure in which the described element or parts are best understood. However, the member or members may be depicted in other figures.
[0025]
FIG. 1 shows a linear stepper motor manufactured according to a first embodiment of the present invention, and is generally designated by the reference numeral 20. The motor 20 includes a shaft or slider 30 that has a smooth outer peripheral surface (at least a portion of which is shown in the figure) and that a stator, generally designated by the reference numeral 32, Inserted for axial back and forth movement.
[0026]
Shaft 30 includes a plurality of alternating non-protruding north and south poles 34 and 36 formed therearound, the magnetic poles of which may be formed as described below. The shaft 30 is preferably a hollow cylinder made of a ceramic or rare earth magnetic material, but the shaft is not hollow, or a core made of ferromagnetic or other material, and a magnetic material disposed around the core. And a hollow cylinder. The shaft 30 may be economically manufactured, for example, by conventional extrusion methods that can manufacture shafts of any given length, or the shaft may be cut from extruded stock to the appropriate length. Good. At least a portion of the shaft 30, including the north and south poles, is not segmented and is made of a single material part.
[0027]
The stator 32 surrounds the shaft 30 and includes a first cylindrical coil 40 and a second cylindrical coil 42 wound around the first annular bobbin 44 and the second annular bobbin 46 in a conventional manner. Including. Bobbins 44 and 46 are comprised of an electrically insulating material such as Delrin®. The first annular bobbin 44 and the second annular bobbin 46 are separated by a first spacer 50, and the second bobbin is separated from the end plate of the motor 20 by a second spacer 54. The first spacer 50 and the second spacer 54 may provide a bearing surface for the shaft 30, in which case the first and second spacers may have a high lubrication, such as Delrin®. Preferably, it is made of a conductive material.
[0028]
First bobbin 44 separates annular plates 60 and 62 and second bobbin 46 separates plates 64 and 66. A steel band surrounds the annular plates 60, 62, 64 and 66 and makes good electrical contact with the annular plates 60, 62, 64 and 66 to complete the annular electromagnetic circuit. The annular plates 60, 62, 64 and 66 have non-protruding poles.
[0029]
It is understood that by appropriately driving the bobbins on which the first and second coils are wound in a conventional manner, the shaft 30 may be made to move stepwise incrementally from side to side in FIG. . It is also understood that one or both ends of the shaft 30 may be attached to or supported by one or more members of another device (not shown).
[0030]
The motor 20 has a set of two-phase stator sections, ie, the motor is shown as having two coils, but it is understood that other arrangements are possible. For example, it is understood that additional stator sections may be added in series in a modular fashion, with two or more sets of two-phase stator sections being provided for greater output.
[0031]
FIG. 2 shows several components of the motor 20 (FIG. 1), showing a conductor 70 used to drive the stator 32 and a mounting hole 72 provided in the end plate 52.
[0032]
When arranged in this manner, the motor 20, shown in a minimal form (in FIG. 1), is manufactured with only 11 individual components, which are mainly made of a suitable glue or a motor 20. May be integrated by other conventional means that may be provided to secure the members together.
[0033]
FIG. 3 shows a mandrel 100 that can be used to manufacture a magnetizing device for the shaft 30 (FIG. 1). Here, the cylindrical mandrel 100 has a plurality of parallel cylindrical grooves 110 cut on the outer periphery thereof, and the grooves have a width approximating the diameter of a conductive wire used for magnetizing the shaft 30. Mandrel 100 is made of a non-magnetic, non-conductive material and the spacing of grooves 110 is determined by the final magnet width of poles 34 and 36 of shaft 30.
[0034]
FIG. 4 shows the conductor 150 that is continuously arranged in the groove 110 of the mandrel 100.
[0035]
FIG. 5 shows the current path of the conductor 150, each of the substantially complete rings shown in FIG. 5 representing one turn of the conductor 150 in one groove 110. Note that the currents represented by the arrows in conductor 150 in the adjacent windings of the conductor are in opposite directions.
[0036]
FIG. 6 shows the mandrel 100 in which the conductor 100 located in the groove 110 is located in a tubular hollow potting device. In this step, a suitable potting compound, such as an epoxy material, is poured into an annulus 210 formed between the outer surface of the mandrel 100 and the potting device 200. After solidification, the potting composition retains the position of the conductor 150 in the groove 110.
[0037]
FIG. 7 shows a completed magnetizing device, generally designated by the reference numeral 300. Apparatus 300 includes a mandrel 100 having an outer coating of potting compound 310 and a distal end of a lead 150 extending from mandrel 100. The center hole 320 is drilled or expanded through the mandrel 100 to bring the wire 150 closer to the inner surface of the mandrel or, if necessary, partially expose it as shown in FIG.
[0038]
The shaft 30 of the motor 20 (FIG. 1) is inserted into the device 300 and a high level of direct current is passed through the conductor 150 to magnetize alternating north and south poles 34 and 36 over a selected length. I do. Such an arrangement provides an economical and quick way of magnetizing the shaft 30, since only one short DC burst is required, which can be a wide range of voltages, and depending on the magnetic material, almost any It can be provided with a magnetized length.
[0039]
Motor 20 (FIG. 1) has a number of important features. For example, motor 20 is a brushless, magnetically conjugated, two-phase, arc-free design, has a long operating life, and has a permanently magnetized output shaft 30. The motor 20 is driven by a conventional stepper motor drive and can be microstepped to increase resolution and accuracy. The shaft 30 is the only moving part and can rotate in any direction, at any time, even when the motor 20 is not energized, in any linear position, either 360 ° continuously or intermittently. There is no conversion with loss of efficiency from rotary motion to linear motion. There are no lead screws, ball screws or ball bearings to wear, and no lubrication is required. The motor 20 can operate in any orientation and can be reverse driven (especially when power input is low or zero), ie, the shaft 30 overwhelms the magnetic force between the shaft and the annular plates 64 and 66. Can be moved. The performance of the motor 20 improves with shorter duty cycles and can be easily manufactured for vacuum environments, i.e., manufactured from materials that do not emit gas into a vacuum, but without lubrication. Has contributed. When the shaft 30 is hollow, it can penetrate lines such as electricity, light and / or liquid.
[0040]
FIG. 8 shows a shaft for a linear stepper motor according to a second embodiment of the present invention, generally designated by the reference numeral 200. Shaft 200 has a magnetized pattern formed on its surface that allows both linear and rotational movement of the shaft. This pattern consists of alternating north and south poles 210 and 212 for linear stepping, similar to the north and south poles of shaft 30 (FIG. 1). In addition, a longitudinally-added section of shaft 200 with very weak or no magnetic pole due to a loop-back pattern of electrical leads 150 (FIG. 5) of mandrel 100 (FIGS. 3 and 4). At least a pair of north and south poles 220 and 222 are provided. This utilizes the "dead band" region of a normally magnetized shaft dedicated to linear motion.
[0041]
In order for the stator assembly (not shown) to complete the motor with the shaft 200 as a component, a typical can-stack style stator section is modularized into the stator 32 (FIG. 1). (In series in the axial direction). This allows for rotation of the shaft 200 during linear motion, or creates additional force to lock the shaft 200 in place. Of course, both the linear movement and the rotational movement of the shaft 200 may be performed simultaneously.
[0042]
FIG. 9 shows a linear motor manufactured according to a third embodiment of the present invention, which is generally designated by the reference numeral 300. The motor 300 has a metal base member 310 on the surface of which a stator 312 inside is fixedly arranged, and has a hollow cylindrical shaft 314 arranged around the stator. A threaded shaft 320 protrudes from the upper end of hollow shaft 314 for engagement with other components (not shown). Of course, other engagement means may be provided, but the exact engagement means is not part of the present invention. Motor 300 is similar to motor 20 (FIG. 1) except that the relative positions of shaft 30 and stator 32 are reversed.
[0043]
FIG. 10 shows the configuration of the motor 300 more clearly. The hollow shaft 314 moves linearly outside the stator 312. Additional two-phase stator sections are stacked axially to enhance the force. In addition to the components described above with respect to motor 20 (FIG. 1), motor 300 includes two sleeve bearings 330 and 332. The metal base member 310 not only provides support but also serves to remove heat from the motor 300.
[0044]
FIG. 11 shows a hollow shaft 314, which is axially magnetized with alternating north and south poles 340 and 342.
[0045]
12-15 show components for magnetizing hollow shaft 314, which are similar to components for magnetizing shaft 30 (FIGS. 1 and 3-5). Solid core copper wire 350 (FIGS. 14 and 15) has a cylindrical non-conductive mandrel 352 (FIGS. 12 and 15) having grooves 354 machined around its circumference to provide the proper spacing and parallelism. 13) is wound in a special pattern. A larger groove 360 (FIGS. 12 and 13) is machined along the length of the mandrel 352, and the groove 360 is deeper than the groove 354, so that it can accommodate the loop inversion section of the conductor 350. Thereafter, the mandrel 352 is coated with a non-conductive epoxy or similar material, and then the outer diameter of the mandrel is finalized and the hollow shaft (FIG. 11) slides over the mandrel. Make it possible. The arrows in FIG. 12 represent the direction of the current in conductor 350 that creates alternating north and south poles 340 and 342 (FIG. 11) in hollow shaft 314.
[0046]
In the embodiments of the invention described above, the individual members and / or features thereof are not necessarily limited to a particular embodiment, and where applicable, are interchangeable, even when not specifically indicated, It will be appreciated that it can be used in any selected embodiment.
[0047]
Terms such as “above”, “below”, “inside”, “outside”, “inward”, “outward”, “vertical”, “horizontal”, etc. As used herein, refers to the location of each member shown in the accompanying drawings, and the invention is not necessarily limited to such locations.
[0048]
Therefore, it is understood that the objects enumerated in the above description, disclosed in the above description, or clarified from the above description can be efficiently achieved, and a certain kind of structure and method described above can be used. Since changes may be made without departing from the scope of the invention, all matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative only and not limiting. Should not be interpreted in any meaningful way.
[0049]
It is intended that the following claims cover all of the general and specific features of the invention described herein, as well as those of the scope of the invention, which may be said to fall between them as a matter of language. It is intended to be an opinion.
[Brief description of the drawings]
[0050]
FIG. 1 is a partial cross-sectional side view of a linear stepper motor manufactured according to a first embodiment of the present invention.
FIG. 2 is an elevation view of a rear surface of the motor shown in FIG. 1;
FIG. 3 is an isometric view of a grooved mandrel for manufacturing a device for magnetizing the shaft of the motor shown in FIG. 1;
FIG. 4 is an isometric view showing a state where a conductor is inserted into the mandrel groove shown in FIG. 3;
FIG. 5 is an isometric schematic view showing a path of a direct current flowing through a conductor.
FIG. 6 is a partially transparent perspective view showing a state in which the mandrel shown in FIG. 3 is inserted into a potting device.
FIG. 7 is an isometric view of a magnetizing device for magnetizing the shaft of the motor shown in FIG. 1;
FIG. 8 is an isometric view showing a shaft according to a second embodiment of the present invention.
FIG. 9 is a top view of a linear motor manufactured according to a third embodiment of the present invention.
FIG. 10 is a partial sectional view of the side surface of the motor shown in FIG. 9;
11 is an isometric perspective view of a side surface of a movable member of the motor shown in FIG. 9;
FIG. 12 is a side view of a mandrel for magnetizing the cylindrical movable member of the motor shown in FIG.
FIG. 13 is a top view of the mandrel shown in FIG. 12;
FIG. 14 is a schematic view of a conductor used for the mandrel shown in FIG. 12;
FIG. 15 is a top view of the conductor shown in FIG. 14;
[Explanation of symbols]
[0051]
20, 300 Motor 30, 200, 314 Shaft 32, 312 Stator 34, 36, 210, 212, 340, 342 N-pole and S-pole 100, 352 alternately arranged in the axial direction Mandrel 150, 350 Conductor 220, 222 Longitudinal N-pole and S-pole 310 potting compound extending in the direction

Claims (26)

A shaft of a cylindrical permanent magnet extending in the axial direction, magnetically interacting with the stator, having a smooth surface along a portion of the shaft, the surface being axially A linear stepper motor having alternately arranged north and south poles in the radial direction. The linear stepper motor according to claim 1, wherein the shaft extends coaxially through the stator. The linear stepper motor according to claim 1, wherein the shaft coaxially surrounds the stator. 2. The method of claim 1, wherein at least one pair of longitudinally extending north and south poles are formed on the smooth surface with at least weak or no magnetic poles so that the shaft can rotate. Linear stepper motor. The linear stepper motor according to claim 1, wherein the part of the shaft is hollow. The linear stepper motor according to claim 1, wherein the portion of the shaft has a solid core. 7. The linear stepper motor according to claim 6, wherein the core is made of a ferromagnetic material. The linear stepper motor according to claim 6, wherein the core is made of a non-magnetic material. The linear stepper motor according to claim 1, wherein the stator includes an annular disk of a highly lubricating material that separates the members of the stator from each other and functions as a bearing surface of the shaft. The linear stepper motor according to claim 1, wherein at least the portion of the shaft comprises a single material part. The linear stepper motor according to claim 1, wherein the shaft can rotate continuously or intermittently 360 ° in any direction regardless of whether the linear stepper motor is driven. 5. The linear stepper motor of claim 4, wherein the at least one pair of longitudinally extending north and south poles can be fixed so that the shaft does not rotate during linear motion. The linear stepper motor according to claim 1, wherein the shaft is drivable in a reverse direction. The linear stepper motor according to claim 1, which can operate in any installation direction. The linear stepper motor according to claim 1, wherein the stator has a modular stator layer. The linear stepper motor according to claim 1, wherein the stator has a coil wound in a conventional manner. The linear stepper motor according to claim 1, wherein the linear stepper motor does not include a bearing. The linear stepper motor according to claim 1, wherein the linear stepper motor does not include a lead screw and a ball screw. The linear stepper motor according to claim 1, wherein no lubricant is required for any of the parts. The linear stepper motor according to claim 1, which does not require converting rotary motion to linear motion. A magnetizing device provided on an outer periphery of a part of a cylindrical smooth shaft extending in an axial direction and magnetizing N-poles and S-poles alternately arranged in an axial direction, comprising a non-magnetic and non-conductive magnet. A hollow cylindrical mandrel made of a material, and a conductive wire disposed in a parallel outer peripheral passage provided on an outer surface of the mandrel,
A potting compound surrounding the mandrel to fix the position of the wire;
A central hole provided through the mandrel in the axial direction about the center,
The magnetizing device, wherein the center hole exposes or substantially exposes the conductive wire, and the center hole has a size to receive the part of the shaft inserted in the axial direction. 22. The apparatus of claim 21, wherein the wires are arranged in the passage such that the direction of DC current flowing in adjacent wires is reversed. A method of providing N-poles and S-poles alternately arranged in a part of the axial direction of a cylindrical smooth shaft extending in the axial direction for a linear stepper motor,
(A) A hollow cylindrical mandrel made of a non-magnetic material, a conductor disposed in a parallel outer peripheral passage provided on an outer surface of the mandrel, and a potting composition surrounding the mandrel to fix the position of the conductor. A central hole extending axially about an object and the mandrel, the central hole being sized to expose or substantially expose the conductor and to receive the portion of the shaft inserted axially; Providing a magnetizing device, including:
(B) inserting the part of the shaft into the center hole;
(C) N poles alternately arranged in the axial direction, including supplying a direct current through the conductor disposed in the passage such that the direction of the direct current flowing in the conductor adjacent to the passage is reversed. And providing a south pole. 24. The method of claim 23, comprising providing the conductors disposed in the parallel outer circumferential passages such that the direction of DC current flowing in adjacent conductors of the passages is reversed. A method of manufacturing a magnetizing device for magnetizing N-poles and S-poles alternately arranged in an axial direction, provided to surround a part of the outer periphery of a cylindrical smooth shaft extending in an axial direction,
Providing a plurality of parallel peripheral passages provided on the outer surface of a cylindrical mandrel made of a non-magnetic material,
Arranging a conducting wire in the parallel outer peripheral passage;
Providing a potting compound surrounding the mandrel to fix the position of the conductor;
A central hole extending axially about the mandrel and exposing or substantially exposing the conductor, the central hole being sized to receive a portion of the shaft inserted axially; And a method of manufacturing a magnetized device. 26. The method of claim 25, comprising providing the conductors disposed in the passage such that the direction of DC current flowing in adjacent conductors is reversed.