Helical magnet torsion spring

Abstract

Systems for helical magnetic springs are presented herein. In one example, a magnetic apparatus includes an outer rotor and an inner rotor concentrically arranged with the outer rotor and separated from the outer rotor by an air gap. Each of the outer rotor and the inner rotor may include at least two interdigitated magnets of different polarity, such that a polarity of the outer rotor changes at least every 360° of the outer rotor and a polarity of the inner rotor changes at least every 360° of the inner rotor, and the outer rotor includes at least two pole-pairs along an axial length of the outer rotor and the inner rotor includes at least two pole-pairs along an axial length of the inner rotor.

Description

Docket No. PSU24305PCTHELICAL MAGNET TORSION SPRINGCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application No. 63 / 701,326, entitled “HELICAL MAGNETIC SPRING AND CONSTANT TORQUE MECHANISM” and filed on September 30. 2024, the entire contents of which are hereby incorporated by reference for all purposes.GOVERNMENT SUPPORT

[0002] This invention was made with government support under contract No. DE-EE0009958 awarded by the Department of Energy. The U.S. government has certain rights in the invention.TECHNICAL FIELD

[0003] Embodiments of the subject matter disclosed herein relate to helical magnet torsion springs.BACKGROUND

[0004] The energy within the ocean is vast, but as the ocean wave frequency is low and creates high forces, the conversion of this energy into useful power has been challenging to cost effectively realize. Currently, a new class of wave energy conversion (WEC) devices are being developed and tested that incorporate negative stiffness springs into their power take-off (PTO) mechanisms. This lowers the WEC’s frequency allowing the WEC to resonate with tire low ocean wave frequencies. For instance, one WEC uses a set of three symmetrically separated pneumatic springs to create an adjustable negative spring constant. Using this approach, with suitable controls, can increase the power output by a factor of six relative to a detuned WEC. The use of reactive springs can also significantly reduce the power generation variability and peak loading on the generator, thereby reducing the generator size and cost.

[0005] If the PTO relies on mechanical gears and pneumatics, then the long-term reliability of such a PTO will be challenging to ensure. In addition, the efficiency of pneumatic springs is often not high. For these reasons, some researchers have recently proposed to use torsional magnetic springs as the negative stiffness springs in the PTO mechanism of a WEC. While the energy density of a magnetic spring is generally lower than a single mechanical spring, a magnetic spring’s stiffness can be easily made negative in value and the stiffness can be adjusted through the simple translation of one rotor relative to the other.

[0006] One example WEC magnetic torsion spring uses tangentially magnetized rotor magnets to create a linear torque over an angular stroke length. However, the example spring design only achieved a stroke length of ±45°. Another example WEC magnetic torsion spring showed that diametric magnetized magnet rotors can create a ±90° stroke length but the torque is sinusoidal, making controlDocket No. PSU24305PCT more difficult. Conventional wisdom dictates that the torque for an electromagnetic device is limited to no greater than 90 mechanical degrees (using 1 pole-pair).SUMMARY

[0007] In one example, a magnetic apparatus includes an outer rotor and an inner rotor concentrically arranged with the outer rotor and separated from the outer rotor by an air gap. Each of the outer rotor and the inner rotor may include at least two interdigitated magnets of different polarity, such that a polarity of the outer rotor changes at least every 360° of the outer rotor and a polarity of the inner rotor changes at least every 360° of the inner rotor, and the outer rotor includes at least two polepairs along an axial length of the outer rotor and the inner rotor includes at least two pole-pairs along an axial length of the inner rotor.

[0008] It should be understood that the summary above is provided to introduce in simplified fonn a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 A depicts a helical magnetic screw configuration.

[0010] FIG. IB depicts a single pole helical magnetic screw.

[0011] FIG.1C depicts a 2-pole helical magnetic screw.

[0012] FIG. 2A depicts a single pole helical magnetic screw integrated into a magnetic spring.

[0013] FIG. 2B depicts a 2-pole helical magnetic screw integrated into a magnetic spring.

[0014] FIG. 3 depicts the sinusoidal torque produced by a plurality of helical magnetic springs.

[0015] FIG. 4A depicts a cross sectional field diagram of a helical magnetic spring.

[0016] FIG. 4B depicts a cross sectional field diagram of a single pole magnetic spring.

[0017] FIG. 4C depicts a cross sectional field diagram of a 2-pole magnetic spring.

[0018] FIGS. 5A and 5B depict Halbach array helical magnetic springs.

[0019] FIG. 6 shows a cross-sectional view of a segmented Halbach array helical magnetic spring.

[0020] FIG. 7A is a plot of FEA calculated torque as a function of rotor angular position for the helical magnetic spring.

[0021] FIG. 7B is a plot of FEA calculated axial force as a function of rotor angular position for the helical magnetic spring.

[0022] FIG. 8 illustrates a helical magnetic torsion spring prototype.

[0023] FIG. 9A shows the assembled inner rotor for the helical magnetic torsion spring.

[0024] FIG. 9B shows the assembled outer rotor for the helical magnetic torsion spring.

[0025] FIG. 9C shows the assembled the test stand for the helical magnetic torsion spring.Docket No. PSU24305PCT

[0026] FIG. 10 is a diagram of a first helical magnetic torsion spring including tw o magnetic spring units.

[0027] FIG. 11 is a perspective view of the first helical magnetic torsion spring including two magnetic spring units.

[0028] FIG. 12 is a perspective view of the first helical magnetic torsion spring including two magnetic spring units integrated into an outer shell.

[0029] FIG. 13 is a diagram of a second helical magnetic torsion spring including tw o magnetic spring units, wherein each magnetic spring includes a Halbach array of magnets.

[0030] FIG. 14 is a perspective view of the second helical magnetic torsion spring including two magnetic spring units.DETAILED DESCRIPTION

[0031] A continuous helical magnet arrangement is used in magnetic lead screw devices, for instance FIG. 1A show's the north-pole for an ideal continuous helical structure 102 used by a magnetic lead screw. If an inner rotor and outer rotor include this magnet arrangement, then w hen the inner rotor rotates relative to the fixed outer rotor, a sinusoidal torque is produced. If the continuous helical magnet arrangement is changed such that after 360° the magnet has tw isted around by only half an axial polepitch, like the single pole magnet 103 illustrated in FIG. IB, then in this case the field polarity will abruptly change sign after 360°. In the example shown in FIG. IB, the field polarity abruptly changes everj' time the single pole magnet 103 intersects w'ith the line 108. The single pole magnet 103 may include a series of segments, such as the first magnetic segment 104 and the second magnetic segment 106, w'ith each segment comprised of a single pole of a magnet w'ith each segment comprising a 360° helix. Using this type of magnet arrangement on both rotors, as shown in FIG. 2A, results in a linearly increasing torque as show n in FIG. 3.

[0032] The helical magnets can also be designed to change polarity every 180°. A 2-polc (p0=2) helical magnet spring 111 is illustrated in FIG. 1C and the corresponding rotor design is show n in FIG. 2B. In the example 2-pole helical magnet spring 111, the 2-pole helical magnet spring 111 is constructed of a series of semicircular segments of the same magnetic polarity arranged in a staggered arrangement. FIG. 1C only show s magnetic segments of a first polarity, but in some examples, magnetic segments of a second polarity may be identical to the magnetic segments of the first polarity and form a cylindrical shell made of segments of alternating polarities. The 2-pole helical magnet springl ll may include a plurality of magnetic segments, including a first magnetic segment 116. a second magnetic segment 118, and a third magnetic segment 120. Each magnetic segment (e.g., the first magnetic segment 116, the second magnetic segment 118, and the third magnetic segment 120) may be semicircular in shape and all the magnetic segments may be identical in shape and size. In one example, the first magnetic segment 116 may be arranged to face a first direction 115. The second magnetic segment 118 may be adjacent to the first magnetic segment 116, but face a direction opposite to the first direction 115. TheDocket No. PSU24305PCT third magnetic segment 120 may be identical to the first magnetic segment 116 but positioned adjacent to the second magnetic segment 118. Each magnetic segment of the 2-pole helical magnet spring 111 is a segment of a cylindrical shell with a width 122, and the polarity of the segments change every 180° of rotation. In the 2-pole helical magnet spring 111, the polarity of the segments changes at a first axis 110 positioned at 0°, and at a second axis 112 positioned at 180°.

[0033] Thus. FIGS. IB and 1C show examples of magnets comprised of discontinuous magnetic segments of the same polarity that are arranged to fonn a helical (or helical-like) structure. For example, FIG. IB shows a first magnet comprised of three magnetic segments of the same polarity, arranged axially. Each magnetic segment of the magnet of FIG. IB may be a helix of one turn, and the magnetic segments may be arranged in a tail to head configuration, such that a tail of the first magnetic segment 104 (e.g., an end of the helix) is positioned adjacent a head of the second magnetic segment 106 (e.g., a beginning of the helix). FIG. 1C shows a second magnet comprised of six magnetic segments of the same polarity. Each magnetic segment of FIG. 1C may comprise one-half a turn (e.g., a semi-circle as explained above). The magnetic segments may be arranged axially in an alternating orientation fashion. For example, the first magnetic segment 116, the second magnetic segment 118, and the third magnetic segment 120 may be distributed axially, with the second magnetic segment 118 intermediate the first magnetic segment 116 and the third magnetic segment 120. but in an opposite orientation.

[0034] The magnets of FIGS. IB and 1C may be interdigitated with a similar magnet of opposite polarity7to form a rotor. Two rotors of similar configuration but different diameters may’ be concentrically arranged to form a helical magnetic spring, as shown in FIGS. 2A and 2B and described below.

[0035] FIG. 2A shows a single-pole magnetic torsion spring 200. The single-pole magnetic torsion spring 200 includes an outer rotor 202 and an inner rotor 204. The outer rotor 202 may be a cylindrical shell that surrounds the inner rotor 204. The inner rotor 204 may also be a cy lindrical shell. The iimer rotor 204 may surround a central gap 206, and the inner rotor 204 may be separated from the outer rotor 202 by an air gap 208. The inner rotor 204 and the outer rotor 202 may both be constructed of single pole magnets, with each single-pole magnet being similar to the single pole magnet 103 illustrated in FIG. IB. The outer rotor 202 may include a first magnet 210 of a first polarity and a second magnet 212 of a second polarity. The first magnet 210 may be comprised of multiple (e.g.. two) magnetic segments that are similar to the first magnetic segment 104. for example. The second magnet 212 may likewise be comprised of multiple magnetic segments (e.g., two magnetic segments). The first polarity may be a radially outward magnetic polarity' and the second polarity may be a radially inward magnetic polarity. The polarity of the iimer rotor 204 and the outer rotor 202 may change every 360° of rotation. A line 213 marks the positions on the outer rotor 202 where the polarity of the magnets that make up the outer rotor 202 change. The first magnet 210 and the second magnet 212 may be interdigitated in such a way that a checkerboard pattern of magnets of the first polarity’ and magnets of the second polarity may be visible across the line 213. There may be a similar line on the inner rotorDocket No. PSU24305PCT204 that marks the positions on the inner rotor 204 where the polarity of the magnets that make up the inner rotor change. The inner rotor 204 may be configured to rotate, and as such the similar line on the inner rotor may be defined by a radius and azimuthal angle that is stationary in a frame of reference that rotates with the inner rotor 204. Similarly to the outer rotor 202, the inner rotor 204 may be made of magnetic segments similar to the single pole magnet 103 illustrated in FIG. IB. The inner rotor may also be made of magnets of the first polarity and of the second polarity constructed to form a cylindrical shell.

[0036] FIG. 2B shows a 2-pole helical magnet spring design integrated into a 2-pole magnetic torsion spring 214. The 2-pole magnetic torsion spring 214 may include an outer rotor 216 and an inner rotor 218. The outer rotor 216 may be a cylindrical shell that surrounds the inner rotor 218. The inner rotor 218 may also be a cylindrical shell. The inner rotor 218 may surround a central gap 220. and the inner rotor 218 may be separated from the outer rotor 216 by an air gap 219. The inner rotor 218 and the outer rotor 216 may both be constructed of magnets, with each magnet being similar to the first magnetic segment 116 or the second magnetic segment 106 of the single pole magnet 103 illustrated in FIG. 1C. The inner rotor 218 and the outer rotor 216 each include a plurality of annular segments, with each annular segment including two magnetic segments of opposite polarity arranged to form a slanted annulus and adjacent annular segments are rotated 180 degrees relative to each other so that magnetic segments of opposite polarity are adjacent to each other. The outer rotor 216 may include a first magnetic segment 222 of a first polarity' that may be joined in face-sharing contact with a second magnetic segment 224 of a second polarity. The magnetic segments that comprise the outer rotor 216 may all be identical in dimensions. For example, all magnetic segments of the outer rotor 216 may have the same inner radius, outer radius, width, etc. The first magnetic segment 222 and the second magnetic segment 224 may form an annular segment of the outer rotor 216. The first magnetic segment 222 may be adjacent to a third magnetic segment 226 of the second polarity. The second magnetic segment 224 may be adjacent to a fourth magnetic segment 228 of the first polarity . The first magnetic segment 222 and the second magnetic segment 224 may form a first slanted annular segment and the third magnetic segment 226 and the fourth magnetic segment 228 may form a second slanted annular segment. The outer rotor 216 may be formed out of a plurality of annular segments in an alternating pattern between annular segments configured like the first slanted annular segment and annular segments configured like the second annular segment.

[0037] Using the one pole magnet arrangement shown in FIG. IB on both rotors, as shown in FIG. 2A, results in a linearly increasing torque as shown in line (a) of FIG. 3. FIG. 3 plots the normalized torque as a function of the angle between the inner rotor and the outer rotor for (a) one pole helical magnet design such as the one shown in FIG. 2A and (b) 2-pole helical magnet design such as the one shown in FIG. 2B and (c) with a Halbach magnet design (shown in FIG. 5 A and described below) rather than only radially magnetized magnets. The comparison was computed using JMAG3-D finite element analysis software with N-50 grade magnets. Note that the radial magnet design used a back-iron, whichDocket No. PSU24305PCT may be a layer of iron or steel on the outer circumference of the outer rotor, and / or a layer of iron or steel on the inner circumference of the inner rotor. The stroke is ±130° in length, greater than the conventional 90° for a tw o-pole rotor. The stroke length exceeds the normal ±90° because the magnet polarity reverses suddenly at zero degrees. This can be further understood by considering the magnetization maps shown in FIGS. 4A and 4B. FIG. 4A and 4B show the magnetization map for one rotor for a magnetic lead screw 400, such as a rotor constructed from the helical magnets depicted in FIG. 1 A, and a single pole helical spring rotor 402. such as the single-pole magnetic torsion spring 200, respectively. One can imagine that when a second equivalent rotor moves above and between the two lines, a first line 408 and a second line 410 shown in FIG. 4A, the radial and azimuthal fields will both slowly change due to the edge interactions increasing as the rotors move past one another. This thereby results in sinusoidal torque. The torque can be computed at the air gap radius (rg) by evaluating the surface integral:

[0039] where Be and B, are the azimuthal and radial magnetic flux density and the superscripts z, o indicate inner and outer rotors, respectively. If one now compares the magnetization map shown in FIG. 4B. it can be noted that the one-pole helical spring magnetization direction suddenly changes from north to south at 0°. This creates a sizable azimuthal field B$ at tire interface, and this will then interact with the outer rotor’s radial flux density B° to create an increasing torque past the normal 90° crossover position, thereby creating the torque profde as show n in FIG. 3.

[0040] Comparing the one pole rotor design shown in FIG. 2A to the 2-pole rotor design shown in FIG. 2B, the 2-pole design creates a higher peak torque, without decreasing the stroke length, as confirmed in the normalized torque plot shown in FIG. 3. The reason the stroke length does not decrease for the 2-pole design can be understood by considering the magnetization plot 406 as shown in FIG. 4C, which shows the same field pattern as in FIG. 4B but with oppositely angled magnets.

[0041] Thus, a helical magnetic spring may be formed from an outer rotor and an inner rotor concentrically arranged with the outer rotor and separated from the outer rotor by an air gap. Each of the outer rotor and the inner rotor may be comprised of at least two interdigitated magnets of different polarity, such that a polarity of the outer rotor changes at least every 360° of the outer rotor and a polarity of the inner rotor changes at least every 360° of the inner rotor. In the example shown in FIG. 2A, the polarity of the changes every 360° and in the example of FIG. 2B, the polarity changes every 180°. As used herein, ‘"every 360°” may include for any point on the outer rotor or inner rotor, a circle along the circumference of the outer rotor or inner rotor that intersects that point will intersect a change in polarity' exactly one time. As used herein, “every 180°” may include for any point on the outer rotor or inner rotor, a circle along the circumference of the outer rotor or inner rotor that intersects that pointDocket No. PSU24305PCT will intersect a change in polarity exactly two times.

[0042] In the example of FIG. 2A, the outer rotor may be comprised of a first radial magnet interdigitated with a second radial magnet, the first radial magnet having a first magnetic polarity and the second radial magnet having a second magnetic polarity, wherein the first magnetic polarity is radially inward and the second magnetic polarity is radially outward. The first radial magnet may be the magnet of FIG. IB and the second radial magnet may be similar to the magnet of FIG. IB, but with an opposite polarity and orientation (e.g., flipped horizontally). Thus, the first radial magnet may be comprised of a first helical magnetic segment and a second helical magnetic segment, each traversing 360° and the second radial magnet may be comprised of a third helical magnetic segment and a fourth helical magnetic segment, each traversing 360°. Along an axial direction (e.g.. parallel to the z axis), the third helical magnetic segment may be arranged intermediate the first helical magnetic segment and the second helical magnetic segment. It is to be appreciated that in the magnet of FIG. IB. each magnetic segment has the same width and the width of a given magnetic segment is constant. However, when incorporated into the helical magnetic spring of FIG. 2A, the outer magnetic segments that form the edges of the spring may decrease or increase in width along the helix. It is to be appreciated that the inner rotor may be identical to the outer rotor, but with a smaller diameter to be arranged concentrically with the outer rotor.

[0043] Similarly, in the example of FIG. 2B, the outer rotor may be comprised of a first radial magnet interdigitated with a second radial magnet, the first radial magnet having a first magnetic polarity7and the second radial magnet having a second magnetic polarity, wherein the first magnetic polarity’ is radially inward and the second magnetic polarity is radially outward. The first radial magnet may be the magnet of FIG. 1C and the second radial magnet may be similar to the magnet of FIG. 1C, but with an opposite polarity and orientation (e.g., flipped horizontally). Thus, the first radial magnet may be comprised of a first magnetic segment, a second magnetic segment, and a third magnetic segment, each traversing f80° and arranged axially, with the second magnetic segment having an opposite orientation as the first and third magnetic segments, and the second radial magnet may be comprised of a fourth magnetic segment, a fifth magnetic segment, and a sixth magnetic segment, each traversing f80° and arranged axially, with the fifth magnetic segment having an opposite orientation as the fourth and sixth magnetic segments. Along an axial direction (e.g., parallel to the z axis), the fifth magnetic segment may be arranged intermediate the first magnetic segment and the third magnetic segment. In this configuration, the polarity' of the outer rotor changes every 180°. It is to be appreciated that the inner rotor may be identical to the outer rotor, but with a smaller diameter to be arranged concentrically with the outer rotor.

[0044] To increase the energy density and remove the back-iron, a Halbach magnet array, as shown in FIGS. 5A and 5B, was also geometrically studied. FIG. 5A is a diagram of a first Halbach array magnetic spring 500. Like the single-pole magnetic torsion spring 200 and the 2-pole magnetic torsion spring 214. the first Halbach array magnetic spring 500 includes an outer rotor 502 and an innerDocket No. PSU24305PCT rotor 504. The first Halbach array magnetic spring 500 may be similar to the 2-pole magnetic torsion spring 214, in that the shape and positioning of the magnetic segments that make up the outer rotor 502 and the inner rotor 504 may be identical in shape to the magnetic segments that make up the inner rotor 218 and the outer rotor 216. However, the segments that make up the iimer rotor 504 and the outer rotor 502 may have different magnetic polarities than the polarities of the segments that make up the 2-pole magnetic torsion spring 214.

[0045] The outer rotor 502 may include a plurality of groups of magnetic segments with different polarities. For example, a first group of magnetic segments includes a first segment 506 of a first polarity, a second segment 508 of a second polarity, a third segment 510 of a third polarity, and a fourth segment 512 of a fourth polarity'. The first polarity may be a first radial direction, such as radially inwards. The second polarity may be a second radial direction antiparallel to the first radial direction. The third polarity may be a first axial direction, parallel to a z-axis 514. and the fourth polarity may be a second axial direction antiparallel to the first axial direction. The first segment 506 may be in face sharing contact with the second segment 508. The first segment 506 may be adjacent to the third segment 510. and the second segment 508 may be adjacent to the fourth segment 512. The third segment 510 may be in face sharing contact with the fourth segment 512.

[0046] A second group of magnetic segments may be positioned next to the first group. For example, the third segment 510 may be adjacent to a fifth segment 516 of the second polarity'. The second segment 508 may be adjacent to a sixth segment 518 of the first polarity. The fifth segment 516 and the sixth segment 518 may be in face sharing contact. The fifth segment 516 may be adjacent to a seventh segment 520 of the fourth polarity. The sixth segment 518 may be adjacent to an eighth segment 522 of the third polarity. The seventh segment 520 may be in face sharing contact with the eighth segment 522.

[0047] The pattern of segment polarities described above may be repeated one or more times based on the length and size of the first Halbach array magnetic spring 500 (c.g., the first Halbach array magnetic spring 500 may include two or more groups of magnetic segments). The magnetic segments that make up the outer rotor 502 and the inner rotor 504 may be slanted at an angle relative to a y-axis 528. However, a flat top 530 and a flat bottom 534 of the first Halbach array magnetic spring 500 may be in a plane parallel to the y-axis 528 and perpendicular to the z-axis 514. For this reason, the magnetic segments that form the flat top 530 and the flat bottom 534 may be incomplete compared to other magnetic segments, such as the sixth segment 518. The magnetic segments of the outer rotor 502 that form the flat top 530 may include a first end segment 524 in face sharing contact with a second end segment 526. The outer rotor 502 may also include a third end segment 532 on the flat bottom 534. The first end segment 524, the second end segment 526, and the third end segment 532 may be partial iterations of segments such as the second segment 508 of the first polarity to provide the flat top 530 and the flat bottom 534.

[0048] The inner rotor 504 may be assembled out of magnetic segments in the same pattern andDocket No. PSU24305PCT arrangement as the outer rotor 502, but with magnetic segments of a smaller size. The inner rotor 504 may further include one or more end segments analogous to the first end segment 524, the second end segment 526, and the third end segment 532 to create the flat top 530 and the flat bottom 534.

[0049] FIG. 5B is a diagram of a second Halbach array magnetic spring 536. The second Halbach array magnetic spring 536 is identical to the first Halbach array magnetic spring 500, with the exception that the end segments of the second Halbach array magnetic spring 536 are comprised of a material that does not have a magnetic polarity (or the end segments may be omitted entirely). For example, the second Halbach array magnetic spring 536 may include a first end segment 538 identical in shape to the first end segment 524, a second end segment 540 identical in shape to the second end segment 526, and a third end segment 542 identical in shape to the third end segment 532, with each of the first end segment 538, the second end segment 540, and the third end segment 542 being made of a non-magnetic material. The inner rotor of the second Halbach array magnetic spring 536 may also include end segments comprised of the non-magnetic material and configured to create a flat top and a flat bottom of the second Halbach array magnetic spring 536.

[0050] Using the same geometric parameters as the other magnet spring configurations, a normalized torque comparison plot is shown as line (c) in Error! Reference source not found. 3. The Halbach magnet array increased the torque by 40% for the same magnet volume, however the linearity did decrease. As an increase in torque density may be the priority for wave energy converter applications, the Halbach array design was selected for further investigation.

[0051] To build the helical design, the magnets may be segmented. In addition, to facilitate manufacturability the magnets are made all the same axial width, these changes result in an axial stepping on the sides of the rotor. This magnet segmented helical magnet design is shown in FIG. 6. Each 180° helix turn is separated into n magnet segments and each magnet is axially displaced by an axial shift length Ls with respect to the adjacent magnet. The length Ls for each 180° helix turn is defined as:

[0052] L 5 — w / n

[0053] where w is the magnet axial width.

[0054] A cross sectional view of an example segmented Halbach design 600 is shown in FIG. 6. In the example segmented Halbach design 600 design n =50 was selected, but other n values are possible. The example segmented Halbach design 600 is similar to first Halbach array magnetic spring 500 in construction. The example segmented Halbach design 600 includes an outer rotor 602 separated from an iimer rotor 604 by an air gap 606. Like first Halbach array magnetic spring 500, the example segmented Halbach design 600 is made of angled semicircular magnetic segments; however, the semicircular magnetic segments of the example segmented Halbach design 600 are each composed of n magnetic segments of the same magnetic polarity, each segment axially displaced a width Ls fromDocket No. PSU24305PCT die adjacent magnets to approximate the curves of the magnetic segments described with respect to FIG. 5A. The Halbach pattern described with respect to FIG. 5A is established in the semicircular magnetic segments that make up the example segmented Halbach design 600.

[0055] The torque and force as a function of imier rotor angular position using the N-50 grade magnets was analyzed through 3 D FEA across various axial rotor offset positions, zt. The torque and axial force plot for the finalized design are shown in FIGS. 7A and 7B respectively. The legend shows the different axial offset positions and how increasing the axial offset reduces the spring stiffness. When the outer rotor is positioned at zt = 50 mm, the resulting torque is zero. When the outer rotor is positioned at zt = 0 mm, the resulting force is zero. The axial force is zero at the maximum stiffness position. The maximum torque, observed at an angle 9 = 130°, was calculated to be Tm = 2307 N-m.

[0056] The proof-of-principle mechanical design 800 is shown in FIG. 8 and the assembled inner rotor 900 and the assembled outer rotor 902are shown in FIGS. 9A and 9B, respectively and FIG. 9C shows the test stand 904 that is under construction. In one example, the inner rotor includes a pa =3- pole inner rotor design for the proof-of-principle prototype. This resulted in the torque decreasing by 26.4%. The experimental prototype used magnets that are all the same width and so the magnets on the edge, as shown in FIG. 5A. are not present. The view shown in FIG. 8 is a partial cross-section view, with the outer rotor shown in cross-section to allow visualization of the inner rotor.

[0057] Thus, a helical magnetic spring may be comprised of a Halbach array to incorporate additional polarities into the spring. Similar to the magnetic springs of FIGS. 2A and 2B, the magnetic springs of FIGS. 5 A. 5B. and 6 may be comprised of an outer rotor and an inner rotor concentrically arranged with the outer rotor and separated from the outer rotor by an air gap. Each of the outer rotor and the inner rotor may be comprised of at least two interdigitated magnets of different polarity7, such that a polarity7of the outer rotor changes at least every7360° of the outer rotor and a polarity of the inner rotor changes at least every 360° of the inner rotor. Further, the outer rotor may be comprised of a first magnet and a second magnet interdigitated with a third magnet and a fourth magnet, the first magnet having a first magnetic polarity and the second magnet having a second magnetic polarity, wherein the first magnetic polarity is radially inward and the second magnetic polarity is radially outward, the third magnet having a third magnetic polarity and the fourth magnet having a fourth magnetic polarity7, wherein the third magnetic polarity is hi a first axial direction and the fourth magnetic polarity is in a second axial direction opposite to the first axial direction. For example, in FIG. 5A, the first magnet may be comprised of the dark blue segments, and thus includes a plurality of discontinuous magnetic segments each having a semi-circular shape and distributed axially, with alternating orientations. In this manner, the first magnet may be similar to the magnet of FIG. 2B, but the magnetic sections may be spaced apart by a greater amount to allow incorporation of additional magnets. The remaining magnets may be configured similarly. For example, the second magnet may be comprised of the red segments, the third magnet may be comprised of the light blue segments, and the fourth magnet may be comprised of the pink segments. In the example of FIG. 6, each magnetic segment may itself be comprised ofDocket No. PSU24305PCT offset segments to create angled segments, as described above. Further, the number of magnetic segments of each polarity may not be equal; in the outer rotor of FIG. 6, the fourth magnet may have fewer segments than the first, second, and third magnets. It is to be appreciated that the inner rotor may be configured similarly as the outer rotor, but with a smaller diameter. In the case of the example of FIG. 6, the third magnet of the inner rotor may have fewer segments than the first, second, and fourth magnets.

[0058] In some examples, a helical magnetic torsion spring, such as the 2-pole magnetic torsion spring 214, may produce a sinusoidal axial torque, and an additional off-axis torque, which may in some examples be sinusoidal. The off-axial torque may cause wear on machinery coupled to the 2-pole magnetic torsion spring 214, such as proof-of-principle mechanical design 800. FIG. 10 shows a magnetic torsion spring 1000 that may be designed to mitigate off-axial torque. FIGS. 10-14 may be described with respect to a Cartesian coordinate system 1010. The Cartesian coordinate system 1010 may include a z-axis. a y-axis, and an x-axis that are mutually orthogonal. Each axis may be represented by an arrow, wherein each arrow represents a positive direction along the listed axis. A filled circle represents an arrow extending directly out of the figure. The magnetic torsion spring 1000 includes a first magnetic spring unit 1004 and a second magnetic spring unit 1006. The first magnetic spring unit 1004 and the second magnetic spring unit 1006 may be cylindrical shells centered around a central shaft 1002. The central shaft 1002 may be a cylindrical shell that has a length along the z-axis greater than the length of the first magnetic spring unit 1004 and the second magnetic spring unit 1006, such that the central shaft 1002 extends past the first magnetic spring unit 1004 and the second magnetic spring unit 1006 along the z-axis. The first magnetic spring unit 1004 and the second magnetic spring unit 1006 may be separated by a gap 1008. The central shaft 1002 may be made of a metallic material such as iron or steel in some examples.

[0059] The first magnetic spring unit 1004 may be a helical magnetic torsion spring similar to the 2-polc magnetic torsion spring 214. The second magnetic spring unit 1006 may be similar to the first magnetic spring unit 1004. The first magnetic spring emit 1004 may include a first outer magnetic segment 1012 and a second outer magnetic segment 1014, among other outer magnetic segments. The second magnetic spring unit 1006 may include a third outer magnetic segment 1016 and a fourth outer magnetic segment 1018, among other magnetic segments. The first outer magnetic segment 1012 and the fourth outer magnetic segment 1018 may each be magnetically polarized in a radially inward direction. The second outer magnetic segment 1014 and the third outer magnetic segment 1016 may each be polarized in a radially outward direction. The first outer magnetic segment 1012 may face the third outer magnetic segment 1016 across the gap 1008 and the second outer magnetic segment 1014 may face the fourth outer magnetic segment 1018 across the gap 1008.

[0060] The magnetic segments of the first magnetic spring unit 1004 may be angled similarly to the magnetic segments of the 2-pole magnetic torsion spring 214 and as shown by the magnetization plot 406, wherein the first magnetic spring unit 1004 includes a plurality of magnetic segments angledDocket No. PSU24305PCT relative to the y axis and in opposition to each other across the z-axis. For example, the magnetic segments of the first magnetic spring unit 1004 are angled relative to the y axis in the -z direction. Similarly, the magnetic segments of the second magnetic spring unit 1006 may be angled similarly to the magnetic segments of the 2-pole magnetic torsion spring 214 and as shown by the magnetization plot 406, wherein the second magnetic spring unit 1006 includes a plurality of magnetic segments angled relative to the y axis and in opposition to each other across the z-axis. For example, the magnetic segments of the second magnetic spring unit 1006 are angled relative to the y axis in the +z direction. In this way. the magnetic segments of the first magnetic spring unit 1004 angle toward the second magnetic spring unit 1006 and the magnetic segments of the second magnetic spring unit 1006 angle toward the first magnetic spring unit 1004.

[0061] A perspective view of the magnetic torsion spring 1000 is shown in FIG. 11. Like the 2- pole magnetic torsion spring 214, the first magnetic spring unit 1004 may include an outer rotor 1102 and an inner rotor 1104. similar to the outer rotor 216 and the inner rotor 218 of the 2-pole magnetic torsion spring 214. The outer rotor 1102 may be a cylindrical shell comprised of magnetic segments of a first radius that surrounds the inner rotor 1104, which is a cylindrical shell comprised of magnetic segments of a second radius. The first outer magnetic segment 1012 and the second outer magnetic segment 1014 may be included in the outer rotor 1102. The inner rotor 1104 may be separated from the outer rotor 1102 by an air gap 1106 to allow the inner rotor 1104 and the outer rotor 1102 to rotate independently from each other. The inner rotor 1104 may have the same length as the outer rotor 1102 in some examples, and in some examples, the width of the magnetic segments that make up the inner rotor 1104 and the outer rotor 1102 may be the same width along the z-axis. In some examples, the inner rotor 1104 may be comprised of the same pattern of magnetic segments as the outer rotor 1102. The second magnetic spring unit 1006 may include an outer rotor and an inner rotor similar in design to the inner rotor 1104 and the outer rotor 1102 but configured to match the second magnetic spring unit 1006. For example, the outer rotor of the second magnetic spring unit 1006 may include the third outer magnetic segment 1016 and the fourth outer magnetic segment 1018.

[0062] In some examples, the magnetic torsion spring 1000 may be integrated into a magnetic spring assembly 1200 shown in FIG. 12. The magnetic spring assembly 1200 may include an outer shell 1202 that is cylindrical in shape and surrounds the first magnetic spring unit 1004 and the second magnetic spring unit 1006. In some examples, the outer shell 1202 may have the same length along the z-axis as the central shaft 1002. In some examples, the outer shell 1202 may be made of the same material as the central shaft 1002. In some examples, the first magnetic spring unit 1004 and the second magnetic spring unit 1006 may be configured to translate and rotate identically, such that the second magnetic spring unit 1006 translates and rotates the same amount as the first magnetic spring unit 1004 when the first magnetic spring unit 1004 translates or rotates. In other examples, the first magnetic spring unit 1004 and the second magnetic spring unit 1006 may translate and rotate independently. TheDocket No. PSU24305PCT magnetic torsion spring 1000 described above may produce minimal torque along the x-axis and the y- axis.

[0063] A Halbach magnetic torsion spring 1300 is shown in FIG. 13. Like die magnetic torsion spring 1000, the Halbach magnetic torsion spring 1300 may include two magnetic spring units configured to be mounted on a common shaft. However, the polarity of the magnetic segments that are included in the Halbach magnetic torsion spring 1300 are arranged in a Halbach pattern rather than the alternating radial inward and radially outward magnetic polarities included in the magnetic torsion spring 1000. The Halbach magnetic torsion spring 1300 includes a first magnetic spring unit 1302 and a second magnetic spring unit 1304 each of which is similar to the second Halbach array magnetic spring 536 (though with fewer magnetic segments). The first magnetic spring unit 1302 and the second magnetic spring unit 1304 may be separated by a gap 1322. The first magnetic spring unit 1302 and the second magnetic spring unit 1304 may be made up of magnetic segments identical in shape to the magnetic segments that make up the first magnetic spring unit 1004 and the second magnetic spring unit 1006.

[0064] The first magnetic spring unit 1302 includes a first magnetic segment 1306, a second magnetic segment 1308, a third magnetic segment 1310, and a fourth magnetic segment 1312. The first magnetic segment 1306 is coupled to the second magnetic segment across the z-axis. and the first magnetic segment 1306 is adjacent to the third magnetic segment 1310 along the z-axis. The Third magnetic segment is coupled to the fourth magnetic segment 1312 across the z-axis. The second magnetic segment 1308 is adjacent to the fourth magnetic segment 1312 along the z-axis. The first magnetic segment 1306 has a first magnetic polarity, the second magnetic segment 1308 has a second magnetic polarity, the third magnetic segment 1310 has a third magnetic polarity, and the fourth magnetic segment has a fourth magnetic polarity. The first magnetic polarity may be in the +z direction, the second magnetic polarity may be in the z direction, the third magnetic polarity may be radially inward and the fourth magnetic polarity may be radially outw ard. Magnetic segments with antiparallcl magnetic polarities may be paired across the z-axis, for example, the first magnetic segment 1306 and the second magnetic segment 1308.

[0065] The second magnetic spring unit 1304 includes a fifth magnetic segment 1314. a sixth magnetic segment 1316, a seventh magnetic segment 1318, and an eighth magnetic segment 1320. The fifth magnetic segment may be coupled to the sixth magnetic segment 1316 across the z-axis, and the fifth magnetic segment 1314 may be adjacent to the seventh magnetic segment 1318 along the z-axis. The seventh magnetic segment 1318 may be coupled to the eighth magnetic segment 1320 across the z-axis. The eighth magnetic segment 1320 may be adjacent to the sixth magnetic segment 1316 along the z-axis. The fifth magnetic segment 1314 has the second polarity, the sixth magnetic segment 1316 has the first polarity, the seventh magnetic segment has the fourth polarity, and the eighth magnetic segment has the first polarity. The third magnetic segment 1310 may face the fifth magnetic segment 1314 across the gap 1322 and the fourth magnetic segment 1312 may face the sixth magnetic segmentDocket No. PSU24305PCT1316 across the gap 1322. The first magnetic segment 1306 has a polarity that is antiparallel to the polarity of the fifth magnetic segment 1314, the second magnetic segment has a polarity that is antiparallel to the polarity of the sixth magnetic segment 1316, the third magnetic segment 1310 has a polarity that is antiparallel to the polarity of the seventh magnetic segment 1318, and the fourth magnetic segment 1312 has a polarity that is antiparallel to the polarity of the eighth magnetic segment 1320. Similar to the magnetic torsion spring 1000, the magnetic segments of the first magnetic spring unit 1302 may angle relative to the y axis, in the -z direction, toward the second magnetic spring unit 1304. The magnetic segments of the second magnetic spring unit 1304 may angle relative to the y axis, in the +z direction, toward the first magnetic spring unit 1302.

[0066] A perspective view of the Halbach magnetic torsion spring 1300 is shown in FIG. 14. In FIG. 14 it is visible that the first magnetic spring unit 1302 includes an inner rotor 1404 and an outer rotor 1402 similar to the inner rotor and the outer rotor of the second Halbach array magnetic spring 536. The inner rotor 1404 may have the same Halbach pattern of magnetic polarities as the outer rotor 1402. The second magnetic spring unit 1304 may include an inner rotor and an outer rotor similar to the inner rotor 1404 and the outer rotor 1402 configured to match the Halbach pattern of the second magnetic spring unit 1304.

[0067] In a first example, a helical magnetic spring include an inner rotor and an outer rotor that may each be constructed from magnetic segments that are each positioned such that after 360 degrees the magnet has tw isted around by only half an axial pole-pitch, and may be referred to as single pole magnets. Two single pole magnetic segments of opposite orientation may be coupled to form a cylindrical shell, and one or more pairs of magnetic segments may be placed adjacently to form a longer cylindrical shell that may make up the inner rotor or outer rotor. Each pair of single pole magnetic segments may include one magnetic segment with a radially inward magnetic polarity and one magnetic segment with a radially outward magnetic polarity .

[0068] In a second example of a helical magnetic spring, the magnetic segments that make up the inner rotor and outer rotor may be arranged to change polarity every 180 degrees. The magnetic segments may each be semicircular in shape, and each magnetic segment may be mated with a magnetic segment of an opposite radial magnetic polarity to form an annular segment (which may be angled in some examples). The annular segments may be arranged to form the inner rotor or tire outer rotor. The annular segments may be arranged so that the magnetic polarity of adjacent segments are opposite. The inner rotor and the outer rotor may be constructed in the same manner, but the inner rotor may have a smaller radius than the outer rotor in order to fit within the outer rotor.

[0069] In a third example of the helical magnetic spring, the magnetic segments may be arranged in the same form as the second example of the helical magnetic spring, but the polarities of the magnets may be arranged in a Halbach pattern. In a Halbach pattern, magnetic segments with antiparallel polarities are paired into annular segments and placed adjacently to magnetic segments that haveDocket No. PSU24305PCT polarities perpendicular to the polarity of adjacent annular segments. In one example, a first set of magnetic segments may have radial polarities and a second set of magnets may have axial polarities.

[0070] In each example of the helical magnetic spring, the helical magnetic spring produces a sinusoidal torque over a stroke length greater than 90 degrees. The stroke length may exceed 90 degrees because the polarity of the magnets that make up tire spring change every 180 degrees. A stroke length larger than 90 degrees allows the helical magnetic spring to increase the distance over which the torque is applied without necessarily increasing the radius of the helical magnetic spring. The above described helical magnetic springs may also be capable of adjusting the magnitude and direction of torque by changing the axial position of the outer rotor relative to the inner rotor, which may in some cases produce a negative spring stiffness. In addition, magnetic springs may be reliable over long time scales and more efficient than pneumatic springs. For the above described advantages, it may be advantageous to include magnetic springs rather than pneumatic springs within a wave energy converter.

[0071] The figures show example configurations with relative positioning of the various components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example. As yet another example, elements shown above / below one another, at opposite sides to one another, or to the left / right of one another may be referred to as such, relative to one another. Further, as shown in the figures, a topmost element or point of element may be referred to as a “top” of the component and a bottommost element or point of the element may be referred to as a “bottom” of the component, in at least one example. As used herein, top / bottom, upper / lower, above / below, may be relative to a vertical axis of the figures and used to describe positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example. As yet another example, shapes of the elements depicted within the figures may be referred to as having those shapes (e g., such as being circular, straight, planar, curved, rounded, chamfered, angled, or the like). Further, elements shown intersecting one another may be referred to as intersecting elements or intersecting one another, in at least one example. Further still, an element shown within another element or shown outside of another element may be referred as such, in one example.

[0072] The disclosure also provides support for a magnetic apparatus, comprising: an outer rotor, and an inner rotor concentrically arranged with the outer rotor and separated from the outer rotor by an air gap, wherein each of the outer rotor and the inner rotor is comprised of at least two interdigitated magnets of different polarity, such that a polarity of the outer rotor changes at least every 360° of the outer rotor and a polarity of the inner rotor changes at least every 360° of the inner rotor, and the outerDocket No. PSU24305PCT rotor includes at least two pole-pairs along an axial length of the outer rotor and the inner rotor includes at least two pole-pairs along an axial length of the inner rotor. In a first example of the apparatus, the outer rotor is comprised of a first radial magnet interdigitated with a second radial magnet, the first radial magnet having a first magnetic polarity and the second radial magnet having a second magnetic polarity, wherein the first magnetic polarity is radially inward and the second magnetic polarity is radially outward. In a second example of the apparatus, optionally including the first example, the first radial magnet is comprised of a first helical magnetic segment and a second helical magnetic segment, each traversing 360°. In a third example of the apparatus, optionally including one or both of the first and second examples, the second radial magnet is comprised of a third helical magnetic segment and a fourth helical magnetic segment, each traversing 360°. In a fourth example of the apparatus, optionally including one or more or each of the first through third examples, along the axial length of the outer rotor, the third helical magnetic segment is arranged intermediate the first helical magnetic segment and the second helical magnetic segment. In a fifth example of the apparatus, optionally including one or more or each of the first through fourth examples, the first radial magnet is comprised of a first magnetic segment, a second magnetic segment, and a third magnetic segment, each traversing 180° and arranged axially, with the second magnetic segment having an opposite orientation as the first and third magnetic segments. In a sixth example of the apparatus, optionally including one or more or each of the first through fifth examples, the second radial magnet is comprised of a fourth magnetic segment, a fifth magnetic segment, and a sixth magnetic segment, each traversing 180° and arranged axially, with the fifth magnetic segment having an opposite orientation as the fourth and sixth magnetic segments. In a seventh example of the apparatus, optionally including one or more or each of the first through sixth examples, along the axial length of the outer rotor, the fifth magnetic segment is arranged intermediate die first magnetic segment and the third magnetic segment. In an eighth example of the apparatus, optionally including one or more or each of the first through seventh examples, the polarity of the outer rotor changes every 180°. In a ninth example of the apparatus, optionally including one or more or each of the first through eighth examples, the outer rotor is comprised of a first magnet and a second magnet interdigitated with a third magnet and a fourth magnet, the first magnet having a first magnetic polarity and the second magnet having a second magnetic polarity, wherein the first magnetic polarity is radially inward and the second magnetic polarity is radially outward, the third magnet having a third magnetic polarity and the fourth magnet having a fourth magnetic polarity, wherein the third magnetic polarity is in a first axial direction and the fourth magnetic polarity is in a second axial direction opposite to the first axial direction. In a tenth example of the apparatus, optionally including one or more or each of the first through ninth examples, each of the first magnet, the second magnet, the third magnet, and the fourth magnet is comprised of at least two discontinuous magnetic segments with alternating orientations. In an eleventh example of the apparatus, optionally including one or more or each of the first through tenth examples, each of the first magnet, the second magnet, the third magnet, and the fourth magnet comprises an equal number of discontinuous magnetic segments. In a twelfth exampleDocket No. PSU24305PCT of the apparatus, optionally including one or more or each of the first through eleventh examples, each magnet of the outer rotor is comprised of a plurality of outer magnetic segments and each magnet of die inner rotor is comprised of a plurality of inner magnetic segments. In a thirteenth example of the apparatus, optionally including one or more or each of the first through tw elfth examples, the plurality of inner magnetic segments includes more magnetic segments than die plurality of inner magnetic segments.

[0073] The disclosure also provides support for a helical magnetic spring, comprising: an inner rotor including one or more first magnetic segments, an outer rotor including one or more second magnetic segments, wherein the outer rotor is a first cylindrical shell of a first radius and the inner rotor is a second cylindrical shell of a second radius, and the outer rotor and the inner rotor are arranged concentrically and centered around a central axis and wherein each of the one or more first magnetic segments and each of the one or more second magnetic segments comprise one turn of a helix of the first radius and a one turn of a helix of the second radius, respectively. In a first example of the helical magnetic spring, the one or more first magnetic segments include a first set of magnetic segments with a first magnetic polarity and a second set of magnetic segments with a second magnetic polarity and wherein the first magnetic polarity is radially inward and the second magnetic polarity is radially outward. In a second example of the helical magnetic spring, optionally including the first example, a first magnetic segment of the first set of magnetic segments is coupled to a second magnetic segment of the second set of magnetic segments to form a first annular segment and wherein the first annular segment and one or more additional annular segments are coupled along the central axis to form the outer rotor. In a third example of the helical magnetic spring, optionally including one or both of the first and second examples, the outer rotor includes a first axis parallel to the central axis and intersects the outer rotor along a line, and wherein the first set of segments and the second set of segments are coupled in such a way that an alternating pattern of magnetic polarities is formed across the line. In a fourth example of the helical magnetic spring, optionally including one or more or each of the first through third examples, the one or more second magnetic segments include a third set of magnetic segments with the first magnetic polarity and a fourth set of magnetic segments with the second magnetic polarity. In a fifth example of the helical magnetic spring, optionally including one or more or each of the first through fourth examples, a first magnetic segment of tire third set of segments is coupled to a second magnetic segment of the fourth set of magnetic segments to form a first annular segment and wherein the first annular segment and one or more additional annular segments are coupled along the central axis to form the inner rotor. In a sixth example of the helical magnetic spring, optionally including one or more or each of the first through fifth examples, the inner rotor includes a second axis parallel to the central axis that intersects the inner rotor along a line, and wherein the third set of magnetic segments and the fourth set of magnetic segments are coupled in such a way that an alternating pattern of magnetic polarities is formed across the line. In a seventh example of the helicalDocket No. PSU24305PCT magnetic spring, optionally including one or more or each of the first through sixth examples, the helical magnetic spring is capable of producing a sinusoidal torque over a stroke length longer than 90 degrees.

[0074] The disclosure also provides support for a helical magnetic spring, comprising: an inner rotor including one or more first magnetic segments, and an outer rotor including one or more second magnetic segments, wherein the outer rotor is a c lindrical shell of a first radius and the inner rotor is a cylindrical shell of a second radius, and the outer rotor and the inner rotor are arranged concentrically and centered around a z-axis, wherein each of the first magnetic segments comprises a semicircle of a first radius that is angled relative to a y-axis perpendicular to the z-axis and each of the second magnetic segments comprises a semicircle of a second radius that is angled relative to the y-axis, wherein a polarity of the outer rotor changes every 180° of the outer rotor and a polarity of the inner rotor changes every 180° of the inner rotor, and the outer rotor includes at least two pole-pairs along an axial length of the outer rotor, parallel to die z-axis, and the inner rotor includes at least two pole-pairs along an axial length of the inner rotor, parallel to the z-axis.

[0075] The disclosure also provides support for a magnetic apparatus, comprising: a first magnetic spring unit comprising a first inner rotor and a first outer rotor, a second magnetic spring unit comprising a second inner rotor and a second outer rotor, wherein the first outer rotor is a first cylindrical shell of a first radius and the first inner rotor is a second cylindrical shell of a second radius, and the first outer rotor and the first inner rotor are arranged concentrically and centered around a central axis to form the first magnetic spring unit, wherein the second outer rotor is a third cylindrical shell of the first radius and the second inner rotor is a fourth cylindrical shell of the second radius, and the second outer rotor and the second inner rotor are arranged concentrically and centered around the central axis to form the second magnetic spring unit, wherein each of the first outer rotor and the first inner rotor is comprised of at least two interdigitated magnets of different polarity, such that a polarity’ of the first outer rotor changes at least every’ 360° of the first outer rotor and a polarity’ of the first inner rotor changes at least every 360° of the first inner rotor, and the first outer rotor includes at least tw o pole-pairs along an axial length of the first outer rotor and the first inner rotor includes at least two pole-pairs along an axial length of the first inner rotor, and wherein each of the second outer rotor and the second inner rotor is comprised of at least two interdigitated magnets of different polarity, such that a polarity of tire second outer rotor changes at least every 360° of the second outer rotor and a polarity of the second inner rotor changes at least every 360° of the second inner rotor, and the second outer rotor includes at least two pole-pairs along an axial length of the second outer rotor and the second inner rotor includes at least two pole-pairs along an axial length of the second inner rotor. In a first example of the magnetic apparatus, the first magnetic spring unit and the second magnetic spring unit are mounted on a common shaft and the first magnetic spring unit is separated from the second magnetic spring unit by a gap. In a second example of the magnetic apparatus, optionally including the first example, the first magnetic spring unit includes a plurality of first magnetic segments tilted in a first direction and the second helical magnetic spring unit includes a plurality of second magnetic segments tilted in a second direction. In aDocket No. PSU24305PCT third example of the magnetic apparatus, optionally including one or both of the first and second examples, the first direction is opposite to the second direction. In a fourth example of the magnetic apparatus, optionally including one or more or each of the first through third examples, the first inner rotor and the second imier rotor are configmed to rotate and translate simultaneously and wherein the first outer rotor and the second outer rotor are configured to rotate and translate simultaneously.

[0076] The description of embodiments has been presented for purposes of illustration and description. Suitable modifications and variations to the embodiments may be performed in light of the above description. The described systems are exemplary in nature, and may include additional elements and / or omit elements. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configmations, and other features, functions, and / or properties disclosed.

[0077] The foregoing described aspects depict different components contained within, or connected with different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being "operably connected." or "operably coupled." to each other to achieve the desired functionality'.

[0078] As used in this application, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is stated. Furthermore, references to “one embodiment” or “one example” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. The terms “first,” “second,” “third,” and so on arc used merely as labels, and are not intended to impose numerical requirements or a particular positional order on their objects. The following claims particularly point out subject matter from the above disclosure that is regarded as novel and non-obvious.

Claims

Docket No. PSU24305PCTCLAIMS:

1. A magnetic apparatus, comprising: an outer rotor; and an inner rotor concentrically arranged with the outer rotor and separated from the outer rotor by an air gap, wherein each of the outer rotor and the inner rotor is comprised of at least two interdigitated magnets of different polarity, such that a polarity of the outer rotor changes at least every 360° of the outer rotor and a polarity of the inner rotor changes at least every' 360° of the inner rotor, and the outer rotor includes at least two pole-pairs along an axial length of the outer rotor and the inner rotor includes at least two pole-pairs along an axial length of the inner rotor.

2. The magnetic apparatus of claim 1 , wherein the outer rotor is comprised of a first radial magnet interdigitated with a second radial magnet, the first radial magnet having a first magnetic polarity and the second radial magnet having a second magnetic polarity, wherein the first magnetic polarity is radially inward and the second magnetic polarity is radially outward.

3. The magnetic apparatus of claim 2, wherein the first radial magnet is comprised of a first helical magnetic segment and a second helical magnetic segment, each traversing 360°.

4. The magnetic apparatus of claim 3, wherein the second radial magnet is comprised of a third helical magnetic segment and a fourth helical magnetic segment, each traversing 360°.

5. The magnetic apparatus of claim 4, wherein along the axial length of the outer rotor, the third helical magnetic segment is arranged intermediate the first helical magnetic segment and the second helical magnetic segment.

6. The magnetic apparatus of claim 2, wherein the first radial magnet is comprised of a first magnetic segment, a second magnetic segment, and a third magnetic segment, each traversing 180° and arranged axially, with the second magnetic segment having an opposite orientation as the first and third magnetic segments.

7. The magnetic apparatus of claim 6, wherein the second radial magnet is comprised of a fourth magnetic segment, a fifth magnetic segment, and a sixth magnetic segment, each traversing 180° and arranged axially, with the fifth magnetic segment having an opposite orientation as the fourth and sixth magnetic segments.Docket No. PSU24305PCT8. The magnetic apparatus of claim 7, wherein along the axial length of the outer rotor, the fifth magnetic segment is arranged intermediate the first magnetic segment and the third magnetic segment.

9. The magnetic apparatus of claim 7, wherein the polarity of the outer rotor changes every 180°.

10. The magnetic apparatus of claim 1, wherein the outer rotor is comprised of a first magnet and a second magnet interdigitated with a third magnet and a fourth magnet, the first magnet having a first magnetic polarity and the second magnet having a second magnetic polarity, wherein the first magnetic polarity is radially inward and the second magnetic polarity is radially outward, the third magnet having a third magnetic polarity and the fourth magnet having a fourth magnetic polarity, wherein the third magnetic polarity is in a first axial direction and the fourth magnetic polarity is in a second axial direction opposite to the first axial direction.

11. The magnetic apparatus of claim 10, wherein each of the first magnet, the second magnet, the third magnet, and the fourth magnet is comprised of at least two discontinuous magnetic segments with alternating orientations.

12. The magnetic apparatus of claim 11, wherein each of the first magnet, the second magnet, the third magnet, and the fourth magnet comprises an equal number of discontinuous magnetic segments.

13. The magnetic apparatus of claim 1, wherein each magnet of the outer rotor is comprised of a plurality of outer magnetic segments and each magnet of the inner rotor is comprised of a plurality of inner magnetic segments.

14. The magnetic apparatus of claim 13, wherein the plurality of imrer magnetic segments includes more magnetic segments than the plurality of inner magnetic segments.

15. A helical magnetic spring, comprising: an inner rotor including one or more first magnetic segments; an outer rotor including one or more second magnetic segments; wherein the outer rotor is a first cylindrical shell of a first radius and the inner rotor is a second cylindrical shell of a second radius, and the outer rotor and the inner rotor are arranged concentrically and centered around a central axis and wherein each of the one or more first magnetic segments and each of the one or more second magnetic segments comprise one turn of a helix of the first radius and a one turn of a helix of the second radius, respectively.Docket No. PSU24305PCT16. The helical magnetic spring of claim 15. wherein the one or more first magnetic segments include a first set of magnetic segments with a first magnetic polarity and a second set of magnetic segments with a second magnetic polarity and wherein the first magnetic polarity' is radially inward and the second magnetic polarity is radially outward.

17. The helical magnetic spring of claim 16, wherein a first magnetic segment of the first set of magnetic segments is coupled to a second magnetic segment of the second set of magnetic segments to form a first annular segment and wherein the first annular segment and one or more additional annular segments are coupled along the central axis to form the outer rotor.

18. The helical magnetic spring of claim 17, wherein the outer rotor includes a first axis parallel to the central axis and intersects the outer rotor along a line, and wherein the first set of segments and the second set of segments are coupled in such a way that an alternating pattern of magnetic polarities is formed across the line.

19. The helical magnetic spring of claim 16, wherein the one or more second magnetic segments include a third set of magnetic segments with the first magnetic polarity and a fourth set of magnetic segments with the second magnetic polarity.

20. The helical magnetic spring of claim 19, wherein a first magnetic segment of the third set of segments is coupled to a second magnetic segment of the fourth set of magnetic segments to form a first annular segment and wherein the first annular segment and one or more additional annular segments are coupled along the central axis to form the inner rotor.

21. The helical magnetic spring of claim 20, wherein the inner rotor includes a second axis parallel to the central axis that intersects the inner rotor along a line, and wherein the third set of magnetic segments and the fourth set of magnetic segments are coupled in such a way that an alternating pattern of magnetic polarities is formed across the line.

22. The helical magnetic spring of claim 15. wherein the helical magnetic spring is capable of producing a sinusoidal torque over a stroke length longer than 90 degrees.

23. A helical magnetic spring, comprising: an inner rotor including one or more first magnetic segments; and an outer rotor including one or more second magnetic segments; wherein the outer rotor is a cylindrical shell of a first radius and the inner rotor is a cylindrical shell of a second radius, and the outer rotor and the inner rotor are arranged concentrically and centeredDocket No. PSU24305PCT around a z-axis, wherein each of tire first magnetic segments comprises a semicircle of a first radius that is angled relative to a y-axis perpendicular to the z-axis and each of the second magnetic segments comprises a semicircle of a second radius that is angled relative to the y-axis, wherein a polarity of the outer rotor changes every 180° of the outer rotor and a polarity of the imier rotor changes every 180° of the inner rotor, and the outer rotor includes at least two pole-pairs along an axial length of the outer rotor, parallel to the z-axis. and the imier rotor includes at least two pole-pairs along an axial length of the imier rotor, parallel to the z-axis.

24. A magnetic apparatus, comprising: a first magnetic spring unit comprising a first inner rotor and a first outer rotor; and a second magnetic spring unit comprising a second inner rotor and a second outer rotor; wherein the first outer rotor is a first cylindrical shell of a first radius and the first inner rotor is a second cylindrical shell of a second radius, and the first outer rotor and the first inner rotor are arranged concentrically and centered around a central axis to form the first magnetic spring unit, wherein the second outer rotor is a third cylindrical shell of the first radius and the second inner rotor is a fourth cylindrical shell of the second radius, and the second outer rotor and the second inner rotor are arranged concentrically and centered around the central axis to form the second magnetic spring unit; wherein each of the first outer rotor and the first inner rotor is comprised of at least two interdigitated magnets of different polarity, such that a polarity of the first outer rotor changes at least every 360° of the first outer rotor and a polarity' of the first inner rotor changes at least every 360° of the first inner rotor, and the first outer rotor includes at least two pole-pairs along an axial length of the first outer rotor and the first inner rotor includes at least two pole-pairs along an axial length of the first inner rotor; and w herein each of the second outer rotor and the second inner rotor is comprised of at least two interdigitated magnets of different polarity, such that a polarity of the second outer rotor changes at least every' 360° of the second outer rotor and a polarity of the second inner rotor changes at least every 360° of the second inner rotor, and the second outer rotor includes at least tw o pole-pairs along an axial length of the second outer rotor and the second inner rotor includes at least tw o pole -pairs along an axial length of the second imier rotor.

25. The magnetic apparatus of claim 24. wherein the first magnetic spring unit and the second magnetic spring unit are mounted on a common shaft and the first magnetic spring unit is separated from the second magnetic spring unit by a gap.

26. The magnetic apparatus of claim 24, wherein the first magnetic spring unit includes a plurality of first magnetic segments tilted in a first direction and the second helical magnetic spring unit includes a plurality of second magnetic segments tilted in a second direction.Docket No. PSU24305PCT27. The magnetic apparatus of claim 26, wherein the first direction is opposite to the second direction.

28. The magnetic apparatus of claim 24, wherein the first iimer rotor and the second imier rotor are configured to rotate and translate simultaneously and wherein the first outer rotor and the second outer rotor are configured to rotate and translate simultaneously.

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