Machine with multi-layered arc-shaped permanent magnets with reduced rotational load

Abstract

Machine (110) with internal permanent magnets, comprising: a rotor (112) configured for magnetic interaction with a stator; first (30), second (32), third (34), fourth (36), fifth (131) and sixth (133) partitions formed in one piece within the rotor (112); wherein the first (30) and second (32) partitions are configured to create a first layer (18) with three respective first segments (3, 4, 5); wherein the third (34) and fourth (36) partitions are configured to create a second layer (20) with three respective second segments (6, 7, 8); wherein the fifth partition (131) is configured to create a third layer (119) with two respective third segments (111, 113); and wherein the sixth partition (133) is designed to create a fourth layer (121) with two respective fourth segments (125);wherein the respective first (3, 4, 5), second (6, 7, 8), third (111, 113) and fourth segments (125) are all substantially arc-shaped; first (40), second (42), third (44), fourth (46), fifth (141) and sixth (143) thicknesses defined by the first (30), second (32), third (34), fourth (36), fifth (131) and sixth (133) partition; wherein the rotor (112) is configured such that the first thickness (40) is equal to the second thickness (42), the third thickness (44) is equal to the fourth thickness (46), and the first thickness (40) differs from the third (44), the fifth (141) and the sixth (143) thicknesses.

Description

CROSS REFERENCE TO RELATED APPLICATIONSThis application claims the benefit of U.S. Provisional Patent Application No. 61 / 568,884, filed December 9, 2011, the disclosure of which is hereby incorporated by reference.TECHNICAL FIELDThe present invention relates generally to an interior permanent magnet machine and, more particularly, to the configuration of the rotor of the interior permanent magnet machine.BACKGROUNDAn electric motor uses potential electrical energy to generate mechanical energy through the interaction of magnetic fields and current carrying conductors. The reverse process, the use of mechanical energy to generate electrical energy, is accomplished by a generator or dynamo. Other electric machines, such as motor / generators, combine various features of both motors and generators. An internal permanent magnet machine generally includes a rotor having a plurality of magnets of alternating polarity around the outer periphery of the rotor. The rotor is rotatable within a stator generally including a plurality of windings and magnetic poles of alternating polarity. The magnets used in machines with permanent magnets located inside typically have a rectangular shape.The publication DE 689 11 570 T2 discloses an electric reluctance synchronous machine with a rotor which consists of axial magnet sections with alternating layers of ferromagnetic material and intermediate layers.In the document DE 696 29 419 T2 a motor is disclosed with built-in permanent magnets arranged in a plurality of groups in the vicinity of an outer periphery of the rotor.The document EP 1 164 683 A2 discloses a permanent magnet rotor with permanent magnets which are embedded in concentric slots in the rotor.The publication LIPO, Synchronous Redundancy Machines-A Visible Alternative for AC Drives?, Electric Machines & Power Systems, Volume 19, Issue 6, pp. 659-671, 1991 discloses that simple bar magnets are arranged in sections between core lamination groups to assist in the generation of torque.The document DE 601 08 424 T2 discloses a permanent magnet rotor in which permanent magnets with different properties are embedded in layers in a rotor core.In the publication DE 10 2005 062 922 A1, a reluctance motor is disclosed which has concentric arc-shaped slots which are filled with permanent magnets.The document JP 2009-296 685 A discloses a rotor core having two flux barriers, which are each divided by radially extending bridges. In addition, a barrier is divided by two bridges running in the circumferential direction.In the document US 2002 / 0 070 620 A1, a permanent magnet rotor is disclosed having slots whose ends are open longitudinally outwards to the circumferential surface of the rotor.US 5 818 140 A discloses an electric reluctance motor whose rotor is provided with a plurality of slots whose ends are arranged close to the periphery of the rotor. Some of the slits are divided by partition walls.In the document JP H11-262 205 A a permanent magnet motor is disclosed which comprises four poles each having four circular arc-shaped slots in which plastic magnets are arranged.JP H09-298 852 A discloses a brushless direct current motor having a rotor in which permanent magnets are embedded in a V-shaped arrangement.The publication JP H11-262 206 A discloses a rotor of an electric motor in which circular arc-shaped permanent magnets are embedded.SUMMARYAn internal permanent magnet machine includes a rotor configured to interact with a stator in a magnetic manner. Within the rotor, first and second partitions are integrally formed and configured to create a first layer having three respective first segments. Each of the respective first segments may be substantially arc-shaped. A plurality of first magnets may be positioned in the first layer. The first magnets may be substantially arc-shaped and defined about an arc center. The placement of baffles or structural struts provides for increased rotational speed and reduced rotational loading compared to a non-split arcuate magnet configuration. In addition, the arrangement of baffles allows a multi-layer configuration with arc-shaped magnets to survive higher operating speeds with improved bending.In one embodiment, third and fourth baffles may be integrally formed within the rotor and configured to create a second layer having three respective second segments. Each of the respective second segments may be substantially arc-shaped. A plurality of second magnets may be positioned within the second layer. The second magnets may be substantially arc-shaped and defined about an arc center.Each of the first, second, third, and fourth baffles defines a respective angle that characterizes the inclination or orientation of the respective baffle. The first bulkhead defines a first angle between a first centerline passing through the first bulkhead and a central axis passing through the arc center. The second bulkhead defines a second angle between a second centerline that passes through the second bulkhead and the central axis. The third bulkhead defines a third angle between a third centerline passing through the third bulkhead and the central axis. The fourth bulkhead defines a fourth angle between a fourth centerline passing through the fourth bulkhead and the central axis. In one example, the first angle is equal to the second angle and the first angle is different than the third angle. In another example, the first, second, third, and fourth angles are each different from one another.In a second embodiment, a fifth partition wall may be integrally formed within the rotor and configured to create a third layer having two respective third segments. A sixth partition may be integrally formed within the rotor and configured to create a fourth layer having two respective fourth segments. Various combinations of the first, second, third and fourth layers may be formed in a single rotor.The above features and advantages and other features and advantages of the present invention will be readily apparent from the following detailed description of the best modes for carrying out the invention when read in connection with the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a schematic partial cross-sectional view of an interior permanent magnet machine having a rotor according to a first embodiment; FIG. 2 is a schematic partial cross-sectional view of the rotor shown in FIG. 1 ; FIG. 3 is a schematic partial cross-sectional view of a second embodiment of an interior permanent magnet machine; FIG. 4 is a schematic partial cross-sectional view of a third embodiment of an interior permanent magnet machine; FIG. 5 is a schematic partial cross-sectional view of a fourth embodiment of an internal permanent magnet machine; and FIG. 6 is a schematic partial cross-sectional view of a fifth embodiment of an interior permanent magnet machine.DETAILED DESCRIPTIONReferring to the Figures, wherein like reference numerals designate like or similar components throughout the several views, FIG. 1 is a schematic cross-sectional view of a portion of an interior permanent magnet machine 10 having a rotor 12. The rotor 12 may be formed by stacking one or more laminations 14, also shown in FIG. 4. The core laminations 14 are typically annular. Referring to FIG. 1, each lamination 14 may surround a shaft 17 centered at an origin 15. For purposes of illustration, only a portion of the core lamination 14 and shaft 17 are shown. The rotor 12 is rotatable within a generally annular stator (not shown).Referring to FIG. 1, a first partition 30 and a second partition 32 are integrally formed within the rotor 12 and configured to provide a first layer 18 having three respective first segments 3, 4, 5. The segments described below are all cavities that extend three-dimensionally into the rotor 12 (or the rotor 112, 212, 312, and 412 in the embodiments described below). All respective first segments 3, 4, 5 are substantially arc-shaped. A plurality of first magnets 22 may be positioned within the first layer 18, for example, one in each of the respective first segments 3, 4, 5. the first magnets 22 may be substantially arc-shaped and defined about a central axis 16 that passes through an arc center point 26. The rotor 12 may include air pockets 28 that are incorporated into the structure at various locations.Similarly, a third and fourth partition walls 34, 36 are integrally formed within the rotor 12 and configured to provide a second layer 20 having three respective second segments 6, 7, 8. The respective second segments 6, 7, 8 are all substantially arc-shaped. A plurality of second magnets 24 may be positioned within the second layer 20. The second magnets 24 may be substantially arc-shaped and defined about the arc center point 26. Any number of baffles may be used within the first and second layers 18, 20.Referring to FIG. 1, a third layer 37 is formed in the rotor 12 with a single third segment 38. An unpartitioned or one piece third magnet 39 may be positioned in the third layer 37. The partitions 30, 32, 34, 36 may be formed by stamping the core laminations 14. The placement of baffles 30, 32, 34, 36 provides for increased rotational speed and reduced rotational loading as compared to a non-split arcuate magnet configuration. The placement of baffles 30, 32, 34, 36 allows a multi-layer configuration with arc-shaped magnets to survive higher operating speeds with improved bending.Referring to FIG. 1, the first, second, third, and fourth baffles 30, 32, 34, 36 may define first, second, third, and fourth thicknesses 40, 42, 44, and 46, respectively (measurable in a cross-sectional view). The rotor 12 may be configured such that the first thickness 40 is equal to the second thickness 42 but is different than the third thickness 44. The fourth thickness 46 may be equal to the third thickness 44. For example only, the first, second, third, and fourth thicknesses 40, 42, 44, 46 may be about 1.0 mm, 1.0 mm, 0.5 mm, and 0.5 mm, respectively. The rotor 12 may be configured such that all four thicknesses 40, 42, 44, 46 are different. For example only, the first second, third, and fourth thicknesses 40, 42, 44, 46 may be about 1.4 mm, 1.2 mm, 0.5 mm, and 0.8 mm, respectively. All of the partitions 30, 32, 34, 36 may be equally spaced along their length.Referring to FIG. 3, a second embodiment of an interior permanent magnet machine 110 having a rotor 112 is shown. The machine 110 in FIG. 3 is similar to the machine 10 in FIG. 1, with like reference numerals indicating similar components. The embodiment shown in FIG. 3 includes additional layers or barriers, as described below.Referring to FIGS. 1 and 3, each of the first, second, third, and fourth baffles 30, 32, 34, 36 may define a respective angle that characterizes the inclination or orientation of the respective baffle. Referring to FIGS. 1 and 3, a first angle 50 is defined between a first centerline 49 (labeled in FIG. 1 ) passing through the first bulkhead 30 and the central axis 16 passing through the arc center 26. A second angle 52 is defined between a second centerline 51 (labeled in FIG. 1 ) passing through the second bulkhead 32 and the central axis 16. A third angle 54 is defined between a third centerline 53 (labeled in FIG. 1 ) passing through the third bulkhead 34 and the central axis 16. A fourth angle 56 is defined between a fourth centerline 55 (labeled in FIG. 1 ) passing through the fourth bulkhead 36 and the central axis 16.Referring to FIG. 1, in one embodiment, the first, second, third, and fourth angles 50, 52, 54, 56 are all different from one another. For example only, the first, second, third, and fourth angles 50, 52, 54, 56 may be about 40, 45, 50, and 55 degrees, respectively. Referring to FIG. 3, in another embodiment, the configuration may be such that the first angle 50 is equal to the second angle 52; the third angle 54 is equal to the fourth angle 56; and the first angle 50 is different from the third angle 54. For example only, the first and second angles 50, 52 may be about 50 degrees and the third and fourth angles 54, 56 may be about 45 degrees. In another embodiment, the first, second, third, and fourth angles 50, 52, 54, 56 are all the same.Referring to FIG. 3, a fifth partition 131 is integrally formed within the rotor 12 and configured to provide a third layer 119 having two respective third segments 111, 113. The third segments 111, 113 are substantially arc-shaped. A plurality of third magnets 123 may be positioned in the third layer 119. The third magnets 123 may be substantially arc-shaped and defined about the arc center point 26.Referring to FIG. 3, a sixth partition 133 is integrally formed within the rotor 112 and configured to provide a fourth layer having two respective fourth segments 115, 117. The fourth segments 115, 117 are substantially arc-shaped. A plurality of fourth magnets 125 may be positioned within the fourth layer 121. The fourth magnets 125 may be substantially arc-shaped and defined about the arc center point 26. As mentioned previously, the third and fourth segments 111, 113, 115, 117 are cavities that extend three-dimensionally into the rotor 112.Referring to FIG. 3, the fifth and sixth partitions 131, 133 may define fifth and sixth thicknesses 141, 143, respectively. For example only, in one embodiment, the first, second, third, and fourth thicknesses 40, 42, 44, 46 (labeled in FIG. 1 ) may be about 1.4 mm, 1.4 mm, 1.2 mm, and 1.2 mm, while the fifth and sixth thicknesses 141, 143 may be about 1.0 mm and 0.8 mm, respectively. The angles and thicknesses may be optimized based on the particular requirements of the particular application using modeling techniques and optimization techniques known to those skilled in the art.Referring to FIG. 4, a third embodiment of an interior permanent magnet machine 210 having a rotor 212 is shown. The machine 210 in FIG. 4 is similar to the machine 110 in FIG. 3 in all respects except for the differences in the fourth layers 121, 221 described below, wherein like reference numerals designate similar components.Referring to FIG. 4, a sixth partition 233 is integrally formed within the rotor 212 and configured to provide a fourth layer 221 having two respective fourth segments 215, 217. Unlike the embodiment shown in FIG. 3, the fourth segments 215, 217 are substantially rectangular. The fourth segments 215, 217 may be symmetrical with respect to the axis 16. The fourth segments 215, 217 may be oriented at an angle 216 between the axis 16 and a centerline 218 through one of the respective fourth segments 215, 217. In one example, the angle 216 is about 45 degrees. A plurality of fourth magnets 225 may be positioned in the fourth layer 221. In other words, each of the segments 215, 217 in the fourth layer 221 may be at least partially filled with one or more fourth magnets 225. The fourth magnets 225 are substantially rectangular. A single rotor 112, 212 (shown in FIGS. 3-4 ) may include various combinations having substantially rectangular and substantially arcuate segments in each of the respective first, second, third, and fourth layers 18, 20, 119, 121 / 221.Referring to FIG. 5, a fourth embodiment of an interior permanent magnet machine 310 having a rotor 312 is shown. Referring to FIG. 6, a fifth embodiment of an interior permanent magnet machine 410 including a rotor 412 is shown. Similar to the embodiments shown in FIGS. 1, 3 and 4, the machines 310, 410 in FIGS. 5 and 6, respectively, include first and second baffles 30, 32 integrally formed within the rotor 12 and configured to provide a first layer 18 having three respective first segments 3, 4, 5. As mentioned above, like reference numerals designate like or similar components throughout the several views. As described in detail above, the baffles 30, 32 may be configured to define different angles and different thicknesses, as described above.Referring to FIG. 5, the rotor 312 includes a second layer 337 having a substantially arc-shaped second segment 338. An non-shared or one piece second magnet 339 may be positioned in the second layer 337. The second magnet 339 may be substantially arc-shaped.Referring to FIG. 6, a third partition 431 may be integrally formed within the rotor 412 and configured to provide a second layer 419 having two respective second segments 411, 413. The second segments 411, 413 are substantially arc-shaped. A plurality of second magnets 423 may be positioned in the second layer 419. Each of the second magnets 423 may be substantially arc-shaped and defined about the arc center point 26. The pattern or configuration shown in FIGS. 1 and 3- 6 may be repeated for the entire rotor 12, 112, 212, 312, 412, respectively.The detailed description and drawings or figures aid in and describe the invention, but the scope of the invention is defined only by the claims. While some of the best modes and other embodiments for carrying out the claimed invention have been described in detail, various alternative designs and embodiments exist for practicing the invention defined in the appended claims.

Claims

An interior permanent magnet machine (110) comprising: a rotor (112) configured to interact with a stator in a magnetic manner; first (30), second (32), third (34), fourth (36), fifth (131), and sixth (133) baffles integrally formed within the rotor (112); wherein the first (30) and second (32) baffles are configured to provide a first layer (18) having three respective first segments (3, 4, 5); wherein the third (34) and fourth (36) baffles are configured to provide a second layer (20) having three respective second segments (6, 7, 8); wherein the fifth baffle (131) is configured to provide a third layer (119) having two respective third segments (111, 113); and wherein the sixth partition (133) is configured to provide a fourth layer (121) having two respective fourth segments (125); wherein the respective first (3, 4, 5), second (6, 7, 8), third (111, 113), and fourth segments (125) are all substantially arc-shaped; first (40), second (42), third (44), fourth (46), fifth (141), and sixth (143) thicknesses defined by the first (30), second (32), third (34), fourth (36), fifth (131), and sixth (133) partitions; wherein the rotor (112) is configured such that the first thickness (40) is equal to the second thickness (42), the third thickness (44) is equal to the fourth thickness (46), and the first thickness (40) is different from both the third (44) and the fifth (141) and the sixth (143) thicknesses.The machine (110) of claim 1, further comprising: a first angle (50) defined by the first bulkhead (30) between a first centerline (49) passing through the first bulkhead (30) and a central axis (16) passing through an arc center (26); a second angle (52) defined by the second bulkhead (32) between a second centerline (51) passing through the second bulkhead (32) and the central axis (16); a third angle (54) defined by the third bulkhead (34) between a third centerline (53) passing through the third bulkhead (34) and the central axis (16); a fourth angle (56) defined by the fourth bulkhead (36) between a fourth centerline (55) passing through the fourth bulkhead (36) and the central axis (16); and wherein the rotor (112) is configured such that the first angle (50) is equal to the second angle (52) and the first angle (50) is different from the third angle (54).The machine (110) of claim 1, further comprising: a first angle (50) defined by the first bulkhead (30) between a first centerline (49) passing through the first bulkhead (30) and a central axis (16) passing through the arc center (26); a second angle (52) defined by the second bulkhead (32) between a second centerline (51) passing through the second bulkhead (32) and the central axis (16); a third angle (54) defined by the third bulkhead (34) between a third centerline (53) passing through the third bulkhead (34) and the central axis (16); a fourth angle (56) defined by the fourth bulkhead (36) between a fourth centerline (55) passing through the fourth bulkhead (36) and the central axis (16); and wherein the rotor (112) is configured such that the first (50), second (52), third (54) and fourth (56) angles are all different from one another.

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