Rotor structure for electric motor assembly

Abstract

The present invention relates to a rotor structure for an electric machine assembly. An electric machine assembly for a vehicle is provided. The electric machine is in operative communication with a traction battery and includes a stator core defining a cavity and a rotor disposed within the cavity, the rotor having an interior region defined by a collection of triangular holes, the triangular holes being inlaid around respective central regions to form a truss structure such that the holes of the truss structure do not affect the magnetic flux paths generated by magnets of the rotor during rotational operation. The rotor may have a strain energy value less than or equal to 16,100 Joules. The truss structure may include a pair of symmetrical sections, each symmetrical section including a member that is arranged with an adjacent rotor section to define a triangular hole.

Description

Technical Field

[0001] The present disclosure relates to a rotor for an electric machine assembly for an electrified vehicle. Background Art

[0002] Extended driving range technologies for electrified vehicles, such as battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs), are continually improving. However, achieving these range increases often requires higher power outputs from traction batteries and electric machines and greater capacity for associated thermal management systems compared to previous BEVs and PHEVs. Improving the weight and stiffness characteristics of electric machine rotors can increase power output and improve vehicle performance. Summary of the invention

[0003] A vehicle includes a traction battery and an electric machine. The electric machine is in operational communication with the traction battery and includes a stator core defining a cavity and a rotor disposed within the cavity, the rotor having an interior region defined by a collection of triangular holes, the triangular holes being inlaid around respective central regions to form a truss structure such that the holes of the truss structure do not affect the magnetic flux path generated by the magnets of the rotor during rotational operation. The rotor may have a strain energy value less than or equal to 16,100 Joules. The truss structure may include a pair of symmetrical portions, each symmetrical portion including a member configured to define a triangular hole together with an adjacent rotor portion. The members may include a first member, a second member, a third member, a fourth member, and a side member, the first member being shared by each of the symmetrical portions in the pair of symmetrical portions. Each first member may be configured to define a first triangular hole and a second triangular hole together with a second member and an adjacent portion of the rotor. Each second member may be configured to define a third triangular hole and a fourth triangular hole together with a third member and a portion of a side member. Each third member may be configured to define a fifth triangular hole and a sixth triangular hole together with a fourth member and another portion of a side member. The fourth member and the base portion of the symmetrical portion may be arranged relative to each other to define a seventh triangular hole. The first member may extend to the base portion of one of the paired symmetrical portions to bisect the seventh triangular hole into two separate openings. The triangular holes may be arranged relative to each other so that the strain energy of the rotor is equal to or less than 16100 joules.

[0004] A motor assembly includes a stator core and a rotor. The stator core defines a cavity. The rotor is disposed in the cavity and includes a plurality of sector-shaped portions arranged radially around a central through hole of the rotor. Each of the plurality of sector-shaped portions includes a truss structure and no more than two magnet openings for accommodating magnets, the no more than two magnet openings being arranged in a V-shape, the truss structure including a plurality of triangular holes defined by members, the members each having an end located in a central region of the triangular hole to form a starburst pattern radiating from the central region. The truss structure may include a first symmetrical portion and a second symmetrical portion. Each symmetrical portion may share a first member, and each symmetrical portion may include a second member and a third member. The first member may be configured to define a first triangular hole and a second triangular hole together with a corresponding second member and an adjacent portion of the rotor. Each second member may be configured to define a third triangular hole and a fourth triangular hole together with a third member and another adjacent portion of the rotor. Each third member may be configured to define a fifth triangular hole between the third member and the base member together with a base member of one of the first symmetrical portion and the second symmetrical portion. The first member may extend to the base member of each of the first symmetrical portion and the second symmetrical portion to bisect the fifth triangular hole. The first member may define a central axis extending between a pair of magnets mounted within the two magnet openings.

[0005] A motor assembly includes a stator core and a rotor. The stator core defines a cavity. The rotor is disposed in the cavity and includes an inner region and an outer region, the inner region having a truss structure, the outer region being used to mount a magnet and being arranged radially from the inner region. The truss structure is dimensioned so that the rotor has a strain energy value of approximately 16,000 joules and a weight of approximately 6.35 kilograms. The truss structure may define a radial length of approximately 54 millimeters. The truss structure may include a first symmetrical portion and a second symmetrical portion. Each symmetrical portion may share a first member, and each symmetrical portion may include a second member, a third member, and a fourth member. The first member may be configured to define a first triangular opening and a second triangular opening together with the corresponding second member and an adjacent portion of the rotor, and each second member may be configured to define a third triangular opening and a fourth triangular opening together with a third member and another adjacent portion of the rotor. Each third member may be configured to define a fifth triangular opening and a sixth triangular opening together with a fourth member and another adjacent portion of the rotor. The fourth member may be configured to define a seventh triangular opening together with a base portion of the symmetrical portion. Each member may define a width of 3 mm to 7 mm, and the rotor may define a diameter of 110 mm to 230 mm. The first member may extend to the base portion of the respective symmetrical portion to bisect the seventh triangular opening. The truss structure may include a first symmetrical portion and a second symmetrical portion. Each symmetrical portion may share a first member and each symmetrical portion may include a second member and a third member. The first member may be configured to define a first triangular opening and a second triangular opening together with the corresponding second member and an adjacent portion of the rotor. Each of the second and third members may be configured to define a third triangular opening and a fourth triangular opening together with another adjacent portion of the rotor. Each third member and the base portion of the respective symmetrical portion may be configured to define a fifth triangular opening between the third member and the base portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic diagram showing an example of an electrified vehicle.

[0007] Figure 2 is an exploded perspective view of an example of a portion of an electric machine.

[0008] Figure 3 is a cross-sectional front view of an example of a rotor showing different rotor regions.

[0009] Figure 4 is a cross-sectional front view of an example of a rotor for an electric machine.

[0010] Figure 5 yes Figure 4 A sectional front view of a portion of a rotor in FIG.

[0011] Figure 6 is a cross-sectional front view of an example of a portion of a rotor for an electric machine.

[0012] Figure 7 is a cross-sectional front view of an example of a portion of a rotor for an electric machine.

[0013] Figure 8 is a cross-sectional front view of an example of a portion of a rotor for an electric machine. DETAILED DESCRIPTION

[0014] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various alternative forms. The drawings need not be drawn to scale; some features may be exaggerated or reduced to show the details of a particular component. Therefore, the specific structural and functional details disclosed herein should not be interpreted as being restrictive, but merely as a representative basis for teaching those skilled in the art to utilize the present disclosure in a variety of ways. It will be understood by those of ordinary skill in the art that the various features shown and described with reference to any of the figures may be combined with the features shown in one or more other figures to produce embodiments that are not explicitly shown or described. The combination of features shown provides representative embodiments for typical applications. However, various combinations and modifications of features consistent with the teachings of the present disclosure may be used for specific applications or implementations.

[0015] Figure 1 A schematic diagram of an example of an electrified vehicle is depicted. In this example, the electrified vehicle is a PHEV referred to as vehicle 12. Vehicle 12 may include one or more electric machines 14 mechanically connected to a hybrid transmission 16. Each electric machine 14 is capable of operating as a motor or a generator. In addition, hybrid transmission 16 is mechanically connected to an engine 18. Hybrid transmission 16 is also mechanically connected to a drive shaft 20, which is mechanically connected to wheels 22. Electric machine 14 can provide propulsion and deceleration capabilities when engine 18 is started or shut down. Electric machine 14 can also operate as a generator and can provide fuel economy benefits by recovering energy that would normally be lost as heat in a friction braking system. Because vehicle 12 can operate in electric mode under certain conditions, electric machine 14 can also provide reduced pollutant emissions.

[0016] The traction battery 24 stores energy that can be used by the motor 14. The traction battery 24 can generally provide a high voltage direct current (DC) output from one or more battery cell arrays (also referred to as battery cell stacks) within the traction battery 24. The battery cell array may include one or more battery cells. The traction battery 24 is electrically connected to one or more power electronics modules 26 through one or more contactors (not shown). The one or more contactors isolate the traction battery 24 from other components when open and connect the traction battery 24 to other components when closed. The power electronics module 26 is also electrically connected to the motor 14 and provides the ability to transfer electrical energy bidirectionally between the traction battery 24 and the motor 14. For example, a typical traction battery 24 can provide a DC voltage, while the motor 14 may require a three-phase alternating current (AC) voltage to operate. The power electronics module 26 can convert the DC voltage into a three-phase AC voltage as required by the motor 14. In regenerative mode, the power electronics module 26 can convert the three-phase AC voltage from the motor 14 used as a generator into the DC voltage required by the traction battery 24. Some of the parts described here are also applicable to pure electric vehicles. For a purely electric vehicle, the hybrid transmission 16 may be a gearbox connected to the electric machine 14 , and the engine 18 may not be present.

[0017] In addition to providing energy for propulsion, the traction battery 24 may also provide energy for other vehicle electrical systems. A typical system may include a DC / DC converter module 28 that converts the high voltage DC output of the traction battery 24 to a low voltage DC supply that is compatible with other vehicle loads. Other high voltage loads (e.g., compressors and electric heaters) may be connected directly to the high voltage without utilizing the DC / DC converter module 28. In a typical vehicle, the low voltage systems are electrically connected to an auxiliary battery 30 (e.g., a 12 volt battery).

[0018] A battery power control module (BECM) 33 may communicate with the traction battery 24. The BECM 33 may serve as a controller for the traction battery 24 and may also include an electronic monitoring system that manages the temperature and state of charge of each cell in the traction battery 24. The traction battery 24 may have a temperature sensor 31, such as a thermistor or other thermometer. The temperature sensor 31 may communicate with the BECM 33 to provide temperature data about the traction battery 24.

[0019] The vehicle 12 may be recharged by an external power source 36, such as an electrical outlet. The external power source 36 may be electrically connected to an electric vehicle supply equipment (EVSE) 38. The EVSE 38 may provide circuitry and controls to regulate and manage the transfer of electrical energy between the power source 36 and the vehicle 12. The external power source 36 may provide DC or AC power to the EVSE 38. The EVSE 38 may have a charging connector 40 for plugging into a charging port 34 of the vehicle 12. The charging port 34 may be any type of port configured to transfer power from the EVSE 38 to the vehicle 12. The charging port 34 may be electrically connected to a charger or an onboard power conversion module 32. The power conversion module 32 may regulate the power supplied from the EVSE 38 to provide the appropriate voltage and current levels to the traction battery 24. The power conversion module 32 may interface with the EVSE 38 to coordinate the transfer of power to the vehicle 12. The charging connector 40 may have pins that mate with corresponding recesses of the charging port 34.

[0020] The various components described above may have one or more associated controllers to control and monitor the operation of the components. The controllers may communicate via a serial bus (eg, a controller area network (CAN)) or via discrete conductors.

[0021] The battery cells of the traction battery 24 (such as square battery cells or pouch-type battery cells) may include electrochemical elements that convert stored chemical energy into electrical energy. The square battery cells or pouch-type battery cells may include a housing, a positive electrode (cathode), and a negative electrode (anode). The electrolyte allows ions to move between the anode and cathode during a discharge operation and then return during a charging operation. The terminals allow current to flow out of the battery cell for use by the vehicle. When located in an array of multiple battery cells, the terminals of each battery cell can be aligned with the opposite terminals (positive and negative) adjacent to each other, and the busbars can help facilitate the series connection between multiple battery cells. The battery cells can also be arranged in parallel so that similar terminals (positive and positive or negative and negative) are adjacent to each other.

[0022] Figure 2 A partially exploded view of an example of a portion of an electric machine (generally referred to herein as electric machine 100) for an electrified vehicle is shown. The electric machine may include a stator core 102 and a rotor 106. As previously described, an electrified vehicle may include more than one electric machine. One of the electric machines may operate primarily as a motor and the remaining electric machines may operate primarily as generators. The motor may operate to convert electrical energy into mechanical energy and the generator may operate to convert mechanical energy into electrical energy. The stator core 102 may define an inner surface 108 and a cavity 110. The rotor 106 may be sized to be placed and operated within the cavity 110. A shaft 112 may be operably connected to the rotor 106 and may be combined with other vehicle components to transfer mechanical energy through the other vehicle components.

[0023] The winding 120 may be disposed within the cavity 110 of the stator core 102. In an example where the electric machine is a motor, current may be supplied to the winding 120 to obtain a rotational force on the rotor 106. In an example where the electric machine is a generator, the current generated in the winding 120 by the rotation of the rotor 106 may be used to power vehicle components. A portion of the winding 120 (such as a winding end 126) may extend from the cavity 110. During operation of the electric machine 100, heat may be generated along the winding 120 and the winding end 126. The rotor 106 may include magnets so that the rotation of the rotor 106 interacts with the current flowing through the winding end 126 to generate one or more magnetic fields. For example, the current flowing through the winding end 126 generates a rotating magnetic field. The magnets of the rotor 106 will be magnetized and rotate with the rotating magnetic field to rotate the shaft 112 to generate mechanical energy.

[0024] Figure 3 An example of a rotor for a vehicle motor, referred to as rotor 130, is shown. Rotor 130 includes a central through hole 134 sized to receive a shaft (not shown) of shaft 112 as previously described and an outer surface 136. Rotor 130 also includes an inner region 138, a middle region 139, and an outer region 140.

[0025] The inner region 138 is adjacent to the central through hole 134 and extends radially around the central through hole 134. The inner region 138 defines a radial length 142. The inner boundary of the inner region 138 is separated from the central through hole 134. The outer region 140 is adjacent to the outer surface 136 and extends radially around the central through hole 134, the inner region 138, and the intermediate region 139. The outer region 140 defines a radial length 144. The intermediate region 139 defines a radial length 146. The openings or cutouts in the regions can provide locations for mounting components and provide weight reduction benefits. The size and location of these openings or cutouts can also affect the stiffness of the rotor 130.

[0026] Typical rotor designs do not include truss structures located in the interior area and may have strain energy values ​​between 16,900 joules and 19,000 joules for a rotor with a mass of 6.35 kg. Strain energy is the energy stored by a system undergoing deformation and is an indicator of the compliance of the structure. Higher strain energy generally reflects higher structural compliance. Compliance can be defined as the inverse of structural stiffness. Lower compliance generally reflects higher stiffness. A rotor structure including a truss structure may be stiffer than a typical design. Higher stiffness helps reduce rotor stress during rotor operation and helps improve rotor durability during rotor operation. Higher stiffness may also help reduce rotor weight.

[0027] Figure 4 and Figure 5Another example of a rotor for a vehicle motor, referred to as rotor 150, is shown. Rotor 150 includes a central through hole 154 and an outer surface 156. The interior region of rotor 150 includes a truss structure 160. A plurality of truss structures 160 may be arranged radially around central through hole 154 and within the interior region. Figure 4 , the rotor 150 is shown to have eight truss structures 160. The truss structures 160 can reduce the weight of the rotor 150 by 20% compared to an embodiment in which the rotor 150 does not have the truss structures 160. The truss structures 160 can provide this weight reduction while also increasing the overall structural stiffness by 20% compared to an embodiment in which the rotor 150 does not have the truss structures 160. In one example, the truss structures 160 of the rotor 150 having a mass of 6.35 kg can contribute to a strain energy of 16,100 joules of the rotor 150. The strain energy value of 16,100 joules represents a 4% to 15% increase in stiffness compared to a typical rotor having a strain energy value of 16,000 joules to 19,000 joules.

[0028] Each truss structure 160 may include a first central member 164 and a second central member 166. Each of the first central member 164 and the second central member 166 may extend outwardly from the central through hole 154 along a central axis 167. Each truss structure 160 may be arranged on the rotor 150 so that current may flow along the central axis 167 to assist in controlling torque when the rotor 150 is operating. Each truss structure 160 also includes a pair of third members 168, a pair of fourth members 170, a pair of fifth members 172, a pair of side members 178, a lower member 182, and an upper member 180. Each of the pair of side members 178 defines an axis 183. Each axis 183 represents a path of movement of magnetic flux from the rotor 150 to the stator (not shown).

[0029] The members may be arranged relative to each other to define a generally triangular opening of the rotor 150. For example, each truss structure 160 may define eight triangular openings. The members may be arranged relative to each other so that the ends of each member converge at a central region of the truss structure 160 between the triangular openings to form a starburst pattern radiating from the central region. For example, the triangular openings may be inlaid around the respective central regions to form respective truss structures 160. These openings are arranged on the rotor 150 to reduce the weight of the rotor 150 compared to a solid embodiment of the rotor 150. Each truss structure 160 may define a radial length based on the size of the rotor 150, the size of the triangular openings, and the size of the truss structure members. In one example, the truss structure 160 may define a radial length of approximately one-quarter the radius of the rotor 150, such as a radial length between fifty millimeters and sixty millimeters.

[0030] Each truss structure 160 may include a first symmetric region and a second symmetric region. Each symmetric region may include a portion of a first central member 164 and a portion of a second central member 166, one of a pair of third members 168, one of a pair of fourth members 170, one of a pair of fifth members 172, one of a pair of side members 178, a portion of an upper member 180, and a portion of a lower member 182.

[0031] Each third member 168, a portion of the upper member 180, and a portion of the first central member 164 may define a first triangular opening. Each third member 168, a portion of one of the fourth members 170, and a portion of one of the side members 178 may define a second triangular opening. Each fourth member 170, a portion of one of the fifth members 172, and a portion of one of the side members 178 may define a third triangular opening. Each fifth member 172, a portion of the second central member 166, and a portion of the lower member 182 may define a fourth triangular opening.

[0032] In embodiments where the rotor 150 defines a diameter between one hundred and ten millimeters and two hundred and thirty millimeters, each third member 168 and fifth member 172 may define a width between three millimeters and seven millimeters. Each side member 178 may define a width between 1.5 millimeters and 3.5 millimeters. Each first central member 164, each second central member 166, the pair of third members 168, the pair of fourth members 170, the pair of fifth members 172, and the pair of side members 178 may define a length between five millimeters and twenty millimeters.

[0033] The outer region of the rotor 150 may include a pair of cutouts 186, each of which is sized to accommodate a magnet. Each of the pair of cutouts 186 may be arranged relative to each other to define a V-shape. The apex of the V-shape may point to the central through hole 154. Each of the pair of cutouts 186 is adjacent to the outer surface 156. The edge of one of the pair of cutouts 186 may be arranged to be parallel to the edge of a member of the truss structure 160. During operation of the rotor 150, the magnets located in each of the pair of cutouts 186 generate magnetic flux. The opening may be provided on the rotor 150 so that the electromagnetic properties of the rotor 150 are not affected. For example, the inner region and the outer region of the rotor 150 may be arranged relative to each other so that the intermediate region defines a radial length of approximately twenty-six millimeters. This radial length provides a spacing between the truss structure 160 and the magnets that may be located in the cutouts 186 so that the electromagnetic properties of the magnets are not affected when the rotor 150 rotates.

[0034] The rotor 150 may include a plurality of sector portions around the central through hole 154. For example, each sector portion may be defined by the shaft 183, a portion of the edge of the central through hole 154, and a portion of the outer surface 156. Each sector portion may be bisected by a central axis 167 and include no more than two cutouts 186 arranged in a V shape relative to each other, the cutouts 186 being used to accommodate two magnets. Each sector portion may include a truss structure 160.

[0035] Figure 6 A portion of a rotor 198 is shown having an example of a truss structure of an inner region referred to as a truss structure 200. The rotor 198 includes a central through hole 204 and an outer surface 206. A plurality of truss structures 200 may be radially arranged about the central through hole 204 and within the inner region. Figure 6 Only one truss structure 200 is shown, however, it should be understood that a complete view of the rotor 198 would include multiple truss structures 200. The truss structures 200 of the rotor 198 may reduce the weight of the rotor 198 compared to a rotor having a solid structure, such as the rotor 130. The truss structures 200 may provide this weight reduction while also increasing the overall structural stiffness by 20% compared to an embodiment of the rotor 198 without the truss structures 200.

[0036] Each truss structure 200 may include a central member 210. Each central member 210 may extend outwardly from the central through hole 204 along a central axis 212. Each truss structure 200 may be disposed on the rotor 198 so that current may flow along the central axis 212 to assist in controlling torque when the rotor 198 is operating. Each truss structure 200 also includes a pair of second members 218, a pair of third members 220, a pair of side members 222, a lower member 224, and an upper member 226. Each of the pair of side members 222 defines an axis 230. Each axis 230 represents a path of movement of magnetic flux from the rotor 198 to the stator (not shown).

[0037] The members may be arranged relative to each other to define a generally triangular opening of the rotor 198. For example, each truss structure 200 may define five triangular openings. These openings are arranged on the rotor 198 to reduce the weight of the rotor 198 compared to a solid embodiment of the rotor 198. Each truss structure 200 may define a radial length based on the size of the rotor 198, the size of the triangular opening, and the size of the truss structure members. In one example, the truss structure 200 may define a radial length that is approximately one-quarter the radius of the rotor 198.

[0038] Each truss structure 200 may include a first symmetry region and a second symmetry region. Each symmetry region may include a portion of a central member 210, one of a pair of second members 218, one of a pair of third members 220, one of a pair of side members 222, a portion of a lower member 224, and a portion of an upper member 226.

[0039] Each second member 218, a portion of the upper member 226, and a portion of the central member 210 may define a first triangular opening. Each second member 218, one of the third members 220, and one of the side members 222 may define a second triangular opening. The third member 220 and the lower member 224 may define a third triangular opening.

[0040] The outer region of the rotor 198 may include a pair of cutouts 234, each of which is sized to accommodate a magnet. Each of the pair of cutouts 234 may be arranged relative to each other to define a V-shape. The apex of the V-shape may point to the central through hole 204. Each of the pair of cutouts 234 is adjacent to the outer surface 206. The edge of one of the pair of cutouts 234 may be arranged to be parallel to the edge of a member of the truss structure 200. The opening may be provided on the rotor 198 so that the electromagnetic properties of the rotor 198 are not affected. For example, the spacing between the truss structure 200 and the magnet that may be located in the cutout 234 may be such a spacing that the electromagnetic properties of the magnet are not affected when the rotor 198 rotates.

[0041] Figure 7 A portion of a rotor 248 is shown having another example of a truss structure of an inner region referred to as a truss structure 250. Rotor 248 includes a central through hole 254 and an outer surface 256. A plurality of truss structures 250 may be radially arranged about central through hole 254 and within the inner region. Figure 7 Only one truss structure 250 is shown, however, it should be understood that a complete view of rotor 248 would include multiple truss structures 250. Truss structures 250 may provide weight reduction compared to embodiments of rotor 248 without truss structures 250 while also increasing overall structural stiffness by 20%.

[0042] Each truss structure 250 may include a central member 260. Each central member 260 may extend outwardly from the central through hole 254 along a central axis 262. Each truss structure 250 may be disposed on the rotor 248 so that current may flow along the central axis 262 to assist in controlling torque when the rotor 248 is operating. Each truss structure 250 also includes a pair of second members 268, a pair of third members 270, a pair of side members 272, a lower member 274, and an upper member 276. Each of the pair of side members 272 defines an axis 280. Each axis 280 represents a path of movement of magnetic flux from the rotor 248 to the stator (not shown).

[0043] The members may be arranged relative to each other to define generally triangular openings of the rotor 248. For example, each truss structure 250 may define six triangular openings. These openings are arranged on the rotor 248 to reduce the weight of the rotor 248 compared to a solid embodiment of the rotor 248. In addition, the openings are sized to provide the benefit of weight reduction while also increasing the stiffness of the rotor 248. Each truss structure 250 may define a radial length based on the size of the rotor 248, the size of the triangular openings, and the size of the truss structure members.

[0044] Each truss structure 250 may include a first symmetric region and a second symmetric region. Each symmetric region may include a portion of a central member 260, one of a pair of second members 268, one of a pair of third members 270, and one of a pair of side members 272.

[0045] Each second member 268, a portion of the upper member 276, and a portion of the central member 260 define a first triangular opening. Each second member 268, a portion of one of the third members 270, and a portion of one of the side members 272 may define a second triangular opening. Each third member 270, a portion of one of the side members 272, and a portion of the lower member 274 may define a third triangular opening.

[0046] The outer region of the rotor 248 may include a pair of cutouts 284, each of which is sized to accommodate a magnet. Each of the pair of cutouts 284 may be arranged relative to each other to define a V-shape. The apex of the V-shape may point toward the central through hole 254. Each of the pair of cutouts 284 is adjacent to the outer surface 256. The edge of one of the pair of cutouts 284 may be arranged to be parallel to the edge of one member of the truss structure 250.

[0047] Figure 8 A portion of rotor 298 is shown having another example of a truss structure of an inner region referred to as truss structure 300. Rotor 298 includes a central through hole 304 and an outer surface 306. A plurality of truss structures 300 may be radially arranged about central through hole 304 and within the inner region. Figure 8 Only one truss structure 300 is shown, however, it should be understood that a complete view of rotor 298 would include multiple truss structures 300. Truss structures 300 of rotor 298 may reduce the weight of rotor 298 as compared to a rotor having a solid structure, such as rotor 130. Truss structures 300 may provide this weight reduction while also providing a satisfactory stiffness factor.

[0048] Each truss structure 300 may include a central member 310. Each central member 310 may extend outwardly from the central through hole 304 along a central axis 312. Each truss structure 300 may be disposed on the rotor 298 so that current may flow along the central axis 312 to assist in controlling torque when the rotor 298 is operating. Each truss structure 300 also includes a pair of second members 318, a pair of third members 320, a pair of fourth members 322, a pair of side members 324, a lower member 326, and an upper member 328. Each of the pair of side members 324 defines an axis 330. Each axis 330 represents a path of movement of magnetic flux from the rotor 298 to the stator (not shown).

[0049] The members may be arranged relative to each other to define a generally triangular opening of the rotor 298. For example, each truss structure 300 may define eight triangular openings. These openings are arranged on the rotor 298 to reduce the weight of the rotor 298 compared to a solid embodiment of the rotor 298. Each truss structure 300 may define a radial length based on the size of the rotor 298, the size of the triangular openings, and the size of the truss structure members.

[0050] Each truss structure 300 may include a first symmetry region and a second symmetry region. Each symmetry region may include a portion of a central member 310, one of a pair of second members 318, one of a pair of third members 320, one of a pair of fourth members 322, one of a pair of side members 324, a portion of a lower member 326, and a portion of an upper member 328.

[0051] A portion of the central member 310, one of the pair of second members 318, and a portion of the upper member 328 may define a first triangular opening. A portion of one of the second members 318, one of the third members 320, and one of the side members 324 may define a second triangular opening. A portion of one of the third members 320, one of the fourth members 322, and one of the side members 324 may define a third triangular opening. The fourth member 322 and the lower member 326 may define a fourth triangular opening.

[0052] The outer region of the rotor 298 may include a pair of cutouts 334, each of which is sized to accommodate a magnet. Each of the pair of cutouts 334 may be arranged relative to each other to define a V-shape. The apex of the V-shape may point toward the central through hole 304. Each of the pair of cutouts 334 is adjacent to the outer surface 306. The edge of one of the pair of cutouts 334 may be arranged to be parallel to an edge of a member of the truss structure 300.

[0053] The openings may be disposed on the rotor 298 such that the electromagnetic properties of the rotor 298 are not affected. For example, the inner region and the outer region may be disposed relative to each other such that the spacing between the truss structure 300 and the magnets located within the cutouts 334 helps ensure that the electromagnetic properties of the magnets are not affected when the rotor 298 rotates.

[0054] The words used in the specification are descriptive words rather than restrictive words, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. As previously mentioned, the features of each embodiment can be combined to form further embodiments of the present invention that may not be clearly described or illustrated. Although with respect to one or more desired characteristics, multiple embodiments may have been described as providing advantages or being superior to other embodiments or the implementation of the prior art, it should be recognized by those of ordinary skill in the art that, according to specific applications and implementations, one or more features or characteristics can be compromised to achieve the desired overall system properties. These attributes may include but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, maintainability, weight, manufacturability, convenience of assembly, etc. Therefore, the embodiments described as being inferior to other embodiments or the implementation of the prior art in one or more characteristics are not outside the scope of the present disclosure, and can be expected to be used for specific applications.

Claims

1. A vehicle comprising: Traction batteries; an electric machine in operative communication with a traction battery and comprising a stator core defining a cavity and a rotor disposed within the cavity, the rotor having an interior region defined by a collection of triangular holes that are inlaid around respective central regions to form a truss structure such that during rotational operation the holes of the truss structure do not interfere with a magnetic flux path generated by magnets of the rotor, The truss structure includes a pair of symmetrical parts, each symmetrical part shares a first member, and each symmetrical part includes a second member, a third member and a side member. wherein the first member together with a second member and an adjacent portion of the rotor are arranged to define a first triangular aperture and a second triangular aperture, and Each second member is configured together with a third member and a portion of a side member to define a third triangular hole and a fourth triangular hole.

2. The vehicle according to claim 1, wherein: The rotor has a strain energy value less than or equal to 16,100 joules.

3. The vehicle according to claim 1, wherein: Each symmetrical portion further comprises a fourth member, wherein each third member together with a fourth member and another portion of a side member is configured to define a fifth triangular hole and a sixth triangular hole, The fourth member and the base portion of the symmetrical portion are arranged relative to each other to define a seventh triangular aperture.

4. The vehicle according to claim 3, wherein: The first member extends to a base portion of one of the paired symmetrical portions to bisect the seventh triangular hole into two separate holes.

5. The vehicle of claim 1, wherein: The triangular holes are arranged relative to each other so that the strain energy of the rotor is equal to or less than 16100 Joules.

6. A motor assembly, comprising: a stator core, defining a cavity; A rotor is disposed in the cavity and includes a plurality of sector-shaped portions radially arranged around a central through hole of the rotor, wherein each of the plurality of sector-shaped portions includes a truss structure and no more than two magnet openings for accommodating magnets, the no more than two magnet openings being arranged in a V-shape, the truss structure including a plurality of triangular holes defined by members, the members each having an end portion located in a central region of the triangular hole, The truss structure includes a first symmetrical part and a second symmetrical part, each symmetrical part shares a first component, and each symmetrical part includes a second component and a third component. wherein the first member together with the corresponding second member and an adjacent portion of the rotor are arranged to define a first triangular aperture and a second triangular aperture, Each second member is arranged together with one of the third members and another adjacent portion of the rotor to define a third triangular aperture and a fourth triangular aperture.

7. The motor assembly according to claim 6, wherein: Each third member is arranged together with a base member of one of the first and second symmetrical portions to define a fifth triangular hole between the third member and the base member.

8. The motor assembly according to claim 7, wherein: The first member extends to the base member of each of the first symmetrical portion and the second symmetrical portion to bisect the fifth triangular hole.

9. The motor assembly according to claim 6, wherein: The first member defines a central axis extending between a pair of magnets mounted within the two magnet openings.

10. A motor assembly, comprising: a stator core, defining a cavity; a rotor disposed in the cavity and including an inner region and an outer region, the inner region having a truss structure, the outer region being used to mount magnets and being arranged radially from the inner region, The truss structure includes a first symmetrical part and a second symmetrical part, each symmetrical part shares a first component, and each symmetrical part includes a second component and a third component. wherein the first member together with the corresponding second member and an adjacent portion of the rotor are arranged to define a first triangular opening and a second triangular opening, and Each second member is arranged together with a third member and another adjacent portion of the rotor to define a third triangular opening and a fourth triangular opening.

11. The motor assembly according to claim 10, wherein: The truss structure is dimensioned such that the rotor has a strain energy value of 16,000 Joules and a weight of 6.35 kg.

12. The motor assembly according to claim 11, wherein: The truss structure defines a radial length of 54 mm.

13. The motor assembly according to claim 11, wherein: Each symmetrical portion further comprises a fourth member, wherein each third member together with a fourth member and a further adjacent portion of the rotor is arranged to define a fifth triangular opening and a sixth triangular opening, The fourth member together with the base portion of the symmetrical portion is arranged to define a seventh triangular opening.

14. The motor assembly according to claim 13, wherein: Each member defines a width of 3 mm to 7 mm, and the rotor defines a diameter of 110 mm to 230 mm.

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