MXPA06006071A - Rotor core with spacers - Google Patents

Abstract

An electric machine that includes a stator core having a stator core length, a first rotor core portion, and second rotor core portion. A spacer is coupled to the first core portion and the second core portion to at least partially define a rotor core. The rotor core has a length that is greater than the stator core length. A permanent magnet is coupled to the rotor core and has a magnet length. The magnet length is greater than the stator core length

Description

ROTOR NUCLEUS WITH SEPARATORS RELATED REQUEST DATA This application claims priority to the provisional patent application of E.U.A. co-pending with serious number 60 / 689,962, filed on May 27, 2005, whose content is incorporated here by reference.

BACKGROUND OF THE INVENTION The invention relates to a rotor core for electrical machines. Most particularly, the invention relates to an electric machine that includes a stator core having a stator core length and a rotor core having a rotor core length that is greater than the length of the stator core. Two prior art engines 10, 15 are shown in figures 1-2. The motor 10 includes a stator core 20 and a rotor core 25 made using the same number of laminations that are punched with a single (given) tool. Specifically, the tool, such as a progressive die, simultaneously punches a stator lamination and a rotor lamination, which is placed within the lamination of the stator in order to reduce waste.

The motor 15 of Figure 2 includes a stator core 20 and a rotor core 25a that have the same length. This construction is advantageous from the point of view of cost, since the same number of laminations is used for both the stator core 20 and the rotor core 25a. The output of the motor 10 of FIG. 1, which uses the same stator core 20 as in FIG. 2, is improved over the output of the motor 15 of FIG. 2 due to the use of a longer rotor core 25 and magnet 30. , whose flow is axially concentrated through the stator. As a result, the air gap flux density, the stator flux link, the specific output of the machine, and / or the efficiency are increased. The main disadvantage of this solution is the increase in cost associated with the need to produce more rotor laminations than stator laminations. The increased number of rotor laminations, compared to the stator laminations of Figure 2, requires the manufacturer to purchase additional laminated steel and invest in complementary tool, which can produce rotor laminations alone, instead of the lamination combination of stator and rotor more common. The invention overcomes this disadvantage through special constructions for which increased motor output is achieved by using approximately the same number of laminations in the stator core and rotor core.

BRIEF DESCRIPTION OF THE INVENTION In one embodiment, the invention provides an electrical machine that includes a stator core having a stator core length, a first rotor core portion, and a second rotor core portion. A spacer is coupled to the first rotor core portion and the second rotor core portion to at least partially define a rotor core having a rotor core length greater than the length of the stator core. A permanent magnet is coupled to the rotor core and has a magnet length. The length of the magnet is greater than the length of the stator core. In another embodiment, the invention provides an electric machine that includes a rotor shaft, an amount of stator laminations stacked adjacent to each other to define a stator core having a stator core length, and a number of rotor laminations. coupled to the rotor arrow. The number of rotor laminations is approximately equal to the number of stator laminations. A permanent magnet is coupled to at least one of the rotor laminations and has a magnet length that is greater than the length of the stator core. The invention also provides a method of manufacturing a motor. The method includes forming an amount of stator laminations, stacking the number of stator laminations to define a stator core having a first and a second end defining a stator length, and form a number of rotor laminations. The method also includes stacking the number of rotor laminations and connecting a separator to at least one of the rotor laminations such that the number of rotor laminations and the separator cooperate to define a rotor core having a length of rotor core. The method further includes fixing a permanent magnet to the rotor core to define a rotor. The permanent magnet has a magnet length that is greater than the length of the stator core. Other aspects and embodiments of the invention will become apparent upon consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The detailed description particularly refers to the appended figures in which: Figure 1 is a schematic illustration of a longitudinal sectional view of a prior art engine including a stator and a rotor; Figure 2 is a schematic illustration of a longitudinal sectional view of another prior art engine including a stator and a rotor; Figure 3 is a schematic illustration of a longitudinal sectional view of a motor including a stator and a rotor; Figure 4 is a schematic illustration of a longitudinal sectional view of a motor including a stator and a rotor including spaces or recesses; Figure 4a is an enlarged schematic illustration of a portion of the motor of Figure 4, within the contour denoted by 4a; Figure 5 is a schematic illustration of a longitudinal sectional view of a rotor including a magnetic separator or expander; Figure 6 is a cross-sectional view of the rotor of Figure 5; Figure 7 is a schematic illustration of a longitudinal sectional view of a motor including a stator and a rotor including a magnetic separator or expander; Figure 8 is a schematic illustration of a longitudinal sectional view of a motor including a stator and a rotor including a non-magnetic separator; Fig. 9 is a schematic illustration of a longitudinal sectional view of another motor including a stator and a rotor having end core extensions; Figure 10 is a perspective view of a separator; Figure 11 is a perspective view of another separator; Figure 12 is a front view of a rotor lamination; and Figure 13 is a front view of another rotor lamination.

DETAILED DESCRIPTION OF THE INVENTION Before explaining in detail any modalities of the invention, it is understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the following figures. The invention is capable of having other modalities and of being implemented or of being carried out in various ways. Also, it is understood that the phraseology and terminology used here is for the purpose of description and should not be considered as limiting. The use of "including", "comprising", or "having" and variations thereof is understood to encompass the points listed below and equivalents thereof as well as additional points. Unless otherwise specified or limited, the terms "assembled", "connected", "supported" and "coupled" and variations thereof are widely used and encompass assemblies, connections, supports and direct and indirect couplings. In addition, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings. Furthermore, where a method, procedure or list of steps is provided, the order in which the method, procedure or list of steps is presented should not be read as limiting the invention in any way. Before proceeding, it should be noted that the invention described herein is especially suitable for brushless motors with circumferentially placed magnets, a typical example being rotor designs with magnets mounted on the surface, which are radially magnetized. However, the invention can also be adapted for other types of rotors, such as but not limited to permanent magnet rotors or "wheel beam" type rotors in which the magnets are at least partially fitted within the rotor core. . Figure 3 illustrates an engine 35 that includes a rotor 40 and a stator 45 positioned to define an air gap therebetween. The stator 45 includes a core 50 that is wound with one or more conductors to define coils and windings 55. The core 50 is formed from a stack of laminations 60 defining a first core end 65 and a second core end 70 A length of the stator core 75 is defined as the length of the core 50 as measured between the first end 65 and the second end 70. The rotor 40 includes an arrow 80 that supports a rotor core 85. The rotor core 85 in turn supports one or more permanent magnets 90. As with the stator core 50, the rotor core 85 is formed from a plurality of stacked laminations 95. In preferred constructions, the rotor core 85 includes approximately the same number of laminations 95 as the stator core 50 (e.g., within about 20 percent). The rotor core 85 includes a first end 100 and a second end 105 cooperating to define a length of the rotor core 110. In the construction illustrated in FIG. 3, the length of the rotor core 110 is approximately equal to the length of the rotor core 110. stator core 75. As illustrated in Figure 3, the permanent magnet 90 is fixed to the outer periphery of the rotor laminations 95 and includes a first end 111 extending beyond the first end 100 and a second end 112 that it extends beyond the second end 105 of the rotor core 85. Therefore, the construction of Figure 3 includes a magnet 90 which defines a length of magnet 113, measured from the first end 111 to the second end 112, which is greater than the length 75 of the stator core 50. However, the length of the rotor core 110 is substantially the same as the length of the stator core 75. Therefore, the magnet 90 protrudes from the rotor core. 85 and the benefits in the stator surface air gap flux density and the stator winding flow link are minimal, mainly due to the increased reluctance of the extreme magnetic field path. Before proceeding, it should be noted that the length of the magnet 113, as well as the length of the stator core 75 and the length of the rotor core 110, are measured from the extreme axial positions of the component. Therefore, constructions using multiple magnets stacked along the axial length will nonetheless define a magnet length that encompasses all magnets. The spaces between the magnets become part of the length of the magnet. Similarly, spaces in the stator core 50 or rotor core 85 would be added to the length of the stator core 75 and to the length of the rotor core 110.

Figures 12 and 13 illustrate two possible laminations 95, 95a, for use in a rotor core 85. The lamination 95 of Figure 12 is substantially circular when viewed from the end and includes four alignment members 115 and a central opening 120 for use in fixing the lamination to the rotor shaft 80. In most constructions, the central aperture 120 is circular and is dimensioned to provide an interference fit between the aperture 120 and the rotor shaft 80. Other constructions they can use other shapes or sizes for opening 120, as desired. The alignment members 115 of Figures 12 and 13 include rectangular openings that are located approximately 90 degrees apart from one another. The openings help to align adjacent laminations 95 during the stacking procedure of the rotor cores 85. In other constructions, lancets, indentations or other features are used as alignment members 115 in place of the rectangular openings. Also, if desired, other quantities or forms could be used. In some constructions, the rotor laminations are welded or bonded together, or other means known to those skilled in the art are used to form a core stack. The lamination 95a of Figure 13 is similar to the lamination 95 of Figure 12 with the exception of eight additional weight reducing apertures 125 extending through the lamination 95a. The weight reducing apertures 125 reduce the weight of the lamination 95a in such a way that the rotor core 85 constructed using the laminations 95a of FIG. 13 is significantly lighter than a rotor core 85 constructed using the laminations 95 of FIG. 12 The rotor cores 85 can be constructed using either the laminations 95, 95a illustrated in Figure 12 or Figure 13, or combinations of these laminations 95, 95a as desired. In addition, if desired, other rolling arrangements not described herein can be used. Fig. 4 illustrates a motor 130 improving the operational characteristics of the motor 35 of Fig. 3. The motor 130 includes three axial motor core modules 135 spaced about equally apart on an arrow 140 to define at least partially a core of rotor 145. Each rotor core module 135 is generally assembled from a plurality of laminations 95, 95a similar to those illustrated in figures 12 or 13. In one construction, a combination of the two illustrated laminations 95, 95a is used. . The majority of laminations 95, 95a are internal laminations 95a such as lamination 95a illustrated in FIG. 13. Each end of internal lamination stack 95a receives at least one end lamination 95 that does not include the weight reducing holes 125. The use of end laminations 95 reduces air friction losses of the rotor core modules 135, while the weight reducing holes 125 of the inner laminations 95a reduce the rotor core weight, and therefore reduce losses mechanical In other rotor constructions, only one type of lamination is used, for example lamination 95a. In preferred constructions, the total axial length of the rotor core modules 135 is chosen to match the axial length of a stator core 150, thus allowing the use of substantially the same number of laminations for each of the rotor core 145 and the stator core 150. In some rotor constructions, such as the construction of FIG. 5, the rotor core modules 135 are spaced apart such that the end of the rotor core 138 is axially aligned (flush) with the end of the magnet 111 and the end of the rotor core 139 is axially aligned with the end of the magnet 112, respectively. As illustrated in Figure 4, each of the rotor core modules 135 is coupled to the rotor shaft 140 and one or more permanent magnets 155 are fixed to the rotor core modules 135 to complete a rotor 160. three rotor core modules 135 are located in such a way that a spacer or space 165 is defined between any two adjacent rotor core modules 35. Therefore,, the length of the rotor core 110, including the axial length of each of the core modules 135 and the spaces 165, is greater than the length of the stator core 75, while still using approximately the same number of laminations. It should be noted that a direct connection of each rotor core module to the shaft is not an absolute requirement. For example, in some constructions, only one rotor core module is directly connected to (ie, in contact with) the arrow and the other modules are connected to the module that is connected to the arrow. Therefore, in this example, only one rotor core module is directly connected to the arrow with the other rotor core module or modules connected to the first rotor core module. Small rings (not shown) can be placed around the arrow 140 to separate the rotor core modules 135 at the desired locations. The rings could be constructed for example from a non-magnetic material such as plastic. Additionally, in some constructions the rotor core modules 135 are manufactured in such a way that the end laminations are widened (bent) outwards, thus further increasing the axial path of the magnetic flux. Due to the improved axial distribution of the non-linear magnetic circuit, the air gap flux density, the stator flux link and the motor output are all increased compared to those of the motor 35 of FIG. 3. Before proceeding , it should be noted that although the construction illustrated in Figure 4 includes three rotor core modules 135, other constructions may use two rotor core modules 135 or four or more rotor core modules 135. As such, the invention should not limited to constructions using three rotor core modules 135. To further increase engine performance, a magnetic separator 170 or extender can be placed between two rotor core modules 135 as shown in Figures 5 and 7. The figures 10 and 11 illustrate two possible magnetic extenders 170, 170a that can be used in a rotor core 145. In preferred constructions, the magnetic extenders 170, 170 a include a ferromagnetic isotropic material, other materials being suitable for use. The separator 170 of Figure 10 includes a substantially ring-shaped portion 175 that includes an outer diameter 180 that is substantially equal to the outer diameter of the rotor laminations 95, 95a, and an internal diameter 185 selected to maintain rotor saturation. and falling mmf to a desirable level, while also reducing the weight of the separator 170. The separator 170 also includes four projections 190 extending from the ring-shaped portion 175. Two projections 190 extend in each axial direction, with the projections 190 extending in the same direction being separated approximately 180 degrees. Each of the projections 190 is dimensioned to engage one of the weight reducing openings 125 of the laminations 95, 95a to fix the position of the separator 170. In other constructions, other arrangements, quantities, sizes and / or shapes may be used. to define the projections 190. A spacer 170a of FIG. 11 is very similar to the spacer 170 of FIG. 10 but also includes weight reducing openings 195, which extend through the ring-shaped portion 175 and reduce the weight e. inertia of spacer 170a when compared to spacer 170 of FIG. 10. The shape, dimensions and position of openings 195 may be the same as or different from openings 125 of lamination 95a.In engines with a relatively high number of poles, the internal diameter of the separator 170, 170a is substantially greater than the external diameter of the arrow. This is advantageous to reduce the weight and cost of the rotor. The separator 170, 170a can be fixed to the rotor core modules 135 using bolts or pins 200 such as those shown in Figure 6. The bolts 200 are at least in partial contact with the separator 170, 170a in order to improve the mechanical rigidity of the rotor assembly 160. In a preferred construction, the magnetic separator 170, 170a is made by mechanically pressing and compacting and concreting magnetic iron powder or soft magnetic mixed materials. Materials with isotropic magnetic characteristics are preferable in order to increase the axial and radial magnetic flux path. To reduce manufacturing costs, the pins or pins 200 can be formed as part of the magnetic extender 170, 170a. In some constructions, the magnetic extenders 170, 170a can be attached to a rotor core comprising laminations 95a by press fitting the projections 190 through lamination openings 125. Returning to FIGS. 5 and 7, a rotor 205 (shown in FIG. Figure 5) includes two rotor core modules 135 that are separated by the separator 170, 170a. Therefore, the rotor 205 defines a length of the rotor core 210 that is equal to the axial length of the two rotor core modules 135 plus the axial width of the spacer 170, 170a. In the illustrated construction, the separator 170, 170a is placed between two rotor core modules of substantially equal length 135. Of course, one skilled in the art will realize that the spacer 170, 170a could be placed between core modules of unequal length rotor 135 and that more core modules and spacers could be used if desired. An engine 215, illustrated in Figure 7, includes the rotor 205 of Figure 5. As can be seen, the rotor 205 includes a rotor core 220 as well as a permanent magnet 225 attached to the rotor core 220. The total axial length of the The rotor core plus the magnetic extender 170, 170a is approximately equal to the axial length 210 of the magnet 225, which is larger than an axial length 230 of a stator core 235. Figure 8 illustrates another motor construction 240 similar to the illustrated in Figure 7. However, instead of placing the magnetic separator 170, 170a near the outer diameter of the rotor core modules 135 as illustrated in Figure 7, a non-magnetic separator 245 placed between the core modules of rotor 135 adjacent to the arrow of the rotor 140. This construction has an advantage in that it reduces the forces generated during the operation as it places the weight of the separator 245 closer to the center of rotation. In addition, lightweight and / or low cost material (eg, plastic) can be used to form the separator 245. Figure 9 illustrates another motor 250 that includes a rotor core 255 that is longer than a stator core 260. The construction of figure 9 includes a laminated rotor core module 135 and two magnetic extenders 265. Each of the two external magnetic extenders 265 engages the laminated rotor core module 135 and extends away from the rotor core module 135. The two magnetic extenders 265 have the same size and shape and are fixed through bolts or pins, or adhesively bonded to the extreme laminations of the laminated core module 135. The end magnetic extenders 265 are made preferably of a material, such as compacted magnetic iron powder or mixed soft magnetic materials, which increase the radial and axial flow path and concentrate the magnetic flux through of the stator core 260. In one construction, the magnetic extenders 265 closely resemble the spacers 170, 170a of FIG. 10 but omit the projections 190 on one side. The constructions previously described use stator and rotor laminations manufactured from the same electric steel. It should be understood that they are also possible, although not preferable, other constructions in which the rotor laminations are produced from material of different thickness and / or degree than the stator laminations. In this case, the number of laminations in the rotor may be different from the number of stator laminations, although the total length of the lamination stack could be the same for the rotor and the stator. Therefore, among other things, the invention provides an electric machine with increased efficiency due to the additional length of the rotor core compared to the stator core. Several features and advantages of the invention are set forth in the following claims.

Claims (36)

NOVELTY OF THE INVENTION CLAIMS

1. - An electrical machine comprising: a stator core having a stator core length; a first rotor core portion; a second rotor core portion; a separator coupled to the first core portion and the second core portion to define at least partially a rotor core having a rotor core length that is greater than the length of the stator core, and a permanent magnet coupled to the rotor. rotor core and having a magnet length, the length of the magnet being greater than the length of the stator core.

2. The electric machine according to claim 1, further characterized in that the length of the rotor core is substantially equal to the length of the magnet.

3. The electric machine according to claim 1, further characterized in that the first core portion and the second core portion include laminations.

4. The electric machine according to claim 1, further characterized in that the first core portion and the second core portion together include a first number of laminations, and wherein the stator includes a second number of laminations that is approximately equal to the first number of laminations.

5. - The electrical machine according to claim 1, further characterized in that the first core portion is separated at a distance other than zero from the second core portion to define a space therebetween.

6. The electric machine according to claim 5, further characterized in that the first core portion defines an outer surface, and wherein the separator is located within the space such that it is adjacent to the outer surface.

7. The electric machine according to claim 5, further characterized in that it comprises a rotor arrow having an outer arrow surface, and wherein the first core portion and the second core portion are coupled to the arrow and the The separator is located within the space such that it is adjacent to the outer surface of the arrow.

8. The electric machine according to claim 7, further characterized in that the separator includes a ferromagnetic isotropic material and projections that engage the first core portion and the second core portion.

9. The electric machine according to claim 1, further characterized in that the separator is formed of magnetic material.

10. The electric machine according to claim 1, further characterized in that the first core portion is in direct contact with the second core portion to define a first core end and a second core end, and wherein the separator it is arranged adjacent to the first core end.

11. The electric machine according to claim 10, further characterized in that it comprises a second separator located adjacent to the second core end.

12. The electric machine according to claim 1, further characterized in that it comprises a third core portion and a second separator, the separator located between the first core portion and the second core portion, and the second separator disposed between the second core portion and third core portion.

13.- The electric machine in accordance with the claim 12, further characterized in that at least one radially magnetized magnet is attached to the outer surface of at least one of the first core portion, the second core portion and the third core portion.

14.- The electric machine in accordance with the claim 12, further characterized in that it comprises an arrow coupled to at least one of the rotor core portions, and a non-magnetic separator located adjacent to the arrow between the first core portion and the second core portion.

15. The electric machine according to claim 12, further characterized in that at least one of the first core portion, the second core portion and the third core portion includes laminations, and wherein at least a portion of those laminations includes weight reducing openings.

16. The electric machine according to claim 15, further characterized in that each of the first core portion, the second core portion and the third core portion includes laminations having weight reducing openings that define a rotor core. , and wherein the most extreme lamination at each end of the rotor core includes laminations that do not include weight reducing apertures.

17.- An electric machine that includes: a rotor arrow; a number of stator laminations stacked together to define a stator core having a stator core length; a number of rotor laminations coupled to the rotor shaft, the number of rotor laminations being approximately equal to the number of stator laminations; and a permanent magnet is coupled to at least one of the rotor laminations and having a magnet length that is greater than the length of the stator core.

18.- The electric machine in accordance with the claim 17, further characterized in that it comprises a separator coupled to the arrow and that cooperates with the number of rotor laminations to define a rotor core having a rotor core length.

19.- The electric machine in accordance with the claim 18, further characterized in that the length of the rotor core is greater than the length of the stator core.

20. The electric machine according to claim 19, further characterized in that the length of the rotor core is substantially equal to the length of the magnet.

21.- The electric machine in accordance with the claim 18, further characterized in that the number of rotor laminations is divided into a first core portion and the second core portion that are separated from one another to define a space, and wherein the separator is located within the space.

22. The electric machine in accordance with the claim 17, further characterized in that the number of rotor laminations are divided into a first core portion and the second core portion that are separated from one another to define a space.

23. The electric machine according to claim 17, further characterized in that the separator is formed of a ferromagnetic material.

24.- The electric machine in accordance with the claim 18, further characterized in that the number of rotor laminations defines a first core end and a second core end, and wherein the spacer is disposed adjacent the first core end.

25. The electric machine according to claim 24, further characterized in that it comprises a second separator located adjacent to the second core end.

26. - The electric machine according to claim 17, further characterized in that it comprises a first separator and a second separator, wherein the number of rotor laminations is divided into a first portion, a second portion and a third portion, and wherein the first separator is disposed between the first portion and the second portion, and the second separator is located between the second portion and the third portion.

27. The electric machine according to claim 17, further characterized in that at least a portion of the rotor laminations include weight reducing openings.

28.- The electric machine in accordance with the claim 27, further characterized in that the amount of rotor laminations at least partially defines a rotor core, and where the most extreme lamination at each end of the rotor core includes laminations that do not include weight reducing apertures.

29.- A method of manufacturing an engine, the method comprises: forming a number of stator laminations; stacking the number of stator laminations to define a stator core having a first end and a second end defining a stator length; forming a number of rotor laminations; stack the number of rotor laminations; connecting a separator to at least one of the rotor laminations such that the amount of rotor laminations and the separator cooperate to define a rotor core having a rotor core length; and fixing a permanent magnet to the rotor core to define a rotor, the permanent magnet having a magnet length that is greater than the length of the stator core.

30. The method according to claim 29, further characterized in that the number of stator laminations is approximately equal to the number of rotor laminations.

The method according to claim 29, further characterized in that it comprises dividing the number of rotor laminations into a first portion and a second portion and locating the separator between the first portion and the second portion.

32. The method according to claim 29, further characterized in that the number of rotor laminations defines a first end and a second end and the spacer is disposed adjacent the first end.

33. The method according to claim 32, further characterized in that it comprises locating a second separator adjacent to the second end.

34. The method according to claim 29, further characterized in that it comprises dividing the number of rotor laminations into a first portion, a second portion and a third portion, locating the separator between the first portion and the second portion, and locating a second separator between the second portion and the third portion.

The method according to claim 29, further characterized in that the length of the magnet is approximately equal to the length of the rotor core.

36. The method according to claim 29, further characterized in that it comprises forming the separator of a magnetic material.