JP5493792B2 - IPM motor rotor and IPM motor - Google Patents

Description

  The present invention relates to a rotor for an IPM motor, in which a magnet is embedded in a rotor disposed inside a stator, and an IPM motor including the rotor.

  In the automobile industry, with the aim of further improving the running performance of hybrid cars and electric cars, developments for driving motors with higher output, lighter weight, and smaller size are in progress every day. In addition, home appliance manufacturers have no choice but to develop further miniaturization and higher performance of motors incorporated in various home appliances.

  Among the motors described above, there are an inner rotor type motor in which a rotor disposed inside the stator rotates, and an outer rotor type motor in which a cylindrical rotor rotates on the outer periphery of the stator.

  By the way, in an IPM motor which is an inner rotor type and has a permanent magnet embedded in the rotor, the distance between the end of the permanent magnet and the inner peripheral surface of the rotor (side surface corresponding to the stator) is as narrow as possible. This makes it difficult for the magnetic flux in this region to flow, reduces leakage magnetic flux, and more effectively uses the magnetic flux of the magnet to improve the torque performance of the motor. This will be described with reference to FIG. 7. With respect to the permanent magnets arranged in the magnet holes E, E arranged in a V shape in a plan view in the rotor R, the region from the end to the side surface of the rotor (region A) (Referred to as “outer bridge”): By shortening L, leakage magnetic flux M is hardly generated.

  However, as described above, the distance from the end of the magnet hole E (permanent magnet) to the side surface of the rotor: L, that is, by reducing the width of the outer bridge, the leakage magnetic flux becomes difficult to flow, but this time the area A is narrowed. Therefore, it is easy to understand that the rotor strength decreases. In particular, in this region A, a centrifugal force acts on the permanent magnet by the rotation of the rotor, and the centrifugal force of this permanent magnet acts directly. Therefore, the region A requires a sufficient strength. Yes. Therefore, in order to improve the strength while narrowing the region A as much as possible, for example, when trying to improve the strength of the electromagnetic steel sheet itself constituting the rotor, the magnetic characteristics of the rotor will deteriorate, The torque performance will be reduced.

  Therefore, Patent Document 1 discloses a rotor (rotor) provided with a high magnetic resistance portion between adjacent permanent magnets, between a permanent magnet and a rotor end portion, or the like, in order to reduce the above-described leakage magnetic flux. ing. Further, as another disclosed technique, a neck portion is provided at an end facing a gap (referred to as a center bridge) in a magnet hole arranged in a V shape, whereby the strength of the center bridge portion is increased. An enhanced rotor is disclosed in US Pat.

JP 2002-281700 A JP-A-2005-57958

  According to the rotor disclosed in Patent Document 1, by providing a relatively high magnetic resistance portion on the iron core on the side of the permanent magnet, the permanent magnet is more permanent than a permanent magnet that does not have such a high magnetic resistance portion. The leakage magnetic flux from the side of the magnet can be reduced. In addition, according to the rotor disclosed in Patent Document 2, it seems that the rotor core strength against centrifugal force is reduced by providing a neck portion that narrows the width of the center bridge portion at first glance. The rotor core strength is improved.

  However, in both the rotors (rotors) disclosed in the above-mentioned documents, the side of the permanent magnet is still in communication with the iron core, and the leakage magnetic flux cannot be completely eliminated. The torque performance of the motor provided with is much inferior to the torque performance of the motor provided with the rotor capable of completely eliminating the leakage magnetic flux.

  The present invention has been made in view of the above problems, and includes a rotor for an IPM motor that can guarantee high strength and can effectively eliminate a leakage magnetic flux from a permanent magnet, and the rotor. An object is to provide an IPM motor.

  In order to achieve the above object, the rotor for an IPM motor according to the present invention has a cylindrical rotor core, and a groove is formed on a side surface thereof, and the rotor is disposed in the groove so as not to contact the groove. The split magnets are sandwiched together with the concave grooves, and are provided with a suppressor composed of a plurality of split bodies formed by laminating steel plates, between the split magnets adjacent in the stacking direction, and between the adjacent split bodies, In each of these, an overhanging portion formed by overhanging a part of the rotor core is interposed, and at least the restraining material is fixed by two end plates arranged at the end of the rotor core.

  The rotor for an IPM motor of the present invention is obtained by sandwiching a magnet that constitutes a magnetic pole between a non-contacting and completely edged rotor core and a restraining material, and fastening them with an end plate, and there is a rotor core on the side of the magnet. By not doing so, at least the outer bridge described above is completely abolished, so that the leakage magnetic flux from the magnet can be completely eliminated. The term “non-contact” as used herein means that the rotor core and the pressing member are not in contact with each other in the side region of the divided magnet, that is, the region corresponding to the outer bridge or the center bridge described above. The overhanging part that constitutes and the holding member (the divided body that constitutes) are in contact.

  As a more specific configuration, in a rotor core having a recessed groove, a plurality of protruding portions are formed by projecting a part of the rotor core into the recessed groove, and a split magnet is interposed in a gap between adjacent protruding portions. By sandwiching a plurality of divided bodies formed by laminating steel plates, the divided magnets are sandwiched and fixed between the concave groove wall surface of the rotor core and the divided bodies, and the divided bodies protrude from the rotor core at both ends (upper and lower sides). It has a structure that is sandwiched and fixed at a location. For example, there may be mentioned a configuration in which a plurality of thin plate-like projecting portions are provided at predetermined intervals in the height direction of the rotor core from concave grooves formed over the entire height of the rotor core. it can.

  The shape of the groove formed in the rotor core is arbitrary. For example, in a form in which a permanent magnet having a rectangular shape in plan view is fixed in the rotor core in a V-shaped arrangement to form one magnetic pole, A concave groove having a side surface (composite surface in which a straight portion and a curved portion are continuous) is formed, and the shape of the restraining material is such that both of the concave grooves are in a posture sandwiching two permanent magnets arranged in a V shape. A form having a substantially arc-shaped side surface corresponding to the shape and an arc-shaped side surface having a side surface serving as an outer peripheral surface of the rotor core can be applied. By applying the rotor structure of the present invention, the center bridge between the two permanent magnets can be eliminated in addition to the outer bridge between the two permanent magnets and the end of the rotor core.

  Here, the restraining material on the stator side relative to the permanent magnet is a magnetic flux contributing to the torque when the motor is driven (magnetic flux contributing to the reluctance torque from the teeth to the adjacent teeth through the restraining material, or from the side of the permanent magnet to the stator side. While the magnetic flux fluctuates significantly, the inner region of the rotor core (here, the rotor core main body in which the concave grooves are formed) has no magnetic flux variation as described above. The influence of the magnetic characteristics of the region on the torque performance of the motor is extremely low. Therefore, while the suppressor uses a structure in which steel sheets such as electromagnetic steel sheets or high grade electromagnetic steel sheets are laminated, the rotor core only needs to secure the rigidity of the core itself, and compared with the suppressor if the flow of magnetic flux is taken into consideration. In consideration of the fact that high magnetic properties are not required, for example, it is integrally molded from cast iron-based magnetic materials (thin plates are also formed integrally with the overhanging portion that protrudes into the concave groove), or the magnetic properties are higher than that of the suppressor. It is economical to form from a steel sheet laminate formed by laminating inferior steel sheets. Incidentally, the “cast iron-based magnetic material” is a carbon-containing material containing iron as a main component, and examples thereof include cast iron and steel, and further, an additive element such as silicon, It is a material containing nickel, cobalt, aluminum, vanadium, boron (boron), tungsten, molybdenum, titanium, phosphorus, etc., and it is cheaper than electromagnetic steel sheets, etc. A core body (rotor core) having a shape can be easily formed.

  A split body that constitutes a split magnet and a restraining material is arranged between a plurality of protruding portions that protrude into the concave groove of the rotor core, and both ends of the rotor core are, for example, nonmagnetic materials such as aluminum and copper, and alloys thereof. The rotor for an IPM motor according to the present invention is formed by sandwiching it with an end plate made of brass or the like and caulking the whole.

  In this rotor, as described above, since the outer bridge and the like of the rotor having the conventional structure can be eliminated, the leakage magnetic flux from the split magnet (permanent magnet) can be completely eliminated, and the rotation efficiency can be reduced. It can be used for an IPM motor with excellent torque performance and rotational performance.

  In addition, since the magnet interposed between the rotor core and the holding member is a split magnet, the magnetic flux passage area can be reduced compared to a general permanent magnet that is not a split magnet, and eddy currents that can occur in the magnet are reduced. Reduction can also be achieved.

  Here, the protruding portion of the rotor core, the divided body, and the divided magnet may be bonded and fixed.

  Lamination of steel cores during caulking, etc., with adhesives with excellent heat resistance, such as epoxy adhesives, where the overhanging part of the rotor core and the split body of the restraining material are bonded and fixed. Excessive stress acts on each steel plate of the restraining material composed of the body, and the problem that the magnetic properties of the steel plate are deteriorated cannot occur.

  Further, as a measure for further increasing the fixing strength when fixing the pressing member with the end plate, in the posture where the protruding portion of the pressing member and the rotor core is positioned, a through hole is formed so as to penetrate the two protruding members. It may face both ends on the end plate side, a bar may be inserted through the through hole, and the bar may be fixed to the two end plates.

  For example, a through hole is opened in the end plate, and at least a bar longer than the total thickness of each divided body and the total thickness of each overhanging portion is inserted into the through hole formed in the holding member, The form which inserts the edge part of the bar material which protrudes from the end plate side end surface of a suppression material to the through-hole of an end plate can be mentioned.

  And it is preferable that the above-mentioned bar is either one in which wire rods having relatively small cross sections are bundled or one in which face materials having relatively small cross sections are laminated. This is because the passage area when the magnetic flux passes through the bar can be made as small as possible by being formed of a wire or face having a small cross section, and possible iron loss can be suppressed.

  For example, magnetic steel plates are laminated to form a bar material, and this laminating direction is set to be a direction orthogonal to the longitudinal direction of the restraining material (bar material insertion direction), and the laminated surface of each electromagnetic steel plate is on the stator side In addition to the prevention of iron loss, the highest cross-sectional rigidity (bending rigidity) of the bar can be expected by inserting the bar through the through-hole (in the radial direction of the rotor core). That is, with respect to a bar whose both ends are constrained by two end plates, when the centrifugal force acting on the permanent magnet as the external force acts on the bar via the suppressor as the external force, the highest bending rigidity cross section is obtained. This external force can be resisted.

  As described above, in the form in which the holding member and the end plate are fixed with the bar, the bar is disposed at a position that does not interfere with the magnetic flux flow inside the holding member. Is desirable.

  As can be understood from the above description, according to the rotor for the IPM motor of the present invention and the IPM motor having the rotor, the bridge portion (outer bridge) between the outer periphery of the rotor and the magnet (permanent magnet) is completely eliminated. In the form in which two permanent magnets form one magnetic pole with a V-shaped arrangement, the center bridge can also be eliminated, so that sufficient strength (rigidity) of the rotor core is secured, The magnetic flux leakage from the magnet can be completely suppressed, and thus an IPM motor with excellent torque performance can be obtained.

1 is an exploded perspective view of an embodiment of a rotor for an IPM motor of the present invention. FIG. 2 is an assembled perspective view of the rotor of FIG. 1. It is a disassembled perspective view of other embodiment of the rotor for IPM motors of this invention. FIG. 4 is an assembled perspective view of the rotor of FIG. 3. FIG. 5 is a diagram illustrating a planar arrangement position of a bar member in a holding member in the rotor of FIG. 4. It is a magnetic field analysis result which compared each torque of an analysis model (example) of a motor provided with a rotor of the present invention, and an analysis model (comparative example) of a motor provided with a rotor of the conventional structure. In the conventional rotor for inner rotor type IPM motors, it is the figure which showed typically the leakage magnetic flux from a permanent magnet.

  Embodiments of the present invention will be described below with reference to the drawings. In the illustrated rotor, two permanent magnets (divided magnets) are arranged in a V shape to form one magnetic pole, but one permanent magnet (divided magnet) that forms one magnetic pole is provided. Of course, it may be a rotor that faces the teeth of a stator (not shown) and is arranged in the circumferential direction of the rotor core by the number of magnetic poles.

  1 is an exploded perspective view of an embodiment of the rotor for an IPM motor of the present invention, FIG. 2 is an assembled perspective view of the rotor of FIG. 1, and FIG. 3 is a view corresponding to FIG. FIG. 4 is an exploded perspective view of another embodiment of the rotor for the IPM motor, and FIG. 4 is an assembled perspective view of the rotor of FIG.

  A rotor 100 shown in FIGS. 1 and 2 includes a rotor core 10 formed by integrally molding a cast iron-based magnetic material, and a plurality of concave grooves 11,... Provided on the side surface of the rotor core 10 in the circumferential direction. A holding member 40 that sandwiches and fixes the divided magnets 2a and 2b between the plurality of divided magnets 2a and 2b (which forms one magnetic pole 20) disposed in the groove 11 and the side surface of the concave groove 11 ( And the end plates 30 and 30 for positioning and fixing the divided magnets 2a and 2b and the holding member 40 and integrally forming the rotor constituent members. A shaft hole opened at the center of the end plate 30 constituting the rotor 100 and a shaft hole 10a opened at the center of the rotor core 10 are positioned coaxially in the completed rotor shown in FIG. It is designed to be inserted.

  Here, the cast iron-based magnetic material forming the rotor core 10 is, for example, a carbon-containing material mainly composed of iron, and examples thereof include cast iron and steel. These materials include silicon, nickel, cobalt, aluminum, vanadium, boron (boron), tungsten, molybdenum, titanium, and phosphorus. Such a material is pressure-molded in a mold to mold the rotor core 10.

  Moreover, each division body which comprises the suppressing material 40 is formed from the steel plate laminated body formed by laminating | stacking the electromagnetic steel plates 4, .... The restraining member 40 through which magnetic flux generated by the magnet generated on the stator side passes is formed from a magnetic steel sheet laminate having excellent magnetic characteristics, and the rotor core 10 with little magnetic flux variation and little magnetic flux contributing to torque is relatively formed. By molding from inexpensive cast iron or the like, it is possible to manufacture the rotor 100 for an IPM motor that is excellent in magnetic characteristics (and therefore has a high torque performance of the motor) and is as inexpensive as possible.

  Here, a plurality of plate-like projecting portions 12 project in the concave groove 11 of the rotor core 10, and the projecting portions 12 and the divided magnets 2a and 2b are bonded with an epoxy adhesive having excellent heat resistance. Further, a holding member 40 that holds the divided magnets 2a and 2b together with the rotor core 10 is also bonded and fixed to the protruding portion 12. In the completed rotor shown in FIG. 2, the end plate 30, the split magnets 2a and 2b located at the end of the core, and the holding member 40 are also bonded and fixed.

  In addition to the form in which each member is bonded and fixed with an adhesive, for example, in the completed form of the rotor shown in FIG. 2, the entire constituent members are integrated by caulking between the end plates 30, 30 at both ends. May be in a form in which

  Even if the illustrated rotor core 10 has a concave groove 11 or a complicated shape having an overhanging portion 12 extending into the concave groove 11 as compared with a general cylindrical rotor core, the rotor core 10 is If the mold for exclusive use of the rotor core 10 is produced by integrally molding with the cast iron-based magnetic material described above, its manufacture is not difficult at all.

  According to the rotor 100 shown in FIGS. 1 and 2, the center bridge between the divided magnets 2a and 2b forming each magnetic pole and the outer bridge between the end portions of the divided magnets 2a and 2b and the rotor core are both discarded. The problem that the rotor of the conventional structure has, that is, the problem that the magnetic flux leaks from the permanent magnet into the rotor core via each bridge, and the motor efficiency and the motor torque are reduced due to the leaked magnetic flux is effectively solved. . Furthermore, since the magnet forming the magnetic pole is a split magnet, the magnetic flux passage area can be reduced as much as possible to reduce eddy current loss. These interactions can contribute to the manufacture of an IPM motor that is superior in torque performance, rotational performance, and rotational efficiency as compared to an IPM motor having a rotor with a conventional structure.

  In addition, each of the divided magnets 2a and 2b is sandwiched between the inner rotor core 10 and the outer restraining member 40 (which is a divided body), and these are firmly integrated by the end plates 30 and 30. Therefore, the strength of the rotor 100 is sufficiently ensured even in the bridgeless structure.

  Next, the rotor according to another embodiment shown in FIGS. The difference in configuration between the rotor 100A and the rotor 100 shown in FIGS. 1 and 2 is that a holding member 40A that holds the divided magnets 2a and 2b together with the rotor core 10 is fixed to the end plate 30A via a bar 50. It is a point that has been applied.

  More specifically, a through hole 4a is opened at an appropriate position of each divided body constituting the holding member 40A, and a fixed hole 32 is also opened at an end plate position corresponding to the through hole 4a in the completed rotor. The bar 50 is inserted into the through hole formed from the through hole 4a and the fixed hole 32, and the whole is integrated.

  Here, the bar 50 is a steel plate laminate in which electromagnetic steel plates 5,... Are stacked. When the bar 50 is inserted into the through hole 4a provided in the control member 40A, the wide surface of the electromagnetic steel plate 5 is the rotor core 10. Are inserted so as to be arranged in the radial direction, that is, the direction along the stator side.

  By inserting the bar 50 into the through hole 4a in such an arrangement mode, a centrifugal force acts on the permanent magnets 2a and 2b when the rotor rotates, and this acts on the bar 50 via the restraining member 40A. In this case, the highest bending rigidity of the bar 50 can be expected.

  Then, the optimum opening position of the through hole 4a in the holding member 40A, in other words, the optimum insertion position of the bar member 50 in the holding member 40A is as shown in FIG. 5 from the respective divided magnets 2a and 2b. It is desirable that it is set at a position (non-interference position HA in the figure) that does not interfere with the bundle of magnetic flux J flowing to the side.

[Analysis model (example) of a motor having a rotor of the present invention and a magnetic field analysis comparing the torques of an analysis model (comparative example) of a motor having a conventional rotor structure)
The inventors have analyzed an analysis model (example) of a motor having the rotor of the present invention shown in FIG. 2 and a motor having a rotor having a conventional structure (a rotor having a bridge portion schematically shown in FIG. 7). Each of these analysis models (comparative examples) was formed in a computer, a magnetic field analysis was performed by applying magnetism having a frequency of 1000 Hz at 1T, and the maximum torques of both were obtained and compared. The result is shown in FIG. In the figure, the maximum torque of the comparative example is normalized to 1, and the torque of the embodiment is shown as a ratio to that.

  From the figure, it is proved that the torque is improved by 10% in the example as compared with the comparative example.

  From the above analysis results and the like, in the motor having the rotor for the IPM motor of the present invention, the torque is improved by about 10% compared to the motor of the conventional structure, and many parts of the rotor core are made as cheap as possible. Since it can be formed of cast iron or the like, many effects are achieved such that the entire manufacturing cost is reduced.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Rotor core, 11 ... Groove, 12 ... Overhang location, 12a ... Hole, 2 ... Split magnet (permanent magnet), 20 ... Magnetic pole, 30, 30A ... End plate, 31 ... Shaft hole, 32 ... Fixed hole, 4 ... Electromagnetic steel plate, 4a ... through hole, 40, 40A ... restraining material (divided body thereof), 5 ... electromagnetic steel plate, 50 ... bar material, 100, 100A ... IPM motor rotor

Claims (7)

In the cylindrical rotor core made of a magnetic material , a concave groove is formed on the side surface,
In a non-contact posture with the concave groove, a split magnet disposed in the concave groove is sandwiched with the concave groove, and includes a suppressor composed of a plurality of divided bodies formed by stacking steel plates,
Between each of the divided magnets adjacent in the stacking direction, and between the adjacent divided bodies, a protruding portion formed by protruding a part of the rotor core is interposed,
A rotor for an IPM motor, wherein at least the restraining material is fixed by two end plates arranged at an end of a rotor core.   The rotor for an IPM motor according to claim 1, wherein the suppressing member has a relatively high magnetic flux density as compared with the rotor core.   The rotor for an IPM motor according to claim 1, wherein the protruding portion of the rotor core, the divided body, and the divided magnet are bonded and fixed. In a posture in which the overhanging portion of the holding member and the rotor core is positioned, a through-hole penetrating them is formed facing both ends on the two end plates side,
The rotor for an IPM motor according to claim 1 or 2, wherein a bar is inserted into the through hole, and the bar is fixed to the two end plates.   5. The IPM motor according to claim 4, wherein the bar is one of a bundle of relatively small cross-section wires or a stack of relatively small cross-section face materials. Rotor.   6. The rotor for an IPM motor according to claim 4, wherein the bar is disposed at a position of the restraining material that does not interfere with a magnetic flux flow inside the restraining material.   An IPM motor comprising the rotor according to any one of claims 1 to 6 and a stator disposed on the outside thereof.

Images