Rotors and rotating electric machines

Abstract

To provide rotors and rotating electric machines with high efficiency characteristics over a wide range. [Solution] According to the embodiment, the rotor 100 comprises a first rotor having a first rotor shaft 111, a first rotor core 112 including a flux barrier band which is a region in which a substantially convex shape toward the rotational center axis and in which a non-magnetic region and a bridge are formed continuously, and two first rotor magnets 113 arranged to sandwich the d-axis; a second rotor 120 having two end plates 114 and 115, and a second rotor shaft 121 and a second rotor core 122 in which the rotational center axis is arranged within the flux barrier band at each magnetic pole 110p; and an elastic body 132 that connects the end plates and the second rotor and generates a rotational torque corresponding to the rotation of the second rotor.

Description

Technical Field

[0001] Embodiments of the present invention relate to a rotor and a rotating electric machine.

Background Art

[0002] A permanent magnet motor incorporating permanent magnets in the rotor has excellent characteristics such as high efficiency, high torque, and small size.

[0003] On the other hand, in the case of a permanent magnet motor, it is also known that the induced voltage increases as the rotational speed increases. In order to be able to drive beyond the upper limit of the output voltage of the inverter that drives the permanent magnet motor, a technique of rotating at high speed while maintaining a certain output by field weakening control has been put into practical use.

[0004] Field weakening control causes an increase in copper loss due to an increase in current, resulting in a decrease in motor efficiency, because it flows a field weakening current component that does not contribute to the output. Also, in both the low to medium torque region and the medium to high speed region, iron loss may increase due to a large permanent magnet flux, and there are also design problems such as causing a decrease in motor efficiency. It is necessary to mount only the amount of permanent magnets necessary to ensure the permanent magnet flux for obtaining high torque, that is, there is a problem that it is impossible to achieve both high efficiency in the high torque region and low speed region and high efficiency in the low to medium torque region and medium to high speed region.

[0005] As a method for solving this problem, a variable flux motor (memory motor) is known that uses a variable magnetic force magnet with relatively low coercive force to instantaneously apply a magnetic field to the magnet and actively change the magnetization state.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] When using a memory motor, a large current is required to increase or decrease the magnetization of the variable magnet, which presents the challenge of increasing the current capacity of the inverter.

[0008] Therefore, it is desirable to solve the aforementioned problems with permanent magnet motors without using variable force magnets. In other words, a rotor and rotating electric machine are desired that do not cause a decrease in efficiency due to weakening flux current or an increase in iron loss in the low to medium torque range and medium to high speed range, while simultaneously achieving high efficiency in the high torque and low speed range, and that do not require a large current in the stator winding, and that have high efficiency characteristics over a wide range. Furthermore, it would be effective to show a specific configuration for the means of solving this problem.

[0009] Therefore, the present invention aims to provide a rotor and a rotating electric machine that have highly efficient characteristics over a wide range. [Means for solving the problem]

[0010] To achieve the above objective, the rotor according to the embodiment is characterized by comprising: a first rotor shaft extending in the axial direction of the rotational center axis; a first rotor core having electromagnetic steel plates attached to the first rotor shaft and stacked in the axial direction, and including a flux barrier band which is a region in which nonmagnetic regions and bridges are continuously arranged in a substantially convex shape toward the rotational center axis when viewed with respect to one magnetic pole sandwiched between two q axes extending from the rotational center axis in a cross-section perpendicular to the axial direction; a plurality of first rotor magnets arranged within the flux barrier band so as to sandwich the electrically central d axis of the two q axes; a second rotor having two end plates provided so as to sandwich the electromagnetic steel plates in the axial direction; a second rotor shaft extending in the axial direction with a rotational center axis disposed within the flux barrier band; and a second rotor core attached to the second rotor shaft; and an elastic body connecting the end plates and the second rotor, which generates a rotational torque corresponding to the rotation of the second rotor. [Brief explanation of the drawing]

[0011] [Figure 1] This is a partial cross-sectional view showing an example of the overall configuration of a rotating electric machine according to the first embodiment. [Figure 2] This is a partial longitudinal cross-sectional view showing an example of the configuration of a rotating electric machine according to the first embodiment. [Figure 3] This is a partial cross-sectional view showing an example of the configuration of the rotation support section for the second rotor of a rotating electric machine according to the first embodiment. [Figure 4] This is an explanatory diagram illustrating the conceptual state of the magnetic flux in the first state of the second rotor in the rotor according to the first embodiment. [Figure 5] This is an explanatory diagram illustrating the conceptual state of the magnetic flux in the second state of the second rotor in the rotor according to the first embodiment. [Figure 6] This is an explanatory diagram illustrating the conceptual state of the magnetic flux in the third state of the second rotor in the rotor according to the first embodiment. [Figure 7] This is a conceptual relationship diagram illustrating the relationship between the rotational torque of the second rotor and the rotational angle of the second rotor, for a rotor according to the first embodiment. [Figure 8] This is a partial cross-sectional view showing an example of the overall configuration of a rotating electric machine according to the second embodiment. [Figure 9] This is a partial cross-sectional view showing the first state of the second rotor of the rotor according to the second embodiment. [Figure 10] This is a partial cross-sectional view showing an adjacent bridge according to a first example of a rotor according to the second embodiment. [Figure 11] This is a partial cross-sectional view conceptually illustrating the magnetic flux in an adjacent magnetic path in the case of a first example of a rotor according to the second embodiment. [Figure 12] This is a partial cross-sectional view showing an adjacent bridge, which is a reference example of a rotor according to the second embodiment, for the first example. [Figure 13] This is a partial cross-sectional view conceptually illustrating the magnetic flux in an adjacent magnetic path in the case of a reference example for the first example of a rotor according to the second embodiment. [Figure 14]It is a partial cross-sectional view showing an adjacent bridge according to a second example of a rotor according to a second embodiment. [Figure 15] It is a partial cross-sectional view showing an adjacent bridge according to a reference example for a second example of a rotor according to a second embodiment. [Figure 16] It is a partial cross-sectional view showing an adjacent bridge according to a third example of a rotor according to a second embodiment. [Figure 17] It is a partial cross-sectional view showing an adjacent bridge according to a reference example for a third example of a rotor according to a second embodiment. [Figure 18] It is a partial cross-sectional view showing an adjacent bridge according to a fourth example of a rotor according to a second embodiment. [Figure 19] It is a partial cross-sectional view showing an adjacent bridge according to a reference example for a fourth example of a rotor according to a second embodiment. [Figure 20] It is a partial cross-sectional view showing an adjacent bridge according to a fifth example of a rotor according to a second embodiment. [Figure 21] It is a partial cross-sectional view showing an adjacent bridge according to a reference example for a fifth example of a rotor according to a second embodiment. [Figure 22] It is a partial cross-sectional view showing an adjacent bridge according to a sixth example of a rotor according to a second embodiment. [Figure 23] It is a partial cross-sectional view showing an adjacent bridge according to a reference example for a sixth example of a rotor according to a second embodiment. [Figure 24] It is a partial cross-sectional view showing an adjacent bridge according to a seventh example of a rotor according to a second embodiment.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, a rotor and a rotating electric machine according to embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes of the parts, etc., are not necessarily the same as those of actual objects. Even when representing the same part, the dimensions and ratios may be represented differently in the drawings. In this specification and each drawing, the same reference numerals are used for elements similar to those described above with respect to previously shown drawings, and detailed explanations are omitted as appropriate.

[0013] [First Embodiment] Figure 1 is a partial cross-sectional view showing an example of the overall configuration of the rotating electric machine 1 according to the first embodiment.

[0014] The rotating electric machine 1 has a rotor 100 and a stator 10 arranged radially outward from the rotor 100.

[0015] The stator 10 has a substantially cylindrical stator core 11 and stator windings 12 wound around the stator core 11. The stator core 11 has a radially outer annular portion called a yoke portion 11y and a plurality of teeth portions 11t arranged at circumferential intervals in the radially inner portion. The adjacent teeth portions 11t form stator slots 11s. The stator windings 12 have a portion housed within the stator slots 11s in the stator core 11 and coil end portions 12a (Figure 2) protruding from both sides of the stator core 11 in the axial direction.

[0016] Power, such as three-phase AC power, is supplied to the stator winding 12 from a power supply unit (not shown).

[0017] The rotor 100 has a first rotor 110 and a second rotor 120 housed in a second rotor housing hole 112h formed within the first rotor 110. The second rotor housing hole 112h functions as a second rotor housing area.

[0018] Here, we define the directions. The axial direction is the direction parallel to the direction in which the rotational axis CL extends. The radial direction is the direction away from the rotational axis CL. For the first rotor 110, the circumferential direction is the direction in which the part of interest moves (direction of rotation) when the first rotor 110 is rotating. For the second rotor 120, the circumferential direction is the direction in which the part of interest moves (direction of rotation) when the second rotor 120 is rotating.

[0019] In Figure 1, the area enclosed by the fan-shaped dashed line represents one magnetic pole 110p. Each magnetic pole 110p is sandwiched between two q-axis extending radially from the rotational axis CL in a cross section perpendicular to the rotational axis CL.

[0020] At each magnetic pole 110p, the rotor 100 has two first rotor magnets 113. The two first rotor magnets 113 are arranged so as to straddle the d-axis, which is the electrically central axis of the two q-axes. In the state shown in Figure 1, each of the two first rotor magnets is positioned so that its north pole is closer to the d-axis. This state is the first state, which will be described later.

[0021] At adjacent magnetic poles 110p, the directions of the magnetic flux from each of the two first rotor magnets 113 alternate between radially outward and radially inward directions.

[0022] Each magnetic pole 110p has a first rotor core 112 with a second rotor housing hole 112h for housing the second rotor 120 and a magnet housing section 112m for housing the first rotor magnet 113. In Figure 1, the lead line of the magnet housing section 112m indicates the space in which the first rotor magnet 113 is housed. An outer flux barrier 112b for the magnet housing section is formed adjacent to the radially outer side of the magnet housing section 112m. In addition, an inner flux barrier 112c for the magnet housing section is formed adjacent to the radially inner side of the magnet housing section 112m.

[0023] In the first rotor core 112, a top bridge 112a is formed between the outer flux barrier 112b of the magnet housing and the outer circumferential surface 112s of the first rotor core. In addition, an inner bridge 112d is formed between the second rotor housing hole 112h and the inner flux barrier 112c of the magnet housing.

[0024] From one point on the outer surface 112s of the first rotor core to the second rotor housing hole 112h, the top bridge 112a, the outer flux barrier 112b of the magnet housing, the magnet housing 112m, the inner flux barrier 112c of the magnet housing, and the inner bridge 112d are arranged continuously. Furthermore, from the second rotor housing hole 112h to another point on the outer surface 112s of the first rotor core, the inner bridge 112d, the inner flux barrier 112c of the magnet housing, the magnet housing 112m, the outer flux barrier 112b of the magnet housing, and the top bridge 112a are arranged continuously. Note that the two sides flanking the second rotor housing hole 112h do not need to be symmetrical with respect to each other in the cross-section shown in Figure 1.

[0025] The outer flux barrier 112b of the magnet housing, the magnet housing 112m, and the inner flux barrier 112c of the magnet housing are non-magnetic regions. Furthermore, the top bridge 112a and the inner bridge 112d are areas of high magnetic resistance. That is, including the second rotor housing hole 112h, a region that obstructs the passage of magnetic flux is continuously formed from one point on the outer surface 112s of the first rotor core to another point on the outer surface 112s of the first rotor core. Therefore, this continuously formed region is collectively referred to as the flux barrier band.

[0026] The center of the second rotor housing hole 112h is located on the flux barrier band. In other words, the rotational axis CX of the second rotor 120 is located at the circumferential center of each flux barrier band. That is, the rotational axis CX of the second rotor 120 is on the d-axis. The second rotor 120 is supported by the second rotor bearing 131 so as to be rotatable around the rotational axis CX. With the second rotor 120 positioned in this way, as will be described later, the rotation of the second rotor 120 makes it possible to effectively change the path of the magnetic flux within the first rotor 110. That is, the magnetic properties of the rotor 100 can be changed. Note that if the magnetic properties of the rotor 100 can be changed by the rotation of the second rotor 120, the rotational axis CX of the second rotor 120 may be located off the d-axis.

[0027] The second rotor 120 includes a second rotor shaft 121, a second rotor core 122, and a second rotor magnet 123.

[0028] The second rotor core 122 has second rotor core gaps 122m formed on both sides of the second rotor shaft 121. Each second rotor magnet 123 is housed in the second rotor core gap 122m. In the following example, the case in which the second rotor 120 has second rotor magnets 123 is shown, but the second rotor magnets 123 may not be provided as long as the second rotor core gaps 122m are formed. That is, even if the second rotor magnets 123 are not provided, the rotation of the second rotor 120 can provide a variable effect on the magnetic properties of the rotor 100.

[0029] An unbalance-forming hole 122h is formed in the second rotor core 122. As shown in Figure 1, when the north pole of the second rotor magnet 123 is radially outward and the south pole is radially inward, the unbalance-forming hole 122h is formed on the d-axis and in the radially outward region of the second rotor core 122. In other words, the unbalance-forming hole 122h is formed radially outward from the north pole when viewed from the second rotor magnet 123. Due to the unbalance-forming hole 122h, in a cross section perpendicular to the axial direction of the second rotor 120, the center of gravity of the second rotor 120 is shifted from the geometric center of the second rotor 120, that is, the center of gravity of the second rotor 120 is eccentric. As a result, the centrifugal force applied to the center of gravity of the second rotor 120 by the rotation of the first rotor 110 becomes the driving force that rotates the second rotor 120.

[0030] Figure 2 is a partial longitudinal cross-sectional view showing an example of the configuration of the rotating electric machine 1 according to the first embodiment. Figure 3 is a partial transverse cross-sectional view showing an example of the configuration of the rotating electric machine 1 according to the first embodiment. Figure 3 is a partial cross-sectional view taken along the XX arrow in Figure 2.

[0031] The first rotor 110 includes a first rotor shaft 111, a first rotor core 112, a first rotor magnet 113 (Figure 1), end plates 114 and 115, a flange 116, and a nut 117, as shown in Figure 2.

[0032] The first rotor shaft 111 extends along the rotational axis CL. The first rotor shaft 111 is also rotatably supported on both sides in the longitudinal direction (axial direction) by bearings (not shown).

[0033] The first rotor core 112 is mounted radially outward of the first rotor shaft 111 and is cylindrical in shape. The first rotor core 112 has a plurality of electrical steel sheets 112p stacked in the axial direction.

[0034] First rotor magnets 113 are housed in the magnet housings 112m on both sides of the circumferential direction, straddling the d-axis. Each first rotor magnet 113 is oriented such that the side closer to the q-axis is the south pole, and the side opposite the q-axis, i.e., closer to the d-axis, is the north pole. Note that for adjacent magnetic poles 110p, the relationship between the north and south poles is reversed.

[0035] Furthermore, the first rotor core 112 has a pivot center at the circumferential center of the flux barrier and a second rotor housing hole 112h for housing the second rotor 120 is formed therein.

[0036] In the state shown in Figure 2, where the unbalance forming hole 122h is not formed, there are two axes of symmetry that are symmetrical. From the viewpoint of maximizing the rotation angle of the second rotor 120 and the second rotor core 122, it is preferable that the unbalance forming hole 122h be formed on one of the axes of symmetry. The shape of the unbalance forming hole 122h is not limited to a circle, but may be an ellipse, polygon, or other shape. It is preferable that the width of the unbalance forming hole 122h be small in the circumferential direction so as not to narrow the magnetic path of the linked magnetic flux between the rotor 100 and the stator 10. Alternatively, the unbalance forming hole 122h may be positioned radially outward at the rotation angle where the linked magnetic flux between the rotor 100 and the stator 10 is smallest.

[0037] End plates 114 and 115 are provided on both sides of the first rotor core 112 in the axial direction, sandwiching the first rotor core 112. The end plates 114 and 115 are attached to the radially outer side of the first rotor shaft 111 and are annular in shape. End plate internal spaces 114h and 115h are formed in each of the end plates 114 and 115, respectively, to house a portion of the second rotor 120. The end plate internal spaces 114h and 115h are formed as recessed circular holes in the surface, opposite the second rotor housing hole 112h.

[0038] As shown in Figure 3, flanges 116 and nuts 117 are provided on the axially outer side of end plate 114 (opposite side of the first rotor core 112) and on the axially outer side of end plate 115 (opposite side of the first rotor core 112), respectively. The flange 116 is integrally formed with the first rotor shaft 111, and the nut 117 has an internal thread that screws into the radially outer surface of the first rotor shaft 111. The flanges 116 and nuts 117 clamp the end plate 114, the first rotor core 112, and the end plate 115 in the axial direction, fixing them to the first rotor shaft 111.

[0039] Next, the second rotor 120 and the rotation support section 130 of the rotor 100 will be described, mainly with reference to Figure 3.

[0040] The second rotor 120 includes a second rotor shaft 121 extending in the axial direction, a second rotor core 122 (Figure 2), a second rotor magnet 123 (Figure 1), and closing plates 125 provided on both outer sides of the second rotor core 122.

[0041] The second rotor shaft 121 passes through the center of the cross-section of the second rotor core 122. Both axial ends of the second rotor shaft 121 are rotatably supported by the second rotor bearings 131 (Figure 2). Here, the second rotor bearings 131 are annular in shape and are housed in the inner spaces 114h and 115h of the end plates, respectively, and are statically supported by the end plates 114 and 115. Here, the support portion of the second rotor shaft 121 of the second rotor bearing 131 (the contact portion with the second rotor shaft 121) may be a bearing such as a roll bearing or a ball bearing, or it may be a sliding member such as a bushing.

[0042] The second rotor core 122 is cylindrical and mounted radially outward from the second rotor shaft 121. The second rotor core 122 is, for example, a laminated structure of electromagnetic steel sheets that are magnetic. The second rotor core 122 has housing holes formed on both sides of the second rotor shaft 121, each housing a second rotor magnet 123, and these holes penetrate axially. As shown in Figure 2, an unbalance-forming hole 122h is formed in one of the two regions of the second rotor core 122 where the two second rotor magnets 123 are not present. Note that Figure 1 illustrates the case where the unbalance-forming hole 122h is circular, but it is not limited to this. That is, it may be of any other shape, such as a notch, as long as it is formed so that a weight imbalance exists between the two regions of the second rotor core 122 where the two second rotor magnets 123 are not present.

[0043] In the state shown in Figure 1, each of the two second rotor magnets 123 is positioned such that the radially inner side is the south pole and the radially outer side is the north pole. As will be explained later, this state is called the first state.

[0044] As shown in Figure 3, the closing plates 125 are provided on both sides in the axial direction of the second rotor core 122 (Figure 2) to prevent the second rotor magnet 123 from protruding from the second rotor core 122.

[0045] Figure 3 is a partial longitudinal cross-sectional view showing an example of the configuration of the rotation support portion 130 of the rotor 100 of the rotating electric machine 1 according to the first embodiment. Figure 3 is a transverse cross-sectional view of the portion of the second rotor 120 as seen by the arrow XX in Figure 2. Figure 3 is also a view of the closing plate 125 side from a plane perpendicular to the second rotor shaft 121 at the position between the closing plate 125 and the second rotor bearing 131 (Figure 2) in the space 114h inside the end plate. Note that the rotation direction of the rotor 100 is assumed to be counterclockwise in Figure 3.

[0046] The rotation support section 130 includes a second rotor bearing 131 (Figure 2), an elastic body 132, an arm 133, and stoppers 134a and 134b (Figure 2). An unbalance forming hole 122h formed in the second rotor core 122 also plays a part in the function of the rotation support section 130.

[0047] As shown in Figure 3, the elastic body 132 is, for example, a coil spring or helical spring wound around the second rotor shaft 121. The first end 132a of the elastic body 132 is engaged with the end plate 114. The second end 132b of the elastic body 132 is engaged with the closing plate 125, or further through the closing plate 125, with the second rotor core 122 (Figure 3). As a result, a rotational torque acts on the elastic body 132 in a direction that prevents rotation of the second rotor 120, depending on the rotation angle of the second rotor 120. Hereinafter, the rotational torque due to the elastic body 132 will also be called the spring torque. Here, the rotation angle means the angle (circumferential angle in the cross-section) at which the second rotor 120 rotates around the second rotor shaft 121. The rotation angle is, for example, the angle from the first state described later.

[0048] In Figure 3, an example is shown where the elastic body 132 is a coil spring wound around the second rotor shaft 121, but the invention is not limited to this. The elastic body 132 may be a coil spring not wound around the second rotor shaft 121, or a leaf spring, as long as it has a similar function.

[0049] The arm 133 is attached to the second rotor shaft 121 and extends away from the second rotor shaft 121. The arm 133 pivots circumferentially in response to the rotation of the second rotor 120.

[0050] The stoppers 134a and 134b are connected to the closing plate 125, or further through the closing plate 125, to the second rotor core 122 (Figure 2). The stoppers 134a and 134b protrude perpendicularly from the closing plate 125 toward the second rotor bearing 131.

[0051] As shown in Figure 3, stopper 134a is provided in the radially inner region of the second rotor shaft 121, and stopper 134b is provided in the radially outer region of the second rotor shaft 121. Stoppers 134a and 134b are stoppers that restrict the movement of the arm 133, thereby limiting the rotation angle of the second rotor 120 to a predetermined range. Figure 3 shows the case where the upper limit of the rotation angle is 180 degrees.

[0052] Within a predetermined range of the rotation angle, the elastic body 132 is in a compressed state. Hereinafter, the force exerted by the arm 133 on the second rotor 120 will be referred to as the spring force, and the rotational torque due to the spring force will be referred to as the spring torque, as described above.

[0053] Here, the state in which the arm 133 shown in Figure 3 is in contact with the stopper 134a, that is, the state in which the unbalance forming hole 122h is on the radially outer side of the second rotor shaft 121, corresponds to the first state. As explained with reference to Figure 2, the state in which the second rotor magnet 123 has the south pole on the radially inner side and the north pole on the radially outer side is called the first state.

[0054] Furthermore, the state in which the arm 133 is in contact with the stopper 134b, that is, the state in which the unbalance forming hole 122h is located radially inward of the second rotor shaft 121, corresponds to the third state. Here, the state in which the second rotor magnet 123 has the north pole on the radially inward side and the south pole on the radially outward side is called the third state.

[0055] <effect> In the second rotor 120 and rotation support section 130 configured as described above, when the rotor 100 is stopped or the rotational speed of the rotor 100 is below a predetermined value, the arm 133 is pressed against the stopper 134a by the spring force of the elastic body 132, and the system is in the first state.

[0056] On the other hand, when the rotational speed of the rotor 100 exceeds a predetermined value, the centrifugal force acting on the unbalanced second rotor core 122 overcomes the spring torque of the elastic body 132, causing the arm 133 to move away from the stopper 134a and towards the stopper 134b. If the rotational speed of the rotor 100 increases further, the arm 133 will eventually reach the stopper 134b, and the rotation will stop. That is, it will transition to the third state.

[0057] Thus, the rotation angle of the second rotor 120 is determined by the balance between the spring torque of the elastic body 132 and the rotational torque due to the centrifugal force caused by the rotation of the rotor 100. As a result, the rotation of the second rotor 120 within the first rotor 110 changes the magnetic properties of the rotor 100. <effect>

[0058] Figure 4 is a conceptual diagram illustrating the magnetic flux conditions of the second rotor 120 in the first state in the rotating electric machine 1 according to the first embodiment. Figure 5 is a conceptual diagram illustrating the magnetic flux conditions of the second rotor 120 in the second state in the rotating electric machine 1 according to the first embodiment. Figure 6 is a conceptual diagram illustrating the magnetic flux conditions of the second rotor 120 in the third state in the rotating electric machine 1 according to the first embodiment. The curves in the figures represent the magnetic flux at each position.

[0059] Here, the first state is when the flux linkage between the stator 10 and the rotor 100 is at its maximum, and the rotation angle of the second rotor is 0 degrees. The second state is when the rotation angle is 90 degrees, and the third state is when the rotation angle is 180 degrees.

[0060] As shown in Figures 4 to 6, as the rotation angle increases, that is, as the system transitions from the first state to the second state and then to the third state, the density of the magnetic flux passing through the rotor 100 and the stator 10, i.e., the flux linkage, decreases. In other words, the field weakening effect increases. Thus, the rotation of the second rotor 120 changes the magnetic properties of the rotor 100.

[0061] Figure 7 is a conceptual graph illustrating the relationship between the rotation angle of the second rotor 120 and the rotational torque of the second rotor for a rotating electric machine according to the first embodiment.

[0062] In Figure 7, the horizontal axis represents the rotation angle [degree] of the second rotor 120, and the vertical axis represents the relative value [pu] of the rotational torque acting on the second rotor 120. The reference for the relative value is arbitrary.

[0063] Curves M1 through M4 each show the dependence of the rotational torque due to centrifugal force acting on the second rotor 120 on the rotation angle. As the curves progress from M1 to M4, the rotational speed of the rotor 100 increases. The dashed line A0 shows the rotational torque (spring torque) acting on the restoring side by the elastic body 132.

[0064] The intersection points S1, S2, S3, and S4, which are the points where curves M1 through M4 intersect with straight line A0, represent the equilibrium points between the rotational torque due to centrifugal force at each rotational speed and the spring torque acting in the opposite direction. In other words, the rotation angle of the second rotor 120 stabilizes at the rotation angle of each equilibrium point.

[0065] Thus, as the rotational speed of rotor 100 increases, the equilibrium point shifts from S1 to S4. As a result, the flux linkage decreases in the high-speed region. In this way, the variable flux effect of flux weakening and strengthening can be obtained by the second rotor 120.

[0066] [Second Embodiment] Figure 8 is a partial cross-sectional view showing an example of the overall configuration of the rotating electric machine 1a according to the second embodiment. This embodiment is a modification of the first embodiment, and the configuration of the rotating electric machine 1a is the same as in the first embodiment. Therefore, the same elements are denoted by the same reference numerals.

[0067] In this embodiment, for the sake of clarity in explaining its features, the shape of some elements of the rotor 100a has been modified from that of the rotor 100 in the first embodiment. Specifically, the length of the polarization side of the second rotor magnet 123 of the second rotor 120 has been increased. Also, the bidirectional length of the flux barrier 112c inside the magnet housing in the d-axis has been increased. As a result, the length of the inner bridge 112d in the direction along the d-axis has been increased. Note that these differences from the first embodiment are simply for the sake of explanation. That is, even if these differences were absent, the effects of each of the following embodiments would not change.

[0068] Figure 9 is a partial cross-sectional view showing the first state of the second rotor 120 of the rotor 100a according to the second embodiment.

[0069] The rotational coordinate axes of the second rotor 120 are defined. The second rotor core 122 of the second rotor 120 has a second rotor core gap 122m formed on either side of the second rotor shaft 121. Therefore, the second rotor core 122 has salient polarity that generates reluctance torque as the second rotor 120 rotates. That is, salient poles are formed. Here, in a plane perpendicular to the axial direction, the axis extending from the rotation center axis CX in the direction of the salient poles is defined as the x-axis. The axis perpendicular to the x-axis is defined as the y-axis. The unbalance forming hole 122h is located on the x-axis.

[0070] Based on the rotating coordinate system of this second rotor 120, the first state is one in which the x-axis direction coincides with the d-axis direction.

[0071] The region ZZ enclosed by the dashed line includes the second rotor shaft 121 of the second rotor 120, the second rotor core 122, the second rotor magnet 123, a portion of the radial basic gap 122g of the second rotor core 122, the inner flux barrier 112c of the magnet housing, and the inner bridge 112d. The radial basic gap 122g is the space of the second rotor housing hole 112h that is not occupied by the second rotor core 122. However, the radial basic gap 122g excludes the gap between the second rotor magnet 123 and the first rotor core 112. That is, the space between the second rotor core 122 and the first rotor core 112 is called the radial basic gap 122g. The inner bridge 112d is a portion of this first rotor core 112.

[0072] The inner bridge 112d functions as the adjacent bridge AB, which is the bridge portion of the first rotor core 112. The same applies to each of the following examples.

[0073] The following describes various embodiments of this model, with each figure representing the first state. Each figure corresponds to the region ZZ in Figure 9. The other portion adjacent to the second rotor magnet 123 may be the same as region ZZ.

[0074] <Example 1> Figure 10 is a partial cross-sectional view showing an adjacent bridge AB according to a first example of a rotor according to the second embodiment.

[0075] The minimum position is defined as the longitudinal position where adjacent bridges AB have their minimum width w. The minimum position is represented by the minimum point Pmin, as shown in Figure 12. Here, the minimum point Pmin is the position with the minimum bridge width w, which is the minimum value of the bridge width. Specifically, the minimum position is the point in the center in the bridge width direction, that is, the point on the center line LC. Here, the bridge width is defined as the distance between the intersection points of the vertical line of the center line and the two edges of the bridge. The point indicated by Qmin in Figure 10 will be explained later.

[0076] In adjacent bridge AB, the magnetic path through which the magnetic flux passes is called the adjacent magnetic path AMP. Let W be the width of the adjacent magnetic path AMP at the minimum point Pmin. As will be described later, not all of the magnetic flux necessarily passes through within the width of the adjacent bridge. That is, the magnetic flux at the minimum point Pmin may pass through, for example, a part of the adjacent second rotor core 122. In such cases, the bridge, which is designed to ensure magnetic resistance and limit the magnetic flux, will not perform its intended function.

[0077] Assume an external cylinder 122z that radially tangent to the second rotor core 122. A basic radial gap 122g of a certain width is formed between the hypothetical external cylinder 122z and the inner surface of the first rotor core 112. There is a portion where an offset gap 122f is formed between the second rotor 120 and the external cylinder 122z. In the case of Figure 10, the offset gap 122f is located within the external cylinder 122z and is in the outer portion that is continuous with the second rotor core gap 122m.

[0078] In the first example shown in Figure 10, the minimum point Pmin in the adjacent bridge AB is formed adjacent to the offset gap 122f. <Effect of the first example> Figure 11 conceptually illustrates the magnetic flux in the adjacent magnetic path AMP in the first example.

[0079] As shown in Figure 11, in the first example, the magnetic flux at the minimum point Pmin that gives the minimum bridge width w shown in Figure 10 is within the minimum bridge width w. That is, the magnetic path width W is substantially the same as the minimum bridge width w. Here, the fact that the magnetic path width W is substantially the same as the minimum bridge width w means, in other words, that the magnetic flux passing through the magnetic path that does not pass through the adjacent bridge AB can be substantially ignored.

[0080] In the first example, the shape of the flux barrier 112c inside the magnet housing differs from that of the reference example described later. Specifically, the inclination of the edge of the flux barrier 112c inside the magnet housing on the adjacent bridge AB side is closer to being parallel to the d-axis. As a result, the minimum point Pmin having the minimum bridge width w of the adjacent bridge AB has shifted. The minimum point Pmin when this magnetic path width W coincides with the minimum bridge width w is denoted as the minimum coincidence point Qmin, as shown in Figure 10.

[0081] <Example of the first example> Figure 12 is a partial cross-sectional view showing an adjacent bridge, which is a reference example of a rotor according to the second embodiment, relative to the first example.

[0082] <Effect in the example> Figure 13 conceptually illustrates the magnetic flux in the adjacent magnetic path AMP in the example. In the example, the minimum point Pmin, which has the minimum bridge width w, is adjacent to the second rotor core 122. That is, the minimum point Pmin is not adjacent to the offset air gap 122f. Therefore, the magnetic path width is effectively wider than the minimum bridge width w. In other words, even if the bridge width is small, the magnetic flux is not effectively limited.

[0083] <Comparison of the first example with a reference example> In the first example, the minimum point Pmin is located adjacent to the offset gap 122f, and not adjacent to the second rotor core 122. The effective magnetic path width W is the same as the actual minimum bridge width w. That is, the minimum bridge width w is functioning effectively. As a result, compared to the reference example, the magnetic flux passing through the adjacent bridge AB is suppressed in the first example.

[0084] <Example 2> Figure 14 is a partial cross-sectional view showing an adjacent bridge according to a second example of the rotor according to the second embodiment. Figure 15 is a partial cross-sectional view showing an adjacent bridge according to a reference example for the second example of the rotor according to the second embodiment.

[0085] In the second example, the polarization width of the second rotor magnet 123 is larger compared to the reference example.

[0086] In the example shown in Figure 15, the minimum point Pmin having the minimum bridge width w is adjacent to the second rotor core 122. Therefore, the magnetic path width is effectively wider than the minimum bridge width w.

[0087] In the second example, because the polarization direction width of the second rotor magnet 123 is larger, the minimum point Qmin having the minimum bridge width w shown in Figure 14 is adjacent to the offset air gap 122f and no longer adjacent to the second rotor core 122. As a result, the effective magnetic path width W matches the actual minimum bridge width w. In other words, the minimum bridge width w is functioning effectively. Consequently, compared to the reference example, the magnetic flux passing through adjacent bridges AB is suppressed in the first example.

[0088] <Third example> Figure 16 is a partial cross-sectional view showing an adjacent bridge according to a third example of the rotor according to the second embodiment. Figure 17 is a partial cross-sectional view showing an adjacent bridge according to a reference example for the third example of the rotor according to the second embodiment.

[0089] In the third example, a cut surface 122c is formed on the radially outer portion of the second rotor core 122 relative to the second rotor magnet 123. The cut surface 122c forms an additional gap, which is a further offset gap 122f between the circumscribing cylinder 122z of the second rotor core 122 and the adjacent bridge AB.

[0090] In the example shown in Figure 17, the minimum point Pmin having the minimum bridge width w is adjacent to the second rotor core 122. Therefore, the magnetic path width is effectively wider than the minimum bridge width w.

[0091] In the third example, since a cut surface 122c is formed on the second rotor core 122, the minimum point Qmin having the minimum bridge width w shown in Figure 16 is adjacent to the offset gap 122f and no longer adjacent to the second rotor core 122. As a result, the effective magnetic path width W matches the actual minimum bridge width w. In other words, the minimum bridge width w is functioning effectively. Consequently, in the first example, the magnetic flux passing through adjacent bridges AB is suppressed compared to the reference example.

[0092] <Example 4> Figure 18 is a partial cross-sectional view showing an adjacent bridge according to a fourth example of the rotor according to the second embodiment. Figure 19 is a partial cross-sectional view showing an adjacent bridge according to a reference example for the fourth example of the rotor according to the second embodiment.

[0093] In the fourth example, a recess 112v is formed in the adjacent bridge AB adjacent to the second rotor core 122 on the radially outer portion of the second rotor magnet 123. Here, we assume the inscribed cylinder 112z of the second rotor housing hole 112h. Due to the formation of the recess 112v, an offset gap 112f is formed between the first rotor core 112 and the inscribed cylinder 112z. That is, the distance between the second rotor core 122 and the circumscribed cylinder 122z is wider than the normal radial basic gap 122g. The minimum point Qmin exists in that portion. The recess 112v forms an offset gap 112f as a further flux barrier between the outer surface of the second rotor core 122 and the adjacent bridge AB.

[0094] In the example shown in Figure 19, the minimum point Pmin having the minimum bridge width w is adjacent to the second rotor core 122. Therefore, the magnetic path width is effectively wider than the minimum bridge width w.

[0095] In the fourth example, since a recess 112v is formed in the adjacent bridge AB, the minimum point Qmin shown in Figure 18 faces the second rotor core 122 across space and is no longer adjacent to the second rotor core 122. As a result, the effective magnetic path width W matches the actual minimum bridge width w. In other words, the minimum bridge width w is functioning effectively. Consequently, in the first example, the magnetic flux passing through the adjacent bridge AB is suppressed compared to the reference example.

[0096] Furthermore, this fourth example may be combined with other examples in which the offset gap 112f is formed on the second rotor 120 side.

[0097] <Example 5> Figure 20 is a partial cross-sectional view showing an adjacent bridge according to a fifth example of the rotor according to the second embodiment. Figure 21 is a partial cross-sectional view showing an adjacent bridge according to a reference example for the fifth example of the rotor according to the second embodiment. Figures 20 and 21 illustrate a case in which the retaining projections 122x for the second rotor magnet 123 are formed on the second rotor core 122.

[0098] The reference example shown in Figure 21 illustrates the case where the minimum point Pmin is located adjacent to the retaining projection 122x. In this case, since the minimum point Pmin is adjacent to the second rotor core 122, the magnetic path width W is effectively wider than the minimum bridge width w.

[0099] In the fifth example shown in Figure 20, the location of the minimum point Qmin is not adjacent to the retaining projection 122x. That is, the minimum point Pmin is adjacent to the offset air gap 122f. As a result, the effective magnetic path width W matches the actual minimum bridge width w. In other words, the minimum bridge width w is functioning effectively. Consequently, compared to the reference example, the magnetic flux passing through the adjacent bridge AB is suppressed in the first example.

[0100] <Example 6> Figure 22 is a partial cross-sectional view showing an adjacent bridge according to a sixth example of the rotor according to the second embodiment. Figure 23 is a partial cross-sectional view showing an adjacent bridge according to a reference example for the sixth example of the rotor according to the second embodiment. Figures 22 and 23 illustrate a case in which the second rotor magnet 123 is housed inside the second rotor core 122, rather than being a surface-mounted type.

[0101] In the sixth example shown in Figure 22, the second rotor core 122 has a second rotor core void 122m that does not communicate with the surface of the second rotor core 122, with the second rotor shaft 121 in between. The second rotor magnets 123 are housed within their respective second rotor core voids 122m. The dashed extension line, extending in the width direction from the minimum point Qmin where the width of the adjacent bridge of the adjacent first rotor core 112 is minimized, intersects with the corner Pm of the second rotor magnet 123.

[0102] In this case, the minimum point Pmin is adjacent to a corner Pm of the second rotor magnet 123. In this case, the width of the portion of the second rotor core 122 adjacent to the adjacent bridge at the minimum point Pmin is minimized. Therefore, the magnetic path width W becomes the minimum magnetic path width Wmin. In the reference example shown in Figure 23, the minimum point Pmin is not adjacent to a corner of the second rotor magnet 123. Therefore, the magnetic path width W at the minimum point Pmin is greater than the minimum magnetic path width Wmin.

[0103] On the other hand, in the sixth example, the minimum point Pmin is adjacent to the corner of the second rotor magnet 123. Therefore, the magnetic path width W at the minimum point Pmin becomes the minimum magnetic path width Wmin. In other words, the minimum bridge width w is functioning effectively. As a result, compared to the reference example, the magnetic flux passing through the adjacent bridge AB is suppressed in the first example.

[0104] <Example 7> Figure 24 is a partial cross-sectional view showing an adjacent bridge AB according to a seventh example of a rotor according to the second embodiment.

[0105] The minimum point Pmin1 is located at the edge of region R, which is outside the region adjacent to the second rotor core 122. The minimum point Pmin is formed within region R adjacent to the offset gap 122f. The presence of the minimum point Pmin in region R is a necessary condition for not being adjacent to the second rotor core 122. By setting the minimum point Pmin in this way, the effective magnetic path width W matches the actual minimum bridge width w. As a result, the minimum bridge width w can be made to function effectively.

[0106] According to the embodiments described above, it is possible to provide rotors and rotating electric machines with high efficiency characteristics over a wide range.

[0107] [Other embodiments] Although embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. Furthermore, the features of each embodiment and example may be combined. Moreover, the embodiments can be carried out in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0108] 1, 1a... Rotating electric machine, 10... Stator, 11... Stator core, 11s... Stator slot, 11t... Teeth section, 11y... Yoke section, 12... Stator winding, 12a... Coil end, 100, 100a... Rotor, 110... First rotor, 110p... Magnetic pole, 111... First rotor shaft, 112... First rotor core, 112a... Top bridge, 112b... Outer flux barrier of magnet housing, 112c... Inner flux barrier of magnet housing, 112d... Inner bridge, 112f... Offset gap, 112h... Second rotor housing hole, 112m... Magnet housing, 112p... Electromagnetic steel sheet, 112s... Outer surface of rotor core, 112v... Recess, 112z... Inscribed cylinder, 113... First Rotor magnet, 114...end plate, 114h...space inside end plate, 115...end plate, 115h...space inside end plate, 116...flange, 117...nut, 120...second rotor, 121...second rotor shaft, 122...second rotor core, 122a...eccentric through hole, 122c...cut surface, 122f...offset gap, 122g...radial basic gap, 122h...unbalance forming hole, 122m...second rotor core gap, 122x...holding projection, 122z...circumscribed cylinder, 123...second rotor magnet, 125...closing plate, 130...rotation support part, 131...second rotor bearing, 132...elastic body, 132a...first end, 132b...second end, 133...arm, 134a, 134b...stopper

Claims

1. A first rotor comprising: a first rotor shaft extending in the axial direction of the rotational center axis; a first rotor core having electromagnetic steel plates attached to the first rotor shaft and stacked in the axial direction, and including a flux barrier band which is a region in which non-magnetic regions and bridges are continuously arranged in a substantially convex shape toward the rotational center axis when viewed with respect to one magnetic pole sandwiched between two q axes extending from the rotational center axis in a cross-section perpendicular to the axial direction; and a plurality of first rotor magnets arranged within the flux barrier band so as to sandwich the electrically central d axis of the two q axes, Two end plates are provided so as to sandwich the aforementioned electromagnetic steel sheet in the axial direction, A second rotor having a pivot axis positioned within the flux barrier band and extending in the axial direction, and a second rotor core attached to the second rotor shaft, An elastic body connects the end plate and the second rotor and generates a rotational torque corresponding to the rotation of the second rotor, A rotor characterized by having the following features.

2. The rotor according to claim 1, characterized in that the second rotor has a center of gravity that is eccentric from the pivot axis in a cross section perpendicular to the axial direction.

3. The rotor according to claim 1, characterized in that the elastic body is a coil spring with one end engaging with the end plate and the other end engaging with the second rotor core.

4. The flux barrier band of the first rotor core is provided with a second rotor housing region in which the second rotor is housed. The second rotor core has a plurality of gaps formed therein that give rise to the salient polarity of the second rotor core. In the cross-section perpendicular to the axial direction, an offset gap is formed between the circumscribed circle of the second rotor core and the second rotor, and between the inscribed circle of the second rotor housing region and the first rotor core. In a cross-section perpendicular to the axial direction, if we define the radial direction from the pivot center axis where the magnetic resistance is minimized due to the salient polarity of the second rotor core as the x-axis direction, and the radial direction where the magnetic resistance is maximized as the y-axis direction, then in the first state where the x-axis direction and the d-axis direction overlap, The minimum position where the width of the bridge portion of the first rotor core adjacent to the second rotor housing region is minimized is adjacent to the offset gap. The rotor according to claim 1, characterized in that

5. The rotor comprises a plurality of second rotor magnets housed inside the second rotor core, The flux barrier band of the first rotor core is provided with a second rotor housing region in which the second rotor is housed. The second rotor core houses each of the plurality of second rotor magnets, and a plurality of second rotor core voids are formed that generate salient polarity in the second rotor core. In a cross-section perpendicular to the axial direction, if we define the radial direction from the pivot center axis where the magnetic resistance is minimized due to the salient polarity of the second rotor core as the x-axis direction, and the radial direction where the magnetic resistance is maximized as the y-axis direction, then in the first state where the x-axis direction and the d-axis direction overlap, The extension line in the width direction from the minimum position where the width of the bridge portion of the first rotor core adjacent to the second rotor housing area is minimized intersects with the corner of the second rotor magnet. The rotor according to claim 1, characterized in that

6. A rotor according to any one of claims 1 to 5, A stator comprising a stator core arranged radially outward from the first rotor core, and stator windings wound around the stator core, A rotating electric machine characterized by being equipped with the following.

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