JP2005261119A - Rotor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent lowering of torque at low-speed rotation and also to suppress loss at high-speed rotation by optimizing the magnetic flux amount of gap corresponding to rotational speed, while improving the reliability and reducing the cost. <P>SOLUTION: A rotor 30 comprises a plurality of permanent magnets 33-36 embedded inside a cylindrical body 31, and magnetic flux barrier spaces 37-40 formed between the permanent magnetics. The magnetic flux barrier space is formed, extending radially in the crossing section, from the central part of the body to the outer periphery side, with at least a part of the magnetic flux barrier space being filled with a magnetic fluid 53 to fill it. At a low rotational speed, the gap magnetic flux amount is increased to increase torque; while at medium to high speed rotation, the gap magnetic flux amount is reduced to suppress loss. Since the magnetic fluid is employed, fixing problem of components cannot occur, and gap magnetic flux amount can be optimized to correspond to the rotational speed, with improved reliability and reduced cost. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rotor, and more particularly, to an interior permanent magnet (IPM) rotor, and more particularly to a rotor embedded with a permanent magnet that generates a very strong magnetic force such as a rare earth magnet.

  In the embedded magnet structure synchronous motor, in addition to the magnetic flux of the embedded magnet, the current flowing in the stator winding induces the magnetic flux, so reluctance torque acts in addition to the magnet torque. Since a large torque and high efficiency can be obtained, it is suitable for use in, for example, an air conditioner, a compressor of a refrigerator, or a power source of an electric vehicle.

  FIG. 6A is a rotor structure diagram of the IPM. In this figure, the rotor 1 has a cylindrical main body 2 and a rotary shaft 3 that is fixed to the axis of the main body 2 and protrudes from both ends of the main body 2. Sheets of permanent magnets 4 to 7 are embedded.

  The permanent magnets 4 to 7 are, for example, strong magnets such as rare earth magnets, and plate-like magnets having a length substantially equal to the axial length L of the main body 2 are used. The magnetic poles (N pole and S pole) of the permanent magnets 4 to 7 are on both sides of the plate, and the magnetic flux of each magnet is directed to the magnet of the adjacent pole.

  FIG. 6B is a path diagram of the magnetic flux. If the directions of the magnetic poles of the permanent magnets 4 to 7 are as shown in the figure, the magnetic flux 8 emitted from the permanent magnet 4 on the upper side of the drawing in the direction of the outer surface of the main body 2 is divided into two hands, a magnetic flux 8a and a magnetic flux 8b. After passing through a stator (not shown), it goes to the adjacent permanent magnets (the permanent magnet 5 on the right side of the drawing and the permanent magnet 7 on the left side of the drawing). Similarly, the magnetic flux 9 emitted from the permanent magnet 6 on the lower side of the drawing toward the outer surface of the main body 2 is also divided into two parts, a magnetic flux 9a and a magnetic flux 9b, and after passing through a stator (not shown), It goes to the permanent magnets (the permanent magnet 5 on the right side of the drawing and the permanent magnet 7 on the left side of the drawing).

  These magnetic flux paths are directed to a stator provided outside the main body 2 of the rotor 1 (representing a magnet utilization rate, also referred to as a gap magnetic flux), but inside the main body 2 (rotation). There is also a magnetic flux path in the child core. That is, the magnetic flux emitted from the permanent magnet 5 on the right side of the drawing in the direction of the rotating shaft 3 is divided into two parts, a magnetic flux 10a and a magnetic flux 10b. Similarly, the magnetic flux emitted from the permanent magnet 7 on the left side of the drawing in the direction of the rotating shaft 3 is divided into two types of magnetic flux 11a and magnetic flux 11b, and the adjacent permanent magnets (permanent magnets on the upper side of the drawing). 4 and the lower permanent magnet 6).

  Here, since the magnetic flux balance of the permanent magnets (the amount of the magnetic flux that has come out and the amount of the magnetic flux that has entered) is equal, if the characteristics of all the permanent magnets 4 to 7 are made uniform, “magnetic flux 8 = magnetic flux 10a + magnetic flux 11a” It should be “magnetic flux 9 = magnetic flux 10b + magnetic flux 11b”. However, due to the presence of leakage magnetic flux in the vicinity of the surface of the main body 2 (magnetic fluxes 12 to 15 indicated by broken arrows in the figure), actually, “magnetic flux 8 + magnetic flux 12 + magnetic flux 15 = magnetic flux 10a + magnetic flux 11a”, “magnetic flux 9 + magnetic flux 13+”. Magnetic flux 14 = magnetic flux 10b + magnetic flux 11b ”. As a result, the gap magnetic flux (magnetic fluxes 8 and 9) is reduced by the amount of the leakage magnetic fluxes 12 to 15, and the utilization factor of the magnet is reduced, and thus the motor torque is reduced.

  Therefore, a magnetic flux barrier space (described later) is provided between the magnetic poles, and measures are taken to reduce the leakage magnetic flux 12 to 15 as much as possible by utilizing the low permeability of the medium (air) existing in the magnetic flux barrier space. It has been broken.

  However, such a measure is beneficial in that the decrease in torque can be minimized by increasing the gap magnetic flux components (magnetic fluxes 8 and 9) by reducing the leakage magnetic fluxes 12 to 15 as much as possible. As the motor rotation speed increases, an induced voltage proportional to the effective magnetic flux and the motor rotation speed is generated in the stator side winding, limiting the rotation range that can be operated and the current to suppress the motor terminal voltage. There is a disadvantage that it causes an increase. In particular, at high speed rotation, the induced voltage increases, the loss due to the current to suppress the motor terminal voltage increases, and the operable speed also decreases, so the problem of induced voltage is inevitable. Yes.

  Therefore, a magnetic flux barrier space provided between the magnetic poles is known to be mechanically closed with a magnetic material when the motor rotates at a high speed (see, for example, Patent Document 1).

  FIG. 6C is a structural diagram of the prior art. In this figure, four magnetic flux barrier spaces 16 to 19 extending radially from the axial center toward the outer peripheral surface of the main body 2 are formed radially inside the main body 2. The respective magnetic flux barrier spaces 16 to 19 are located between the adjacent permanent magnets 4 to 7. Magnetic flux short-circuiting iron pieces 20 to 23 are placed inside the magnetic flux barrier spaces 16 to 19, and these magnetic flux short-circuiting iron pieces 20 to 23 are usually pulled in the axial direction of the main body 2 by the force of the springs 24 to 27. However, when the rotational speed of the main body 2 increases and the centrifugal force exceeds the force of the springs 24 to 27, the inside of the magnetic flux barrier spaces 16 to 19 moves toward the outer peripheral surface of the main body 2, The leakage magnetic fluxes 12 to 15 are positively generated through the magnetic flux short-circuit iron pieces 20 to 23.

  7 (a) and 7 (b) are diagrams for explaining the operation of the prior art. According to this prior art, (a) at the time of low motor rotation, the above leakage magnetic flux is caused by the low permeability of the medium (air) in the magnetic flux barrier spaces 16 to 19 provided between the permanent magnets of adjacent poles. While the amount of gap magnetic flux (magnetic fluxes 8 and 9) can be increased by reducing 12 to 15 and the cause of torque reduction can be eliminated, (b) the magnetic flux short-circuiting iron pieces 20 to 23 can prevent the magnetic flux barrier space during high motor rotation. The portions 16 to 19 are closed, and the leakage magnetic fluxes 12 to 15 are positively generated by the high permeability of the magnetic flux short-circuiting iron pieces 20 to 23 to reduce the amount of the gap magnetic flux (magnetic fluxes 8 and 9). Loss can be suppressed.

JP-A-11-275788 ([0014]-[0015], FIG. 1)

  However, in the above prior art, the magnetic flux barrier spaces 16 to 19 provided between the adjacent permanent magnets 4 to 7 are made of a magnetic material (magnetic flux short-circuited iron pieces 20 to 23) when the motor rotates at high speed. There is a problem that it is inferior in cost and reliability because it is a mechanism for mechanically closing.

  FIGS. 7C and 7D are explanatory diagrams of problems in the prior art. As shown in (c), the magnetic flux barrier spaces 16 to 19 are openings having a predetermined length along the axial direction of the main body 2 (a length slightly shorter than the axial length L of the main body 2). The short-circuiting iron pieces 20 to 23 have a plate-like shape inserted into the magnetic flux barrier spaces 16 to 19. Ideally, the magnetic flux short-circuiting iron pieces 20 to 23 have a magnetic flux due to the balance between the urging forces of the springs 24 to 27 and the centrifugal force accompanying the rotation of the rotor 1 as indicated by the white arrow 28 in FIG. When the inside of the barrier spaces 16 to 19 must move smoothly and in an equilibrium state, if an unbalanced movement as shown in (d) occurs, the magnetic flux short-circuiting iron pieces 20 to 23 are inclined. And the edge part of the magnetic flux short circuit iron pieces 20-23 and the inner wall face of the magnetic flux barrier space parts 16-19 may adhere. When such a fixed state has occurred, the above-mentioned operational effects (FIGS. 7C and 7D) can no longer be expected, and there is a problem in terms of reliability. Further, since individual parts such as the magnetic flux short-circuiting iron pieces 20 to 23 and the springs 24 to 27 are required, there is a problem that the cost of manufacturing and assembling these parts is increased.

  Therefore, an object of the present invention is to realize an appropriate gap magnetic flux amount corresponding to the rotation speed while improving reliability and reducing cost, preventing torque reduction at low speed rotation, and suppressing loss at high speed rotation. Another object of the present invention is to provide a rotor capable of achieving both an increase in the operable rotation range.

The rotor according to the present invention has a plurality of permanent magnets embedded in a cylindrical main body, and a magnetic flux barrier space formed between the permanent magnets. The main body is formed in a cross-sectional shape extending substantially radially from the center to the outer peripheral side, and is filled with an amount of magnetic fluid that fills at least a part of the magnetic flux barrier space.
Preferably, the magnetic fluid is a fluid or powder having soft magnetism (a property of being magnetized when the magnet is brought closer and demagnetizing when the magnet is moved away), fluidity and mass.
In the present invention, when the rotational speed of the rotor is low (low speed rotation), the centrifugal force acting on the magnetic fluid filled in the magnetic flux barrier space is small, and the internal magnetic flux from the permanent magnet (the depth of FIG. Most ferrofluids remain in the center of the magnetic flux barrier space because they are magnetized and attracted by the internal magnetic flux 45-48). Therefore, the vicinity of the outer peripheral side of the magnetic flux barrier space portion is only air (low magnetic permeability) in which no magnetic fluid exists, and the magnetic flux passing through the vicinity of the outer peripheral side due to the low magnetic permeability (shallow internal magnetic flux 49 in FIG. 1B). ˜52) is reduced, and the gap magnetic flux amount is increased.
On the other hand, when the rotational speed of the rotor is high (high-speed rotation), the centrifugal force acting on the magnetic fluid filled in the magnetic flux barrier space increases, and this centrifugal force attracts the internal magnetic flux (deep internal magnetic flux) from the permanent magnet. When the force is exceeded, the magnetic fluid moves from the center of the magnetic flux barrier space to the outer peripheral side by centrifugal force. Therefore, the vicinity of the outer peripheral side of the magnetic flux barrier space is filled with the magnetic fluid contrary to the above-mentioned low speed rotation, and the magnetic flux passing through the outer peripheral side due to the high permeability of the magnetic fluid (shallow internal magnetic flux) Increases, and the gap magnetic flux amount is reduced.
Even when the rotational speed of the rotor is moderately high (medium speed rotation), the magnetic fluid moves from the central part of the magnetic flux barrier space to the outer peripheral side. Since the amount of movement is smaller than the amount of movement, the shallow internal magnetic flux is increased and the gap magnetic flux is decreased at the medium speed rotation, although it is smaller than that at the high speed rotation.
As described above, the present invention takes advantage of the characteristic that the magnetic flux density distribution in the magnetic flux barrier space portion is highest in the narrowest portion when the high-speed rotational operation is changed to the low-speed rotational operation again. The gap magnetic flux is maximized again by pulling back the magnetic fluid on the side toward the inner peripheral side (the center of the main body). That is, the magnetic flux density in the magnetic flux barrier space portion becomes higher (dense) as the interval (width) of the passing space becomes smaller, so the magnetic flux density passing through the inner peripheral side of the magnetic flux barrier space portion is higher than that on the outer peripheral side. However, if the centrifugal force applied to the magnetic fluid (mass) becomes small, the magnetic fluid on the outer peripheral side stays in the inner peripheral space in a form that is attracted by the magnetic flux density on the inner peripheral side of the magnetic flux barrier space. The effect of the present invention is not lost even when the rotation is shifted from the rotation to the low-speed rotation again.
Preferably, the magnetic flux barrier space is located on a magnetic flux path between the magnetic poles, and is a first magnetic flux path (shallow internal magnetic flux) that passes near the outer peripheral side of the main body in the magnetic flux path. Space portion (for example, refer to the fan-shaped magnetic flux barrier space portion 37b in FIG. 1C) and a second space serving as a passage portion of magnetic flux (deep internal magnetic flux) passing near the center portion of the main body in the magnetic flux path. Part (see, for example, the longitudinal magnetic flux barrier space 37a in FIG. 1C), and the filling amount of the magnetic fluid is an amount that can fill at least the second space part. And
In this case, since the shallow internal magnetic flux passes through the first space portion and the deep internal magnetic flux passes through the second space portion, the magnetic fluid from the first space portion to the second space portion Corresponding to the movement and the amount of movement, the amount of the shallow internal magnetic flux is adjusted, and a variable rotational speed characteristic of the gap magnetic flux is obtained.
Preferably, the second space portion and the radial direction of the main body are non-parallel. In this case, by increasing or decreasing the non-parallel degree, It is possible to adjust the magnitude of the centrifugal force required for the movement of the magnetic fluid filled in the second space to the first space.

  In the present invention, it is possible to increase the torque by increasing the gap magnetic flux amount at the time of low rotation, and to suppress the loss by reducing the gap magnetic flux amount at the time of medium / high speed rotation, and because the magnetic fluid is used, The problem of fixing components as in the prior art cannot occur, and the amount of gap magnetic flux corresponding to the number of rotations can be optimized while improving reliability and reducing costs.

  Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the specific details or examples in the following description and the illustrations of numerical values, character strings, and other symbols are only for reference in order to clarify the idea of the present invention, and the present invention may be used in whole or in part. Obviously, the idea of the invention is not limited. In addition, a well-known technique, a well-known procedure, a well-known architecture, a well-known circuit configuration, and the like (hereinafter, “well-known matter”) are not described in detail, but this is also to simplify the description. Not all or part of the matter is intentionally excluded. Such well-known matters are known to those skilled in the art at the time of filing of the present invention, and are naturally included in the following description.

First, the configuration will be described.
Fig.1 (a) is a block diagram of the rotor in this embodiment. In this figure, a rotor 30 includes a cylindrical main body 31 formed by laminating a large number of disk-shaped electrode steel plates, and a rotary shaft that is fixed to the axis of the main body 31 and protrudes from both ends of the main body 31. 32, and, for example, four permanent magnets 33 to 36 are embedded in the main body 31, and magnetic flux barrier spaces 37 to 40 are formed between the permanent magnets 33 to 36, respectively. However, it is different in that a magnetic fluid (described later) is put inside the magnetic flux barrier space portions 37 to 40. The number of permanent magnets 33 to 36 is four in this embodiment, but this is only an example.

  FIG. 1B is a cross-sectional view of the main body 31 of the rotor 30. In this figure, four permanent magnets 33 to 36 are arranged at equal intervals around the rotary shaft 32, and these permanent magnets 33 to 36 are substantially the axial length L of the main body 31 (FIG. 6A). A plate-like magnet (particularly a strong magnet such as a rare earth magnet) is used. The magnetic poles (N pole and S pole) of the permanent magnets 33 to 36 are on both sides of the plate, and the magnetic flux of each magnet is directed to the adjacent pole magnet.

  Here, the magnetic flux 41 and the magnetic flux 42 are so-called gap magnetic fluxes that exit from the rotor 30 toward the stator (not shown), and the magnetic flux 43 and the magnetic flux 44 are return magnetic fluxes of the gap magnetic flux. Further, the magnetic fluxes 45 to 48 and the magnetic fluxes 49 to 52 are internal magnetic fluxes of the main body 31 generated between the adjacent permanent magnets 33 to 36, and the magnetic fluxes 45 to 48 thereof are deep near the rotating shaft 32 of the main body 31. Internal magnetic flux generated in the portion (for convenience, referred to as “deep internal magnetic flux”), and the remaining magnetic fluxes 49 to 52 are internal magnetic flux generated in a shallow portion near the outer surface of the main body 31 (for convenience, referred to as “shallow internal magnetic flux”). . The shallow internal magnetic fluxes 49 to 52 correspond to the “leakage magnetic flux” (see FIGS. 7A and 7B) described at the beginning.

  FIG.1 (c) is sectional drawing of the magnetic flux barrier space parts 37-40. As described above, the magnetic flux barrier spaces 37 to 40 are formed between the permanent magnets 33 to 36, and the magnetic flux barrier spaces 37 to 40 have the same shape. That is, the magnetic flux barrier space portion 37 is continuous to the longitudinal magnetic flux barrier space portion 37a (second space portion) extending in the radial direction from the center portion to the outer peripheral side of the main body 31, and the tip of the longitudinal magnetic flux barrier space portion 37a. Similarly, the magnetic flux barrier space 38 is formed in a shape having a fan-shaped magnetic flux barrier space 37b (first space), and the magnetic flux barrier space 38 extends in the radial direction from the center of the main body 31 to the outer peripheral side. It is formed into a shape having a space 38a (second space) and a fan-shaped magnetic flux barrier space 38b (first space) continuous to the tip of the longitudinal magnetic flux barrier space 38a. The barrier space portion 39 is continuous to the longitudinal magnetic flux barrier space portion 39a (second space portion) extending in the radial direction from the center portion of the main body 31 to the outer peripheral side and the tip of the longitudinal magnetic flux barrier space portion 39a. The magnetic flux barrier space 40 is formed in a shape having a fan-shaped magnetic flux barrier space 39b (first space), and the magnetic flux barrier space 40 extends in the radial direction from the center of the main body 31 to the outer peripheral side. It is formed into a shape having a space 40a (second space) and a fan-shaped magnetic flux barrier space 40b (first space) continuous at the tip of the longitudinal magnetic flux barrier space 40a.

  A predetermined amount of magnetic fluid 53 is placed in each of the magnetic flux barrier spaces 37 to 40. Here, the “magnetic fluid” is a fluid having soft magnetism, fluidity and mass. For example, a system in which ferromagnetic ultrafine particles such as high-concentration magnetite are stably dispersed in a liquid is known. ing. Here, soft magnetism means that it is magnetically soft, that is, has a property of being magnetized when the magnet is brought closer and demagnetized when being moved away. In addition, fluidity refers to the property of moving freely by changing its shape. Usually, the magnetic fluid is composed of three components: a liquid (base solution) that is a medium, magnetic ultrafine particles, and a surfactant that is chemically adsorbed firmly on the surface of the magnetic particles. A stable dispersion state is always maintained without agglomeration due to mutual repulsion. In general, the magnetic fluid is “liquid”, but the present invention is not limited to this interpretation. For example, it may be in the form of powder (or granules) containing magnetic ultrafine particles as a main component without containing the base solution.

  The filling amount of the magnetic fluid 53 (for convenience sake, A) is about A = B, where B is the volume of the longitudinal magnetic flux barrier spaces 37a-40a of the magnetic flux barrier spaces 37-40. That is, when the longitudinal magnetic flux barrier spaces 37a to 40a of the magnetic flux barrier spaces 37 to 40 are filled with the magnetic fluid 53, the fan-shaped magnetic flux barrier spaces 37b to 40b of the magnetic flux barrier spaces 37 to 40 are empty ( The amount is sufficient to maintain the state of being filled with air with low magnetic permeability.

Next, the operation will be described.
<Operation at low rotation>
When the rotor 30 rotates at a low speed, the magnetic fluid 53 filled in the magnetic flux barrier spaces 37 to 40 remains in the longitudinal magnetic flux barrier spaces 37a to 40a of the magnetic flux barrier spaces 37 to 40, It does not move to the fan-shaped magnetic flux barrier spaces 37b to 40b. This is because the magnetic fluid 53 is magnetized and attracted by the magnetic flux (the deep internal magnetic fluxes 45 to 48) passing through the longitudinal magnetic flux barrier spaces 37 a to 40 a due to the “soft magnetism” of the magnetic fluid 53. This is because the parts 37a to 40a are kept as they are. Moreover, since the rotor 30 rotates at a low speed, the centrifugal force acting on the “mass” of the magnetic fluid 53 is also small. When the rotor 30 is rotating at a low speed due to the above two points (magnetization and small centrifugal force), the magnetic fluid 53 filled in the magnetic flux barrier spaces 37 to 40 is in the magnetic flux barrier spaces 37 to 40. It remains in the longitudinal magnetic flux barrier spaces 37a to 40a as it is, and does not move to the fan-shaped magnetic flux barrier spaces 37b to 40b. The magnetic fluid 53 shown in FIGS. 1B and 1C is obtained when the rotor 30 is rotating at a low speed. Thus, during the low-speed rotation, the magnetic flux barrier space portions 37 to 37 are used. The magnetic fluid 53 filled in the inside 40 is retained in the longitudinal magnetic flux barrier spaces 37a to 40a of the magnetic flux barrier spaces 37 to 40 as they are. Therefore, at the time of low speed rotation, since the fan-shaped magnetic flux barrier spaces 37b to 40b of the magnetic flux barrier spaces 37 to 40 are in an empty state (only air), the magnetic flux passing through the fan-shaped magnetic flux barrier spaces 37b to 40b The amount of shallow internal magnetic flux 49-52) is minimized, and eventually the amount of gap magnetic flux (magnetic fluxes 41-44) is maximized.

<Operation during medium rotation>
FIGS. 2A and 2B are views showing a state when the rotor 30 is rotating at a medium speed. Here, “medium speed rotation” means that the centrifugal force acting on the “mass” of the magnetic fluid 53 is a slight attracting force of the magnetic flux (the deep internal magnetic fluxes 45 to 48) passing through the longitudinal magnetic flux barrier spaces 37a to 40a. It means the rotation that exceeds. In this medium speed rotation, a part of the magnetic fluid 53 filled in the magnetic flux barrier spaces 37 to 40 is pulled by the centrifugal force and moves to the fan-shaped magnetic flux barrier spaces 37b to 40b. That is, as schematically shown in FIG. 2B, the movement of the magnetic fluid 53 at that time, a part of the magnetic fluid 53 is pulled by the centrifugal force, and the fan-shaped magnetic flux barrier space portions of the magnetic flux barrier spaces 37 to 40. The amount of magnetic flux (shallow internal magnetic flux 49-52) passing through the fan-shaped magnetic flux barrier spaces 37b-40b of the magnetic flux barrier spaces 37-40 increases due to the magnetic permeability of the moved magnetic fluid 53. The amount of gap magnetic flux (magnetic fluxes 41 to 44) decreases by the increase.

<Operation at high rotation>
FIGS. 2C and 2D are views showing a state when the rotor 30 is rotating at a high speed. Here, “high speed rotation” refers to rotation when the centrifugal force acting on the “mass” of the magnetic fluid 53 is maximized. In this high-speed rotation, almost all of the magnetic fluid 53 filled in the magnetic flux barrier spaces 37 to 40 is pulled by the centrifugal force and moves to the fan-shaped magnetic flux barrier spaces 37b to 40b. That is, as schematically shown in FIG. 2D, the movement of the magnetic fluid 53 at that time, almost all of the magnetic fluid 53 is pulled by the centrifugal force, and the fan-shaped magnetic flux barrier space portions of the magnetic flux barrier spaces 37 to 40. The amount of magnetic flux (shallow internal magnetic flux 49 to 52) passing through the fan-shaped magnetic flux barrier spaces 37b to 40b of the magnetic flux barrier spaces 37 to 40b is maximized by the magnetic permeability of the moved magnetic fluid 53. The amount of gap magnetic flux (magnetic fluxes 41 to 44) is greatly reduced by the increase.

<Summary of action during each rotation>
As described above, the rotor 30 according to the present embodiment fills the magnetic flux barrier spaces 33 to 36 formed in the main body 31 with the required amount of the magnetic fluid 53, and magnetizes almost all of the magnetic fluid 53 at the time of low rotation. Thus, the amount of the shallow internal magnetic flux 49-52 can be minimized by retaining it in the longitudinal magnetic flux barrier spaces 37a-40a of the magnetic flux barrier spaces 33-36. 44) can be maximized. Therefore, during this low rotation, the torque can be improved by a large gap magnetic flux.

  Further, during the middle rotation, a part of the magnetic fluid 53 can be moved to the fan-shaped magnetic flux barrier spaces 37b to 40b of the magnetic flux barrier spaces 33 to 36 by centrifugal force to increase the amount of the shallow internal magnetic flux 49 to 52. Thus, the gap magnetic flux (magnetic fluxes 41 to 44) can be reduced by the increment. Therefore, during this middle rotation, the gap magnetic flux decreases, so that the loss of the stator winding does not increase.

  Further, at the time of high rotation, almost all of the magnetic fluid 53 is moved to the fan-shaped magnetic flux barrier spaces 37b to 40b of the magnetic flux barrier spaces 33 to 36 by centrifugal force to maximize the amount of the shallow internal magnetic flux 49 to 52. Thus, the gap magnetic flux (magnetic fluxes 41 to 44) can be greatly reduced by the increase. Therefore, the gap magnetic flux is greatly reduced at the time of this high rotation, so that the loss of the stator winding is not increased.

  FIG. 3 is a characteristic diagram showing the above effects. The vertical axis represents the amount of gap magnetic flux (magnetic fluxes 41 to 44), and the horizontal axis represents the rotational speed. As shown in this figure, the magnetic fluid 53 filled in the magnetic flux barrier spaces 33 to 36 gradually increases in centrifugal force as the rotational speed increases, and the longitudinal magnetic flux in the magnetic flux barrier spaces 33 to 36 is increased. It moves from the barrier spaces 37a to 40a to the fan-shaped magnetic flux barrier spaces 37b to 40b. The amount of movement and the rotational speed do not necessarily have a linear relationship, but if it has a linear relationship for convenience, between the gap magnetic flux amount and the rotational speed of the rotor 30 of the present embodiment, As shown in the figure, a linear characteristic 54 is established in which the gap magnetic flux amount decreases as the rotational speed increases.

  Therefore, according to the rotor 30 of the present embodiment, the gap magnetic flux amount can be changed according to the number of rotations, the torque can be improved at low speeds, and the stator windings can be improved at medium and high speeds. Both propositions of loss control can be achieved together. In addition, according to the rotor 30 of the present embodiment, since mechanical parts (magnetic flux short-circuited iron pieces 20 to 23 and springs 24 to 27) as in the prior art are not used, manufacturing costs and assembly costs can be reduced. In addition, the problem of adhering these mechanical parts (see FIG. 7D) does not occur, and an exceptional effect is obtained in terms of reliability.

<Modification>
The present invention is not limited to the above embodiment. It goes without saying that various developments and modifications are included within the scope of the technical idea.
FIG. 4 is a diagram showing a modification thereof. In this figure, a different point from said embodiment exists in the shape of magnetic flux barrier space part. First, the 1st modification shown to (a) is demonstrated. The imaginary line A is a line passing through the longitudinal magnetic flux barrier spaces 55a to 58a (second spaces) of the magnetic flux barrier spaces 55 to 58 formed between the permanent magnets 33 to 36. Is obliquely intersecting the tangent line B of the outer peripheral surface of the main body 31. When the crossing angle in the rotation direction of these two lines A and B is α, α> 90 degrees (where α is less than 180 degrees). In such a case, the magnetic fluid filled in the magnetic flux barrier spaces 55 to 58 (see the magnetic fluid 53 in FIGS. 1 and 2) is a fan-shaped magnetic flux unless the centrifugal force associated with the rotation of the main body 31 is significantly increased. It does not move to the barrier space portions 55b to 58b (first space portion). The magnitude of the centrifugal force necessary for movement (that is, the rotational speed) depends on the angle α, and the larger the angle α, the larger the rotational speed required for moving the magnetic fluid. Therefore, according to this first modified example, the larger the angle α, the more magnetic fluid can be allowed to move on the higher rotation side.

  The second modification shown in (b) is such that the reverse characteristics of the first modification can be obtained, and the crossing angle α in the rotational direction of the two lines A and B is set to 90. It should be less than or equal to (but exceeding 0 degrees). In such a case, the magnetic fluid filled in the magnetic flux barrier spaces 55 to 58 (see the magnetic fluid 53 in FIGS. 1 and 2) is a fan-shaped magnetic flux barrier even when the centrifugal force accompanying the rotation of the main body 31 is considerably small. It moves easily to the space portions 55b to 58b. Therefore, according to the second modification, the smaller the angle α, the more the magnetic fluid can be allowed to move on the lower rotation side.

In the above embodiment and its modifications, the shape of the magnetic flux barrier space formed inside the main body 31 is composed of a “longitudinal magnetic flux barrier space” and a “fan-shaped magnetic flux barrier space”. However, it is not limited to this.
FIG. 5 is a diagram illustrating another shape example of the magnetic flux barrier space. That is, the magnetic flux barrier space 59 in (a) is composed of a longitudinal magnetic flux barrier space 59a and a rectangular magnetic flux barrier space 59b, and the magnetic flux barrier space 60 in (b) is a longitudinal magnetic flux barrier space. 60a (second space portion) and an elliptical magnetic flux barrier space portion 60b (first space portion), and the magnetic flux barrier space portion 61 in (c) is a long fan-shaped magnetic flux barrier space portion 61a (second space portion). ) And a rectangular fan-shaped magnetic flux barrier space 61b (first space), and the magnetic flux barrier space 62 in (d) is a sawtooth wall magnetic flux barrier space 62a (second space). And a fan-shaped magnetic flux barrier space 62b (first space). Any of the magnetic flux barrier spaces 59 to 62 is filled with a magnetic fluid.

  One of the selection conditions for each of the above shapes is the magnetic fluid retention performance during low-speed rotation. That is, at the time of low speed rotation, the longitudinal magnetic flux barrier space 59a, the longitudinal magnetic flux barrier space 60a, the long fan-shaped magnetic flux barrier space 61a or the saw-tooth wall magnetic flux barrier space of each of the magnetic flux barrier spaces 59 to 62 illustrated above. It is required to securely hold the magnetic fluid in 62a. For this purpose, it is easy to magnetize the magnetic fluid by facilitating the passage of the aforementioned “deep internal magnetic fluxes 45 to 48” (see FIG. 1B). There is a need to. In this regard, the longitudinal magnetic flux barrier space 59a, the longitudinal magnetic flux barrier space 60a, the long fan-shaped magnetic flux barrier space 61a, or the saw-tooth wall magnetic flux barrier space 62a of each of the magnetic flux barrier spaces 59 to 62 illustrated above is shown in the drawing. The direction widths D1 to D4 are preferably as narrow as possible. This is because the deep internal magnetic fluxes 45 to 48 act on the entire magnetic fluid, and can magnetize the magnetic fluid with a large magnetic force and keep it in place.

  The sawtooth wall surface magnetic flux barrier space 62a of the magnetic flux barrier space 62 in (d) is different from other shape examples in that the inner wall surface is “sawtooth”. “Sawtooth” means that, as shown in (e), a falling surface (rising surface in the reverse direction) 63 and an acute rising surface (falling surface in the reverse direction) 64 at a predetermined angle. A shape that repeats at regular intervals. The magnetic fluid particles 65 receive a large flow resistance when moving in the direction toward the rising surface 64. Accordingly, in the sawtooth wall surface magnetic flux barrier space portion 62a of the magnetic flux barrier space portion 62d in (d), the magnetic fluid flowing from the sawtooth wall surface magnetic flux barrier space portion 62a to the fan-shaped magnetic flux barrier space portion 62 is changed by changing the direction of the sawtooth. The flow resistance can be increased, and conversely, the flow resistance of the magnetic fluid from the fan-shaped magnetic flux barrier space 62 to the sawtooth wall magnetic flux barrier space 62a can be increased.

It is a block diagram of the rotor in this embodiment, sectional drawing of the main body 31 of the rotor 30, and sectional drawing of the magnetic flux barrier space parts 37-40. It is a figure which shows a mode when the rotor 30 is rotating at medium speed, and a figure which shows a mode when the rotor 30 is rotating at high speed. It is a characteristic view which shows the effect of this embodiment. It is a figure which shows the modification of this embodiment. It is a figure which shows the other example of a shape of magnetic flux barrier space part. FIG. 3 is a structural diagram of a rotor embedded with permanent magnets, a magnetic flux path diagram, and a prior art structural diagram. It is operation | movement explanatory drawing of a prior art, and the subject explanatory drawing of a prior art.

Explanation of symbols

30 Rotor 31 Main Body 33 Permanent Magnet 34 Permanent Magnet 35 Permanent Magnet 36 Permanent Magnet 37 Magnetic Flux Barrier Space 37a Longitudinal Magnetic Barrier Space (Second Space)
37b Fan-shaped magnetic flux barrier space (first space)
38 Magnetic flux barrier space 38a Longitudinal magnetic flux barrier space (second space)
38b Fan-shaped magnetic flux barrier space (first space)
39 Magnetic flux barrier space 39a Longitudinal magnetic flux barrier space (second space)
39b Fan-shaped magnetic flux barrier space (first space)
40 Magnetic flux barrier space 40a Longitudinal magnetic flux barrier space (second space)
40b Fan-shaped magnetic flux barrier space (first space)
53 Magnetic fluid 55 Magnetic flux barrier space 55a Longitudinal magnetic flux barrier space (second space)
55b Fan-shaped magnetic flux barrier space (first space)
56 Magnetic flux barrier space 56a Longitudinal magnetic flux barrier space (second space)
56b Fan-shaped magnetic flux barrier space (first space)
57 Magnetic flux barrier space 57a Longitudinal magnetic flux barrier space (second space)
57b Fan-shaped magnetic flux barrier space (first space)
58 Magnetic flux barrier space 58a Longitudinal magnetic flux barrier space (second space)
58b Fan-shaped magnetic flux barrier space (first space)
59 Magnetic flux barrier space 59a Longitudinal magnetic flux barrier space (second space)
59b Rectangular magnetic flux barrier space (first space)
60 Magnetic flux barrier space 60a Longitudinal magnetic flux barrier space (second space)
60b Elliptic magnetic flux barrier space (first space)
61 Magnetic flux barrier space 61a Long fan-shaped magnetic flux barrier space (second space)
61b Rectangular fan-shaped magnetic flux barrier space (first space)
62 Magnetic flux barrier space 62a Sawtooth wall magnetic flux barrier space (second space)
62b Fan-shaped magnetic flux barrier space (first space)

Claims (4)

A plurality of permanent magnets embedded in a cylindrical body, and a magnetic flux barrier space formed between the permanent magnets;
The magnetic flux barrier space is formed in a cross-sectional shape extending substantially radially from the center to the outer periphery of the main body, and is filled with an amount of magnetic fluid that fills at least a part of the magnetic flux barrier space. Rotor characterized by that. The magnetic flux barrier space is located on a magnetic flux path between the magnetic poles, and a first space portion serving as a magnetic flux passage portion passing near the outer peripheral side of the main body in the magnetic flux path, and the magnetic flux path And a second space portion serving as a magnetic flux passage portion passing near the inner peripheral side of the main body, and the filling amount of the magnetic fluid is an amount capable of filling at least the second space portion. The rotor according to claim 1. The rotor according to claim 1, wherein the magnetic fluid is a fluid or powder having soft magnetism, fluidity, and mass. The rotor according to claim 2, wherein the second space and the radial direction of the main body are non-parallel.

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