Rotary machine

Abstract

This rotary machine (100) comprises: a rotor (1) that rotates about a rotation axis (AX); a stator (2) that is disposed on the outer circumference or the inner circumference of the rotor (1) in a manner so as to be separated from the rotor (1) with a gap (4) therebetween; and a support member (3) that is disposed on at least one side of the rotor (1) in the axial direction along the rotation axis (AX) and supports the rotor (1) such that displacement of the rotor (1) in the axial direction and the inclination direction is restricted. At least one of the rotor (1) and the stator (2) has an iron core. At least the other of the rotor (1) and the stator (2) has a magnetic force generating member. The iron core and the magnetic force generating member are arranged such that the displacement of the rotor (1) in the axial direction and the inclination direction is restored by a force by which the stator (2) magnetically attracts the rotor (1). The rotor (1) is supported by the support member (3) at a position that is displaced with respect to the stator (2) in the axial direction.

Description

Rotating machines

[0001] The present disclosure relates to a rotating machine in which a rotor is supported without contact with a stator.

[0002] Conventionally, rotating machines such as magnetic bearings and bearingless motors, in which a rotor is supported without contact with a stator, are known. Magnetic bearings have the function of generating a support force to support the rotor without contact with the stator. Bearingless motors have both the function of an electric motor that generates torque and the function of a magnetic bearing that generates a support force to support the rotor without contact with the stator, on the same magnetic circuit. To support the rotor without contact with the stator, it is necessary to either actively control all five degrees of freedom of the rotor except for the direction of rotation around the rotor's rotation axis, or to create a passively stable structure in which some of the five degrees of freedom of the rotor except for the direction of rotation around the rotor's rotation axis are not actively controlled.

[0003] The five degrees of freedom mean one degree of freedom in the axial direction, two degrees of freedom in the radial direction, and two degrees of freedom in the tilt direction. The axial direction is the direction parallel to the rotation axis of the rotor (direction along the Z axis). The radial direction is the direction perpendicular to the rotation axis of the rotor, and includes two directions: the direction along the X axis perpendicular to the Z axis, and the direction along the Y axis perpendicular to the Z axis and the X axis. The tilt direction is the direction of rotation around the X axis (θ x ) and the rotation direction around the Y axis (θ y Passively stable means that the rotor will return to a specific position without the need to sense the rotor position and control the current value.

[0004] Generally, a two-degree-of-freedom control rotating machine uses sensors to detect the rotor position for only two of the five degrees of freedom mentioned above, namely, the radial direction (directions along the X-axis and the Y-axis), and adjusts the rotor's radial support force so that the detected position matches the target position. In other words, a two-degree-of-freedom control rotating machine actively controls only the radial direction, and does not actively control the three degrees of freedom (axial and tilt directions), resulting in a passively stable structure.

[0005] A known technique for achieving a passively stable structure with three degrees of freedom (axial and tilt) is to utilize the attractive force generated between the rotor's permanent magnets and the stator's core. For example, Patent Document 1 describes a technique in which, when the rotor is displaced from its ideal position in the axial direction, magnetic flux flowing between the rotor's permanent magnets and the stator's core generates a force that magnetically attracts the rotor, and a restoring force acts on the rotor to return the rotor's axial displacement. Patent Document 1 also describes a technique in which, when the rotor is displaced from its ideal position in the tilt direction, magnetic flux flowing between the rotor's permanent magnets and the stator's core generates a force that magnetically attracts the rotor, and a restoring torque acts on the rotor to return the rotor's tilt. The restoring force increases in proportion to the rotor's axial displacement. The restoring torque increases in proportion to the rotor's displacement around the X-axis and the Y-axis. Hereinafter, the axial displacement of the rotor, the displacement around the X-axis, and the displacement around the Y-axis may be collectively referred to as rotor displacement.

[0006] In either case, the rotor moves toward an ideally aligned position. As a result, the magnetic flux generated by the permanent magnets ensures rotor rigidity in the three degrees of freedom (axial and tilt). By making the rotor positively stiff in the axial and tilt directions, a passively stable structure can be achieved in the three degrees of freedom (axial and tilt).

[0007] Japanese Patent Application Laid-Open No. 2005-121157

[0008] In the technology disclosed in Patent Document 1, the stability of the rotor in the axial and tilt directions depends solely on the restoring force and restoring torque due to the magnetic flux generated by the permanent magnets. However, the technology disclosed in Patent Document 1, which only generates a restoring force and restoring torque proportional to the rotor displacement, has the problem that it is not possible to suppress rotor vibration in the axial and tilt directions when it occurs.

[0009] The present disclosure has been made in consideration of the above, and aims to provide a rotating machine that can suppress vibration of the rotor in the axial and tilt directions while having a passively stable structure with respect to three degrees of freedom in the axial and tilt directions of the rotor.

[0010] In order to solve the above-mentioned problems and achieve the object, the rotating machine according to the present disclosure includes a rotor that rotates about a rotation axis, a stator that is arranged on the outer or inner circumference of the rotor with a gap between the rotor and the stator, and a support member that is arranged on at least one axial side of the rotor along the rotation axis and supports the rotor so as to limit displacement of the rotor in the axial and tilt directions. At least one of the rotor and the stator has an iron core. At least the other of the rotor and the stator has a magnetic force generating member. The iron core and the magnetic force generating member are arranged so that displacement of the rotor in the axial and tilt directions is restored by the force of the stator magnetically attracting the rotor. The rotor is supported by the support member at a position displaced axially relative to the stator.

[0011] The rotating machine according to the present disclosure has the advantage of being able to suppress vibration of the rotor in the axial and tilt directions while having a passively stable structure with respect to three degrees of freedom in the axial and tilt directions of the rotor.

[0012] a perspective view showing the configuration of a rotating machine according to a first embodiment; a cross-sectional view showing the configuration of a rotating machine according to the first embodiment, illustrating a radial support force acting on the rotor; a cross-sectional view showing the configuration of a rotating machine according to the first embodiment, illustrating an axial force acting on the rotor; a cross-sectional view showing the configuration of a rotating machine according to a first modified example of the first embodiment; a cross-sectional view showing the configuration of a rotating machine according to a second modified example of the first embodiment; a perspective view showing the configuration of a rotating machine according to a third embodiment; a cross-sectional view showing the configuration of a rotating machine according to a modified example of the third embodiment; a perspective view showing the configuration of a support member of a rotating machine according to a fourth embodiment; a view showing the configuration of a rotor of a rotating machine according to a modified example of the fourth embodiment, illustrating the rotor as viewed in the axial direction; a perspective view showing the configuration of a part of a stator core of a rotating machine according to a fifth embodiment; a cross-sectional view showing the configuration of a rotating machine according to the fifth embodiment, illustrating an axial force acting on the rotor;

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rotating machine according to an embodiment will be described in detail below with reference to the accompanying drawings.

[0014] First Embodiment Fig. 1 is a perspective view showing the configuration of a rotating machine 100 according to a first embodiment. For ease of understanding, Fig. 1 shows the rotating machine 100 cut in half along the axial direction. Cross-sectional hatching is omitted in Fig. 1. As shown in Fig. 1, the rotating machine 100 includes a rotor 1, a stator 2, and a support member 3. Although not shown, the rotating machine 100 also includes a frame that houses the rotor 1, the stator 2, and the support member 3, a shaft provided at the center of the rotor 1, and the like. The rotor 1 rotates relative to the stator 2 about a rotation axis AX.

[0015] Hereinafter, when describing the directions of each component of the rotating machine 100, the direction parallel to the rotation axis AX is referred to as the axial direction, the direction perpendicular to the rotation axis AX is referred to as the radial direction, and the direction of rotation around the rotation axis AX is referred to as the circumferential direction. The X-axis, Y-axis, and Z-axis shown in each drawing are three mutually perpendicular axes. The Z-axis is parallel to the rotation axis AX. The direction along the Z-axis (Z-axis direction) is parallel to the axial direction. The X-axis and Y-axis are perpendicular to the rotation axis AX. The direction along the X-axis (X-axis direction) is a direction perpendicular to the axial direction and is included in the radial direction. The direction along the Y-axis (Y-axis direction) is a direction perpendicular to the axial direction and is included in the radial direction. Hereinafter, when there is no need to distinguish between the X-axis direction and the Y-axis direction, they will be collectively referred to as the XY-axis direction. Furthermore, the rotation direction θ around the X-axis x and the rotation direction around the Y axis θ ｙ When there is no need to distinguish between the Z axis and the Z direction, they are collectively referred to as the tilt direction. For each axis, the direction of the arrow is the positive direction, and the direction opposite to the arrow is the negative direction. In this embodiment, a case is illustrated in which the direction along the rotation axis AX is parallel to the vertical direction. In this embodiment, the positive direction of the Z axis is the vertically upward direction, and the negative direction of the Z axis is the vertically downward direction.

[0016] The rotor 1 rotates about a rotation axis AX. The rotor 1 has a rotor core 1a and a plurality of permanent magnets 1b. In this embodiment, the rotor core 1a has a cylindrical shape. A through hole 1c extending in the axial direction is formed at the center of the rotor core 1a. A shaft (not shown) is disposed in the through hole 1c.

[0017] The multiple permanent magnets 1b are arranged on the outer periphery of the rotor core 1a. The multiple permanent magnets 1b are arranged at equal angles in the circumferential direction. The permanent magnets 1b, which are magnetic force generating members, may be fixed to the rotor core 1a by magnetic force, or may be fixed to the rotor core 1a by a fixing member such as an adhesive. In this embodiment, the permanent magnets 1b are attached to the surface of the rotor core 1a, but they may also be embedded inside the rotor core 1a.

[0018] The stator 2 is disposed on the outer periphery of the rotor 1, separated from the rotor 1 by a gap 4. The stator 2 has a stator core 2a, which is an iron core, and a plurality of windings 2b. The stator core 2a and the windings 2b constitute an electromagnet, which is a magnetic force generating member.

[0019] In this embodiment, the stator core 2a has a cylindrical shape. The stator core 2a has a plurality of teeth 2c arranged in a row in the circumferential direction and a back yoke portion 2d that connects the plurality of teeth 2c at the outer periphery of each tooth 2c. The plurality of teeth 2c are arranged radially around the rotation axis AX. The plurality of teeth 2c are arranged at equal angles in the circumferential direction. The back yoke portion 2d is formed in a cylindrical shape.

[0020] The windings 2b are wound around the teeth 2c, respectively, and generate a magnetic field for rotating the rotor 1 in the circumferential direction.

[0021] The support member 3 is disposed on at least one side of the rotor 1 in the axial direction along the rotation axis AX and supports the rotor 1 so as to limit displacement of the rotor 1 in the axial and tilt directions. In this embodiment, the axial direction along the rotation axis AX is parallel to the vertical direction, and the support member 3 is disposed vertically below the rotor 1. The shape of the support member 3 is cylindrical in this embodiment, but is not particularly limited as long as it can support the rotor 1. In this embodiment, the shape of the support member 3 is hollow, but it may also be solid. The support member 3 is fixed to a frame (not shown). In FIG. 1 , the inner diameter of the support member 3 is shown smaller than the inner diameter of the rotor 1 to clearly distinguish the support member 3 from the rotor 1, but this is not limited to the illustrated example. The inner diameter of the support member 3 may be larger than the inner diameter of the rotor 1 or may be the same as the inner diameter of the rotor 1.

[0022] The support member 3 has a support surface 3a that supports the rotor 1. The support surface 3a is in circumferential contact with one axial surface of the rotor 1. The support member 3 has a low-friction portion that reduces the frictional force with the rotor 1. By using a material for the support member 3 that has a lower friction coefficient than the rotor 1, the low-friction portion may be formed on the entire support member 3 or a part of the support member 3 (the portion of the support member 3 that contacts the rotor 1), or the low-friction portion may be constituted by a lubricant applied to the portion of the support member 3 that contacts the rotor 1. An example of a material with a low friction coefficient is Teflon (registered trademark). An example of a lubricant is grease.

[0023] The rotor 1 is supported by the support members 3 at a position displaced axially relative to the stator 2. In this embodiment, the rotor 1 is supported by the support members 3 at a position sunken vertically downward relative to the stator 2. The stator core 2a and the permanent magnets 1b are arranged so that the force of the stator 2 magnetically attracting the rotor 1 restores the displacement of the rotor 1 in the axial and tilt directions. The rotor core 1a and the electromagnets are also arranged so that the force of the stator 2 magnetically attracting the rotor 1 restores the displacement of the rotor 1 in the axial and tilt directions. In other words, even if the magnetic flux from the permanent magnets 1b of the rotor 1 is replaced by the magnetic flux from the electromagnets of the stator 2, a force that attempts to restore the displacement of the rotor 1 in the axial and tilt directions acts on the rotor 1 in the same way.

[0024] Here, referring to FIG. 2 , the radial support force acting on the rotor 1 (in the X- and Y-axis directions) will be described. FIG. 2 is a cross-sectional view showing the configuration of the rotating machine 100 according to the first embodiment, illustrating the radial support force acting on the rotor 1. Each cross-sectional view, including FIG. 2 , is a cross-sectional view taken along the axial direction. The number of poles when the north-pole permanent magnets 1b and the south-pole permanent magnets 1b are alternately arranged in the circumferential direction on the surface of the rotor core 1a is defined as p. A magnetic field with the number of poles p is generated by passing a current through the winding 2b of the stator 2, i.e., by passing a fluctuating current i through the winding 2b of the stator 2. When the magnetic field with the number of poles p is rotated by changing the phase of the current passing through, the rotor 1 is attracted to the rotation of the magnetic field with the number of poles p and rotates accordingly. This generates torque, allowing the rotation speed and angle of the rotor 1 to be controlled. Furthermore, when a magnetic field with the number of poles p±2 is generated, an angle at which the density of the magnetic flux 7a increases and an angle at which the density of the magnetic flux 7a decreases are generated in the gap portion 4. This difference in density of the magnetic flux 7a generates a radial (XY axis direction) supporting force, which is a force that magnetically attracts the rotor 1 in the radial direction relative to the stator 2. This allows the rotor 1 to be supported relative to the stator 2 without contact.

[0025] If the rotating machine 100 is a general bearingless motor such as a surface permanent magnet bearingless motor, generating a magnetic field with pole numbers p±2 will, as described above, create angles at which the density of the magnetic flux 7a increases and angles at which the density of the magnetic flux 7a decreases in the gap 4, thereby generating a radial (XY-axis) supporting force. On the other hand, if the rotating machine 100 is a consequent-pole bearingless motor in which only one of the north and south pole permanent magnets 1b is attached between the salient-pole rotor core 1a, or a homopolar bearingless motor in which a salient-pole rotor core 1a and a permanent magnet 1b magnetized in the axial direction are used, generating a magnetic field with pole number two will create angles at which the density of the magnetic flux 7a increases and angles at which the density of the magnetic flux 7a decreases in the gap 4, thereby generating a radial (XY-axis) supporting force.

[0026] Next, the axial force acting on the rotor 1 will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view showing the configuration of the rotating machine 100 according to the first embodiment, and is a diagram for explaining the axial force acting on the rotor 1. Fig. 3 shows a case where gravity mg acts on the rotor 1.

[0027] The rotor 1 is displaced vertically downward relative to the stator 2, i.e., in the axial direction, due to gravity mg. As a result, parts of the rotor 1 and stator 2 do not face each other in the radial direction, and magnetic flux 7b is generated that passes obliquely between the rotor 1 and stator 2. In Figure 3, the rotor 1 is displaced vertically downward relative to the stator 2, and therefore magnetic flux 7b is shown emerging from the rotor 1 and entering obliquely onto the underside of the tip of the teeth 2c of the stator 2. Here, the axial displacement of the rotor 1 relative to the stator 2 is defined as z (z<0), and the axial rigidity of the rotor 1 is defined as kz.

[0028] When the rotor 1 is displaced axially relative to the stator 2, a restoring force f1 is generated in the direction opposite to the axial displacement z of the rotor 1. More specifically, the magnetic flux 7b passing obliquely between the rotor 1 and the stator 2 generates a restoring force f1 that attempts to return the rotor 1 to its axial magnetic center, i.e., the position of z = 0. The restoring force f1 increases in proportion to the axial displacement z of the rotor 1. As described above, if the axial stiffness of the rotor 1 is kz, then f1 = -kz × z. A negative sign for the axial stiffness kz of the rotor 1 means that the rotor 1 is attracted to the stator 2 in the direction opposite to the displacement direction of the rotor 1. The restoring force f1 is a magnetic force that supports the rotor 1 in the axial direction, and in the illustrated example, it is a force that attempts to move the rotor 1 vertically upward.

[0029] The rotor 1 is also supported in the axial direction by the support members 3. The force with which the rotor 1 is supported in the axial direction by the support members 3 is defined as the support force f2. Since the support force f2 is equal to the remaining component of gravity mg that cannot be supported by the restoring force f1, the following equation (1) holds true: f2 = mg - f1 (1)

[0030] On the other hand, if the rotor 1 is not displaced in the axial direction relative to the stator 2, that is, if z=0, the restoring force f1=0. In this case, the following equation (2) holds true: f2=mg (2)

[0031] Therefore, from the above equations (1) and (2), by making the axial displacement z of the rotor 1 relative to the stator 2 a negative value and increasing its absolute value, i.e., by increasing the amount of displacement of the rotor 1 in the direction of gravity mg acting on the rotor 1 (in the negative direction of the Z-axis), the restoring force f1 can be increased. This allows the restoring force f1 to support most of gravity mg, and the remaining component, the supporting force f2, can be reduced. Note that the supporting force f2 is also the force by which the rotor 1 is supported in the tilting direction by the support members 3. In other words, the supporting force f2 is the force by which the rotor 1 is supported in the axial and tilting directions by the support members 3.

[0032] Although not shown, when the rotor 1 is displaced in a tilt direction relative to the stator 2, a restoring torque is generated in the direction opposite to the tilt displacement of the rotor 1. Specifically, the magnetic flux 7b passing obliquely between the rotor 1 and the stator 2 generates a restoring torque that attempts to return the rotor 1 to the magnetic center in the tilt direction. The restoring torque increases in proportion to the displacement of the rotor 1 in the tilt direction. In this embodiment, for the three degrees of freedom in the axial and tilt directions of the rotor 1, even without detecting the position of the rotor 1 and controlling the value of the current, the restoring forces and restoring torque that attempt to return the rotor 1 displaced in the axial and tilt directions to the magnetic center in the axial and tilt directions are generated in the gap 4, resulting in a passively stable structure. Because torque, radial supporting forces, restoring force f1, and restoring torque are generated in the gap 4, the rotating machine 100 can be made smaller and lighter than when the portions generating the torque and radial supporting forces and the portions generating the restoring force f1 and restoring torque are separated.

[0033] Next, the effects of the rotating machine 100 according to this embodiment will be described.

[0034] In this embodiment, as shown in FIG. 3 , the stator core 2a and the permanent magnet 1b, which is a magnetic force generating member, are arranged so that the stator 2 magnetically attracts the rotor 1 to restore the axial and tilt displacements of the rotor 1. Also, in this embodiment, the rotor core 1a and the electromagnet, which is a magnetic force generating member, are arranged so that the stator 2 magnetically attracts the rotor 1 to restore the axial and tilt displacements of the rotor 1. Also, in this embodiment, the rotating machine 100 includes a support member 3 that is arranged on at least one side of the rotor 1 in the axial direction along the rotation axis AX and supports the rotor 1 to limit the displacement of the rotor 1 in the axial and tilt directions. This configuration allows the support member 3 to support the rotor 1 in the axial and tilt directions in addition to the restoring force and restoring torque that are generated in proportion to the displacement of the rotor 1. Therefore, further axial and tilt displacements of the rotor 1 are suppressed. This suppresses vibration of the rotor 1 in the axial and tilt directions.

[0035] For example, vibrations occurring in the rotor 1 when an impact is applied to the rotor 1 from outside the rotating machine 100 can be suppressed, and the duration of vibrations occurring in the rotor 1 can also be suppressed. Furthermore, there is a frequency at which vibrations of the rotor 1 are likely to occur, determined by the rigidity of the rotor 1 and the mass and moment of inertia of the rotor 1. Even when the value of this frequency matches the rotation speed of the rotor 1, resonance phenomena can be avoided and vibration of the rotor 1 can be suppressed. Conventionally, care had to be taken to rotate the rotor 1 so as to avoid resonance phenomena. However, in this embodiment, by using the support member 3, the rotor 1 can be rotated in a wide operating range without paying attention to avoiding resonance phenomena. As described above, in this embodiment, a rotating machine 100 can be obtained that is passively stable with respect to the three degrees of freedom of the rotor 1, i.e., the axial and tilt directions, while being able to suppress vibrations of the rotor 1 in the axial and tilt directions.

[0036] In this embodiment, as shown in FIG. 3 , the rotor 1 is supported by the support members 3 at a position displaced axially relative to the stator 2. This configuration allows the restoring force f1 to be increased and the support force f2 to be reduced. For example, the ratio of the restoring force f1 to the support force f2 shown in FIG. 3 may be set to, for example, 9:1 or 19:1, thereby making the support force f2 close to zero. By reducing the support force f2 in this manner, the frictional heat generated by the support members 3 during rotation of the rotor 1 is significantly reduced. Furthermore, by reducing the support force f2, wear on the support members 3 is reduced, thereby reducing the frequency of replacement of the support members 3 and enabling the rotating machine 100 to operate for a longer period of time. Furthermore, by reducing the support force f2, torque loss caused by physical contact between the rotor 1 and the support members 3 is reduced, thereby improving the overall operating efficiency of the rotating machine 100. As a result, compared to a case where the support members 3 are not present, it is possible to suppress vibration of the rotor 1 in the axial and tilt directions while maintaining substantially the same torque loss and overall operating efficiency of the rotating machine 100.

[0037] 3, in this embodiment, the support members 3 are in circumferential contact with the rotor 1. With this configuration, the support members 3 support the rotor 1 over the entire circumference of the rotor 1, which makes it possible to further suppress further displacement of the rotor 1 in the axial direction and displacement of the rotor 1 in the tilt direction.

[0038] 3 includes a low-friction portion that reduces the frictional force with the rotor 1. This configuration reduces the frictional force generated between the rotor 1 and the support member 3, thereby achieving the same effect as when the support force f2 described in paragraph 0036 above is reduced.

[0039] Conventionally, a known technique involves placing repulsive magnets, which function as magnetic bearings, on both the stator and rotor, and utilizing the repulsive force generated between the repulsive magnets to passively stabilize the rotor in three degrees of freedom (axial and tilt directions). This conventional technique suffers from problems such as the repulsive performance being affected by the magnetization state and installation accuracy of the repulsive magnets, increased size and cost due to the repulsive magnets, and performance degradation and thermal demagnetization of the repulsive magnets due to temperature increases. In this regard, in the present embodiment, as shown in FIG. 3 , the rotor 1 is supported by the support member 3 at a position displaced axially relative to the stator 2, eliminating the need for repulsive magnets. In other words, in this embodiment, the stator 2 generates a magnetically attractive force on the rotor 1, thereby achieving a passively stable structure in three degrees of freedom (axial and tilt directions) of the rotor 1, eliminating the need for repulsive magnets. This eliminates the need for repulsive magnets. This prevents the above-mentioned problems from occurring.

[0040] In the rotating machine 100 shown in Fig. 3, a method can be considered in which a repulsive magnet is used to repel the rotor 1 vertically downward against the stator 2, and the sum of the gravity mg and the repulsive force is supported by a supporting force f2. However, with this method, the supporting force f2 exceeds the gravity mg of the rotor 1. This causes problems such as an increase in frictional heat generated in the support members 3, increased wear of the support members 3, a shortened lifespan of the support members 3, and increased torque loss. In this regard, in the present embodiment, the restoring force f1 generated between the stator 2 and the rotor 1 makes the supporting force f2 smaller than the gravity mg of the rotor 1, thereby preventing the occurrence of the above-mentioned problems.

[0041] Next, a modification of the first embodiment will be described.

[0042] In this embodiment, as shown in Figure 1, the rotating machine 100 is an inner rotor type in which the rotor 1 is arranged on the inner circumference of the stator 2, but it may also be an outer rotor type rotating machine 100 in which the rotor 1 is arranged on the outer circumference of the stator 2.

[0043] 1, in this embodiment, the rotation axis AX (Z-axis) of the rotor 1 is parallel to the vertical direction, but the entire rotating machine 100 may be tilted with respect to the vertical direction so that there is an angular difference between the rotation axis AX of the rotor 1 and the vertical direction. In other words, the rotation axis AX of the rotor 1 may be inclined with respect to the vertical direction.

[0044] In this embodiment, as shown in FIG. 3 , assuming that gravity mg acts on the rotor 1, a case has been illustrated in which a portion of gravity mg acting on the rotor 1 is supported by the support member 3. However, a portion of forces other than gravity mg can also be supported by the support member 3. For example, a load such as a fan or a pump may be attached to the rotor 1. In this case, a reaction force acts on the rotor 1 when the load, such as the fan or pump, pumps a fluid. This causes an axial displacement z of the rotor 1 relative to the stator 2. Therefore, a portion of the reaction force acting on the rotor 1 may be supported by the support member 3. Furthermore, when gravity mg and a reaction force act on the rotor 1, a portion of gravity mg and the reaction force acting on the rotor 1 may be supported by the support member 3. Note that a reaction force is generated even when the axial direction of the rotor 1 is parallel to the horizontal direction. In other words, even if the rotation axis AX of the rotor 1 is parallel to the horizontal direction, an axial displacement z of the rotor 1 relative to the stator 2 may occur. Therefore, the rotation axis AX of the rotor 1 may be parallel to the horizontal direction. Furthermore, when the position of the stator 2 in the axial direction is taken as a reference position, the support members 3 only need to support the rotor 1 at a position where the rotor 1 is displaced from the reference position in the axial direction in the direction of gravity mg acting on the rotor 1 or in the direction in which a reaction force acts on the rotating rotor 1. In this way, the support force f2 generated by the support members 3 is reduced by the burden of the axial restoring force f1 generated between the stator 2 and the rotor 1, compared to when the rotor 1 is supported at a position where it is not displaced axially from the reference position.

[0045] 1, the present embodiment illustrates a case in which the rotor 1 has a permanent magnet 1b and the stator 2 has a stator core 2a, which is an iron core, but the rotor 1 may have an iron core and the stator 2 may have a permanent magnet. That is, when a permanent magnet is arranged on a magnetic circuit and the stator 2 magnetically attracts the rotor 1 to restore the displacement of the rotor 1 in the axial direction and in the tilt direction, it is sufficient that at least one of the rotor 1 and the stator 2 has an iron core and at least the other of the rotor 1 and the stator 2 has a permanent magnet.

[0046] In this embodiment, the rotating machine 100 has permanent magnets 1b provided on the rotor 1, but the rotating machine 100 may not have permanent magnets 1b provided on the rotor 1. For example, by forming salient poles or slits in the rotor core 1a, the rotating machine 100 may be modified to become a synchronous reluctance motor in which reluctance, which is the difficulty of magnetic flux passing, changes depending on the rotation angle of the rotor 1.

[0047] In this embodiment, as shown in Fig. 1, the rotor 1 has a hollow shape, but it may also be solid. If the rotor 1 has a hollow shape, the hollow space may be used, for example, as a path for passing wires or as a flow path for a fluid. Furthermore, by having the rotor 1 be hollow, the weight of the entire rotating machine 100 can be reduced. Furthermore, by having the rotor 1 be hollow, when the rotor 1 generates heat, heat can be dissipated into the hollow space, thereby improving the cooling effect of the rotor 1.

[0048] In the present embodiment, as shown in Fig. 2, a configuration has been illustrated in which a radial (X- and Y-axis) support force acting on the rotor 1 is generated by placing a permanent magnet 1b on a magnetic circuit in addition to flowing a fluctuating current i that contributes to increasing or decreasing the radial (X- and Y-axis) support force through the windings 2b, but this is not limiting. For example, as shown in Fig. 4, a radial (X- and Y-axis) support force acting on the rotor 1 may be generated by flowing a bias current I through each winding 2b in addition to flowing a fluctuating current i that contributes to increasing or decreasing the radial (X- and Y-axis) support force through the windings 2b. Fig. 4 is a cross-sectional view showing the configuration of a rotating machine 100A according to a first modification of the first embodiment.

[0049] The rotor 1 shown in Figure 4 has only a rotor core 1a and does not have a permanent magnet 1b. There is no reluctance difference in the rotor 1. The stator core 2a and winding 2b form an electromagnet. Here, we will explain the case where a supporting force is generated in the X-axis direction. A winding 2b1 is wound around the tooth 2c located in the positive direction of the X-axis. A winding 2b2 is wound around the tooth 2c located in the negative direction of the X-axis. A current of I+i (A: Ampere), which is the sum of the bias current I and the fluctuating current i, flows through winding 2b1, and a current of I-i (A: Ampere), which is the difference between the bias current I and the fluctuating current i, flows through winding 2b2. At this time, the density of the magnetic flux 7a in the gap portion 4 can be increased or decreased.

[0050] Furthermore, considering that the current is proportional to the density of the magnetic flux 7a and that the force is proportional to the square of the density of the magnetic flux 7a, the force acting on the surface of the rotor 1 facing the gap portion 4 located in the positive direction of the X-axis, where k is a constant, is k(I+i) 2 The force acting on the surface of the rotor 1 facing the gap 4 in the negative X-axis direction is k(I−i) 2 The difference between these two forces is 4×k×I×i. Therefore, the rotor 1 receives a force of 4×k×I×i in the positive direction along the X-axis. In other words, by passing a bias current I through each of the windings 2b1 and 2b2 and then adjusting the fluctuating current i flowing through each of the windings 2b1 and 2b2, a support force in the X-axis direction proportional to the magnitude of the fluctuating current i can be generated. To generate a support force in the Y-axis direction as well, simply adjust the fluctuating current i flowing through the other winding 2b in the same way as when generating a support force in the X-axis direction. This allows the rotating machine 100A to function as a magnetic bearing that generates a support force in the radial direction (X-axis and Y-axis directions).

[0051] In this modification, the rotor core 1a and electromagnets, which are magnetic force generating members, are arranged so that the stator 2 magnetically attracts the rotor 1, restoring the rotor 1 to its axial and tilt directions. With this configuration, as in the first embodiment, this modification also achieves a passively stable structure for the three degrees of freedom of the rotor 1 in the axial and tilt directions, because restoring forces and restoring torques are generated that return the rotor 1, displaced in the axial and tilt directions, to its magnetic center in the axial and tilt directions, without detecting the rotor 1's position and controlling the current value. Also, as in the first embodiment, this modification also allows the support members 3 to suppress vibration of the rotor 1 in the axial and tilt directions. Note that at least one of the rotor 1 and the stator 2 must have an iron core, and at least the other of the rotor 1 and the stator 2 must have a magnetic force generating member. Furthermore, the rotor 1 may have both a permanent magnet 1b and an electromagnet as magnetic force generating members. In this configuration, the electromagnet is made up of, for example, a rotor core 1a and a winding wound around the rotor core 1a.

[0052] As shown in FIG. 5 , the rotating machine 100B may include an adjustment member 5 that can adjust the position of the support member 3 in the axial direction. FIG. 5 is a cross-sectional view showing the configuration of a rotating machine 100B according to a second modified example of the first embodiment. FIG. 5 illustrates a frame 6. The frame 6 has a cylindrical shape with both axial ends open. The frame 6 has a peripheral wall portion 6a and a shaft end wall 6b. The peripheral wall portion 6a is a cylindrical portion extending in the circumferential direction. One axial end of the peripheral wall portion 6a is open. The other axial end of the peripheral wall portion 6a is closed by the shaft end wall 6b. The shaft end wall 6b has a hole 6c through which a shaft (not shown) is inserted.

[0053] The stator 2 is fitted and fixed to the inner peripheral surface of the peripheral wall portion 6a of the frame 6. The support member 3 is fixed to the axial end wall 6b of the frame 6 via an adjustment member 5. The adjustment member 5 is, for example, a screw. The adjustment member 5 axially penetrates the axial end wall 6b of the frame 6 from the outer surface to the inner surface. The tip of the adjustment member 5 is inserted into the support member 3. The position of the support member 3 in the axial direction is changed by rotating the screw that is the adjustment member 5.

[0054] In this modification, the position of the support member 3 in the axial direction can be adjusted by rotating the screw that serves as the adjustment member 5. Therefore, the position at which the support member 3 supports the rotor 1, i.e., the axial displacement z of the rotor 1, can be adjusted. This allows the ratio of the restoring force f1 to the supporting force f2 to be easily changed. For example, the value of the supporting force f2 can be changed to the smallest value within a range that is unlikely to cause vibration of the rotor 1 in the axial direction or tilt direction. Furthermore, in this modification, even if a load such as a fan or pump is attached to the rotor 1 and the gravity mg of the entire rotor 1 changes, or even if a reaction force acts on the rotor 1 when a load such as a fan or pump pumps fluid, the ratio of the restoring force f1 to the supporting force f2 can be quickly and easily changed without disassembling or replacing the entire rotating machine 100B. Therefore, the rotor 1 can be rotated while suppressing vibration of the rotor 1 due to changes in the gravity mg of the entire rotor 1 or the reaction force acting on the rotor 1. Note that the adjustment member 5 may be omitted.

[0055] Second Embodiment Next, a rotating machine 100C according to a second embodiment will be described with reference to Fig. 6. Fig. 6 is a perspective view showing the configuration of the rotating machine 100C according to the second embodiment. This embodiment differs from the first embodiment in that the rotating machine 100C includes a plurality of support members 3. Note that in the second embodiment, parts that overlap with those in the first embodiment are denoted by the same reference numerals and will not be described again. For ease of understanding, Fig. 6 illustrates the rotating machine 100C as viewed from one side in the axial direction.

[0056] The rotating machine 100C includes three support members 3. In this embodiment, the shape of each support member 3 is cylindrical, but is not particularly limited as long as it can support the rotor 1. Hereinafter, when distinguishing between the three support members 3, they will be referred to as support member 3A, support member 3B, and support member 3C. The three support members 3A, 3B, and 3C are arranged spaced apart from one another in the circumferential direction. The three support members 3A, 3B, and 3C are arranged at equal angular intervals in the circumferential direction. The three support members 3A, 3B, and 3C are arranged at 120-degree intervals in the circumferential direction. Each of the three support members 3A, 3B, and 3C supports the rotor 1. In other words, the rotor 1 is supported by the three support members 3A, 3B, and 3C that are spaced apart from one another in the circumferential direction.

[0057] Next, the effects of the rotating machine 100C according to this embodiment will be described.

[0058] In this embodiment, the rotor 1 is supported by three support members 3A, 3B, and 3C that are spaced apart from one another in the circumferential direction. With this configuration, support forces f21, f22, and f23 are generated at each of the three support members 3A, 3B, and 3C, respectively, supporting the rotor 1 in the axial and tilt directions. This suppresses further displacement of the rotor 1 in the axial direction and in the tilt direction. This suppresses vibration of the rotor 1 in the axial and tilt directions. The points of application of the support forces f21, f22, and f23 are preferably positioned at equal angles in the circumferential direction; in this embodiment, they are positioned at 120-degree intervals in the circumferential direction. This configuration further suppresses further displacement of the rotor 1 in the axial direction and in the tilt direction.

[0059] In this embodiment, as in the first embodiment, the rotor 1 is displaced vertically downward relative to the stator 2, and is supported by the support members 3 at a position where the rotor 1 is sunken vertically downward relative to the stator 2. Therefore, the force supporting the gravity mg acting on the rotor 1 is the sum of the restoring force f1, which is the force with which the stator 2 magnetically attracts the rotor 1, and the supporting force f2, which is the sum of the supporting forces f21, f22, and f23, which are the forces with which the rotor 1 is supported in the axial direction by each of the support members 3A, 3B, and 3C. Since the supporting forces f21, f22, and f23 are equal to the remaining component of the gravity mg that cannot be supported by the restoring force f1, the following equation (3) holds true. f21 + f22 + f23 = mg - f1 (3)

[0060] Therefore, from the above formula (3), the more negative the axial displacement z of the rotor 1 relative to the stator 2 is made and the larger its absolute value is, the more the restoring force f1 can be increased, and therefore the supporting force f2 can be reduced. This makes it possible to achieve the same effect as the effect achieved when the supporting force f2 is reduced as described in paragraph 0036 above.

[0061] In this embodiment, the rotor 1 is supported by three support members 3A, 3B, and 3C that are spaced apart in the circumferential direction. This configuration allows each of the support members 3A, 3B, and 3C to be made smaller and lighter than when using a single support member 3. Furthermore, if a malfunction occurs in one of the three support members 3A, 3B, and 3C, only the malfunctioning member needs to be replaced, thereby reducing the cost of replacement.

[0062] Next, a modification of the second embodiment will be described.

[0063] In this embodiment, the number of support members 3 is three, but it may be four or more. That is, the rotor 1 in this embodiment may be supported by three or more support members 3 that are spaced apart from each other in the circumferential direction. If the positions of the support members 3 vary in the axial direction, for example, a phenomenon may occur in which three of the four or more support members 3 support the rotor 1, and the remaining support members 3 do not support the rotor 1. Even if one of the support members 3 supporting the rotor 1 loses its support function due to wear or damage, if there are four or more support members 3, three or more support members 3, including the support member 3 that was not supporting the rotor 1, will newly support the rotor 1. This ensures redundancy of the support members 3, thereby improving the reliability of the rotating machine 100C.

[0064] As in the first embodiment, each of the three support members 3A, 3B, and 3C may have a low-friction portion that reduces the frictional force with the rotor 1. In this way, the frictional force generated between the rotor 1 and the support members 3 can be reduced, and the same effect as that achieved by reducing the support force f2 described in paragraph 0036 above can be achieved.

[0065] Third Embodiment Next, a rotating machine 100D according to a third embodiment will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view showing the configuration of a rotating machine 100D according to the third embodiment. This embodiment differs from the first and second embodiments in that the support member 3 functions as a hydrostatic bearing that supports the rotor 1. In the third embodiment, parts that overlap with those in the first and second embodiments are denoted by the same reference numerals, and description thereof will be omitted.

[0066] The support member 3 is a single member. A flow path 3b through which a fluid flows is formed inside the support member 3. Reference numeral 8 in FIG. 7 schematically indicates the flow of the fluid. The fluid may be a gas or a liquid. Examples of gas include air. Examples of liquid include water and oil. The shape of the support member 3 is, for example, a hollow disk, but is not particularly limited as long as the fluid can flow toward the rotor 1. An inlet 3f is formed on the outer peripheral surface 3c of the support member 3 for allowing the fluid to flow into the flow path 3b. An outlet 3g is formed on the surface 3d of the support member 3 facing the rotor 1 for allowing the fluid to flow from the flow path 3b toward the rotor 1. The outlet 3g has a circumferential shape extending in the circumferential direction. The fluid flowing out from the outlet 3g toward the rotor 1 supports the rotor 1 in the axial and tilt directions. The fluid flowing out from the outlet 3g toward the rotor 1 supports the rotor 1 circumferentially. In other words, the fluid flowing out from the outlet 3g toward the rotor 1 supports the rotor 1 over the entire circumference of the rotor 1. In this embodiment, the support member 3 functions as a hydrostatic bearing that supports the rotor 1.

[0067] Next, the effects of the rotating machine 100D according to this embodiment will be described.

[0068] In this embodiment, a flow path 3b through which a fluid flows is formed inside the support member 3, and an outlet 3g for discharging the fluid from the flow path 3b toward the rotor 1 is formed on the surface 3d of the support member 3 facing the rotor 1. This configuration suppresses further displacement of the rotor 1 in the axial direction and displacement of the rotor 1 in the tilt direction. This makes it possible to suppress vibration of the rotor 1 in the axial direction and the tilt direction. Furthermore, with the above configuration, the support member 3 functions as a hydrostatic bearing that supports the rotor 1, thereby further reducing the frictional force generated between the rotor 1 and the support member 3.

[0069] In this embodiment, the rotor 1 is displaced vertically downward relative to the stator 2, and is supported by the support member 3 at a position where the rotor 1 is sunken vertically downward relative to the stator 2. With this configuration, a restoring force f1 is generated by the axial displacement z of the rotor 1, thereby reducing the support force f2. This makes it possible to reduce the flow rate and pressure of the fluid flowing out from the outlet 3g toward the rotor 1. This makes it possible to reduce the input energy required to prepare the fluid to flow from the inlet 3f into the flow path 3b of the support member 3, and also to reduce torque loss caused by physical contact between the rotor 1 and the support member 3.

[0070] Next, a modification of the third embodiment will be described.

[0071] As shown in FIG. 8 , the rotating machine 100E may include multiple support members 3. FIG. 8 is a cross-sectional view showing the configuration of a rotating machine 100E according to a modified example of the third embodiment. Although FIG. 8 illustrates two support members 3, the rotating machine 100E actually includes three support members 3. Although FIG. 8 illustrates support forces f21 and f22, which are forces by which the rotor 1 is supported in the axial direction and tilt direction by each of the two support members 3A and 3B, in reality, a support force f23 (not shown) is also generated by the remaining support member 3 (not shown) supporting the rotor 1 in the axial direction and tilt direction. The three support members 3 are arranged spaced apart from each other in the circumferential direction. The three support members 3 are arranged at equal angles in the circumferential direction. The three support members 3 are arranged at 120-degree intervals in the circumferential direction.

[0072] A flow path 3b through which a fluid flows is formed inside each of the three support members 3. The shape of each support member 3 is, for example, a hollow cylinder, but is not particularly limited as long as the fluid can flow toward the rotor 1. An inlet 3f is formed on the surface 3e of each support member 3 facing away from the rotor 1, allowing the fluid to flow into the flow path 3b. An outlet 3g is formed on the surface 3d of each support member 3 facing the rotor 1, allowing the fluid to flow from the flow path 3b toward the rotor 1. The fluid flowing out from the outlets 3g of each of the three support members 3 toward the rotor 1 supports the rotor 1 in the axial and tilt directions. The fluid flowing out from the outlets 3g of each of the three support members 3 toward the rotor 1 supports the rotor 1 in a point-like manner. In other words, the rotor 1 is supported by the fluid flowing out from the outlets 3g of each of the three support members 3 that are spaced apart from one another in the circumferential direction. In this modification, each support member 3 also functions as a hydrostatic bearing that supports the rotor 1.

[0073] This modification can also achieve the same effects as in embodiment 3. In this modification, the number of support members 3 is three, but it may be four or more. That is, the rotor 1 of this modification only needs to be supported by the fluid flowing out from the respective outlets 3g of three or more support members 3 that are spaced apart from one another in the circumferential direction.

[0074] Fourth Embodiment Next, a rotating machine 100F according to a fourth embodiment will be described with reference to Fig. 9. Fig. 9 is a perspective view showing the configuration of a support member 3 of a rotating machine 100F according to the fourth embodiment. This embodiment differs from the first embodiment in that the support member 3 functions as a hydrodynamic bearing that supports the rotor 1. In the fourth embodiment, parts that overlap with those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0075] A surface 3d of the support member 3 facing the rotor 1 (not shown) has a plurality of grooves 3h that open toward the rotor 1. The grooves 3h are arranged spaced apart from one another in the circumferential direction. The grooves 3h are arranged at equal angles in the circumferential direction. In this embodiment, the number of grooves 3h is five, but is not particularly limited. The grooves 3h are recessed toward the side opposite to the side where the rotor 1 is located in the axial direction. Flat portions 3i are formed between adjacent grooves 3h in the circumferential direction. The flat portions 3i are flat portions that are perpendicular to the axial direction. The flat portions 3i are arranged closer to the rotor 1 in the axial direction than the grooves 3h. The grooves 3h and the flat portions 3i are arranged alternately in the circumferential direction.

[0076] The groove 3h has a first groove surface 3h1, a second groove surface 3h2, and a third groove surface 3h3. The first groove surface 3h1 is a surface extending in the axial direction. The first groove surface 3h1 is continuous with one of two flat portions 3i adjacent to the groove 3h. The first groove surface 3h1 extends in the axial direction away from one of the flat portions 3i. The second groove surface 3h2 is a surface extending in the circumferential direction. The second groove surface 3h2 extends in the circumferential direction from an end of the first groove surface 3h1 opposite to the end that is continuous with one of the flat portions 3i. The third groove surface 3h3 is an inclined surface that inclines toward the rotor 1 as it extends in the circumferential direction away from the second groove surface 3h2. The third groove surface 3h3 is inclined with respect to the axial direction. The third groove surface 3h3 extends in the circumferential direction from an end of the second groove surface 3h2 opposite to the end continuing to the first groove surface 3h1. The end of the third groove surface 3h3 opposite to the end continuing to the second groove surface 3h2 continues to the other of the two flat portions 3i adjacent to the groove 3h.

[0077] Next, the effects of the rotating machine 100F according to this embodiment will be described.

[0078] In this embodiment, a groove 3h opening toward the rotor 1 is formed on the surface 3d of the support member 3 facing the rotor 1. With this configuration, when the rotor 1 rotates, the groove 3h eliminates a fluid path, allowing the fluid to flow from the support member 3 toward the rotor 1. This generates pressure in the fluid flowing from the support member 3 toward the rotor 1. This allows the rotor 1 to rotate without physical contact with the support member 3. This further reduces frictional heat generated between the rotor 1 and the support member 3 and torque loss caused by physical contact between the rotor 1 and the support member 3. As shown in FIG. 9 , the groove 3h preferably has a third groove surface 3h3, which is an inclined surface inclined relative to the axial direction. In this manner, when the rotor 1 rotates, the three-dimensional inclination of the groove 3h eliminates a fluid path, facilitating the fluid flow from the support member 3 toward the rotor 1.

[0079] The phenomenon in which the rotor 1 and the support member 3 are no longer in physical contact occurs when the rotor 1 rotates. For this reason, when the rotor 1 is stationary, the support member 3 does not function as a dynamic pressure bearing that supports the rotor 1. However, when the rotor 1 is rotating, if the rotation speed of the rotor 1 exceeds a certain threshold, the support member 3 functions as a dynamic pressure bearing that supports the rotor 1.

[0080] In this embodiment, a portion of the gravity mg acting on the rotor 1 is supported by the restoring force f1, and the remaining portion of the gravity mg of the rotor 1 can be supported by the pressure of the fluid flowing from the support member 3 toward the rotor 1. This makes it possible to reduce the support force f2. Therefore, the threshold rotation speed of the rotor 1 at which the rotor 1 and the support member 3 are physically out of contact can be set low, and the support member 3 functions as a hydrodynamic bearing that supports the rotor 1 over a wide operating range of the rotating machine 100F.

[0081] In this embodiment, the inclination of the three-dimensional grooves 3h can be reduced to design the rotor 1 so as to reduce the pressure of the fluid flowing from the support member 3 toward the rotor 1. This reduces the input energy of the fluid, thereby improving the operating efficiency of the entire rotating machine 100F.

[0082] Next, a modification of the fourth embodiment will be described.

[0083] As shown in FIG. 10 , grooves 1e may be formed on the rotor 1. FIG. 10 is a diagram illustrating the configuration of the rotor 1 of a rotating machine 100G according to a modified example of the fourth embodiment, viewed from the axial direction of the rotor 1. In FIG. 10 , grooves 1e are hatched with dots for ease of understanding. A surface 1d of the rotor 1 facing the support member 3 (not shown) is formed with a plurality of grooves 1e that open toward the support member 3. The grooves 1e are spaced apart from one another in the circumferential direction. The grooves 1e are arranged at equal angles in the circumferential direction. In this embodiment, the number of grooves 1e is nine, but is not particularly limited. The grooves 1e are recessed axially toward the side opposite the side where the support member 3 is located. Flat portions 1f are formed between adjacent grooves 1e in the circumferential direction. The flat portions 1f are flat portions perpendicular to the axial direction. The flat portions 1f are positioned closer to the support member 3 in the axial direction than the grooves 1e. The grooves 1e and the flat portions 1f are arranged alternately in the circumferential direction.

[0084] Each groove 1e extends radially and is formed from the outer peripheral surface to the inner peripheral surface of the rotor 1. Each groove 1e extends while curving to one side of the circumferential direction as it moves from the outer radial direction to the inner radial direction. When the extension direction of each groove 1e is projected onto a plane normal to the rotation axis AX of the rotor 1, the extension direction of each groove 1e is positioned at a position offset from the rotation axis AX of the rotor 1. The openings 1g of each groove 1e that open onto the outer peripheral surface of the rotor 1 are spaced apart at equal angles in the circumferential direction. The openings 1h of each groove 1e that open onto the inner peripheral surface of the rotor 1 are spaced apart at equal angles in the circumferential direction. The openings 1g and 1h of each groove 1e are offset from each other in the circumferential direction. The groove width D of each groove 1e narrows as it moves from the outer radial direction to the inner radial direction. In other words, the groove width D of each groove 1e is wider as it moves radially outward and narrower as it moves radially inward.

[0085] In this modification, when the rotor 1 rotates, the fluid flows into the groove 1e from the radially outer side, and as it flows radially inward within the groove 1e, it has nowhere to go and flows from the rotor 1 toward the support member 3. This generates pressure in the fluid flowing from the rotor 1 toward the support member 3, causing the rotor 1 to repel away from the support member 3 in the axial direction. This allows the rotor 1 to rotate without physical contact with the support member 3. This makes it possible to further reduce frictional heat generated between the rotor 1 and the support member 3, and also reduces torque loss caused by physical contact between the rotor 1 and the support member 3.

[0086] The phenomenon in which the rotor 1 and the support member 3 become physically out of contact occurs when the rotor 1 rotates. Therefore, when the rotor 1 is stationary, the support member 3 does not function as a dynamic pressure bearing supporting the rotor 1. However, when the rotor 1 is rotating and the rotation speed of the rotor 1 exceeds a certain threshold, the support member 3 functions as a dynamic pressure bearing supporting the rotor 1. Note that a groove 3h having the same shape as the groove 1e shown in Fig. 10 may be formed on the surface 3d of the support member 3 facing the rotor 1 shown in Fig. 9, or a groove 1e having the same shape as the groove 3h shown in Fig. 9 may be formed on the surface 1d of the rotor 1 facing the support member 3 shown in Fig. 10. Furthermore, it is sufficient that the grooves 3h, 1e opening toward the other side are formed on either the surface 3d of the support member 3 facing the rotor 1 or the surface 1d of the rotor 1 facing the support member 3.

[0087] Fifth Embodiment Next, a rotating machine 100H according to a fifth embodiment will be described with reference to Figs. 11 and 12. Fig. 11 is a perspective view showing the configuration of a portion of a stator core 2a of the rotating machine 100H according to the fifth embodiment. Fig. 12 is a cross-sectional view showing the configuration of the rotating machine 100H according to the fifth embodiment, and is a diagram for explaining the axial force acting on the rotor 1. This embodiment differs from the first embodiment described above in that the permeance decreases in one direction from one end of the axial direction to the other. In the fifth embodiment, parts that overlap with those in the first embodiment described above are assigned the same reference numerals, and description thereof will be omitted.

[0088] As shown in Figures 11 and 12, each tooth 2c has multiple tooth body portions 2e that protrude radially inward from the back yoke portion 2d, and multiple tooth tip portions 2f that protrude in both circumferential directions from the tip of each tooth body portion 2e. The tooth tip portions 2f are shaped like a flange that is wider than the circumferential width of the tooth body portion 2e. This allows a large amount of magnetic flux 7c, 7d to pass between the stator 2 and rotor 1 shown in Figure 12. The dashed line in Figure 12 schematically indicates the boundary between the tooth 2c and the back yoke portion 2d.

[0089] As shown in Figure 11, the number of tooth main body portions 2e and the number of tooth tip portions 2f on each tooth 2c are not particularly limited, but in this embodiment, there are two of each. Two tooth main body portions 2e are stacked in the axial direction. Two tooth tip portions 2f are stacked in the axial direction. Hereinafter, the tooth main body portion 2e and tooth tip portion 2f located on one side in the axial direction will be referred to as the first tooth main body portion 2e1 and the first tooth tip portion 2f1, respectively, and the first tooth main body portion 2e1 and the first tooth tip portion 2f1 will be collectively referred to as the first tooth portion 2c1. Furthermore, the tooth main body portion 2e and tooth tip portion 2f located on the other side in the axial direction will be referred to as the second tooth main body portion 2e2 and the second tooth tip portion 2f2, respectively, and the second tooth main body portion 2e2 and the second tooth tip portion 2f2 will be collectively referred to as the second tooth portion 2c2. In this embodiment, the first teeth 2c1 are disposed vertically above the second teeth 2c2.

[0090] The circumferential width W1 of the first tooth tip 2f1 is wider than the circumferential width W2 of the second tooth tip 2f2. In other words, the circumferential width of the tooth tip 2f narrows in one direction from one axial direction where the first tooth tip 2f1 exists to the other axial direction where the second tooth tip 2f2 exists. The radial length L1 of the first tooth 2c1 is longer than the radial length L2 of the second tooth 2c2. In other words, the radial length of the teeth 2c decreases in one direction from one axial direction where the first tooth 2c1 exists to the other axial direction where the second tooth 2c2 exists. This results in a tooth length difference G, which is the difference between the radial length L1 of the first tooth 2c1 and the radial length L2 of the second tooth 2c2.

[0091] Here, we will explain permeance. Permeance refers to a quantity that represents the ease with which magnetic flux 7c, 7d passes through at least one of the gap portion 4 and the stator core 2a, which is an iron core, in a magnetic path that circulates around the stator 2 and the rotor 1 in the radial and circumferential directions. Generally speaking, magnetic flux passes more easily through iron than through air, so if the magnetic path is an iron core, permeance increases. Furthermore, permeance increases as the width of the magnetic path increases, and as the magnetic path length of the air decreases and the magnetic path length of the iron core increases. In this embodiment, the circumferential width W1 of the first tooth tip portion 2f1 is wider than the circumferential width W2 of the second tooth tip portion 2f2, and the radial length L1 of the first tooth portion 2c1 is longer than the radial length L2 of the second tooth portion 2c2. Therefore, the permeance of the second tooth portion 2c2 is smaller than that of the first tooth portion 2c1. In other words, the permeance, which is a quantity that represents the ease with which magnetic flux 7c, 7d passes through at least one of the gap portion 4 and the stator core 2a, which is the iron core, in the magnetic path that circles the stator 2 and the rotor 1 in the radial and circumferential directions, decreases in one direction from one side in the axial direction to the other.

[0092] Next, a description will be given of the axial force acting on the rotor 1. In FIG.

[0093] 12 , the force acting on the rotor 1 to support gravity mg is the sum of a restoring force f1, which is the force with which the stator 2 magnetically attracts the rotor 1, and a supporting force f2, which is the force with which the support member 3 supports the rotor 1 in the axial direction. Here, because the rotor 1 is displaced axially relative to the stator 2 due to gravity mg, magnetic flux 7d is generated, passing obliquely between the rotor 1 and the underside of the tip of each second tooth 2c2. Therefore, restoring force f1 includes restoring force f12 generated by magnetic flux 7d. Furthermore, due to the difference between the circumferential width W1 of the first tooth tip 2f1 and the circumferential width W2 of the second tooth tip 2f2 and the tooth length difference G shown in FIG. 11 , magnetic flux 7c is also generated, passing obliquely between the rotor 1 and the underside of the tip of each first tooth 2c1, the exposed portion of the second tooth 2c2. Therefore, the restoring force f1 also includes the restoring force f11 generated by the magnetic flux 7c. As a result, the restoring force f1 is generated at a plurality of axial positions of the stator 2, and is the sum of the restoring forces f11 and f12. As a result, even if the axial displacement z of the rotor 1 is the same as in the first embodiment, in this embodiment, the restoring force f1 increases by the amount of the restoring force f11 compared to the first embodiment, and the supporting force f2 decreases by the amount of the increase in the restoring force f1. Therefore, the following equation (4) holds true: f2=mg-f11-f12 (4)

[0094] Next, the effects of the rotating machine 100H according to this embodiment will be described.

[0095] In this embodiment, the permeance, which represents the ease with which magnetic flux 7c, 7d passes through at least one of the gap portion 4 and the stator core 2a in the magnetic path that circumferentially and radially surrounds the stator 2 and the rotor 1, decreases in one direction from one end of the axial direction to the other. This configuration allows the restoring force f1 to increase in one direction from the other end of the axial direction to the other end. This further reduces frictional heat generated between the rotor 1 and the support member 3 and reduces torque loss caused by physical contact between the support member 3 and the rotor 1. This further extends the life of the support member 3 and improves the operating efficiency of the entire rotating machine 100H.

[0096] In this embodiment, the generation of the restoring force f11 means that, when the support force f2 is constant, the axial displacement z of the rotor 1 can approach 0. As the axial displacement z of the rotor 1 approaches 0, the area where the rotor 1 and the stator 2 face each other in the radial direction increases, and the support force and torque in the radial direction (X and Y axes directions) increase. This reduces the current required to generate the same support force and torque in the radial direction (X and Y axes directions), thereby improving the operating efficiency of the entire rotating machine 100H.

[0097] Next, a modification of the fifth embodiment will be described.

[0098] Although the present embodiment illustrates a case in which both the circumferential width and the radial length of the first teeth 2c1 and the second teeth 2c2 are different, it is also possible to change only one of them. Also, while the present embodiment illustrates a case in which the circumferential width and the radial length of two teeth, the first teeth 2c1 and the second teeth 2c2, are different, it is also possible to change either one of the circumferential width and the radial length of three or more teeth.

[0099] The support member 3 of this embodiment may be modified to a configuration that functions as a hydrostatic bearing that supports the rotor 1, as in the above-described embodiment 3, or may be modified to a configuration that functions as a hydrodynamic bearing that supports the rotor 1, as in the above-described embodiment 4. In this embodiment, by increasing the restoring force f1, it is possible to further reduce the fluid pressure required when the support member 3 functions as a hydrostatic bearing or a hydrodynamic bearing.

[0100] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0101] 1 rotor, 1a rotor core, 1b permanent magnet, 1c through hole, 1d, 3d, 3e surface, 1e, 3h groove, 1f, 3i flat portion, 1g, 1h opening, 2 stator, 2a stator core, 2b, 2b1, 2b2 winding, 2c teeth, 2c1 first teeth portion, 2c2 second teeth portion, 2d back yoke portion, 2e teeth main body portion, 2e1 first teeth main body portion, 2e2 second teeth main body portion, 2f teeth tip portion, 2f1 first teeth tip portion, 2f2 second teeth tip portion, 3, 3A, 3B, 3C support member, 3a support surface, 3b flow path, 3c outer peripheral surface, 3f inlet, 3g outlet, 3h1 first groove surface, 3h2 second groove surface, 3h3 Third groove surface, 4 Gap portion, 5 Adjustment member, 6 Frame, 6a Peripheral wall portion, 6b Shaft end wall, 6c Hole, 7a, 7b, 7c, 7d Magnetic flux, 8 Fluid flow, 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H Rotating machine, AX Rotating shaft.

Claims

1. A rotor that rotates about a rotation axis, a stator that is disposed on the outer periphery or inner periphery of the rotor with a gap therebetween, and a support member that is disposed on at least one side in the axial direction along the rotation axis of the rotor and supports the rotor so as to limit displacement of the rotor in the axial direction and the tilt direction. At least one of the rotor and the stator has an iron core, and at least the other of the rotor and the stator has a magnetic force generating member. The iron core and the magnetic force generating member are arranged such that the stator restores displacement of the rotor in the axial direction and the tilt direction by a force that magnetically attracts the rotor. The rotor is supported by the support member at a position displaced axially with respect to the stator. A rotating machine characterized by this.

2. The support member contacts the rotor in a circumferential shape, and the support member is provided with a low friction portion that reduces the frictional force with the rotor. The rotating machine according to claim 1, characterized by this.

3. The rotor is supported by three or more of the support members that are separated from each other in the circumferential direction. The rotating machine according to claim 1 or 2, characterized by this.

4. The axial direction along the rotation axis is parallel to the vertical direction, and the support member is disposed below the rotor in the vertical direction. The rotating machine according to any one of claims 1 to 3, characterized by this.

5. When the position of the stator in the axial direction is taken as a reference position, the support member supports the rotor at a position where the rotor is displaced from the reference position in the direction of gravity acting on the rotor in the axial direction or the direction in which a reaction force acting on the rotor during rotation is generated. The support force generated by the support member is reduced by the burden of the axial restoring force generated between the stator and the rotor as compared with the case where the rotor is supported at a position where it does not axially displace from the reference position. The rotating machine according to any one of claims 1 to 3, characterized by this.

6. A rotating machine according to any one of claims 1 to 5, characterized by comprising an adjustment member capable of adjusting the position of the support member in the axial direction.

7. A fluid flow path is formed inside the support member, and an outlet for discharging the fluid from the flow path toward the rotor is formed on the surface of the support member facing the rotor. The rotary machine according to claim 1, characterized in that.

8. A groove opening toward the other is formed on either one of the surface of the support member facing the rotor and the surface of the rotor facing the support member. The rotary machine according to claim 1, characterized in that.

9. The permeance, which is an amount representing the ease of magnetic flux passing through at least one of the gap portion and the iron core in a magnetic path that circulates along the radial direction and the circumferential direction between the stator and the rotor, decreases in one direction from one axial end to the other. The rotary machine according to any one of claims 1 to 6, characterized in that.

Images