JP7135786B2 - Stator, magnetic bearing, rotating machine - Google Patents

Description

The present invention relates to stators, magnetic bearings, and rotating machines.

2. Description of the Related Art As a method for fixing a winding core to a housing in a stator of a motor, generator, or the like, there is a method of fixing the winding core to the housing by shrink fitting.
However, in the above method, a gap is generated between the housing and the winding core during shrink fitting, and the winding core may not be coaxially installed with respect to the rotor. Therefore, as described in Patent Document 1, the position of the winding core is fixed by molding with resin or the like while press-fitting the winding core into the housing.

Japanese Utility Model Laid-Open No. 6-29364

In the method described above, a resin mold is used. However, when a fluid coolant is used in a motor or the like, depending on the types of the mold material and the coolant, the mold material may come into contact with the coolant and react with the coolant. Furthermore, when the molding material comes into contact with the coolant, the molding material expands and may interfere with the rotor shaft. In addition, depending on the properties of the coolant, it may be absorbed by the mold material and fail to exhibit sufficient performance as a coolant.

SUMMARY OF THE INVENTION The present invention has been made in view of the problems described above, and an object of the present invention is to enable a winding core to be attached to a housing even when a fluid coolant is used.

The present invention provides, as a first means relating to a stator for solving the above problems, a stator comprising a housing and an annular winding core through which a shaft accommodated in the housing is inserted, A retaining ring is attached to the outer periphery of the annular winding core, the housing is formed with a fitting hole into which the winding core and the retaining ring are fitted, and the annular winding core is: A configuration is employed in which a preload is applied radially inward from the retaining ring.

As second means relating to the stator, in the first means, the coefficient of linear expansion of the winding core is equal to or less than the coefficient of linear expansion of the retaining ring, and the coefficient of linear expansion of the retaining ring is equal to or greater than the coefficient of linear expansion of the housing. A structure having a linear expansion coefficient or higher is adopted.

As a third means relating to the stator, in the first or second means, a configuration is adopted in which the retaining ring is made of the same material as the housing.

As a fourth means relating to the stator, in any one of the first to third means, the retainer ring has a smaller Young's modulus than the winding core.

As a fifth means relating to the stator, a configuration is adopted in which the retaining ring is fastened to the housing with bolts.

As a sixth means relating to the stator, a configuration is adopted in which the bolt holes formed in the retaining ring are formed at positions overlapping the poles of the winding core in the circumferential direction.

A configuration comprising the stator according to any one of claims 1 to 6 is adopted as a first means relating to the magnetic bearing.

As a first means relating to a rotary machine, a configuration comprising the stator according to any one of claims 1 to 6 and a rotor provided inside the stator is employed.

According to the invention, a retaining ring retains the winding core, and the retaining ring is secured to the housing. This eliminates the need for shrink-fitting the winding core to the housing, and the securing of the retaining ring to the housing allows the winding core to be secured to the housing at a precise position. Therefore, there is no need to mold the winding core, and the cooling medium is not affected by the molding material.

It is a sectional view showing the whole generator in this embodiment. 2 is a cross-sectional view along the axial direction of the magnetic bearing according to the embodiment; FIG. It is the top view seen from the axial direction of the magnetic bearing which concerns on this embodiment.

An embodiment of a rotating machine according to the present invention will be described below with reference to the drawings.

First, a motor 100 using the magnetic bearing 1 according to this embodiment will be described.
As shown in FIG. 1 , the motor 100 includes a substantially cylindrical housing 110 , a stator 120 arranged in a space inside the housing 110 , and a rotor shaft 130 arranged inside the stator 120 . , and a magnetic bearing 1 that is attached to the housing 110 and supports the rotor shaft 130 .
In the following description, the direction of rotation of rotor shaft 130 is defined as the circumferential direction, the direction along the rotation axis of rotor shaft 130 is defined as the axial direction, and the direction along the radial direction of rotor shaft 130 is defined as the radial direction.

Stator 120 includes winding core 121 and winding 122 . The winding core 121 is a substantially cylindrical member made of a magnetic material, and is formed by laminating a plurality of annular members. The winding 122 is wound around the winding core 121 and has an end electrically connected to an external power transmission cable.

The rotor shaft 130 is an elongated member, and turbine blades and the like are provided at the ends thereof. Further, a magnet (not shown) is installed in the rotor shaft 130 . The rotor shaft 130 is housed inside the stator 120 and is rotatably supported by the magnetic bearings 1 on both axial sides of the stator 120 with respect to the housing 110 .

The magnetic bearing 1 includes a magnetic bearing housing 2, a bearing winding core 3, a retaining ring 4, bearing windings 5, and bolts 6, as shown in FIGS. In addition, in this embodiment, the magnetic bearing 1 corresponds to the stator according to the present invention. Moreover, the bearing winding core 3 and the retaining ring 4 are made of a non-magnetic member.

The magnetic bearing housing 2 is a substantially annular member extending from the inner peripheral surface of the stator 120 to the inner peripheral side, provided on both sides in the axial direction with the stator 120 interposed therebetween. The magnetic bearing housing 2 has a concave portion on the surface facing the stator 120 that is concaved in the opposite direction to the facing stator 120 . A fitting hole 2a extending in the axial direction is formed in the concave portion, and the rotor shaft 130 is inserted therein. A retaining ring 4 is fitted and retained in the recess. That is, the retaining ring 4 faces the stator 120 in this embodiment. A magnetic bearing 1 is attached to the inner peripheral side of the retaining ring 4 . A plurality of bolt holes 2b (eight holes in this embodiment) are formed in these magnetic bearing housings 2, and bolts 6 are screwed to clamp a retaining ring 4, thereby attaching the retaining ring 4. As shown in FIG.

The bearing winding core 3 is a cylindrical metal member having an opening in the center. The bearing winding core 3 has eight teeth 3a (poles) projecting radially inward. Bearing windings 5 are wound around the teeth 3a. Moreover, the bearing winding core 3 is held in contact with the inner circumference of the retaining ring 4 without any gap by being shrink-fitted to the retaining ring 4 . A rotor shaft 130 is inserted into the center opening of the bearing winding core 3 .

As shown in FIG. 3, the retaining ring 4 of this embodiment is an annular member and does not have a cut surface that divides in the axial direction. In other words, the retaining ring 4 includes a portion that continues for one round in the circumferential direction. In addition, in this embodiment, it is made of the same material as the magnetic bearing housing 2 . The radial dimension of the retaining ring 4 is smaller than the radial dimension (thickness) of the bearing winding core 3 . The retaining ring 4 of this embodiment is set to be sufficiently smaller in volume than the bearing winding core 3 . Such a retaining ring 4 is provided on the outer circumference of the bearing winding core 3, and has a plurality of openings 4a (eight locations in this embodiment) formed at regular intervals in the circumferential direction. The opening 4a of this embodiment is formed to be larger than the diameter of the threaded portion of the bolt to be fitted (it is a so-called through hole). The openings 4a are arranged at positions overlapping the teeth 3a of the bearing winding core 3 in the radial direction during assembly. Further, the opening 4a is provided so as to overlap the bolt hole 2b of the magnetic bearing housing 2 in the axial direction, and the bolt 6 is inserted (that is, the bolt hole 2b is a so-called tapped hole in which a spiral groove is formed). ). The retaining ring 4 is thereby fastened to the magnetic bearing housing 2 .
Further, the retaining ring 4 of the present embodiment also has through holes formed at positions between the circumferentially adjacent openings 4a. The through hole extends over a wider range in the circumferential direction than the opening 4a. The retaining ring 4 is formed with a thin portion having a reduced thickness in the radial direction at the circumferential position where the through hole is located. On the other hand, the retaining ring 4 has a thick portion that is thicker in the radial direction than the thin portion between the through hole and the opening 4a. That is, the retaining ring 4 has a plurality of thin-walled portions and thick-walled portions alternately formed in the circumferential direction. By making the holding ring 4 thin, the magnitude of the preload applied to the bearing winding core 3 is adjusted.
Since the retaining ring 4 is made of the same material as the magnetic bearing housing 2 , the coefficient of linear expansion is the same as that of the bearing winding core 3 . Young's modulus is also small. In addition, the retaining ring 4 is set to have a smaller diameter than the outer diameter of the bearing winding core 3 before shrink-fitting. As a result, a state of contact with the bearing winding core 3 is achieved.

The bearing winding 5 is a thin metal wire wound around the teeth 3 a of the bearing winding core 3 . The bearing windings 5 are connected to a power source (not shown), and change the magnetic field when a current is passed through them. Thereby, the rotor shaft 130 arranged inside the bearing winding core 3 is held in a non-contact state.

The rotor shaft 130 of the motor 100 in this embodiment is rotated by the magnetic force from the stator 120 .

A method of mounting the magnetic bearing 1 included in the motor 100 will be described.
First, the bearing winding core 3 is inserted while the retaining ring 4 is heated. At this time, the retaining ring 4 expands by being heated and expands radially outward. In this state, when the bearing winding core 3 is fitted into the retaining ring 4, the volume of the retaining ring 4 is reduced due to the decrease in temperature, and the bearing winding core 3 receives a force (preload) radially inward. As a result, the adhesion with the bearing winding core 3 is improved. The retaining ring 4 to which the bearing winding core 3 is attached is fitted into the fitting hole 2a of the magnetic bearing housing 2 at room temperature, and is attached to the magnetic bearing housing 2 with bolts 6. As shown in FIG. At this time, the outer periphery of the retaining ring 4 is in contact with the magnetic bearing housing 2 .

According to the magnetic bearing 1 of this embodiment, the retaining ring 4 is attached to the magnetic bearing housing 2 after the bearing winding core 3 is shrink-fitted to the retaining ring 4 made of the same material as the magnetic bearing housing 2 . . As a result, even when a fluid coolant is used, the bearing winding core 3 can be attached to the magnetic bearing housing 2 while maintaining coaxiality with the rotor shaft 130 .

Furthermore, the linear expansion coefficient of the bearing winding core 3 is greater than that of the retaining ring 4 . Therefore, when the bearing winding core 3 is shrink-fitted to the retaining ring 4, the space between the retaining ring 4 and the bearing winding core 3 widens in the direction of creating a gap, but this is offset by the interference due to the shrink fitting. Therefore, it is possible to hold the bearing winding core 3 by the retaining ring 4 without deforming the shape of the bearing winding core 3 because the bearing winding core 3 is in close contact with the inner peripheral surface of the retaining ring 4 without a gap.

Further, since the retaining ring 4 and the magnetic bearing housing 2 are made of the same material, they have the same coefficient of linear expansion. Therefore, even if the temperature changes during operation of the motor 100, the volume is deformed with the same coefficient of linear expansion. A change in the relative positional relationship with the winding core 3 is suppressed, and coaxiality of the retaining ring 4 with the rotor shaft 130 can be ensured.

Further, according to this embodiment, the Young's modulus of the retaining ring 4 is smaller than that of the bearing winding core 3 . Therefore, the retaining ring 4 is softer than the bearing winding core 3 , and suppresses a significant decrease in the strength of the bearing winding core 3 when preloading the bearing winding core 3 .

Further, since the retaining ring 4 is provided with the opening 4a, it is not necessary to form an opening for the bolt in the bearing winding core 3. FIG.

Further, the openings 4a are provided at positions overlapping the teeth 3a of the bearing winding core 3 in the radial direction. As a result, a large decrease in the strength of the bearing winding core 3 integrated with the retaining ring 4 is suppressed.

Further, in this embodiment, the retaining ring 4 is fitted to the magnetic bearing housing 2 without molding with a molding material. Therefore, when replacing the bearing winding core 3, it is possible to remove the retaining ring 4 and the bearing winding core 3 from the magnetic bearing housing 2, facilitating maintenance and replacement.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the above embodiments. The various shapes, combinations, and the like of the constituent members shown in the above-described embodiment are merely examples, and can be variously changed based on design requirements and the like without departing from the gist of the present invention.

In the above embodiment, an example in which the present invention is applied to the magnetic bearing 1 has been described. However, the present invention is not limited to this, and may be applied to the stator 120 of the motor 100. In this case, the winding core 121 of the stator 120 is shrink-fitted to the retaining ring 4 and then fitted and fixed to the housing 110 . As a result, the stator 120 does not need to be shrink-fitted directly to the housing 110, and the position of the winding core 121 can be fixed to the housing 110 without using a molding material. Therefore, it is possible to secure coaxiality with the rotor shaft 130 (rotor) and install the winding core 121 at an accurate position.

Similarly, the present invention can also be applied to a generator having a stator. In this case, too, the retaining ring 4 is shrink-fitted to the winding core of the motor, and the retaining ring 4 is fitted and fixed to the housing. This eliminates the need to directly shrink-fit the winding core to the housing, and the position of the winding core can be fixed to the housing without using a molding material. Therefore, it is possible to ensure the coaxiality of the winding core with respect to the rotor and install it at an accurate position.

Further, in the above embodiment, the retaining ring 4 and the magnetic bearing housing 2 are made of the same material. However, the present invention is not limited to this, and the magnetic bearing housing 2 and the retaining ring 4 may be made of different materials having close coefficients of linear expansion. Note that the coefficient of linear expansion of the retaining ring 4 is preferably equal to or greater than the coefficient of linear expansion of the magnetic bearing housing 2 .

It is also possible to make the retaining ring 4 thinner in the axial direction than the bearing winding core 3 . In this case, when the bearing winding core 3 is shrink-fitted, excessive stress acting on the bearing winding core 3 and deformation of the bearing winding core 3 can be suppressed.

Further, when mounting the magnetic bearing 1, it is also possible to cool the bearing winding core 3 to reduce its volume and fit it into the retaining ring 4 at room temperature. In this case, the volume of the bearing winding core 3 expands as it reaches room temperature, and the retaining ring 4 and the bearing winding core 3 come into contact with each other, so that a compressive force acts on the bearing winding core 3 . .

In the above embodiment, the case where the bearing winding core 3 is inserted while the retaining ring 4 is heated has been described. may be inserted. In this case, the temperature difference between the bearing winding core 3 and the retaining ring 4 becomes smaller, so that the bearing winding core 3 expands and a preload is applied from the retaining ring 4 to the inner peripheral side.

1 Magnetic bearing 2 Magnetic bearing housing 2a Fitting hole 2b Bolt hole 3 Bearing winding core 3a Teeth (pole)
4 retaining ring 4a opening 5 bearing winding 6 bolt 100 motor 110 housing 120 stator 121 winding core 122 winding 130 rotor shaft

Claims (7)

A stator comprising a housing and an annular winding core through which a shaft housed in the housing is inserted,
A retaining ring attached to the outer periphery of the annular winding core,
The housing is formed with a fitting hole into which the winding core and the retaining ring are fitted,
A preload is applied to the annular winding core radially inward from the retaining ring ,
A stator, wherein the retaining ring has a Young's modulus smaller than that of the winding core . a coefficient of linear expansion of the winding core is equal to or less than a coefficient of linear expansion of the retaining ring;
2. The stator according to claim 1, wherein a coefficient of linear expansion of said retaining ring is greater than or equal to a coefficient of linear expansion of said housing. 3. A stator according to claim 1, wherein said retaining ring is made of the same material as said housing. The stator according to any one of claims 1 to 3 , wherein the retaining ring is fastened to the housing by bolts . 5. The stator according to claim 4 , wherein the bolt holes formed in the retaining ring are formed at positions overlapping the poles of the winding core in the circumferential direction . A magnetic bearing comprising the stator according to any one of claims 1 to 5. a stator according to any one of claims 1 to 5;
a rotor provided inside the stator;
A rotating machine comprising:

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