JP7387487B2 - air dynamic bearing motor - Google Patents

Description

Embodiments of the invention relate to air dynamic bearing motors.

Generally, air dynamic pressure bearing motors, which are motors using air dynamic pressure bearings, are known. For example, an axial fan that includes an air dynamic pressure bearing motor and has improved durability in consideration of thermal expansion has been disclosed (see, for example, Patent Document 1).

JP2019-60280A

However, the bearing sleeve that constitutes the air dynamic pressure bearing may be deformed when it comes into contact with the winding core due to a difference in thermal expansion coefficient. Such deformation of the bearing sleeve reduces the performance of the air dynamic bearing.

An object of the embodiments of the present invention is to provide an air dynamic bearing motor including an air dynamic bearing that takes thermal expansion into consideration.

According to an embodiment of the present invention, it is possible to provide an air dynamic pressure bearing motor including an air dynamic pressure bearing that takes thermal expansion into consideration.

An air dynamic pressure bearing motor according to an embodiment of the present invention includes a shaft, a radial bearing by the air dynamic pressure of the shaft, a cylindrical bearing sleeve with a groove formed on the side surface, and a cylindrical bearing sleeve formed with a groove on the side surface. a core provided adjacent to a side surface and forming a stator; and an adhesive applied to the groove to adhere the bearing sleeve and the core, the groove being disposed between the bearing sleeve and the core. A first gap is formed by a portion to which the adhesive is not applied, and a second gap is formed between the core and the side surface of the bearing sleeve that is not the groove, and the coaxial precision of the core is achieved . It is formed adjacent to the gap No. 1 .

1 is a sectional view showing the configuration of a motor according to a first embodiment of the present invention. FIG. 2 is a perspective view showing an example of the shape of the core of the motor according to the first embodiment. FIG. 3 is a state diagram showing a state before the winding core of the motor according to the first embodiment is adhered to the side surface of the bearing sleeve. FIG. 3 is a state diagram showing a state in which the winding core of the motor according to the first embodiment is being adhered to the side surface of the bearing sleeve. FIG. 3 is a graph diagram showing the effect of suppressing deformation of the bearing sleeve depending on the width of the gap between the bonded portions according to the first embodiment. FIG. 3 is a graph diagram showing the effect of suppressing deformation of the bearing sleeve due to the hardness of the adhesive according to the first embodiment. FIG. 2 is a sectional view showing the configuration of a motor according to a second embodiment of the present invention. FIG. 3 is a sectional view showing the configuration of a motor according to a third embodiment of the present invention.

(First embodiment)
FIG. 1 is a sectional view showing the configuration of a motor 10 according to a first embodiment of the present invention. In the drawings, the same parts are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.
The motor 10 is an air dynamic bearing motor that employs an air dynamic bearing. For example, motor 10 is used in an axial fan. Specifically, an axial fan is configured by providing blades such as an impeller so as to be rotated by the drive of the motor 10. Note that the motor 10 is not limited to an axial fan, and may be provided in any device.

The motor 10 includes a shaft 1, a bearing sleeve 2, a thrust bearing 3, a hub 4, a winding core 5, and an adhesive 6.

The shaft 1 is a rotation axis of a rotary body, and has a cylindrical shape whose longitudinal direction is the rotation axis direction. A shaft 1 is rotatably inserted into a bearing sleeve 2.

The bearing sleeve 2 is provided to maintain the shaft 1 inserted therein at the center of rotation of the motor 10. The bearing sleeve 2 has a cylindrical shape whose longitudinal direction is in the direction of the rotation axis, and a groove 21 is formed on the side surface of the cylinder. For example, the material of the bearing sleeve 2 is stainless steel (SUS) or brass.

The bearing sleeve 2 is an air dynamic pressure bearing for suppressing the movement of the shaft 1 in the radial direction. When the shaft 1 rotates, the air dynamic pressure around the shaft 1 keeps the gap between the shaft 1 and the bearing sleeve 2 constant, thereby suppressing fluctuations in the shaft 1. Therefore, when the shaft 1 rotates, the shaft 1 and the bearing sleeve 2 are kept out of contact.

The groove 21 is a place where the adhesive 6 for bonding the winding core 5 is applied. The groove 21 is formed around the circumference of the side surface of the bearing sleeve 2 . The groove 21 may be one groove formed over the entire circumference of the side surface of the bearing sleeve 2, or may be a plurality of grooves formed at each location where the winding core 5 is bonded. The groove 21 is formed from slightly below the upper end of the winding core 5 to the upper end of the hub 4 in the direction of the rotation axis.

The thrust bearing portion 3 is a portion that constitutes a bearing that suppresses fluctuations in the thrust direction of the shaft 1. The thrust bearing section 3 is composed of a fixed magnet 31 and a rotating magnet 32. The fixed magnet 31 is provided on the stator side (for example, the hub 4). The rotating magnet 32 is provided so as to cover the circumferential side surface of the convex portion 11 protruding from the center of rotation of the shaft 1 . Due to the attractive force between the fixed magnet 31 and the rotating magnet 32, fluctuations in the thrust direction of the shaft 1 are suppressed. Although the thrust bearing section 3 is of a non-contact type in which the shaft 1 is kept in a non-contact manner like a permanent magnet bearing, it may be of a contact type. Moreover, the thrust bearing part 3 may not be provided.

The hub 4 is located on the bottom surface of the motor 10 and is provided to support the lower part of the bearing sleeve 2. The hub 4 has a generally low cylindrical shape. The lower part of the bearing sleeve 2 is press-fitted into the upper part of the hub 4. Note that the hub 4 may have any configuration as long as it supports the bearing sleeve 2, and may be composed of any number of members. In addition, even if the hub 4 is press-fitted into the bearing sleeve 2 and assembled, the hub 4 is designed to be made of a material with the same or similar coefficient of linear expansion as the bearing sleeve 2, so that the influence of deformation due to temperature changes is reduced. It is desirable that

The winding core 5 constitutes the stator of the motor 10, and is a member in which a coil is wound around the core (iron core). The winding core 5 is arranged so that the side surface of the bearing sleeve 2 fits into the central hole. As a result, the inner peripheral surface of the winding core 5 is adjacent to the circumference of the side surface of the bearing sleeve 2. On the side surface of the winding core 5, protruding portions that serve as the core are provided in the radial direction at equal intervals on the circumference. A coil is wound around each of these protruding parts. By bringing the lower end surface of the inner peripheral side of the winding core 5 into contact with the upper end of the hub 4, the perpendicularity of the winding core 5 is achieved. Note that any number of winding cores 5 may be provided. Further, the core 51 of the winding core 5 may be formed by stacking thin plates in the direction of the rotation axis to suppress eddy current loss. For example, the material of the winding core 5 is a silicon steel plate.

An example of the shape of the core 51 constituting the winding core 5 will be described with reference to FIG. 2.
The core 51 includes a cylindrical portion 511 and a plurality of cores 512 . The cylindrical portion 511 is formed into a cylindrical shape so as to fit around the outer periphery of the bearing sleeve 2 . The winding core 512 is formed to protrude from the side surface of the cylindrical portion 511 at equal intervals on the circumference. Although FIG. 2 shows the core 51 in which nine winding cores 512 are formed, any number may be provided. The winding core 5 is formed by winding a coil around each winding core 512.

The adhesive 6 is an adhesive for bonding the bearing sleeve 2 and the winding core 5, and is used to prevent external force caused by deformation of the winding core 5 due to temperature changes from being transmitted to the side surface of the bearing sleeve 2. It has the function of a cushioning material. The adhesive 6 is made of a material that has a predetermined elasticity even after hardening in order to function as a buffer material. The hardness of the adhesive 6 is desirably A30 or more and A80 or less in terms of durometer hardness.

Between the side surface of the bearing sleeve 2 and the winding core 5, a pilot part P1, a non-bonded part P2, and a bonded part P3 are formed, and between the side surface of the bearing sleeve 2 and the inner circumferential surface of the hub 4, , a press-fit portion P4 is formed.

The pilot part P1 is a part for achieving coaxial precision of the winding core 5. For example, the gap between the pilot part P1 is about 0.02 mm, and the vertical length of the pilot part P1 is preferably 0.5 mm or more.

The non-adhesive portion P2 is a groove 21 on the side surface of the bearing sleeve 2, and is a portion to which the adhesive 6 is not applied. The non-adhesive part P2 is a gap for preventing the adhesive 6 from flowing into the spigot part P1. The length of the non-bonded portion P2 in the vertical direction is preferably 0.5 mm or more. Any number of non-bonded parts P2 may be provided anywhere as long as at least one non-bonded part P2 is provided between the spigot part P1 and the bonded part P3.

The adhesive portion P3 is a groove 21 on the side surface of the bearing sleeve 2, and is a portion where the adhesive 6 is applied. The adhesive portion P3 is a buffer portion that prevents external force caused by deformation of the winding core 5 due to temperature change from being transmitted to the side surface of the bearing sleeve 2 due to the elasticity of the adhesive 6. The gap between the adhesive portions P3 is desirably 0.03 mm or more and 0.2 mm or less. Any number of adhesive parts P3 may be provided.

The press-fitting portion P4 is a portion where the bearing sleeve 2 is press-fitted into the hub 4, so that the outer circumferential surface of the bearing sleeve 2 and the inner circumferential surface of the hub 4 are in close contact with each other. Thereby, the bearing sleeve 2 is fixed to the hub 4.

Here, the hub 4 has a high degree of freedom in material and shape. For this reason, even if the hub 4 is press-fitted into the bearing sleeve 2 and assembled, the hub 4 is designed to be made of a material with the same or similar linear expansion coefficient as the bearing sleeve 2, so that the influence of deformation due to temperature changes is reduced. is done.

A method of bonding the winding core 5 to the side surface of the bearing sleeve 2 using the adhesive 6 will be described with reference to FIGS. 3 and 4.
FIG. 3 is a state diagram showing a state before the winding core 5 is bonded to the side surface of the bearing sleeve 2. FIG. 4 is a state diagram showing a state in which the winding core 5 is being adhered to the side surface of the bearing sleeve 2.

First, as shown in FIG. 3, the adhesive 6 is applied to the groove 21 while the bearing sleeve 2 is press-fitted into the hub 4. The height of the swell of the applied adhesive 6 is made larger than the gap between the adhesive portions P3 (or the depth of the grooves 21). That is, the highest part of the adhesive 6 is made to exceed the height of the side surface of the bearing sleeve 2 where the groove 21 is not formed.

Next, as shown in FIG. 4, the winding core 5 is attached so as to cover the bearing sleeve 2 from above. As a result, the adhesive 6 is stretched over the groove 21 at the lower end of the winding core 5, so that the adhesive 6 is filled so as to fill the gap in the adhesive portion P3. Moreover, since the adhesive 6 is stretched downward, the adhesive 6 does not enter into the gap of the spigot part P1.

With reference to FIGS. 5 and 6, verification results of changes in the inner diameter of the bearing sleeve 2 due to temperature changes will be described.
FIG. 5 is a graph diagram showing the effect of suppressing deformation of the bearing sleeve 2 depending on the width of the gap of the adhesive portion P3. A plus sign indicates that the inner diameter is wider, and a minus sign indicates that the inner diameter is tighter.

The verification conditions were as follows: the material of the winding core 5 was a silicon steel plate, the inner diameter of the bearing sleeve 2 was 8 mm, the reference temperature was 23°C, and the confirmation temperature after changing the inner diameter was 80 to 85°C.

Sample S1 has a gap of 0.02 mm between adhesive parts P3, sample S2 has a gap of 0.05 mm between adhesive parts P3, and sample S3 has a gap of 0.1 mm between adhesive parts P3.

As shown in FIG. 5, it can be seen that the larger the gap between the adhesive portions P3 is, the more the change in the inner diameter of the bearing sleeve 2 is suppressed.

FIG. 6 is a graph showing the effect of suppressing deformation of the bearing sleeve 2 due to the hardness of the adhesive 6. As shown in FIG. A plus sign indicates that the inner diameter is wider, and a minus sign indicates that the inner diameter is tighter.

The verification conditions are as follows: The material of the winding core 5 is a silicon steel plate, the inner diameter of the bearing sleeve 2 is 9 mm in diameter, the gap between the adhesive part P3 is 0.1 mm, the reference temperature is 23°C, and the confirmation temperature after changing the inner diameter is 85°C. went.

In sample S4, the hardness of the adhesive 6 is A90, in sample S5, the hardness of the adhesive 6 is A70, and in sample S6, the hardness of the adhesive 6 is A30. Note that the hardness is expressed in durometer hardness.

As shown in FIG. 6, it can be seen that the lower the hardness of the adhesive 6, the more the change in the inner diameter of the bearing sleeve 2 is suppressed.

According to this embodiment, grooves 21 for applying the adhesive 6 are provided on the side surface of the bearing sleeve 2, and the winding core 5 is bonded to the side surface of the bearing sleeve 2 with the adhesive 6. Deformation of the bearing sleeve 2 can be suppressed. Thereby, even if the winding core 5 becomes high in temperature while the motor 10 is being driven, the performance of the air dynamic pressure bearing can be prevented from deteriorating.

By providing the spigot portion P1 between the inner circumferential upper end portion of the winding core 5 and the portion above the groove 21 of the bearing sleeve 2, the coaxial precision of the winding core 5 can be achieved. Further, by manufacturing the motor 10 as shown in FIGS. 3 and 4, it is possible to prevent the spigot part P1 from being filled with the adhesive 6. Note that the spigot part P1 may be provided between the lower end portion of the inner peripheral side of the winding core 5 and the portion of the bearing sleeve 2 located below the groove 21.

Here, the hub 4 has a high degree of freedom in material and shape. Therefore, the material or shape of the hub 4 can be determined so as to suppress the influence of deformation due to temperature changes, such as by using a material with the same or similar coefficient of linear expansion as the bearing sleeve 2. On the other hand, since the core 51 plays the role of a rotor constituting the motor, there are restrictions on the material and shape. Therefore, the core 51 cannot take the same measures as the hub 4. Even with the core 51 having such restrictions, by configuring it as in this embodiment, it can be fixed to the bearing sleeve 2 so as to suppress the influence of deformation due to temperature changes.

(Second embodiment)
FIG. 7 is a sectional view showing the configuration of a motor 10A according to a second embodiment of the present invention.
The motor 10A is the motor 10 according to the first embodiment shown in FIG. 1 in which the bearing sleeve 2 is replaced with a bearing sleeve 2A. The bearing sleeve 2A has a groove 21A formed by extending the groove 21 downward (towards the hub 4) in the bearing sleeve 2 according to the first embodiment. That is, the groove 21A is formed so as to protrude from the lower side of the winding core 5. Other points are similar to the first embodiment.

When the bearing sleeve 2A is press-fitted into the hub 4, the lower part of the groove 21A enters the hub 4, and a non-bonded part P5 is formed between the side surface of the bearing sleeve 2A and the inner peripheral surface of the hub 4. be done. A press-fitting part P4 is located below the non-adhesive part P5. Other points are similar to the first embodiment.

Like the non-bonded part P2 located at the upper part of the winding core 5, the non-bonded part P5 serves as a buffer to prevent external force caused by deformation of the winding core 5 due to temperature change from being transmitted to the side surface of the bearing sleeve 2. become a part. Part or all of the non-adhesive portion P5 may be filled with the adhesive 6. Even in this case, since the side surface of the hub 4 is thinner than the winding core 5, it is difficult to generate an external force that would deform the bearing sleeve 2A.

According to the present embodiment, by forming the groove 21A on the side surface of the bearing sleeve 2A that extends to the portion inserted into the inside of the hub 4, in addition to the effects of the first embodiment, the temperature is lower than that of the first embodiment. Deformation of the bearing sleeve 2 due to changes can be suppressed.

(Third embodiment)
FIG. 8 is a sectional view showing the configuration of a motor 10B according to a third embodiment of the present invention.
The motor 10B is obtained by replacing the bearing sleeve 2 with a bearing sleeve 2B in the motor 10 according to the first embodiment shown in FIG. The bearing sleeve 2B has grooves 21B formed in the bearing sleeve 2 according to the first embodiment such that the lowest part of the grooves 21 is located above the lower end of the winding core 5. That is, the groove 21B is formed to be shorter than the length of the winding core 5 in the rotation axis direction. Other points are similar to the first embodiment.

When the winding core 5 is attached to the bearing sleeve 2B, a pilot part P1a and a non-bonded part P2a are formed in the upper part of the winding core 5, and a pilot part P1b and a non-bonded part P2a are formed in the lower part of the winding core 5. P2b is formed. Other points are similar to the first embodiment.

The spigot parts P1a and P1b are the same as the spigot part P1 according to the first embodiment except for the positions where they are provided. The non-adhesive parts P2a and P2b are the same as the non-adhesive part P2 according to the first embodiment except for the positions where they are provided.

According to this embodiment, the two spigot parts P1a and P1b can be provided by forming the groove 21B on the side surface of the bearing sleeve 2B, which is shorter than the length of the winding core 5 in the rotation axis direction. Thereby, in addition to the effects of the first embodiment, coaxial precision or perpendicular precision of the winding core 5 can be more easily achieved than in the first embodiment.

Note that the present invention is not limited to the embodiments described above, and constituent elements may be deleted, added, or changed. Even if such embodiments are directly different from the embodiments described above, those having the same meaning as the present invention are treated as embodiments of the present invention, and the explanation thereof will be omitted.

DESCRIPTION OF SYMBOLS 1... Shaft, 2... Bearing sleeve, 3... Thrust bearing part, 4... Hub, 5... Winding core, 6... Adhesive, 10... Motor, 21... Groove, P1... Pilot part, P2... Non-adhesive part, P3 ...adhesive part, P4...press-fit part.

Claims (5)

shaft and
a cylindrical bearing sleeve that constitutes a radial bearing by air dynamic pressure of the shaft and has a groove formed on a side surface;
a core that is provided adjacent to a side surface of the bearing sleeve and constitutes a stator;
an adhesive applied to the groove to adhere the bearing sleeve and the core;
A first gap is formed between the bearing sleeve and the core by a portion of the groove to which the adhesive is not applied;
An air dynamic pressure bearing, characterized in that a second gap, in which coaxial accuracy of the core is achieved , is formed adjacent to the first gap between the non-groove side surface of the bearing sleeve and the core. motor. The air dynamic pressure bearing motor according to claim 1, wherein the adhesive has a durometer hardness of A80 or less. The first gap is formed at an upper part and a lower part of the core,
The air dynamic pressure bearing motor according to claim 1, wherein the second gap is formed between the upper and lower parts of the core. comprising a support member that supports the bearing sleeve in a state where the lower part of the bearing sleeve is inserted;
2. The air dynamic pressure bearing motor according to claim 1, wherein the core has perpendicularity accuracy due to contact with the upper end of the support member. comprising a support member that supports the bearing sleeve in a state where the lower part of the bearing sleeve is inserted;
The air dynamic pressure bearing motor according to claim 1, wherein a third gap is formed between the bearing sleeve and the support member by the groove.

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