Retaining structure for ball bearing and fan motor

Abstract

The present disclosure provides a retaining structure of a ball bearing and a fan motor capable of suppressing deformation of the ball bearing that can occur when the bearing retainer is press-fitted. The retaining structure of a ball bearing (2) rotatably supported on a shaft includes a bearing retainer (4) having a cylindrical retainer portion into which the ball bearing is fitted from one side in the axial direction of the shaft and a positioning portion provided on the other side in the axial direction of the retainer portion and abutting against the ball bearing from the other side, and a mounting plate having a cylindrical mounting portion into which a portion of the retainer portion is press-fitted from the other side. An adhesive surface is provided on the inner surface of the retainer portion, which is adhered to the outer peripheral surface of the ball bearing by an adhesive. An avoidance surface is provided on the inner surface of the retainer portion, which has a larger inner diameter than the inner diameter of the adhesive surface on the one side thereof. A step surface is provided on the inner surface of the retainer portion, which connects the adhesive surface and the avoidance surface. In a state where the ball bearing is fitted and mounted to the bearing retainer, the axial position of the step surface is a position overlapping the ball bearing.

Description

Technical Field

[0001] The present invention relates to a retaining structure for supporting a shaft as a rotatable ball bearing and a fan motor using the retaining structure. Background Technology

[0002] Conventionally, ball bearings that support the shaft for rotation are held in the outer contour and base (base) of devices such as motors and reducers that have a shaft as a rotating axis. For example, Patent Document 1 discloses a structure in which a ball bearing is held in a bearing cage that is pressed into and fixed to the base of a spindle motor in a fitted manner.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 8-228453 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, in the ball bearing retaining structure disclosed in Patent Document 1, because the bearing cage is pressed and fixed to the base, the pressed-in portion deforms radially inward, narrowing the space used to retain the ball bearing. Consequently, when the ball bearing is fitted and mounted in the bearing cage, the outer ring of the ball bearing is compressed, and the space for the balls to pass through inside the ball bearing deforms. This deformation of the ball passage space leads to uneven ball velocity during shaft rotation, which in turn relates to the generation of abnormal noise.

[0008] This application addresses this problem, and one of its objectives is to provide a ball bearing retaining structure capable of suppressing deformation of the ball bearing that may occur due to the bearing cage being pressed in and fixed, and a fan motor employing this retaining structure. It should be noted that, not limited to this objective, another objective of this application is to achieve the effects that the structures shown in the detailed embodiments described below cannot be obtained through existing technology.

[0009] Solution for solving the problem

[0010] The ball bearing retaining structure and fan motor disclosed herein can be implemented using the solutions or application examples disclosed below, solving at least a portion of the aforementioned problems.

[0011] (1) The ball bearing retaining structure disclosed herein is a retaining structure for a ball bearing that supports a shaft for rotation, comprising: a bearing cage having a cylindrical cage portion for the ball bearing to be fitted into one side of the shaft along the axial direction, and a positioning portion disposed on the other side of the cage portion along the axial direction and abutting against the ball bearing from the other side; and a mounting plate having a cylindrical mounting portion for a portion of the cage portion to be pressed into from the other side. The inner surface of the cage portion is provided with: an adhesive surface, which is bonded to the outer peripheral surface of the ball bearing by an adhesive; a clearance surface, which has an inner diameter larger than the inner diameter of the adhesive surface at a position closer to the adhesive surface; and a stepped surface, which connects the adhesive surface and the clearance surface, wherein, when the ball bearing is fitted and mounted in the bearing cage, the axial position of the stepped surface overlaps with the ball bearing.

[0012] (2) Preferably, when the bearing cage and the mounting plate are combined, the axial position of the end face of the other side of the mounting portion overlaps with the ball bearing. In this case, it is preferable that the axial position of the stepped surface overlaps with both the mounting portion and the ball bearing.

[0013] (3) Preferably, the inner diameter of the clearance surface is larger than the value obtained by adding the interference fit of the cage portion to the outer diameter of the ball bearing.

[0014] (4) Preferably, the outer diameter of the ball bearing is 12 mm, and the viscosity of the adhesive is 2000 mPa•s or more and 3000 mPa•s or less. In this case, it is preferable that the difference between the outer diameter of the ball bearing and the inner diameter of the clearance surface is 150 μm or more and 255 μm or less.

[0015] In addition, the fan motor disclosed herein includes a motor section having: a rotor that rotates integrally with the fan section via a shaft; and a stator that is disposed opposite to the rotor, wherein the ball bearing holding structure described in any one of (1) to (4) above is applied to the ball bearing that supports the shaft as a rotatable bearing.

[0016] Invention Effects

[0017] According to the ball bearing retaining structure and fan motor disclosed herein, deformation of the ball bearing that may occur during the pressing and fixing of the bearing cage can be suppressed. Attached Figure Description

[0018] Figure 1 This is an axial cross-sectional view showing the retaining structure of the ball bearing according to an embodiment.

[0019] Figure 2 yes Figure 1An enlarged view of the X part.

[0020] Figure 3 It is shown Figure 1 The bearing cage of the ball bearing, in its state before being pressed into the mounting plate, is a part of the bearing cage. Figure 2 An axial sectional view of the portion shown.

[0021] Figure 4 This is an axial cross-sectional view of the motor section of a fan motor that utilizes a ball bearing retaining structure according to an embodiment.

[0022] Explanation of reference numerals in the attached figures:

[0023] 1 axis

[0024] 2. Bearings (First bearing, ball bearing)

[0025] 2f outer perimeter

[0026] 3 Mounting Plate

[0027] 4. Bearing cage

[0028] 10. Electric Motor Department

[0029] 13 Rotors

[0030] 14 Stator

[0031] 31 Installation Department

[0032] 31f The other end face (the end face on the other side of the mounting part)

[0033] 40. Cage section

[0034] 41 Press-in section (part of the cage section)

[0035] 42 Adhesive surface

[0036] 43. Avoidance surface

[0037] 44 Stepped surface

[0038] 45 Positioning Section

[0039] D1 bearing outer diameter

[0040] D2 Inner diameter of the bonding surface

[0041] D3 is the inner diameter of the clearance surface. Detailed Implementation

[0042] The retaining structure of the ball bearing and the fan motor as embodiments will be described with reference to the accompanying drawings. The embodiments shown below are merely illustrative and are not intended to exclude various modifications and applications of techniques not described in these embodiments. The structures of this embodiment can be implemented with various modifications without departing from its spirit. Furthermore, selections can be made as needed, or appropriate combinations can be made.

[0043] [1. Cage Structure of Ball Bearings]

[0044] Reference Figures 1-3 The retaining structure (hereinafter also referred to as "retaining structure") of the ball bearing in this embodiment will be described. Figure 1 As shown, the retaining structure of this embodiment is a structure that retains the ball bearing 2 (hereinafter also simply referred to as "bearing 2") that supports the shaft 1 so that it can rotate freely. Here, an example is shown for one end side of the shaft 1 ( Figure 1 The bearing 2 is supported at its lower end 1a. The shaft 1 is fixedly supported by the bearing 2 by pressing its end 1a into the inner ring of the bearing 2. It should be noted that the size of the bearing 2 is not particularly limited, and a relatively small size such as an outer diameter of 12 mm can be used.

[0045] Hereinafter, the direction in which the centerline C of shaft 1 extends is called the axial direction, the direction orthogonal to the centerline C is called the radial direction, and the direction surrounding the centerline C is called the circumferential direction. In the axial direction, one end of shaft 1 (having end 1a) Figure 1 The side below the center line (C) is called "one side," and the opposite side (the top side in the diagram) is called "the other side." Additionally, radially, the side near the center line C is called "inner side," and the opposite side (the side furthest from the center line C) is called "outer side."

[0046] The retaining structure includes a mounting plate 3 and a bearing cage 4. The mounting plate 3 is a component that is fixed to the outer contour and base (platform) of the device (not shown) for which the shaft 1 is mounted. Examples of such devices include motors and reducers. It should be noted that the mounting plate 3 may not be separate from the outer contour and base of the device, but may be constructed as part of the outer contour and base. The bearing cage 4 is a component that holds the bearing 2 by bonding the bearing 2 to its inner side, and is pressed and fixed to the mounting plate 3. The bearing cage 4 and the bearing 2 are bonded together with adhesive. Hereinafter, unless otherwise specified, the descriptions of components 3 and 4 are based on... Figure 1 The description will focus on the state shown, where the bearing 2 of the support shaft 1 is fitted and installed in the bearing cage 4, and the bearing cage 4 is pressed and fixed to the mounting plate 3.

[0047] As described above, the mounting plate 3 is a component fixed to the outer contour and base of the device on which the shaft 1 is mounted. The mounting plate 3 is formed, for example, from ferrous steel sheet such as galvanized steel sheet. However, the mounting plate 3 is not limited to the above-mentioned material as long as it is formed from a material with higher strength than the material forming the bearing cage 4. The mounting plate 3 is provided with a cylindrical mounting portion 31 into which the bearing cage 4 can be pressed. The mounting plate 3 of this embodiment includes the mounting portion 31 and a base portion 32 connected to one side of the mounting portion 31. The base portion 32 is a plate-shaped portion extending outward from one side of the mounting portion 31 and is mounted to the outer contour and base of the device.

[0048] The mounting portion 31 is a cylindrical section extending axially. Here, an example is shown where the inner and outer circumferential surfaces each have the same diameter in the axial direction. The centerline of the mounting portion 31 coincides with the centerline C of the shaft 1. One end 46 of the bearing cage 4 (hereinafter referred to as "one end 46") is pressed into and fixed to the mounting portion 31 from the other side. Therefore, in the state before the mounting plate 3 is assembled with the bearing cage 4, the inner diameter of the mounting portion 31 is set to be smaller than the outer diameter of the one end 46 of the bearing cage 4.

[0049] The axial position of the end face 31f on the other side of the mounting portion 31 (hereinafter referred to as "the other end face 31f") is set to overlap with the ball bearing 2 in the axial direction. That is, the mounting portion 31 extends axially to one side from the position where it overlaps with the ball bearing 2 in the axial direction. In this embodiment, as Figure 2 As shown, the other end face 31f is positioned on the other side of the axial center position E of the bearing 2 and overlaps with the bearing 2 axially (a position that does not protrude from the other end face of the bearing 2 to the other side). The mounting portion 31 extends axially from the position of the other end face 31f to a position, for example, approximately the same as the end face of one end 46 of the bearing cage 4. However, the axial position and length of the mounting portion 31 are not limited thereto, as long as the bearing cage 4 can at least be pressed and fixed to the mounting portion 31.

[0050] As described above, the bearing cage 4 is a component that is pressed and fixed to the mounting plate 3 and for the bearing 2 to be fitted and mounted inside. In order to assemble the bearing 2 with good precision inside the bearing cage 4, the bearing cage 4 is formed of an aluminum-based material such as hard aluminum. However, the material forming the bearing cage 4 is not limited to this; for example, it can also be brass.

[0051] The bearing cage 4 includes a cylindrical cage portion 40 for housing the bearing 2 and a positioning portion 45 defining the axial position of the bearing 2. A portion (one side portion) of the cage portion 40 is a press-in portion 41 that is press-fitted into the mounting portion 31, and this press-in portion 41 includes one side end 46 of the bearing cage 4 described above. Here, a cylindrical cage portion 40 is shown that extends axially in accordance with the shape of the mounting portion 31 and has a centerline that coincides with the centerline C of the shaft 1. The outer peripheral surface of the cage portion 40 has the same outer diameter in the axial direction. When the press-in portion 41 including one side end 46 is press-fitted into the mounting portion 31, the outer peripheral surface of the press-in portion 41 is pressed against the inner peripheral surface of the mounting portion 31.

[0052] The positioning part 45 is provided as a portion that protrudes inward from the inner circumference of the cage portion 40 on the other side. The bearing 2 is embedded in the cage portion 40 from one side and abuts against the positioning part 45, thereby restricting the displacement of the bearing 2 to the other side and thus determining its axial position.

[0053] Before the mounting plate 3 is assembled with the bearing cage 4, the outer diameter of one end 46 of the bearing cage 4, i.e., the outer diameter of the cage portion 40, is set to be larger than the inner diameter of the mounting portion 31 in a manner that satisfies the set interference fit range. For example, when the interference fit (press-in interference fit) of the cage portion 40 relative to the mounting portion 31 is set to be between 35 μm and 45 μm, the outer diameter of the cage portion 40 is set to be larger than the inner diameter of the mounting portion 31 in a manner that satisfies this range. It should be noted that the press-in interference fit is not limited to the above range. However, from the viewpoint of preventing the bearing cage 4 from detaching from the mounting plate 3, it is preferable to set the press-in interference fit within a range that can prevent such detachment.

[0054] Here, when the bearing cage 4 is pressed into the mounting plate 3, deformation occurs on the inner side of the cage portion 40 corresponding to the interference fit for pressing. Due to this deformation, the following problem arises: when the space inside the cage portion 40 narrows and the outer ring of the bearing 2 is compressed, the ball passage space inside the bearing 2 deforms. This deformation of the ball passage space leads to uneven ball speed during shaft 1 rotation, resulting in abnormal noise. It should be noted that the more firmly the bearing cage 4 is fixed relative to the mounting plate 3, in other words, the larger the interference fit for pressing, the greater the deformation of the bearing cage 4.

[0055] Therefore, in this embodiment, the inner surface of the retainer portion 40 is provided with a structure to suppress the pressure on the outer ring of the bearing 2 caused by pressing. Specifically, as... Figure 2 and Figure 3As shown, the inner circumferential surface of the retainer portion 40 includes: an adhesive surface 42, which is bonded to the bearing 2 by an adhesive; and a clearance surface 43, which has an inner diameter larger than the inner diameter of the adhesive surface 42 at a point closer to the adhesive surface 42. Furthermore, a stepped surface 44 is provided on the inner surface of the retainer portion 40 to connect the adhesive surface 42 and the clearance surface 43. In other words, the inner surface of the retainer portion 40 has a stepped shape with two inner circumferential surfaces 42 and 43 having different inner diameters.

[0056] The boundary position of the bonding surface 42 and the clearance surface 43, i.e., the axial position of the stepped surface 44, is set to overlap with the bearing 2. In this embodiment, the axial position of the stepped surface 44 is set to overlap with both the bearing 2 and the mounting portion 31. For the deformation of the cage portion 40 caused by pressing, the portion where the outer peripheral surface of the cage portion 40 is pressed (closed) with the inner peripheral surface of the mounting portion 31, i.e., the portion closer to one side from the axial position of the other end face 31f of the mounting portion 31, experiences greater deformation. Therefore, by setting the axial position of the stepped surface 44 to overlap with both the bearing 2 and the mounting portion 31, in other words, by providing a clearance surface 43 in the range from this position to one side, the compression of the outer ring of the bearing 2 caused by the deformation of the cage portion 40 can be suppressed.

[0057] Here, a stepped surface 44 is shown provided on one side of the axial center position E of the bearing 2. By providing the stepped surface 44 on one side of the axial center position E of the bearing 2, the area of ​​the bonding surface 42 can be ensured to be larger. Therefore, the bonding of the bearing 2 to the cage portion 40 can be performed more firmly.

[0058] It should be noted that the axial position of the stepped surface 44 is not limited to the position described above. For example, when the stepped surface 44 is positioned closer to the other side than the axial center position E of the bearing 2, it is more effective to suppress the compression of the outer ring of the bearing 2 at the axial center position E. Therefore, it is more effective to suppress the deformation of the passage space of the ball disposed inside the bearing 2. When designing the cage portion 40, the axial position of the stepped surface 44 can be determined, for example, by experimenting or simulating where and to what extent the cage portion 40 deforms from the pressure, and based on the results. It should be noted that in this embodiment, the stepped surface 44 is provided as a plane extending radially, but the stepped surface 44 may also be inclined relative to the radial direction, or it may not be a plane.

[0059] When the bearing 2 is fitted and mounted on the bearing cage 4, adhesive is applied to the stepped surface 44 (or also includes the periphery of the stepped surface 44). During the fitting of the bearing 2, the adhesive spreads through friction between the outer peripheral surface 2f of the bearing 2 and the adhesive surface 42, forming a defined adhesive film. In other words, the stepped surface 44 of this embodiment not only connects the adhesive surface 42 and the clearance surface 43, but also functions as a mark for applying adhesive. The inner diameter D2 of the adhesive surface 42 (refer to...) Figure 3 The degree to which an adhesive film of appropriate thickness can be formed between the adhesive surface 42 and the outer peripheral surface 2f of the bearing 2 is set to be larger than the outer diameter D1 of the bearing 2.

[0060] The appropriate thickness varies depending on factors such as the adhesive material (viscosity) and the outer diameter D1 of the bearing 2. For example, when using a relatively small bearing 2 with an outer diameter of 12 mm, the viscosity of the adhesive used is the viscosity recommended for bonding the bearing 2 to the bearing cage 4 (e.g., in the range of 2000 mPa•s or more and 3000 mPa•s or less at room temperature (around 25°C)). In this case, it is preferable that the difference (adhesion amount) between the outer diameter D1 of the bearing 2 and the inner diameter D2 of the bonding surface 42 is in the range of 1 μm or more and 16 μm or less. Therefore, the inner diameter D2 of the bonding surface 42 is set to be larger than the outer diameter D1 of the bearing 2 in a way that satisfies the above-mentioned adhesion amount range (1 μm to 16 μm).

[0061] The inner diameter D3 of the clearance surface 43 is set to be at least larger than the inner diameter D2 of the bonding surface 42 before the mounting plate 3 is assembled with the bearing cage 4. The inner diameter D3 of the clearance surface 43 is preferably set to be larger than the value obtained by adding the outer diameter D1 of the bearing 2 to the interference fit (for pressing) of the bearing cage 4 relative to the mounting plate 3 (D3 > D1 + interference fit).

[0062] As described above, when the bearing 2 is fitted and mounted on the bearing cage 4, the adhesive is applied to the stepped surface 44. Therefore, the inner diameter D3 of the clearance surface 43 is more preferably set to a value that allows an appropriate amount of adhesive to be applied to the stepped surface 44. This value varies mainly depending on the material (viscosity) of the adhesive, and more specifically, it varies depending on the outer diameter D1 of the bearing 2. For example, the viscosity of the adhesive is in the range of 2000 mPa•s to 3000 mPa•s at the aforementioned room temperature (around 25°C), and the outer diameter D1 of the bearing 2 is 12 mm. In this case, it is preferable that the difference between the outer diameter D1 of the bearing 2 and the inner diameter D3 of the clearance surface 43 is set to be 150 μm or more and 255 μm or less. It should be noted that, here, the inner diameter D3 of the clearance surface 43 is defined by the difference between it and the outer diameter D1 of the bearing 2, rather than by the difference between it and the inner diameter D2 of the bonding surface 42. This is because the inner diameter D2 of the bonding surface 42 and the inner diameter D3 of the clearance surface 43 are set based on the size and tolerance of the bearing 2 for such design reasons, and the aforementioned bonding amount is very small relative to this difference.

[0063] As part of the assembly steps for the shaft 1, bearing 2, mounting plate 3, and bearing cage 4, for example, after pressing the bearing cage 4 into and fixing it to the mounting plate 3, the bearing 2, with the shaft 1 already pressed in and fixed, is fitted and installed into the bearing cage 4. Alternatively, after pressing the bearing cage 4 into and fixing it to the mounting plate 3, the bearing 2 can be fitted and installed into the bearing cage 4, and then the shaft 1 can be pressed into and fixed to the bearing 2. It should be noted that the bearing cage 4 can also be pressed into and fixed to the mounting plate 3 after assembling the mounting plate 3 onto the outer contour and base of the device.

[0064] [2. Application examples of ball bearing retaining structures]

[0065] Figure 4 This is an axial sectional view of the motor section 10 of the fan motor that utilizes the retaining structure of this embodiment. The fan motor corresponds to the "device for mounting the shaft 1" described above. Figure 4 As shown, the fan motor is equipped with two ball bearings 2 and 12 that are axially separated from each other on the shaft 1. The retaining structure of this embodiment is suitable for retaining the ball bearing 2 located on one side of the axial direction (lower side in the figure). Hereinafter, the ball bearing located on one side of the two ball bearings 2 and 12 will be referred to as the first bearing 2, and the ball bearing located on the other side of the axial direction (upper side in the figure) will be referred to as the second bearing 12. It should be noted that the centerline C of the shaft 1 is aligned with the centerline of the fan motor.

[0066] In this embodiment, the bearing cage 4 holds both ball bearings 2 and 12. Therefore, in addition to the aforementioned cage portion 40 and positioning portion 45, the bearing cage 4 is provided with a cylindrical second cage portion 48 for holding the second bearing 12. The second cage portion 48 extends axially from the positioning portion 45 toward the other side. The outer diameter of the other end portion 47 of the bearing cage 4, including the second cage portion 48, is formed to be smaller than the outer diameter of one end portion 46. Furthermore, on the outer peripheral surface of the bearing cage 4, a mounting surface 49 is provided in the portion overlapping the positioning portion 45 axially, connecting the outer peripheral surface of one end portion 46 to the outer peripheral surface of the other end portion 47. The stator core 14a, described later, is mounted on this mounting surface 49.

[0067] The fan motor is, for example, a centrifugal fan that directs intake air radially outward. A fan section (not shown) with multiple blades is connected to end 1b on the other side of shaft 1. The fan motor includes a motor section 10, which has a rotor 13 that rotates integrally with the fan section via shaft 1; and a stator 14 disposed inside the rotor 13. That is, the fan motor is an external rotor type brushless motor. Two ball bearings 2, 12 are disposed inside the stator 14 via bearing cages 4. Shaft 1 is supported by the two ball bearings 2, 12 such that one end 1a and the axial center portion are rotatable.

[0068] The rotor 13 has a cup-shaped rotor yoke 13a and a magnet 13b fixed to the inner circumferential surface of the rotor yoke 13a. A shaft hole 13h is formed axially through the inner side of the rotor yoke 13a. The rotor 13 is fixed relative to the shaft 1 in a manner that prevents relative rotation, for example, by pressing the shaft 1 into the shaft hole 13h. The magnet 13b comprises, for example, a long rectangular rubber magnet. The rubber magnet 13b is formed by connecting its two ends in a ring shape, the ring having an outer diameter equal to or smaller than the inner circumferential diameter of the rotor yoke 13a. It should be noted that multiple magnets 13b can be arranged circumferentially spaced along the inner circumferential surface of the rotor yoke 13a. With the stator 14 assembled inside the rotor 13, the magnets 13b are arranged to surround the stator core 14a at a position opposite to the stator core 14a of the stator 14 with an open gap.

[0069] The stator 14 has an annular stator core 14a and a coil 14c wound relative to the stator core 14a through an insulating member 14b. The stator core 14a is an annular laminated core formed by stacking multiple steel plates of the same shape. The stator core 14a is externally fixed to the other end 47 of the bearing cage 4 at its center with the stacking direction of the steel plates aligned with the axial direction. As a fixing method, for example, the outer peripheral surface of the other end 47 can be bonded to the inner peripheral surface of the stator core 14a with an adhesive. The stator core 14a can also be fixed to the bearing cage 4 by pressing the other end 47 into its inner hole. Thus, the stator 14 is fixed to the outer contour and base of the fan motor (not shown) via the bearing cage 4 and the mounting plate 3.

[0070] [3. Functions and Effects]

[0071] (1) In the above-described retaining structure, the inner surface of the retainer portion 40 is provided with an adhesive surface 42, a clearance surface 43 with a diameter larger than that of the adhesive surface 42, and a stepped surface 44 connecting the aforementioned surfaces 42 and 43, and the axial position of the stepped surface 44 is set to overlap with the bearing 2. That is, the clearance surface 43 is located on one side of the axial direction relative to the position overlapping with the bearing 2. As a result, it is possible to suppress the situation where one side of the outer peripheral surface 2f of the bearing 2 is pressed by the inner surface of the retainer portion 40 due to the deformation of the retainer portion 40 caused by a part of the retainer portion 40 (press-in portion 41) being pressed and fixed to the mounting portion 31. Therefore, it is possible to suppress the deformation of the bearing 2 that may occur due to the deformation of the retainer portion 40. Furthermore, it is possible to keep the ball passage speed of the bearing 2 constant, thereby suppressing the generation of abnormal noise.

[0072] Furthermore, since the adhesive can be applied using the stepped surface 44 as a marker, it is possible to apply the adhesive to the appropriate location within the retainer portion 40. The adhesive spreads to the other side due to friction when the bearing 2 is inserted. Therefore, by applying the adhesive to the stepped surface 44, which serves as the base point on one side of the adhesive surface 42, it is possible to suppress the adhesive from spreading to the other side of the bearing 2 and ensure a wider adhesive area.

[0073] (2) In the above-described retaining structure, the axial position of the stepped surface 44 is set at a position that overlaps with both the mounting portion 31 and the bearing 2. As described above, for the deformation of the retainer portion 40 caused by pressing, the portion where the outer peripheral surface of the retainer portion 40 presses against the inner peripheral surface of the mounting portion 31, that is, the portion closer to one side from the position of the other end face 31f of the mounting portion 31, experiences greater deformation. Therefore, by setting the axial position of the stepped surface 44, which serves as the base point on the other side of the clearance surface 43, to a position that overlaps with the bearing 2 and the other end face 31, that is, a position that overlaps with both the bearing 2 and the mounting portion 31, the amount of deformation (pressure) of the retainer portion 40 can be suppressed, thereby further suppressing the pressure on the outer ring of the bearing 2 caused by this deformation.

[0074] (3) In the above-described retaining structure, the inner diameter D3 of the clearance surface 43 is set to be larger than the value obtained by adding the press-in interference to the outer diameter D1 of the bearing 2. Although the retainer portion 40 is compressed and deformed when it is pressed into and fixed to the mounting portion 31, the amount of deformation (compression) will not exceed the press-in interference. That is, even if the retainer portion 40 deforms, it will only deform within a range smaller than the interference. Therefore, by setting the inner diameter D3 of the clearance surface 43 to be larger than the value obtained by adding the press-in interference to the outer diameter D1 of the bearing 2, the deformation of the bearing 2 embedded in the retainer portion 40 can be suppressed more reliably.

[0075] (4) In the above-described retaining structure, when the outer diameter D1 of the bearing 2 is 12 mm and the viscosity of the adhesive is 2000 mPa•s or more and 3000 mPa•s or less, the difference between the outer diameter D1 of the bearing 2 and the inner diameter D3 of the clearance surface 43 is set to be 150 μm or more and 255 μm or less. Therefore, in the retaining structure using a relatively small bearing 2 with an outer diameter of 12 mm, applying an appropriate amount of adhesive to the step surface 44 can form a suitable adhesive film. Thus, the bonding between the bearing 2 and the adhesive surface 42 can be achieved more reliably.

[0076] (5) In the above-described retaining structure, the bearing cage 4 is firmly fixed to the mounting plate 3 by pressing, and a structure is provided on the inner surface of the bearing cage 4 to suppress the deformation of the bearing 2 that may occur due to the pressing and fixing of the bearing cage 4. Therefore, by applying the above-described retaining structure in the fan motor, it is possible to prevent the shaft 1, which is fixed to the mounting plate 3 via the bearing cage 4, and the rotor 13, which rotates integrally with the shaft 1, from separating from the fan unit, and it is possible to suppress the generation of abnormal noise in the fan motor. It should be noted that in the above-described fan motor, not only the shaft 1, the fan unit, and the rotor 13, but also the stator 14 is fixed to the mounting plate 3 via the bearing cage 4. Therefore, if the fan motor using the above-described retaining structure is applied, it is also possible to prevent the stator 14 from coming off.

[0077] [4. Other]

[0078] The ball bearing retaining structure and fan motor structure described in the above embodiments are examples, and are not limited to the structures described above. The fan motor may not be a centrifugal fan, nor may it be an external rotor type brushless motor. The fan motor may also be, for example, an axial flow fan that causes fluid to flow axially along shaft 1. The device using the ball bearing retaining structure is only required for mounting shaft 1 and is not limited to a fan motor.

[0079] The amount of adhesion between bearing 2 and bonding surface 42 is not limited to the range of values ​​described above (1 μm to 16 μm), and can be appropriately set according to the viscosity of the adhesive and the outer diameter D1 of bearing 2. For example, the adhesive used may be a medium- or high-viscosity adhesive with a lower limit greater than the upper limit of the viscosity described above (3000 mPa•s). In this case, the range of adhesion amount can be set to a specified range (a range of a lower limit greater than 1 μm and an upper limit greater than 16 μm) greater than the range described above (1 μm to 16 μm). Furthermore, for example, when a bearing with an outer diameter larger than that of bearing 2 described above is applied to this retaining structure, the range of adhesion amount is set to a specified range (a range of a lower limit greater than 1 μm and an upper limit greater than 16 μm) greater than the range described above (1 μm to 16 μm).

[0080] Similarly, the difference between the outer diameter D1 of bearing 2 and the inner diameter D3 of clearance surface 43 is not limited to the range of values ​​mentioned above (150μm to 255μm), and can be appropriately set according to, for example, the viscosity of the adhesive and the outer diameter D1 of bearing 2. The inner diameter D3 of clearance surface 43 only needs to be at least larger than the inner diameter D2 of bonding surface 42, and is not limited to the set value mentioned above.

[0081] The interference fit for pressing the mounting plate 3 and the bearing cage 4 is not limited to the range described above. For example, the interference fit for pressing can be appropriately set according to the outer diameter D1 of the bearing 2. For example, a bearing with an outer diameter larger than that of the bearing 2 described above can be used in this retaining structure. In this case, the interference fit for pressing can be set within a specified range (a range of a lower limit greater than 35 μm and an upper limit greater than 45 μm) larger than the range described above (35 μm to 45 μm). In addition, the interference fit can be appropriately set according to the weight of the components held by the mounting plate 3 via the bearing cage 4. Examples of the aforementioned held components include, for example, the bearing 2, the shaft 1, components supported on the shaft 1 (e.g., rotor 13), and other components fixed to the mounting plate 3 via the bearing cage 4 (e.g., stator 14). The interference fit can also be appropriately set according to the operating conditions of the device using this retaining structure (based on external forces such as external vibrations at the place of use) to meet the required fastening force.

[0082] The shape of the mounting plate 3 is not limited to the shape described above, as long as it has the shape of the mounting portion 31. For example, the base portion 32 can be provided in such a way that it blocks the inner hole of the mounting portion 31 from one side. The base portion 32 can extend outward from the other side of the mounting portion 31, or it can extend outward from the entire area of ​​the outer peripheral surface of the mounting portion 31. In addition, for example, if the base portion 32 is thick, the hole formed through the base portion 32 along the thickness direction can be used as the mounting portion 31 itself. It should be noted that the base portion 32 can also be omitted.

[0083] The shape of the mounting portion 31 is not limited to a cylindrical shape, as long as it can be pressed into the inner side of the retainer portion 40. Similarly, the shape of the retainer portion 40 is not limited to a cylindrical shape. The retainer portion 40 can be pressed into the mounting portion 31 and can be fitted into the inner side of the bearing 2. It should be noted that... Figure 1 In the retention structure shown, the base portion 32 of the mounting plate 3 (one end of the mounting portion 31) is coplanar with the end face of one end portion 46 of the retainer portion 40. However, the one end portion 46 may protrude to one side from the base portion 32 or may be provided on the other side from the base portion 32.

[0084] The positioning portion 45 of the cage portion 40 is not limited to the above structure as long as it abuts against the bearing 2 from the other side to restrict the displacement of the bearing 2 to the other side. For example, the positioning portion 45 can be configured to block the bottom part of the inner hole of the cage portion 40 from the other side. In this case, the bearing 2 can also support the other end of the shaft 1 so that it can rotate. Alternatively, the positioning portion 45 can also be configured as a separate component from the cage portion 40.

Claims

1. A retaining structure for a ball bearing that supports a shaft for free rotation, characterized in that, The retaining structure of the ball bearing includes: A bearing cage having a cylindrical cage portion for the ball bearing to be fitted into one axial side of the shaft, and a positioning portion disposed on the other axial side of the cage portion and abutting against the ball bearing from the other side; and Mounting plate having a cylindrical mounting portion into which a portion of the retainer portion is pressed in from the other side. The inner surface of the cage portion is provided with: an adhesive surface, which is bonded to the outer peripheral surface of the ball bearing by an adhesive; a clearance surface, which has an inner diameter larger than the inner diameter of the adhesive surface at a location closer to the adhesive surface; and a stepped surface, which connects the adhesive surface and the clearance surface and allows the adhesive to be applied when the ball bearing is fitted and mounted in the bearing cage. With the ball bearing fitted and mounted in the bearing cage, the axial position of the stepped surface is the position that overlaps with the ball bearing.

2. The retaining structure of the ball bearing according to claim 1, characterized in that, With the bearing cage and the mounting plate combined, The axial position of the end face on the other side of the mounting part is the position that overlaps with the ball bearing. The axial position of the stepped surface is the position that overlaps with both the mounting part and the ball bearing.

3. The retaining structure of the ball bearing according to claim 1, characterized in that, The inner diameter of the clearance surface is larger than the outer diameter of the ball bearing plus the interference fit of the cage portion.

4. The retaining structure of the ball bearing according to claim 2, characterized in that, The inner diameter of the clearance surface is larger than the outer diameter of the ball bearing plus the interference fit of the cage portion.

5. The retaining structure of the ball bearing according to any one of claims 1 to 4, characterized in that, The outer diameter of the ball bearing is 12mm. The viscosity of the adhesive is above 2000 mPa•s and below 3000 mPa•s. The difference between the outer diameter of the ball bearing and the inner diameter of the clearance surface is more than 150 μm and less than 255 μm.

6. A fan motor, characterized in that, The fan motor includes a motor section comprising: a rotor that rotates integrally with the fan section via a shaft; and a stator disposed opposite to the rotor. The retaining structure of any one of claims 1 to 4 is applied to the ball bearing that supports the shaft as a rotatable ball bearing.

7. A fan motor, characterized in that, The fan motor includes a motor section comprising: a rotor that rotates integrally with the fan section via a shaft; and a stator disposed opposite to the rotor. The retaining structure of the ball bearing as described in claim 5 is applied to the ball bearing that supports the shaft as a rotatable ball bearing.

8. A method for manufacturing a retaining structure for a ball bearing, characterized in that, The retaining structure is provided with: A bearing cage having a cylindrical cage portion and a positioning portion disposed on the opposite side of the shaft along the axial direction of the cage portion; and Mounting plate, which has a cylindrical mounting section, The inner surface of the retainer portion is provided with: The bonding surface is bonded to the outer peripheral surface of the ball bearing by an adhesive. A clearance surface having an inner diameter larger than the inner diameter of the adhesive surface on the side closer to the axial direction than the adhesive surface; and A stepped surface that connects the bonding surface and the clearance surface. The manufacturing method includes the following steps: The ball bearing is fitted into the cage portion from one side, and the positioning portion abuts against the ball bearing from the other side, thereby determining the axial position of the ball bearing, and the ball bearing is fitted and installed in the bearing cage; and A portion of the retainer portion is pressed into the mounting portion from the other side. The fitting and installation process includes the following steps: The adhesive is applied to the stepped surface; and By fitting the ball bearing into the bearing cage, the adhesive applied to the stepped surface is spread through friction between the outer peripheral surface and the bonding surface, thereby bonding the outer peripheral surface to the bonding surface. With the ball bearing fitted and mounted in the bearing cage, the axial position of the stepped surface is the position that overlaps with the ball bearing.

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