Bearing devices and motors

Abstract

To provide a bearing device capable of suppressing vibrations generated at high-speed rotating.SOLUTION: A bearing device is equipped with a cylindrical sleeve 110 including an inner peripheral projecting portion 111 projecting inward in a radial direction at a center part, a shaft 150 held inside the sleeve 110, and a first ball bearing 120 and a second ball bearing 130 which are disposed on both sides of the inner peripheral projecting portion, and rotatably hold the shaft 150 with respect to the sleeve 110. Elastic adhesive is arranged between outer peripheries of outer rings 122 and 132 of the first and second ball bearings 120 and 130 and an inner periphery of the sleeve 110, and an O-ring 160 is disposed between an end surface of the outer ring 122 of the first bearing 120 and an end surface of the inner peripheral projecting portion 111 of the sleeve 110.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a bearing device for a high-speed rotating motor mounted on a household electrical appliance such as a blower, and particularly relates to a technique for suppressing vibration (for example, primary rotational vibration) that becomes prominent when rotating at high speed.

Background Art

[0002] For example, Patent Document 1 discloses a motor in which a ball bearing 41 is held in a bearing holding portion 52 formed in a bracket 50, and an elastic sealing agent 70 is provided between the bearing holding portion 52 and the ball bearing 41.

[0003] Further, Patent Document 2 discloses a bearing device in which angular ball bearings 5A and 5B are held in a housing 2 with their backs facing each other, and an elastic body 10 that biases the outer ring 11B of the angular ball bearing 5B on the axially rear end side outward in the axial direction is interposed between the outer ring 11B and the inner diameter side protruding portion 2a of the housing 2.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Disclosure of the Invention

Problems to be Solved by the Invention

[0005] However, in the technologies of Patent Documents 1 and 2, since an elastic body is provided only in one of the two ball bearings, it is insufficient for suppressing vibration. That is, in a ball bearing, vibration occurs due to rotation. In particular, when the shaft rotates at high speed, the vibration of the device becomes prominent, which may affect the performance of the bearing.

[0006] This invention has been made in view of the above circumstances, and aims to provide a bearing device that can suppress vibrations that occur when rotating at high speed. [Means for solving the problem]

[0007] The present invention comprises a cylindrical outer member having an inner circumferential projection projecting radially inward from its central portion, a shaft member held inside the outer member, and a first ball bearing and a second ball bearing positioned on both sides of the inner circumferential projection to hold the shaft member in a rotatable state relative to the outer member, wherein a first elastic member is positioned between the outer circumference of the outer rings of the first and second ball bearings and the inner circumference of the outer member, and a second elastic member is positioned between the end face of the outer ring of the first ball bearing and the end face of the inner circumferential projection of the outer member. A sealing member is provided on the inner circumferential surface of the outer ring of the first ball bearing to cover the space between the outer ring and the inner ring of the first ball bearing, and a spacer is fitted to the portion of the shaft member adjacent to the first ball bearing, with the outer diameter of the spacer being larger than the inner diameter of the sealing member. It is a bearing device. The present invention relates to a bearing device comprising: a cylindrical outer member having an inner circumferential projection projecting radially inward from its central portion; a shaft member held inside the outer member; and a first ball bearing and a second ball bearing positioned on both sides of the inner circumferential projection to hold the shaft member rotatably relative to the outer member; a first elastic member positioned between the outer circumference of the outer rings of the first and second ball bearings and the inner circumference of the outer member; a second elastic member positioned between the end face of the outer ring of the first ball bearing and the end face of the inner circumferential projection of the outer member; a seal member provided on the inner circumferential surface of the outer ring of the first ball bearing to cover the space between the outer ring and the inner ring of the first ball bearing; and a spacer fitted between the first and second ball bearings of the shaft member, wherein the outer diameter of the spacer is larger than the inner diameter of the seal member. [Effects of the Invention]

[0008] According to the present invention, vibrations in the bearing device are suppressed because the first elastic member suppresses radial vibrations and the second elastic member suppresses axial vibrations. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing a bearing device according to a first embodiment of the present invention. [Figure 2] This is an enlarged view of the area indicated by arrow II in Figure 1. [Figure 3] This is a cross-sectional view showing a motor according to an embodiment of the present invention. [Figure 4] This is a cross-sectional view showing a bearing device as an example of a modified embodiment. [Figure 5] This is an enlarged view of the area indicated by arrow V in Figure 4. [Figure 6] This is a cross-sectional view showing a conventional bearing device. [Modes for carrying out the invention]

[0010] 1. Bearing device An embodiment of the present invention will now be described. Prior to describing the embodiment of the present invention, a conventional bearing device that formed the basis for the development of the present invention will be described with reference to Figure 6. This bearing device 10 has a pair of ball bearings 12 arranged at both ends of a sleeve 11. A spacer 14 is interposed between the inner rings 12a of the ball bearings 12 to fix the inner rings 12a to the shaft 13, and a coil spring 15 is interposed between the outer rings 12b of the ball bearings 12. The biasing force of the coil spring 15 biases the outer rings 12b outward in the axial direction, and with preload applied to the ball bearings 12, the outer rings 12b are bonded and fixed to the inner circumferential surface of the sleeve 11, resulting in fixed-position preload. In addition, a plurality of balls 17 are arranged at equal intervals in the circumferential direction by a cage 16 in the raceways formed on the inner rings 12a and outer rings 12b.

[0011] In the bearing device 10 with the above configuration, the pitch circle diameter (mm) and rotational speed (min) of the ball 17 are specified. -1 When the rotation speed was such that the dmn value, which is the product of ), exceeded 1 million, it became impossible to completely suppress the vibrations transmitted to the sleeve 11.

[0012] Figures 1 and 2 show a bearing device 100 according to an embodiment of the present invention. The bearing device 100 includes a cylindrical sleeve (outer member) 110. An inner circumferential projection 111 is formed in the axial center of the sleeve 110, projecting radially inward. A first ball bearing 120 and a second ball bearing 130 are arranged on both sides of the inner circumferential projection 111.

[0013] A spacer 140 is interposed between the inner ring 121 of the first ball bearing 120 and the inner ring 131 of the second ball bearing 130. The inner rings 121 and 131 are firmly fixed to the shaft (shaft member) 150 on both sides of the spacer 140 by means of press-fitting, adhesive, or other means.

[0014] An O-ring (elastic member) 160 is interposed between the outer ring 122 of the first ball bearing 120 and the end face of the inner peripheral protrusion 111. In the states shown in FIGS. 1 and 2, the O-ring 160 is compressed, and the outer ring 122 is biased axially to the left side (outer side) by the reaction force thereof. That is, the outer ring 122 is biased axially to the left side (outer side) with respect to the inner ring 121, and a constant-pressure preload is applied to the ball bearing 120. This constant-pressure preload can be realized, for example, by making the axial length of the spacer  140 where the inner ring 121 of the first ball bearing 120 and the inner ring 131 of the second ball bearing 130 abut smaller than the sum of the diameter of the uncompressed O-ring 160 and the axial length of the inner peripheral protrusion 111. Thereby, the outer ring 122 can move axially with respect to the sleeve 110. Note that the O-ring 160 is not limited to having a circular cross section, and the cross-sectional shape can be arbitrary, such as rectangular or elliptical.

[0015] In FIG. 2, reference numeral 125 denotes balls, and a plurality of balls 125 are arranged at regular intervals in the circumferential direction between the raceway ring 121a of the inner ring 121 and the raceway ring 122a of the outer ring 122 by a cage 126. Here, the ratio (load / inner diameter) of the preload load (N) by the O-ring 160 to the inner diameter (mm) of the inner ring 121 is set to 2 or less. By setting the preload small in this way, the contact area between the balls 125 and the raceway rings 121a and 122a can be made small. Therefore, the frictional resistance during high-speed rotation can be reduced, and the vibration suppression effect can be enhanced. Note that the ratio (load / inner diameter) is preferably 1 or less, more preferably 0.5 or less.

[0016] When the ratio (load / inner diameter) of the preload (N) by the O-ring 160 to the inner diameter (mm) of the inner ring 121 is set to 2 or less, the radius of curvature R1 of the raceway ring 122a of the outer ring 122 is 50.5 to 56% of the diameter of the ball 125, preferably 50.5 to 54%, more preferably 50.5 to 53.5%. By setting it in this way, the relative movement amount between the outer ring 122 and the ball 125 can be reduced, and the vibration suppression effect can be enhanced. The above settings can also be made in the second ball bearing 130. In the embodiment of the present invention, the radius of curvature R2 of the raceway ring 121a of the inner ring 121 is 52.5 to 60% of the diameter of the ball 125.

[0017] The outer peripheral surface of the outer ring 122 is adhered to the inner peripheral surface of the sleeve 110 by an elastic adhesive. The elastic adhesive is in a liquid or paste state having kinematic viscosity when applied and has elasticity after curing. As the elastic adhesive, a moisture-curing type or photo-curing type silicone adhesive or the like can be used. Thereby, the outer ring 122 can move slightly in the axial direction and the radial direction with respect to the sleeve 110. In the present embodiment, the fit between the outer peripheral surface of the outer ring 122 and the inner peripheral surface of the sleeve 110 is in a clearance fit relationship defined by JIS B 4101-1 and -2.

[0018] The outer peripheral surface of the outer ring 132 of the second ball bearing 130 is adhered to the inner peripheral surface of the sleeve 110 by the same elastic adhesive as described above. Thereby, the outer ring 132 can move in the axial direction with respect to the sleeve 110. Also, the end surface between the end surface of the outer ring 132 and the inner peripheral protrusion 111 is adhered by the same elastic adhesive (elastic member) 161. Thereby, the vibration suppression effect in the second ball bearing 130 can be enhanced.

[0019] Annular grooves 123 are formed at both axial ends of the inner surface of the outer ring 122, and the outer peripheral edge of a ring-shaped sealing member 170 is fitted into the annular grooves 123. On the other hand, stepped portions 124, which are smaller in diameter than the central portion, are formed at both ends of the inner surface of the inner ring 121, and the inner peripheral edge of the sealing member 170 faces the stepped portion 124 with a small gap between them. This suppresses leakage of grease filled in the bearing space between the inner ring 121 and the outer ring 122, and the intrusion of water, dust, etc. from the outside. Such a sealing member 170 is also provided in the second ball bearing 130. Furthermore, the inner diameter of the sealing member 170 is smaller than the outer diameter of the spacer 140. This suppresses leakage of grease into the inside of the sleeve 110. Note that the inner ring 121 does not necessarily need to have the stepped portion 124 formed thereon.

[0020] A spacer 180 is fixed to the shaft 150 adjacent to the inner ring 121 of the first ball bearing 120. Meanwhile, a hub cap 190, which is an annular member, is fixed to the opening at the left end of the sleeve 110 by press-fitting or rigid adhesive, and abuts against the end face of the outer ring 122. The hub cap 190 is ring-shaped, and its inner peripheral edge faces the outer peripheral surface of the spacer 180 with a gap between them. As a result, the gap between the sealing member 170 and the stepped portion 124 and the hub cap 190 overlap in the axial direction, effectively suppressing grease leakage and the intrusion of water, dust, etc. from the outside, as well as preventing the outer ring 122 from peeling off the sleeve 110. Alternatively, a circumferential groove may be provided in the opening of the sleeve 110, and a C-ring or the like may be fitted in place of the hub cap 190.

[0021] 2. Motor An embodiment of the present invention, the motor 200, will be described with reference to Figure 3. The motor 200 uses the bearing device 100 described above. In Figure 3, reference numeral 210 denotes the casing. The casing 210 is cylindrical in shape.

[0022] A stator core 220 is fixed to the inner circumferential surface of the casing 210. The stator core 220 is made of multiple thin, ring-shaped soft magnetic material sheets (e.g., electrical steel sheets) stacked in the axial direction, and has multiple pole teeth that protrude radially inward. The multiple pole teeth are arranged at equal intervals along the circumferential direction, and a coil 221 is wound around each of them.

[0023] A cylindrical rotor magnet 230 is fixed to the shaft 150 adjacent to the spacer 180. The rotor magnet 230 is magnetized such that adjacent portions of SNSN·· along the circumferential direction alternate in polarity. The outer circumference of the rotor magnet 230 faces the inner circumference of the pole teeth of the stator core 220 with a gap between them. When a drive current is supplied to the coil 221, a driving force is generated that attempts to rotate the rotor magnet 230, causing the rotor magnet 230 to rotate around the shaft 150 as its axis relative to the casing 210.

[0024] The shaft 150 protrudes from an opening 211a formed in the front cover 211, and an impeller (operating part) 240 is attached to its end. In this way, the motor 200 is configured as a blower.

[0025] 3. Effects When the blower with the above configuration rotates at high speed, vibrations occur due to the rotation of the first and second bearings 120 and 130. However, in the above embodiment, since the O-ring 160 and elastic adhesive 161 are placed between the end faces of the outer rings 122 and 132 of the first and second ball bearings 120 and 130 and the end face of the inner circumferential projection 111, axial vibrations are suppressed. Furthermore, since the outer circumferential surfaces of the outer rings 122 and 132 and the inner circumferential surface of the sleeve 110 are bonded with elastic adhesive, primary vibrations generated from the dynamic unbalance of the balls 17 are absorbed, and vibrations of the bearing device 100 can be reduced.

[0026] In particular, in the above embodiment, since the O-ring 160 is placed between the outer ring 122 and the inner circumferential projection 111 of the first ball bearing 120 on the rotor magnet 230 side, the positioning accuracy of the impeller 240 mounted on the shaft 150 can be improved.

[0027] Furthermore, in the above embodiment, since hub caps 190 that abut the end faces of the outer rings 122 and 132 are fixed to the openings at both ends of the sleeve 110, the preload applied to the first and second ball bearings 120 and 130 can be maintained.

[0028] 4. Example of changes The present invention is not limited to the embodiments described above, and various modifications are possible as follows. i) Figures 4 and 5 show modified examples of the above embodiment. In these modified examples, the thickness of the spacer 181 is increased compared to that of the above embodiment, and the outer diameter of the spacer 181 is made larger than the inner diameter of the seal member 170. As a result, the gap between the seal member 170 and the stepped portion 124 and the spacer 181 overlap in the axial direction, suppressing grease leakage and the intrusion of water, dust, etc. from the outside. For this reason, in these modified examples, the inner diameter of the hub cap 191 is set to be larger.

[0029] ii) In the above embodiment, an O-ring 160 may be interposed between the end face of the outer ring 132 of the second ball bearing 130 and the end face of the inner circumferential projection 111 of the sleeve 110 instead of the elastic adhesive 161. Conversely, an elastic adhesive 161 may be interposed between the end face of the outer ring 122 of the first ball bearing 120 and the end face of the inner circumferential projection 111 instead of the O-ring 160.

[0030] iii) If the first ball bearing 120 and the second ball bearing 130 are precisely positioned, the spacer 140 is not necessarily required. iv) Although the above embodiments apply the present invention to deep groove ball bearings, it can also be applied to angular contact ball bearings.

[0031] v) In addition to the O-ring 160 and elastic adhesive 161, other elastic members such as coil springs, disc springs, and wave washers can also be used.

[0032] vi) The third and fourth ball bearings can be arranged in order from left to right between the first and second ball bearings 120 and 130. In this case, the third ball bearing can be configured in the same way as the first ball bearing 120, and the fourth ball bearing can be configured in the same way as the second ball bearing 130.

[0033] vii) The motor 200 shown in Figure 3 is configured to have an impeller 240 attached to its shaft, but any other moving part can be attached. For example, it can be configured to have a mirror for a LiDAR device or a propeller for an unmanned aerial vehicle such as a drone attached. [Examples]

[0034] The bearing device of the inventive example shown in Figure 1 was attached to the casing, and the drive rotor and casing were attached to the base, with the shafts of both connected. The vibration level (mm / s) was measured by rotating the drive rotor at 140,000 rpm with the vibration pickup meter of a vibration analyzer (RAION Corporation, VA-12) in contact with the base. The same measurement was performed using the bearing device shown in Figure 6 as a conventional example. As a result, it was confirmed that the rotational primary vibration level of the inventive example was approximately 11% of that of the conventional example. [Industrial applicability]

[0035] This invention can be used in household electrical appliances such as vacuum cleaners, hair dryers, and blowers, as well as in electrical equipment such as LIDAR and unmanned aerial vehicles. [Explanation of Symbols]

[0036] 100...Bearing device, 110...Sleeve (outer member), 111...Inner circumferential projection, 120...First ball bearing, 121,131...Inner ring, 122,132...Outer ring, 121a,122a...Raceway ring, 123...Annular groove, 124...Step, 125...Ball, 130...Second ball bearing, 140...Spacer, 150...Shaft (shaft member), 160...O-ring (elastic member), 161...Elastic adhesive (elastic member), 170...Seal member, 180,181...Spacer, 190,191...Hub cap, 200...Motor, 210...Casing, 220...Stator core, 221...Coil, 230...Rotor magnet, 240...Impeller (operating part), R1...Radius of curvature, R2...Radius of curvature.

Claims

1. A cylindrical outer member having an inner circumferential projection that protrudes radially inward from the central part, The shaft member held inside the outer member, A first ball bearing and a second ball bearing are arranged on both sides of the inner circumferential protrusion to hold the shaft member in a rotatable state relative to the outer member, Equipped with, A first elastic member is placed between the outer circumference of the outer rings of the first and second ball bearings and the inner circumference of the outer member. A second elastic member is placed between the end face of the outer ring of the first ball bearing and the end face of the inner circumferential protrusion of the outer member. A bearing device comprising a sealing member provided on the inner circumferential surface of the outer ring of the first ball bearing to cover the space between the outer ring and the inner ring of the first ball bearing, a spacer fitted to the portion of the shaft member adjacent to the first ball bearing, and the outer diameter of the spacer being larger than the inner diameter of the sealing member.

2. A cylindrical outer member having an inner circumferential projection that protrudes radially inward from the central part, The shaft member held inside the outer member, A first ball bearing and a second ball bearing are arranged on both sides of the inner circumferential protrusion to hold the shaft member in a rotatable state relative to the outer member, Equipped with, A first elastic member is placed between the outer circumference of the outer rings of the first and second ball bearings and the inner circumference of the outer member. A second elastic member is placed between the end face of the outer ring of the first ball bearing and the end face of the inner circumferential protrusion of the outer member. A bearing device comprising a sealing member provided on the inner circumferential surface of the outer ring of the first ball bearing to cover the space between the outer ring and the inner ring of the first ball bearing, a spacer fitted between the first and second ball bearings of the shaft member, and the outer diameter of the spacer being larger than the inner diameter of the sealing member.

3. The bearing device according to claim 1 or 2, wherein the first elastic member is an elastic adhesive and the second elastic member is an O-ring.

4. The bearing device according to claim 1 or 2, wherein an elastic adhesive is placed between the end face of the outer ring of the second ball bearing and the end face of the inner circumferential projection of the outer member.

5. The bearing device according to claim 1 or 2, wherein annular members that abut the end faces of the outer ring are fixed to the openings at both ends of the outer member.

6. The bearing device according to claim 5, wherein the gap between the sealing member and the inner ring and the annular member overlap in the axial direction.

7. The bearing device according to claim 1 or 2, wherein the ratio (load / inner diameter) of the preload load (N) by the second elastic member to the inner diameter (mm) of the inner ring is 2 or less.

8. The bearing device according to claim 7, wherein the radius of curvature of the raceway of the outer ring is 50.5 to 56% of the diameter of the ball.

9. A motor comprising a casing, a bearing device according to claim 1 or 2, and a stator, wherein a rotor magnet is provided on the shaft member of the bearing device, with its outer circumferential surface facing the inner circumferential surface of the stator with a gap between them.

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