JP2007113744A - Ball bearing and brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the degradation of conductivity to maintain conductivity over a long period of time while keeping torque low and preventing the generation of a sealing sound by suppressing electrolytic corrosion in a bearing raceway surface. <P>SOLUTION: A seal member 20 using a conductive material for a rubber material portion contacts with a seal groove 12 of an inner ring 2 in a position around the outside of a contact surface 22a of a seal lip 22. Consequently, when electricity flows to an outer ring 1, electricity flows to the inner ring 2 through the seal member 20. The contact surface 22a of the seal lip 22 has fine protruding parts 30 of 0.01-0.10 mm by providing a die with a large number of dimple-like recesses by electric discharge machining or the like. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ball bearing that constitutes a rotation support portion of a motor incorporated in a general electric appliance such as an air conditioner fan motor or a small motor for automobile parts, and particularly to electrolytic corrosion generated in a bearing for an inverter control motor. The present invention relates to a ball bearing and a brushless motor.

  2. Description of the Related Art Conventionally used ball bearings for electric corrosion prevention use an insulating ceramic ball as a rolling element. Since electricity does not pass through the outer ring, rolling element and inner ring, the occurrence of electrolytic corrosion on the raceway surface can be prevented. However, on the other hand, the cost is high.

  As a conventional measure using a seal member, in Patent Document 1, the energizing seal is composed of two seal plates formed of a conductive metal plate, and is fixedly supported on either the inner or outer raceway ring. And a sliding contact portion formed of conductive rubber and slidably contacted with the other raceway ring, and the sliding contact portion is sandwiched and fixed between two seal plates of the main portion. It is.

Further, in Patent Document 2, an outer race ring, an inner race ring, a plurality of rolling elements arranged between the race rings and rolling on the raceway surface, and an axial direction from the raceway surface Rolling element having at least one member disposed at a distance from each other and in contact with both race rings, the rolling element has non-conductivity, and at least one member in contact with both race rings has good conductivity So that transmission of electric current from the bearing without any disturbance and transmission of electric signals through the bearing can be permitted for processing outside the bearing.
Japanese Utility Model Publication No. 6-73457 JP-A-9-310721

  However, in the conventional contact-type seal members disclosed in Patent Documents 1 and 2, the conductivity tends to decrease with time.

  In some cases, conductive grease is used as a lubricant to prevent electric corrosion. However, since powder such as carbon is inserted, there is a problem that the sound rises and the current flows through the raceway surface, resulting in damage.

  As described above, the countermeasures using the conventional sealing member have a problem in that the conductivity tends to decrease with the passage of time, resulting in an increase in torque and generation of a sealing noise.

  The present invention has been made in view of the above-described circumstances, and can suppress electrolytic corrosion on the bearing raceway surface, prevent deterioration of conductivity, and maintain conductivity for a long period of time. It is an object of the present invention to provide a ball bearing and a brushless motor that can suppress torque to a low level and prevent generation of a sealing noise.

In order to achieve the above object, the ball bearing according to the present invention has a ball interposed between the outer ring and the inner ring so as to freely roll,
In ball bearings with contact type seal members on the sides of the outer and inner rings,
The seal member is made of a conductive material, and when the current flows through the bearing by contacting the outer ring or the inner ring partly or partially, the current flows through the seal member, and the bearing raceway. It is characterized by being able to suppress electric corrosion that occurs on the surface.

  Preferably, fine concave portions or convex portions are formed on the contact surface of the seal lip of the seal member or on the seal groove of the outer ring or the inner ring.

  Preferably, conductive grease is applied to the contact surface of the seal lip of the seal member or to the seal groove of the outer ring or the inner ring.

  Further preferably, the seal lip of the seal member is formed so as to hold conductive grease.

  A brushless motor according to the present invention is characterized in that the ball bearing according to any one of claims 1 to 4 is mounted.

  According to the present invention, it is possible to suppress electrolytic corrosion on the bearing raceway surface, to prevent deterioration of conductivity, to maintain conductivity for a long period of time, to keep torque low, and to generate seal noise. Can be prevented.

  Hereinafter, ball bearings and brushless motors according to embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view of a ball bearing according to a first embodiment of the present invention.

  FIG. 2 is an enlarged view of the contact surface of the seal lip of the seal member.

  The ball bearing according to the present embodiment is, for example, a ball bearing that constitutes a rotation support portion of a motor incorporated in a general electric appliance such as an air conditioner fan motor or a small motor for automobile parts, and particularly for an inverter control motor. It is possible to prevent electric corrosion generated in the bearing of the motor, and for example, it is mounted on a brushless motor.

  As shown in FIG. 1, a ball 3 is interposed between an outer ring 1 and an inner ring 2 so as to be able to roll, and the ball 3 is maintained at a predetermined interval by a cage 4.

  Seal grooves 11 and 12 are formed on both sides of the outer ring 1 and the inner ring 2, respectively.

  A seal member 20 in which a core metal member 21 is embedded is attached to the seal groove 11 of the outer ring 1, and the seal lip 22 is configured to contact the seal groove 12 of the inner ring 2.

  In the seal member 20, a conductive material is used for the rubber material portion, and is in contact with the seal groove 12 of the inner ring 2 at a position around the contact surface 22 a of the seal lip 22.

  As a result, when electricity flows through the outer ring 1, electricity flows through the seal member 20 to the inner ring 2.

  On the contact surface 22a of the seal lip 22, by forming a large number of dimple-shaped concave portions in the mold by electric discharge machining or the like, fine convex portions 30 of 0.01 mm to 0.10 mm are formed as shown in FIG. It is. Note that such a fine convex portion 30 may be formed on the seal groove 12 side. Moreover, it may replace with the convex part 30 and the recessed part may be formed.

  The seal lip 22 of the seal member 20 is formed so as to hold conductive grease. That is, there is a space S for holding conductive grease between the seal groove 12 of the inner ring 2 and the seal lip 22 of the seal member 20, and the conductive grease is applied thereto.

  From the above, when the current flows through the conventional bearing, since the outer ring 1 → the ball 3 → the inner ring 2 passes through the outer ring 1 → the seal member 20 → the inner ring 2, the bearing raceway surface is not damaged.

  Conventionally, the sealed grease of the bearing flows into the contact surface of the seal member 20 and the resistance value increases, and the conductivity of the seal member 20 tends to decrease. However, the convex portion 30 is formed on the contact surface 22a of the seal lip 22. Alternatively, the deterioration of the conductivity can be suppressed by providing the recess and applying the conductive grease to the contact surface 22a.

  Since the shape of the seal member 20 is such that the conductive grease applied to the contact surface 22a is retained, the lubrication of the conductive grease can be maintained and leakage of the conductive grease to the inside and outside of the bearing can be prevented. It can also be prevented.

  Moreover, since the convex part 30 or the recessed part exists in the contact surface 22a, a torque can be made lower than the conventional contact seal and a seal sound can also be prevented.

  The torque can be lowered by making the contact surface 22a of the seal lip 22 contact several points instead of the entire circumference.

  Therefore, this embodiment has the following effects.

  In the bearing, when electricity flows through the bearing, current does not flow through the balls 3 but flows through the conductive seal member 20, so that the occurrence of electrolytic corrosion can be suppressed.

  Further, by applying conductive grease to the contact surface 22a of the seal lip 22, it is possible to prevent the deterioration of the conductivity and maintain the conductivity for a long time.

  By providing the fine convex part 30 or the concave part on the contact surface 22a of the seal lip 22, the frictional resistance can be reduced and the generation of the sealing noise can be prevented.

  The cost of the conventional countermeasures using the ceramic balls is high, but in this embodiment, the cost can be suppressed because it is made of a material cheaper than the ceramic balls.

  Although the present embodiment shows an example using a rubber seal, it is also effective to apply conductive grease to the labyrinth portion of the metal shield plate.

(Second Embodiment)
FIG. 3 is a cross-sectional view of a ball bearing according to a second embodiment of the present invention.

  In the present embodiment, an example in which the seal lip 22 is inward is shown. That is, the contact surface 22 a of the seal lip 22 is in contact with the inner side of the seal groove 12 of the inner ring 2.

  Other configurations, operations, and effects are the same as those in the first embodiment described above.

(Third embodiment)
FIG. 4 is a cross-sectional view of a ball bearing according to a third embodiment of the present invention.

  In the present embodiment, an example in which the seal lip 22 is around the center is shown. That is, the contact surface 22 a of the seal lip 22 is in contact with the approximate center of the seal groove 12 of the inner ring 2.

  Other configurations, operations, and effects are the same as those in the first embodiment described above.

(Fourth embodiment)
5A and 5B relate to a fourth embodiment of the present invention, in which FIG. 5A is a cross-sectional view of a seal member, FIG. 5B shows an example of the entire contact of a seal lip, and FIG. An example of lip four-point contact is shown.

  5A, the seal lip 22 of the seal member 20 has a contact surface 22a whose width is d.

  As shown in FIG. 5 (b), the contact surface 22a of the seal lip 22 may be configured to be in full contact, and as shown in FIG. 5 (c), several points (as in the illustrated example). And 4 points) contact.

  Other configurations, operations, and effects are the same as those in the first embodiment described above.

(Fifth embodiment)
FIG. 6 is a sectional view of a ball bearing according to a fifth embodiment of the present invention.

  In the present embodiment, there is a space S that holds conductive grease between the seal groove 12 of the inner ring 2 and the seal lip 22 of the seal member 20, and the conductive grease is applied thereto. In the bearing, when electricity flows through the bearing, current does not flow through the balls 3 but flows through the conductive seal members 20 and the conductive grease on both sides of the bearing, thereby suppressing the occurrence of electrolytic corrosion. Can do.

  On the other hand, normal grease is applied between the raceway surfaces of the outer ring 1 and the inner ring 2 and the balls 3. This grease has a viscosity sufficient to form an oil film during steady rotation and has a high volume resistance.

  As a result, it becomes easier to discharge toward the seal member 20. In addition, the acoustic characteristics and durability are excellent.

  Other configurations, operations, and effects are the same as those in the first embodiment described above.

  In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible. For example, the conductive seal member 20 may be used only on one side. Further, the conductive seal member 20 may be in inner ring contact or outer ring contact.

It is sectional drawing of the ball bearing which concerns on 1st Embodiment of this invention. It is an enlarged view of the contact surface of the seal lip of a seal member. It is sectional drawing of the ball bearing which concerns on 2nd Embodiment of this invention. It is sectional drawing of the ball bearing which concerns on 3rd Embodiment of this invention. (A) is sectional drawing of a sealing member, (b) shows the example of the perimeter contact of a seal lip, (c) is 4 points | pieces of a seal lip according to 4th Embodiment of this invention. An example of contact is shown. It is sectional drawing of the ball bearing which concerns on 5th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Inner ring 3 Ball 4 Cage 11, 12 Seal groove 20 Seal member 21 Core metal member 22 Seal lip 22a Contact surface 30 Convex part

Claims (5)

A ball is interposed between the outer ring and the inner ring so as to roll freely.
In ball bearings with contact type seal members on the sides of the outer and inner rings,
The seal member is made of a conductive material, and when the current flows through the bearing by contacting the outer ring or the inner ring partly or partially, the current flows through the seal member, and the bearing raceway. A ball bearing characterized by being able to suppress electric corrosion occurring on the surface.   The ball bearing according to claim 1, wherein fine concave portions or convex portions are formed on a contact surface of a seal lip of the seal member or on a seal groove of the outer ring or the inner ring.   3. The ball bearing according to claim 1, wherein conductive grease is applied to a contact surface of a seal lip of the seal member or to a seal groove of the outer ring or the inner ring.   The ball bearing according to claim 1, wherein the seal lip of the seal member is formed so as to hold conductive grease.   5. A brushless motor, wherein the ball bearing according to claim 1 is mounted.

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