JP2023074928A - rolling bearing device - Google Patents

Abstract

To provide a structure of a rolling bearing device which can maintain sufficient conduction between an outer member and an inner member even when a rotation speed is accelerated faster and faster.SOLUTION: A deep groove ball bearing 1 includes an outer ring 2, an inner ring 3, a plurality of balls 4, and a magnetic field generation device 6. The magnetic field generation device 6 generates a magnetic field in an annular space 11 existing between an inner peripheral face of the outer ring 2 and an outer peripheral face of the inner ring 3 in a direction of an auto-rotation axis of the balls 4. Particularly, the magnetic field generated by the magnetic field generation device 6 is configured to change in magnitude in a circumferential direction of the annular space 11. By revolving the balls 4 so as to cross the magnetic field generated by the magnetic field generation device 6, the balls 4 generates electromotive force in a direction of a contact angle.SELECTED DRAWING: Figure 2

Description

The present invention relates to rolling bearing devices.

The vehicle body of an automobile is charged with static electricity due to friction with the air that occurs during travel. It is known that when a certain amount of electric charge accumulates in the vehicle body, dielectric breakdown occurs and a discharge phenomenon (spark) occurs. Such sparks can cause radio noise and damage the on-board computer.

One of the causes of static electricity in the car body is the insulation between the rolling elements and the bearing ring of the rolling bearing device called hub unit bearing, which is used to rotatably support the wheel, when the car is running. A highly non-conductive EHL oil film is formed.

When the vehicle is stopped, the rolling elements and the bearing rings that make up the rolling bearing device are in direct metal contact with each other without passing through the EHL oil film. However, when the vehicle is running, an EHL oil film is formed between the rolling elements and the bearing rings, making it impossible for the charged static electricity to flow from the vehicle body to the tires. That is, the EHL oil film insulates between the vehicle body and the tires. As a result, the vehicle body is likely to be charged with static electricity during running.

If the EHL oil film is removed from between the rolling element and the bearing ring, it becomes possible to suppress electrification of the vehicle body. Therefore, it is not possible to adopt a countermeasure to remove the EHL oil film in order to suppress electrification of the vehicle body.

In view of such circumstances, for example, Japanese Patent Application Laid-Open No. 2015-102200 (Patent Document 1) discloses that an outer member and an inner member, which are a pair of bearing rings constituting a rolling bearing device, are replaced by a seal ring. Techniques for providing electrical continuity by means of constituent conductive rubber and conductive grease are described. According to the rolling bearing device having the conventional structure described in Japanese Patent Application Laid-Open No. 2015-102200, since the conductive rubber and the conductive grease allow the outer member and the inner member to conduct, it is possible to remove the EHL oil film. Therefore, it is possible to suppress electrification of the vehicle body.

Japanese Patent Application Laid-Open No. 2015-102200

However, the rolling bearing device having the conventional structure described in Japanese Patent Application Laid-Open No. 2015-102200 has room for improvement in discharging the static electricity charged in the vehicle body for the following reasons.

In other words, when the temperature of the conductive rubber constituting the seal ring rises or when a mechanical force is applied, the Brownian motion of the rubber polymer intensifies, weakening the binding force between the conductive component and the ionic component, which reduces the electrical conductivity. tends to decrease. In addition, when the conductive grease is agitated, the bonds between the conductor components are easily broken, and the conductivity tends to decrease. For this reason, the rolling bearing device having the conventional structure described in Japanese Patent Laid-Open No. 2015-102200 tends to have lower conductivity during rotation (during operation) that causes temperature rise and agitation. sex tends to decline.

On the other hand, the vehicle body is more likely to be charged with static electricity as the traveling speed increases. Therefore, it becomes difficult to sufficiently discharge the static electricity charged on the vehicle body during running by using the rolling bearing device having the conventional structure described in Japanese Patent Application Laid-Open No. 2015-102200. In addition, when carbon black is used as a conductor component contained in conductive grease, agglomeration is likely to occur. There is also a possibility that a sudden change in rolling resistance due to being caught between the surface and the rolling element).

As described above, the rolling bearing device provides insulation between two members, such as between the vehicle body and the tire, and prevents static electricity from escaping from one of the two members to the other. This problem is not peculiar to rolling bearing devices (hub unit bearings), but can also occur in rolling bearing devices incorporated in rotation support portions of various mechanical devices.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems, and to provide a rolling bearing device capable of sufficiently conducting the outer member and the inner member even when the rotational speed increases. for the purpose.

A rolling bearing device according to one aspect of the present invention includes an outer member, an inner member, a plurality of rolling elements, and a magnetic field generator.
The outer member is electrically conductive and has an outer ring raceway on its inner peripheral surface.
The inner member is electrically conductive and has an inner ring raceway on its outer peripheral surface.
The rolling elements are electrically conductive and arranged between the outer ring raceway and the inner ring raceway.
The magnetic field generator generates a magnetic field in a direction that coincides with the direction of the rotation axis of the rolling element in an annular space existing between the inner peripheral surface of the outer member and the outer peripheral surface of the inner member.
The direction that coincides with the direction of the axis of rotation also includes a direction that substantially coincides with the direction of the axis of rotation, that is, a direction that is slightly (about 10°) inclined with respect to the direction of the axis of rotation.
In the rolling bearing device according to one aspect of the present invention, the magnetic field generated by the magnetic field generator changes in magnitude in the circumferential direction of the annular space, and the rolling elements revolve across the magnetic field. Thus, an electromotive force is generated in the rolling element in the direction of the contact angle.
Note that the direction of the magnetic field generated by the magnetic field generator refers to the direction of the rolling elements that traverse the magnetic field, not the direction of the rolling elements that are located away from the magnetic field in the circumferential direction. Further, the direction of the contact angle is a direction orthogonal to the direction of the rotation axis in a virtual plane containing the revolution axis and the rotation axis, and the direction of the line of action of the load acting on the rolling element is means.

In a rolling bearing device according to an aspect of the present invention, the magnetic field generating device has a plurality of magnetic field generating sections each having an N pole and an S pole so as to sandwich the rolling element from both sides with respect to the direction of the rotation axis. and the magnetic field generators can be arranged at regular intervals in the circumferential direction of the annular space.
In this case, the number of the rolling elements can be an integral multiple of the number of the magnetic field generators.
Alternatively, the magnetic field generator can be composed of one magnetic field generator arranged at one place in the circumferential direction of the annular space.
Further, in a rolling bearing device in which a loaded zone and a non-loaded zone exist during use, at least one of the magnetic field generators can be arranged in the loaded zone.

In the rolling bearing device according to one aspect of the present invention, one of the outer member and the inner member is a stationary ring that does not rotate during use, and the other of the outer member and the inner member is a stationary ring that does not rotate during use. It can be a rotating wheel that rotates with the wheel. In this case, the rolling bearing device becomes a hub unit bearing.

In the rolling bearing device according to one aspect of the present invention, the annular space can be filled with a non-conductive lubricant.
Alternatively, in the rolling bearing device according to one aspect of the present invention, the annular space may be filled with a conductive lubricant.

According to the present invention, it is possible to realize a rolling bearing device that allows sufficient electrical continuity between the outer member and the inner member even when the rotational speed increases.

FIG. 1 is a schematic diagram showing a state in which a deep groove ball bearing according to a first embodiment is viewed from the axial direction. FIG. 2 is a schematic cross-sectional view taken along line AA of FIG. FIG. 3 is a diagram corresponding to FIG. 2, showing a modification of the first example of the embodiment. FIG. 4 is a half sectional view showing a hub unit bearing according to a second embodiment.

[First example of embodiment]
A first example of the embodiment will be described with reference to FIGS. 1 and 2. FIG. In this example, a deep groove ball bearing 1 is used as an example of a rolling bearing device. Regarding the deep groove ball bearing 1, the axially outer side means both sides in the left-right direction in FIG. 2, and the axially inner side means the center side in the left-right direction in FIG.

A deep groove ball bearing 1 includes an outer ring 2 as an outer member, an inner ring 3 as an inner member, a plurality of balls 4 each as a rolling element, a pair of shield plates 5a and 5b, and a magnetic field generator. 6.

The outer ring 2 is made of an electrically conductive metal such as medium carbon steel or high carbon chromium bearing steel, and has an annular shape as a whole. The outer ring 2 has a deep-grooved outer ring raceway 7 (with an arcuate cross-section) in the axially intermediate portion of the inner peripheral surface. In addition, the outer ring 2 has locking recessed grooves 8a and 8b on both axially outer sides of the inner peripheral surface. The radial outer ends of the shield plates 5a and 5b are locked in the locking grooves 8a and 8b. The outer ring 2 is fitted and fixed to a housing (not shown) and does not rotate during use.

The inner ring 3 is made of an electrically conductive metal such as medium carbon steel or high carbon chromium bearing steel, and has an annular shape as a whole. The inner ring 3 is arranged radially inward of the outer ring 2 and coaxial with the outer ring 2 . The inner ring 3 has a deep-grooved inner ring raceway 9 (with an arcuate cross-section) in the axially intermediate portion of the outer peripheral surface. In addition, the inner ring 3 has seal grooves 10a and 10b having a U-shaped cross section or a J-shaped cross section on both axially outer sides of the outer peripheral surface. The inner ring 3 is fitted and fixed to a rotating shaft (not shown) and rotates during use.

An annular space 11 having an annular shape is provided between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the inner ring 3 . The annular space 11 is filled with a lubricant (grease) (not shown) for the purpose of forming an EHL oil film between the outer ring raceway 7 and the inner ring raceway 9 and the rolling surfaces of the balls 4 . The lubricant used in this example is a conventional non-conductive lubricant, but a conductive lubricant can also be used in the practice of the present invention.

The balls 4 are made of a conductive hard metal such as high-carbon chromium bearing steel, and are arranged between the outer ring raceway 7 and the inner ring raceway 9 so as to be free to roll. That is, the balls 4 are arranged in the annular space 11 . The balls 4 are arranged inside the annular space 11 at regular intervals in the circumferential direction. When the inner ring 3 rotates together with the rotating shaft, the balls 4 rotate about the rotation axis R arranged in parallel with the central axis of the deep groove ball bearing 1 and directed in the horizontal direction in FIG. Further, since the contact angle of the balls 4 of the deep groove ball bearing 1 is 0 degrees, the direction of the contact angle of the balls 4 (=the direction of the line of action of the load of the balls 4) It faces the radial direction (the radial direction in FIG. 1 and the vertical direction in FIG. 2). When carrying out the present invention, a retainer made of a non-magnetic material such as synthetic resin may be further provided in order to retain the balls so that they can roll freely.

The shield plates 5 a and 5 b are sealing members and prevent foreign matter from entering the annular space 11 . The shield plates 5a and 5b are made of a corrosion-resistant metal plate such as a non-magnetic stainless steel plate, and have an annular shape as a whole. The shield plates 5a and 5b are arranged at openings on both axially outer sides of the annular space 11 so as to sandwich the balls 4 from both axial sides. Each of the shield plates 5a and 5b is fixed to the outer ring 2 by engaging radially outer ends thereof with the engaging grooves 8a and 8b. The radially inner ends of the shield plates 5a and 5b are closely opposed to the inner surfaces of the seal grooves 10a and 10b and are not in contact with the inner ring 3. As shown in FIG. Therefore, the shield plates 5a and 5b constitute a non-contact sealing device. As the sealing member, it is also possible to use a contact seal having a structure in which an elastic material having a seal lip is vulcanized and adhered to a metal core, as described in Japanese Patent Application Laid-Open No. 2015-102200. In this case, the elastic member is made of non-conductive rubber, and the metal core is made of non-magnetic stainless steel plate. Magnetic leakage through the outer ring 2 or the inner ring 3 can be prevented by making the shield plates 5a and 5b or the metal cores constituting the contact seals made of non-magnetic stainless steel.

The magnetic field generator 6 is supported by a pair of shield plates 5a and 5b fixed to the outer ring 2, and has a plurality of magnetic field generators 12 (four in the illustrated example). When carrying out the present invention, the number of magnetic field generators 12 is not particularly limited. The deep-groove ball bearing 1 is used with an internal clearance remaining after it is assembled between a housing (not shown) and a rotating shaft. Therefore, in the deep groove ball bearing 1, less than 50% (30% to 50%) of the entire circumference is a load zone that supports the load, and the remaining range is a non-load zone that does not support the load. Here, since there is a gap between the ball 4 and the outer ring raceway 7 or the inner ring raceway 9, which are present in the non-load zone, the outer ring 2 and the inner ring 3 cannot be electrically connected. Therefore, if only one (one place) magnetic field generator 12 is provided in the annular space 11, the magnetic field generator 12 is fixed so that one magnetic field generator 12 enters the load zone. It is necessary to adjust the positions of the shield plates 5a and 5b and align the phases of the deep groove ball bearing 1 with each other. On the other hand, when four or more magnetic field generators 12 are provided in the annular space 11 at equal intervals in the circumferential direction, at least one Since the magnetic field generating part 12 of is in the load zone, the operation of phasing the deep groove ball bearing 1 can be omitted.

Each of the magnetic field generators 12 is supported by a pair of shield plates 5a and 5b, and has a configuration in which an N pole and an S pole are arranged so as to sandwich the ball 4 from both sides with respect to the direction of the rotation axis R. there is For this reason, in this example, the magnetic field generator 12 is composed of a pair of magnet elements 13a and 13b each made of a permanent magnet. In the case of carrying out the present invention, instead of the magnet element made of a permanent magnet, a shield plate (or a metal core constituting a contact seal) magnetized with vulcanized magnetic rubber is used as the magnet element. can also

Each of the magnet elements 13a and 13b is piece-shaped, for example, cylindrical or prismatic, and has an N pole in one half and an S pole in the other half. ing. The radial width dimension of the magnet elements 13a and 13b is smaller than the diameter of the ball 4 when the magnet elements 13a and 13b are supported by the shield plates 5a and 5b.

One magnetic element 13a constituting the magnetic field generating section 12 is supported and fixed to the axial inner surface of the shield plate 5a with the N pole directed toward the ball 4 and the S pole directed toward the shield plate 5a. ing. On the other hand, the other magnetic element 13b, which constitutes the magnetic field generating section 12, faces the inner surface of the shield plate 5b in the axial direction with the S pole facing the ball 4 and the N pole facing the shield plate 5b. Among them, it is supported and fixed to a portion whose phase in the circumferential direction matches that of the one magnetic element 13a. Therefore, the north pole of the magnet element 13a and the south pole of the magnet element 13b are arranged to face each other in the axial direction. A gap slightly larger than the diameter of the ball 4 is provided between the end surface of the magnetic element 13a on the N pole side and the end surface of the magnetic element 13b on the S pole side. Although the means for attaching the magnet elements 13a and 13b to the shield plates 5a and 5b is not particularly limited, they can be attached using an adhesive, for example. Moreover, the mounting phases of the pair of magnetic elements 13a and 13b that constitute the magnetic field generating section 12 are preferably the same, but may be slightly (about 10°) out of phase.

The magnetic field generating unit 12 is provided in the annular space 11 in the direction of rotation of the ball 4 as indicated by the arrow α in FIG. A magnetic field is generated in a direction coinciding with the direction of the axis R. Specifically, the direction of the magnetic field generated by the magnetic field generator 12 coincides with the direction of the rotation axis R of the ball 4, which exists in the portion where the circumferential position coincides with the magnetic field generator 12 (that is, crosses the magnetic field). do. When the direction of the magnetic field generated by the magnetic field generator 12 coincides with the direction of the rotation axis R of the ball 4, it not only completely coincides with the direction of the rotation axis R, but also substantially coincides (10° It also includes cases where it is off by a degree.

In this example, the magnetic field generators 12 each composed of a pair of magnet elements 13a and 13b are arranged at regular intervals in the circumferential direction of the annular space 11 . For this reason, the magnetic field generator 6 of this example generates a magnetic field in a direction coinciding with the direction of the rotation axis R of the ball 4 at a plurality of locations in the annular space 11 that are equally spaced in the circumferential direction. Therefore, the magnitude of the magnetic field generated in the annular space 11 is larger in the portion where the phase in the circumferential direction matches that of the magnetic field generator 12 than in the portion where the phase in the circumferential direction deviates from the magnetic field generator 12 . As a result, the magnitude of the magnetic field generated by the magnetic field generator 6 of this example changes in the circumferential direction of the annular space 11 . In other words, the magnetic field generator 6 generates a magnetic field that is not uniform in the circumferential direction of the annular space 11 . Specifically, the magnitude of the magnetic field (the strength of the magnetic field) generated by the magnetic field generator 6 alternately changes with respect to the circumferential direction of the annular space 11 .

In this example, the number (total number) of the magnetic field generators 12 is regulated in relation to the number (total number) of the balls 4 . That is, the number of balls 4 and the number of magnetic field generators 12 are regulated so that the number of balls 4 is an integral multiple of the number of magnetic field generators 12 . Note that FIG. 1 shows a case where the number of balls 4 is eight, which is twice the number of magnetic field generators 12 .

When the deep groove ball bearing 1 is in operation (when the inner ring 3 rotates), the balls 4 rotate about the rotation axis R pointing in the horizontal direction in FIG. , revolves around the annular space 11. When the ball 4 revolves in the annular space 11, the ball 4 crosses the magnetic field generated by the magnetic field generator 6 in the circumferential direction. Since the ball 4 is made of a conductive metal material, an electromotive force is generated in the ball 4 in the direction of the contact angle (vertical direction in FIG. 2) according to Fleming's right-hand rule when crossing the magnetic field.

Specifically, the direction of the magnetic field is the direction of the arrow α in FIG. 2, and the ball 4 is revolving from the front side to the back side in FIG. ), an electromotive force directed radially inward (lower side in FIG. 2) is generated in the ball 4 . Therefore, when the outer ring 2 side is positively charged, or when the inner ring 3 side is negatively charged, static electricity can be removed efficiently. On the other hand, the direction of the magnetic field is the direction of the arrow α in FIG. 2, and the ball 4 is revolving from the back side to the front side in FIG. 2 (revolving in the direction of the arrow Y in FIG. 1). In this case, an electromotive force directed radially outward (upper side in FIG. 2) is generated in the ball 4 . Therefore, when the outer ring 2 side is negatively charged, or when the inner ring 3 side is positively charged, static electricity can be removed efficiently. If the direction of static elimination does not match, the direction of static elimination can be matched by replacing the right and left sides of the deep groove type ball bearing 1 and assembling them.

In particular, in the deep groove ball bearing 1 of this example, the magnetic field generators 12 are arranged at a plurality of locations in the circumferential direction of the annular space 11, and the magnetic field in the circumferential direction of the annular space 11 is not uniform. The electromotive force generated at is a pulse-wave electromotive force (an electromotive force that periodically changes between a maximum value and a minimum value whose positive and negative do not change). Therefore, a pulse wave current tends to flow through the ball 4 each time it crosses the magnetic field generated by the magnetic field generator 12 .

Since the annular space 11 is filled with a lubricant, a non-conductive EHL oil film with high insulation is formed between the outer ring raceway 7 and the inner ring raceway 9 existing in the load zone and the rolling elements of the balls 4. be. However, every time the magnetic field generated by the magnetic field generator 12 is traversed, a pulse-wave electromotive force is generated in the ball 4, so a dielectric phenomenon occurs in the EHL oil film, allowing current to pass through the EHL oil film. That is, a displacement current flows through the EHL oil film as if a voltage with a time-varying magnitude is applied to a capacitor. In this example, the outer ring 2 and the inner ring 3 can be electrically connected by such a principle.

Moreover, the higher the rotational speed of the deep groove ball bearing 1 (the rotational speed of the inner ring 3), the higher the revolution speed of the balls 4, and the more frequently the balls 4 cross the magnetic field (the shorter the time interval). The frequency of the generated pulsed electromotive force increases. Therefore, the effect of conduction between the outer ring 2 and the inner ring 3 due to the dielectric phenomenon increases as the rotational speed of the deep groove ball bearing 1 increases. Therefore, according to the deep groove type ball bearing 1 of this example, the outer ring 2 and the inner ring 3 can be sufficiently electrically connected even when the rotational speed increases.

Furthermore, the deep groove type ball bearing 1 of this example utilizes the pulse-wave electromotive force generated in the balls 4 to rotate one of the housing in which the outer ring 2 is fitted and the rotating shaft in which the inner ring 3 is fitted. Static electricity can be released (removed) from one (charged and having a higher absolute voltage) to the other.

In the deep-groove ball bearing 1 of this example, the ball 4 generates a pulse-wave electromotive force to cause a dielectric phenomenon in the EHL oil film, thereby allowing the outer ring 2 and the inner ring 3 to conduct. (non-conductive) lubricants can be used. Therefore, the outer ring 2 and the inner ring 3 can be electrically connected without sacrificing the low torque and long life of the deep groove ball bearing 1 .

Moreover, unlike the electric discharge phenomenon caused by dielectric breakdown, the rolling surfaces of the outer ring raceway 7, the inner ring raceway 9, and the balls 4 do not suffer from electrolytic corrosion, so the life of the bearing does not decrease. Moreover, since it is not necessary to use conductive grease, the deep groove type ball bearing 1 does not increase the rotational resistance or give a rough feeling unlike the case where carbon black is used as a conductor component.

Furthermore, in this example, since the number of balls 4 is an integer multiple of the number of magnetic field generators 12, the current phase can be made in phase. Therefore, current can flow simultaneously in a plurality of balls 4, and the total amount of instantaneous current flowing between the outer ring 2 and the inner ring 3 can be increased. Therefore, for example, it is possible to prevent the timing of the two generated currents from being shifted, as in the case where the magnetic field generators are arranged at two diametrically opposite sides of the annular space and the number of balls is an odd number. Therefore, the outer ring 2 and the inner ring 3 can be effectively connected.

Even when a conductive lubricant (grease) is used instead of a non-conductive lubricant, the lubricant has dielectric properties similar to those of a capacitor in addition to conductivity. Therefore, the effect of energization between the outer ring and the inner ring can be enhanced by the pulse-wave electromotive force generated in the ball. In addition, since the movement of the lubricant induces current in the conductor component, the conductive effect can be further enhanced.

[Modification of the first example of the embodiment]
A modification of the first example of the embodiment will be described with reference to FIG.

In the deep groove ball bearing 1 of this example, the outer ring 2a and the inner ring 3a are each made of non-magnetic stainless steel, and the structure of the plurality of magnetic field generators 12a constituting the magnetic field generator 6a is the same as that of the first embodiment. Modified from the structure of the example.

That is, in the magnetic field generator 6a of this example, each of the plurality of magnetic field generators 12a is composed of only one magnet element 13c supported by one shield plate 5a (5b). Also in this example, instead of the shield plates 5a and 5b, contact seals such as those described in Japanese Patent Application Laid-Open No. 2015-102200 can be used.

Each of the magnet elements 13c is piece-shaped, for example, cylindrical or prismatic, and has an N pole in one half and an S pole in the other half. . The magnetic element 13c is aligned with the axis of the shield plate 5a (5b) with the N pole (or S pole) facing the ball 4 and the S pole (or N pole) facing the shield plate 5a (5b). It is supported and fixed on the direction inside surface.

The magnetic field generating part 12a exits from the end face of the magnet element 13c on the N pole side and enters (returns to) the end face of the magnet element 13c on the S pole side in the annular space 11 in a direction coinciding with the direction of the rotation axis of the ball 4. Generate a magnetic field. The magnitude of the magnetic field (strength of the magnetic field) generated by the magnetic field generator 12a is smaller than the magnitude of the magnetic field generated by the magnetic field generator 12 according to the first example of the embodiment.

In this example, the magnetic field generators 12a having the configuration as described above are arranged at regular intervals in the circumferential direction of the annular space 11 . Therefore, in the case of the magnetic field generator 6a of the present embodiment as well, magnetic fields are generated in a direction coinciding with the direction of the axis of rotation of the balls 4 at a plurality of locations in the annular space 11 which are equally spaced in the circumferential direction. That is, the magnetic field generator 6 a generates a magnetic field that is not uniform in the circumferential direction of the annular space 11 .

In the case of this example as described above, although the conduction effect is lower than that of the structure of the first example of the embodiment, a pulse-wave-like electromotive force is generated in the ball 4 and a dielectric phenomenon occurs in the EHL oil film. By doing so, the outer ring 2a and the inner ring 3a can be electrically connected. Further, since the magnetic field generator 12a is composed of only one magnet element 13c, the weight and cost of the rolling bearing device 1 can be reduced.
Other configurations and effects are the same as those of the first embodiment.

[Second example of embodiment]
A second example of the embodiment will be described with reference to FIG. In this example, as an example of a rolling bearing device, a hub unit bearing 14 for rotatably supporting a wheel of an automobile will be used for explanation.

The hub unit bearing 14 is an inner ring rotating type and is a so-called third generation hub unit bearing for a driven wheel. The hub unit bearing 14 includes an outer ring 15 as an outer member, a hub 16 as an inner member, a plurality of rolling elements 17a and 17b, a seal ring 18, a cap 19, a pair of magnetic field generators 20a, 20b.
Regarding the hub unit bearing 14, the axially outer side is the left side in FIG. is the right side of FIG.

The outer ring 15 is made of a conductive metal such as medium carbon steel and has a substantially cylindrical shape. The outer ring 15 has double-row outer ring raceways 21a and 21b on its inner peripheral surface, and has a stationary flange 22 protruding radially outward at an axially intermediate portion of its outer peripheral surface. The stationary flange 22 has support holes 23 axially penetrating therethrough at a plurality of locations in the circumferential direction. The outer ring 15 is supported and fixed to the suspension system constituting the vehicle body by bolts inserted through the support holes 23, and does not rotate even when the wheels rotate.

The hub 16 is arranged radially inside the outer ring 15 coaxially with the outer ring 15, and comprises a hub ring 24 made of a conductive metal such as medium carbon steel and a conductive metal made of a high carbon chromium steel. and an inner ring 25 of The hub 16 has double-row inner ring raceways 26a and 26b at portions of the outer peripheral surface facing the double-row outer ring raceways 21a and 21b.

The hub ring 24 is a shaft member that fits and holds the inner ring 25 , and has a shaft portion 27 , a rotary flange 28 and a pilot portion 29 . In this example, since the hub unit bearing 14 is used for the driven wheel, the hub wheel 24 is configured in a solid shape. However, when the present invention is applied to a hub unit bearing for a drive wheel, a hub wheel having a spline hole axially penetrating in the radial center portion can be used. A drive shaft forming a constant velocity joint is spline-engaged with the spline hole.

The shaft portion 27 is provided in a range from the axially inner portion to the axially intermediate portion of the hub wheel 24 . The axially inner portion of the shaft portion 27 has a small-diameter portion 30 having an outer diameter smaller than that of the portion adjacent to the axially outer side and onto which the inner ring 25 is fitted. It has an outer row of inner ring raceways 26a. The shaft portion 27 has a crimped portion 31 that presses the axially inner end face of the inner ring 25 at its axially inner end portion. When carrying out the present invention, the inner ring may be fixed to the hub wheel by forming a male threaded portion on the outer peripheral surface of the axially inner end portion of the shaft portion and screwing a nut onto the male threaded portion. good.

The rotating flange 28 is provided in a portion of the hub wheel 24 located axially outside the axially outer end of the outer ring 15 and has a substantially circular ring shape. The rotating flange 28 has mounting holes 32 axially penetrating therethrough at a plurality of locations in the circumferential direction of the radially intermediate portion. A stud 33 is press-fitted into each of the mounting holes 32 . A nut (not shown) is screwed onto the tip of the stud 33 . As a result, the wheel and the braking rotor that constitute the wheel are fixed to the outside of the rotating flange 28 in the axial direction. When carrying out the present invention, a female screw hole is formed in the rotary flange, and a hub bolt is directly screwed into the female screw hole to fix the wheel and the braking rotor to the outside of the rotary flange in the axial direction. good.

The pilot portion 29 is provided on the outer end portion of the hub wheel 24 in the axial direction, and has a substantially cylindrical shape for externally fitting the wheel and the braking rotating body with a loose fit without backlash. there is

The inner ring 25 has an annular shape, and has an inner ring raceway 26b in an axially inner row at an axially intermediate portion of the outer peripheral surface. The inner ring 25 is fitted onto the small diameter portion 30 provided on the shaft portion 27 by interference fit.

An annular space 11 a having an annular shape is provided between the inner peripheral surface of the outer ring 15 and the outer peripheral surface of the hub 16 . In the case of this example as well, in the annular space 11a, an EHL oil film (not shown) is provided for the purpose of forming an EHL oil film between the outer ring raceways 21a, 21b and the inner ring raceways 26a, 26b and the rolling surfaces of the rolling elements 17a, 17b. A non-conductive lubricant (grease) is enclosed.

The rolling elements 17a, 17b are made of an electrically conductive hard metal such as high carbon chromium bearing steel. A plurality of rolling elements 17a in the outer row arranged axially outward are arranged at regular intervals in the circumferential direction between the outer ring raceway 21a and the inner ring raceway 26a, and are made of a non-magnetic material such as synthetic resin. is rotatably held by a retainer 34a. On the other hand, the plurality of rolling elements 17b in the inner row arranged axially inward are arranged at regular intervals in the circumferential direction between the outer ring raceway 21b and the inner ring raceway 26b, and are made of synthetic resin or the like. It is rotatably held by a retainer 34b made of a non-magnetic material. Thereby, the hub 16 is rotatably supported radially inwardly of the outer ring 15 .

Although balls are used as the rolling elements 17a and 17b in this example, tapered rollers may be used instead of the balls. In this example, the pitch diameter of the rolling elements 17a in the axially outer row and the pitch diameter of the rolling elements 17b in the axially inner row are the same. The diameter and the pitch diameter of the rolling elements of the axially inner row can also differ from each other.

The seal ring 18 closes the axial outer opening of the annular space 11a. The seal ring 18 includes a metal core 35 and a seal material 36 .

The core metal 35 is formed into an annular shape as a whole by bending a non-magnetic stainless steel plate. The cored bar 35 is internally fitted and fixed to the axially outer end of the outer ring 15 .

The sealing material 36 is made of an elastic material such as an elastomer such as rubber, and is supported and fixed to the metal core 35 by vulcanization adhesion. The sealing member 36 has at least one (three in the illustrated example) sealing lips 37 . Each tip of the seal lip 37 is in sliding contact with the outer peripheral surface of the shaft portion 27 and/or the axial inner surface of the rotary flange 28 over the entire circumference.

The cap 19 is fitted to the axially inner end of the outer ring 15 and closes the axially inner opening of the outer ring 15 . The cap 19 is made of a non-magnetic stainless steel plate or resin, and has a bottomed cylindrical shape as a whole. That is, the cap 19 includes a cylindrical fitting tube portion 38 fitted inside the axially inner end portion of the outer ring 15 and a fitting tube portion 38 that is bent radially inward from the axially inner end portion of the fitting tube portion 38 . and a bottom plate portion 39 that closes the axially inner opening of the fitting cylinder portion 38 .

The magnetic field generator 20a generates a magnetic field in the axially outer space of the annular space 11a where the rolling elements 17a of the axially outer row are arranged, in the direction of the rotation axis R _O of the rolling elements 17a. . On the other hand, the magnetic field generator 20b is installed in the axially inner space of the annular space 11a where the rolling elements 17b of the axially inner row are arranged, in the direction that coincides with the direction of the rotation axis _Ri of the rolling elements 17b. Generate a magnetic field.

The magnetic field generator 20a has a plurality of magnetic field generators 40a. Each of the magnetic field generators 40a has a configuration in which an N pole and an S pole are arranged so as to sandwich the rolling element 17a from both sides with respect to the direction of the rotation axis _RO . For this reason, in this example, the magnetic field generating section 40a is composed of a pair of magnet elements 41 and 42 each made of a permanent magnet.

The magnetic field generator 20b has a plurality of magnetic field generators 40b. In this example, the number of the magnetic field generating units 40b constituting the magnetic field generating device 20b is the same as the number of the magnetic field generating units 40a constituting the magnetic field generating device 20a, and the plurality of magnetic field generating units 40b are replaced by the plurality of magnetic field generating units. It is arranged in the same phase as 40a. Each of the magnetic field generators 40b has a configuration in which an N pole and an S pole are arranged so as to sandwich the rolling element 17b from both sides with respect to the direction of the rotation axis _Ri . For this reason, in this example, the magnetic field generator 40b is composed of a pair of magnet elements 42 and 43 each made of a permanent magnet.

Thus, in this example, one magnet element 42 is shared by two magnetic field generators, ie, the magnetic field generator 40a and the magnetic field generator 40b. In other words, the magnet element 42 is used not only for configuring the magnetic field generating section 40a, but also for configuring the magnetic field generating section 40b.

Each of the magnet elements 41, 42, and 43 is piece-shaped, for example, cylindrical or prismatic, and has an N pole in one half and an S pole in the other half. have. In the illustrated example, the size of the magnet element 41 arranged on the outer side in the axial direction is made smaller than the size of the magnet element 42 arranged in the intermediate portion in the axial direction and the size of the magnet element 43 arranged on the inner side in the axial direction. However, when implementing the present invention, the size of the magnet elements 41, 42, 43 can be changed as appropriate. Also, although the magnitude of the magnetic field is reduced, the magnet element 42 can be replaced with a non-magnetized ferromagnetic material.

The magnetic element 41 constituting the magnetic field generating part 40a is arranged in the axial direction of the core metal 35 constituting the seal ring 18 with the S pole directed toward the rolling element 17a side and the N pole directed toward the seal ring 18 side. It is supported and fixed on the side.

When carrying out the present invention, instead of the magnetic element 41 that constitutes the magnetic field generating section 40a, a magnet element made of a permanent magnet may be replaced with a magnetic rubber that is vulcanized and molded separately from the sealing material that constitutes the seal ring. By bonding and magnetizing the magnetic rubber material, the magnetized portion can be used as a magnet element.

The magnet elements 42 constituting the magnetic field generating section 40a and the magnetic field generating section 40b are in a state in which the north pole is directed toward the axially outer row of the rolling elements 17a and the south pole is directed toward the axially inner row of the rolling elements 17b. , and is supported by a holder 44 at an axially intermediate portion of the inner peripheral surface of the outer ring 15 . The holder 44 is made of a non-magnetic material such as synthetic resin, and is supported and fixed to an axially intermediate portion of the inner peripheral surface of the outer ring 15 .

The magnetic element 43 forming the magnetic field generating section 40b is arranged on the axial outer surface of the bottom plate section 39 forming the cap 19 with the N pole facing the rolling element 17b side and the S pole facing the cap 19 side. supported and fixed. The mounting means of the magnet element 41 to the seal ring 18, the mounting means of the magnet element 42 to the holder 44, and the mounting means of the magnet element 43 to the cap 19 are not particularly limited, but they can be attached using an adhesive, for example.

The magnetic field generating part 40a is located in the space outside the annular space 11a in the axial direction _. generates a magnetic field oriented in the direction of On the other hand, the magnetic field generating part 40b is located in the space inside the annular space 11a in the axial direction. A magnetic field is generated in a direction coinciding with the direction of the rotation axis _Ri . The hub unit bearing 14 for rotatably supporting the right wheel and the hub unit 14 for rotatably supporting the left wheel rotate in opposite directions when the vehicle is traveling forward (or backward). Therefore, the directions of the magnetic fields generated by the magnetic field generators 40a and 40b are opposite in the hub unit bearing 14 for the right wheel and the hub unit bearing 14 for the left wheel.

In this example, the magnetic field generators 40a each composed of a pair of magnet elements 41 and 42 are arranged at regular intervals in the circumferential direction of the annular space 11a. For this reason, the magnetic field generator 20a generates a magnetic field in a direction coinciding with the direction of the rotation axis R _O of the rolling element 17a at a plurality of circumferentially equally spaced locations in the annular space 11a. Therefore, the magnitude of the magnetic field generated in the axially outer portion of the annular space 11a is greater at the portion where the phase in the circumferential direction matches that of the magnetic field generator 40a than at the portion where the phase in the circumferential direction deviates from the magnetic field generator 40a. will also grow. As a result, the magnitude of the magnetic field generated by the magnetic field generator 20a of this example changes in the circumferential direction of the annular space 11a. In other words, the magnetic field generator 20a generates a magnetic field that is not uniform in the circumferential direction of the annular space 11a. Specifically, the magnitude of the magnetic field (the strength of the magnetic field) generated by the magnetic field generator 20a changes alternately in the circumferential direction of the annular space 11a.

In this example, the magnetic field generators 40b, which are composed of a pair of magnet elements 42 and 43, are arranged at regular intervals in the circumferential direction of the annular space 11a. For this reason, the magnetic field generator 20b generates a magnetic field in a direction coinciding with the direction of the rotation axis _Ri of the rolling element 17b at a plurality of equally spaced locations in the annular space 11a. Therefore, the magnitude of the magnetic field generated in the inner portion of the annular space 11a in the axial direction is greater in the portion where the phase in the circumferential direction matches that of the magnetic field generator 40b than in the portion where the phase in the circumferential direction deviates from the magnetic field generator 40b. will also grow. As a result, the magnitude of the magnetic field generated by the magnetic field generator 20b of this example changes in the circumferential direction of the annular space 11b. In other words, the magnetic field generator 20b generates a non-uniform magnetic field in the circumferential direction of the annular space 11a. Specifically, the magnitude of the magnetic field (strength of the magnetic field) generated by the magnetic field generator 20b alternately changes in magnitude along the circumferential direction of the annular space 11a.

In this example, the number of magnetic field generators 40a is regulated in relation to the number of rolling elements 17a, and the number of magnetic field generators 40b is regulated in relation to the number of rolling elements 17b. That is, the number of rolling elements 17a and the number of magnetic field generating sections 40a are regulated so that the number of rolling elements 17a is an integral multiple of the number of magnetic field generating sections 40a, and the number of rolling elements 17b is the number of magnetic field generating sections 40a. The number of rolling elements 17b and the number of magnetic field generating portions 40b are regulated so as to be integral multiples of the number of portions 40b.

When the hub unit bearing 14 is in operation, the rolling elements 17a and 17b revolve around the center axis O of the hub unit bearing 14 in the annular space 11a while rotating around the rotation axes R _O and _Ri . When the rolling elements 17a in the axially outer row revolve in the annular space 11a, the rolling elements 17a circumferentially cross the magnetic field generated by the magnetic field generator 20a. , an electromotive force is generated in the direction of the contact angle (direction perpendicular to the rotation axis _RO ). In addition, when the rolling elements 17b in the axially inner row revolve in the annular space 11a, the rolling elements 17b cross the magnetic field generated by the magnetic field generator 20b in the circumferential direction. Also, an electromotive force is generated in the direction of the contact angle (direction perpendicular to the rotation axis _Ri ). In addition, since the vehicle body is normally positively charged, when the vehicle is traveling forward (or backward), the magnetic field is generated so that the rolling elements 17a and 17b generate an electromotive force directed inward in the radial direction. It regulates the direction of the magnetic field generated by the portions 40a and 40b and the revolving direction of the rolling elements 17a and 17b when the vehicle is traveling forward.

In the hub unit bearing 14 of this example, the magnetic field generators 40a and 40b are arranged at a plurality of locations in the circumferential direction of the annular space 11a. The electromotive force generated in the rolling elements 17a and 17b becomes a pulse-wave electromotive force. Therefore, a pulse wave current tends to flow through each of the rolling elements 17a and 17b every time the magnetic fields generated by the magnetic field generators 40a and 40b are crossed.

Therefore, in the case of this example as well, the outer ring 15 and the hub 16 can be electrically connected by generating an electromotive force in the rolling elements 17a and 17b and causing a dielectric phenomenon in the EHL oil film. As a result, the static electricity charged on the vehicle body can be efficiently released to the tire side through the hub unit bearing 14 .

In addition, rubber tires have the characteristics of a parallel circuit of resistors and capacitors electrically, so conduction by pulse-wave electromotive force lowers the resistance value and removes static electricity from the vehicle body. You can increase the effect. For this reason, as in this example, the number of rolling elements 17a and the number of magnetic field generating sections 40a are regulated such that the number of rolling elements 17a is an integer multiple of the number of magnetic field generating sections 40a, and By regulating the number of rolling elements 17b and the number of magnetic field generators 40b so that the number of moving bodies 17b is an integral multiple of the number of magnetic field generators 40b, the number of currents generated by the plurality of magnetic field generators 40a is reduced. Since the phases can be made the same and the phases of the currents generated by the plurality of magnetic field generators 40b can be made the same, conduction to the tire can be improved.

Moreover, as the rotation speed of the hub unit bearing 14 (the rotation speed of the hub 16) increases, the revolution speed of the rolling elements 17a and 17b increases, and the frequency at which the rolling elements 17a and 17b cross the magnetic field increases (the time interval increases). shorter), so the frequency of the generated pulsed current increases. Therefore, the conduction effect between the outer ring 15 and the hub 16 increases as the rotation speed of the hub unit bearing 14 increases. Therefore, according to the hub unit bearing 14 of the present embodiment, as the vehicle speed increases and the vehicle body is more likely to be charged with static electricity, the conduction effect between the outer ring 15 and the hub 16 can be enhanced. You can escape efficiently to the side.
Other configurations and effects are the same as those of the first embodiment.

Although illustration is omitted, as a modification of the second example of the embodiment, the magnetic element 41 constituting the magnetic field generating section 40a disposed axially outside is omitted, and the magnetic field generating section 40a is replaced by the magnetic element 42 only. Alternatively, the magnetic element 42 constituting the magnetic field generating section 40a arranged axially outside is omitted, the magnetic field generating section 40a is constructed only from the magnetic element 41, and the magnetic field generating section 40b is constructed only from the magnetic element 43. Can also be configured. In these cases, although the conductive effect of the hub unit bearing 14 is reduced, the Hals wave-like electromotive force generated in each of the axially outer row and the axially inner row will not cancel each other out. can enhance the energization effect of

Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate without departing from the technical idea of the invention. In addition, the structures of the respective examples of the embodiments can be implemented in combination as appropriate as long as there is no contradiction.

When implementing the present invention, when a plurality of magnetic field generators constituting a magnetic field generator are provided, the plurality of magnetic field generators can be arranged at unequal intervals in the circumferential direction. Alternatively, only one magnetic field generating section may be provided to configure the magnetic field generating device. Furthermore, the magnetic element that constitutes the magnetic field generator can be made of a permanent magnet, or can be made of magnetized magnetic rubber. Also, the shape and size of the magnet element are not limited to the structure of each example of the embodiment, and can be changed as appropriate. Furthermore, the rolling bearing device of the present invention is not limited to deep groove type ball bearings and hub unit bearings, and may be single row or double row angular contact ball bearings, cylindrical roller bearings, needle bearings, tapered roller bearings, spherical roller bearings. etc., can be applied to various bearings. Further, the rolling bearing device of the present invention is applicable not only to the structure of the inner ring rotating type, but also to the structure of the outer ring rotating type.

1 deep groove ball bearing 2, 2a outer ring 3, 3a inner ring 4 ball 5a, 5b shield plate 6, 6a magnetic field generator 7 outer ring raceway 8a, 8b locking groove 9 inner ring raceway 10a, 10b seal groove 11, 11a annular space 12, 12a magnetic field generators 13a, 13b, 13c magnet element 14 hub unit bearing 15 outer ring 16 hubs 17a, 17b rolling elements 18 seal ring 19 caps 20a, 20b magnetic field generators 21a, 21b outer ring raceway 22 stationary flange 23 support hole 24 hub Ring 25 Inner rings 26a, 26b Inner ring raceway 27 Shaft 28 Rotary flange 29 Pilot portion 30 Small diameter portion 31 Crimping portion 32 Mounting hole 33 Studs 34a, 34b Cage 35 Core metal 36 Sealing material 37 Seal lip 38 Fitting cylinder portion 39 Bottom plate portion 40a, 40b magnetic field generator 41 magnet element 42 magnet element 43 magnet element 44 holder

Claims (5)

a conductive outer member having an outer ring raceway on its inner peripheral surface;
a conductive inner member having an inner ring raceway on its outer peripheral surface;
a plurality of conductive rolling elements arranged between the outer ring raceway and the inner ring raceway;
a magnetic field generator that generates a magnetic field in a direction that matches the direction of the rotation axis of the rolling element in an annular space that exists between the inner peripheral surface of the outer member and the outer peripheral surface of the inner member; prepared,
The magnetic field generated by the magnetic field generator changes in magnitude in the circumferential direction of the annular space,
By revolving the rolling element so as to traverse the magnetic field, the rolling element generates an electromotive force in the direction of the contact angle,
Rolling bearing device. The magnetic field generator has a plurality of magnetic field generators each having an N pole and an S pole so as to sandwich the rolling element from both sides with respect to the direction of the rotation axis,
The magnetic field generators are arranged at regular intervals in the circumferential direction of the annular space,
A rolling bearing device according to claim 1. 3. The rolling bearing device according to claim 2, wherein the number of said rolling elements is an integral multiple of the number of said magnetic field generators. one of the outer member and the inner member is a stationary ring that does not rotate during use;
The other of the outer member and the inner member is a rotating wheel that rotates with the wheel when in use.
A rolling bearing device according to any one of claims 1 to 3. 5. The rolling bearing device according to claim 1, wherein said annular space is filled with a non-conductive lubricant.

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