JP2011058523A - Rolling bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a rolling bearing unit which employs grease capable of securing lubricating performance required even during temperature rise time, and which can suppress rotational resistance low immediately after the start of operation. <P>SOLUTION: In the rolling bearing unit, a sheet-like or strip electric heater 13 is set up on the outer circumferential surface of an outer ring 2 in a state of being stuck or wound on the outer ring 2. It is made possible to supply electric power from a photovoltaic power generation panel 14 installed on a roof surface of an automobile to the electric heater 13. The power supply from the photovoltaic power generation panel 14 to the electric heater 13 is controlled (ON, OFF) based on the temperature of the grease to prevent the grease temperature from rising excessively (so much as it becomes impossible to secure the required lubricating performance exceeding the extent that the rotational resistance of the hub 3 can be suppressed). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an improvement of a rolling bearing unit such as a wheel supporting hub unit for rotatably supporting a wheel with respect to a suspension device of an automobile. Specifically, at the time of start-up, the rotational resistance (dynamic torque) is kept low from the initial stage to reduce the energy required to drive the rotating part.

  A wheel supporting hub unit for rotatably supporting a wheel with respect to a suspension device is widely known, for example, as described in Patent Document 1. FIG. 5 shows an example of such a wheel supporting hub unit 1. In this wheel support hub unit 1, a hub 3 that is a rotation side raceway is concentrically disposed on an inner diameter side of an outer ring 2 that is a stationary side raceway. And between the double row outer ring raceways 4, 4 provided on the inner peripheral surface of the outer ring 2 and the double row inner ring raceways 5, 5 provided on the outer peripheral surface of the hub 3, each is a rolling element. A plurality of balls 6, 6 are provided for each row, and are held by cages 7, 7 so as to be able to roll, and the hub 3 is rotatably supported on the inner diameter side of the outer ring 2. Yes. Both end openings of the bearing internal space 8 in which the balls 6 and 6 are installed are sealed with a seal ring 9 and a cover 10, which are seal members. Further, grease is sealed in the bearing internal space 8 located between the seal ring 9 and the cover 10, and the rolling surfaces of the balls 6, 6, the outer ring raceways 4, 4, and the Lubrication of the rolling contact portions with both inner ring raceways 5 and 5 is intended.

  In the use state of the wheel support hub unit 1 as described above, the outer ring 2 is provided on the outer peripheral surface of the outer ring 2 on a support member such as a knuckle, an axle housing, an axle beam, etc. The stationary side flange 18 is used for coupling and fixing, and the portion of the hub 3 near the outer end in the axial direction (outside with respect to the axial direction is the outer side in the width direction when attached to the vehicle body, and conversely the central side in the width direction. The wheel is supported and fixed to the rotation-side flange 11 provided in the axial direction, thereby supporting the wheel rotatably with respect to the suspension device.

  The rotational resistance of the hub 3 constituting the wheel support hub unit 1 as described above (dynamic torque of the wheel support hub unit 1) is determined by the preload of the balls 6 and 6 and the grease in addition to the dimensions and materials of each part. It is greatly influenced by the viscosity. Of these, it is difficult to change the dimensions, material, and preload taking into account only the reduction of rotational resistance, in order to ensure necessary performance such as rigidity of the wheel supporting hub unit 1. On the other hand, with respect to the grease, the lower the viscosity, the lower the resistance to rotation. However, considering the formation of a sufficiently thick oil film at each rolling contact portion, there is a limit to reducing the viscosity. is there. Considering securing the required oil film thickness even when the temperature of the grease rises due to the stirring resistance associated with the rotation and revolution of the balls 6 and 6 during high speed traveling, etc. In this case, it is necessary to use a grease having a certain degree of viscosity.

  On the other hand, the viscosity of the grease is unavoidably changed depending on the temperature even if there is a difference depending on the composition. Specifically, the viscosity decreases as the temperature increases. The temperature of the grease sealed in the wheel supporting hub unit 1 is the lowest when the air temperature (environmental temperature) is constant, and it is the lowest when the vehicle is stopped for a long time. Gradually increases. Therefore, the rotational resistance of the hub 3 becomes the largest immediately after starting and gradually decreases. For this reason, the resistance is large immediately after the start of traveling of the automobile, and accordingly, the traveling performance and the fuel efficiency performance centering on the acceleration performance are deteriorated. In order to improve these performances immediately after the start of running, the use of grease with low viscosity even at low temperatures ensures the necessary lubrication performance (oil film retention performance) even after the temperature rise of the grease, as described above. Therefore, it cannot be adopted.

  In view of the circumstances as described above, the present invention adopts a grease that can ensure the necessary lubrication performance even when the temperature rises, and to realize a rolling bearing unit that can keep the rotational resistance low immediately after the start of operation. Invented.

Each of the rolling bearing units of the present invention includes a rotation side raceway and a stationary side raceway, a rotation side raceway and a stationary side raceway, a plurality of rolling elements, a seal member, and grease.
Of these, the rotation-side raceway and the stationary-side raceway are arranged concentrically with each other.
The rotating side raceway surface and the stationary side raceway surface are respectively provided on the circumferential surfaces of the both raceways facing each other.
Each of the rolling elements is installed between the rotating side raceway surface and the stationary side raceway surface so as to roll freely.
Further, the seal member seals the end opening of the bearing internal space where the rolling elements are installed.
Furthermore, the grease is sealed in the bearing internal space.

In particular, in the rolling bearing unit according to claim 1, the grease is obtained by attaching a heater to at least one of the peripheral surface portion of the stationary side race and the bearing internal space portion. Can be heated.
When the invention described in claim 1 is carried out, preferably, the heater is an electric heater as in the invention described in claim 2. And it supplies with electricity to this electric heater with a photovoltaic power generation panel.

In the rolling bearing unit according to claim 3, at least a part of the surface of at least one of the rotating-side bearing ring and the stationary-side bearing ring that is in contact with outside air is used. A heat insulating layer is provided.
Furthermore, in the rolling bearing unit according to claim 4, heat is higher between the stationary side bearing ring and a support member for fixing the stationary side bearing ring than a material constituting the stationary side bearing ring. A spacer made of a material having a low transmission rate is interposed.

The rolling bearing unit of the present invention as described above is implemented as a wheel supporting hub unit for rotatably supporting a wheel with respect to a suspension device, for example, as in the invention described in claim 5. To do.
In this case, a plurality of rolling elements are arranged for each of the two rows between the rotation side raceway surface arranged in the double row and the stationary side raceway surface arranged in the double row.
Further, a pair of seal members are provided in a state in which both end openings of the bearing internal space are sealed.
Then, in the state of use, the stationary side race is not rotated in a state of being coupled and fixed to a suspension device, but the rotation side race is rotated together with this wheel while the wheel is supported and fixed.

According to the rolling bearing unit of the present invention configured as described above, the grease that can ensure the necessary lubrication performance even when the temperature rises can be adopted, and the rotational resistance can be kept low immediately after the start of operation.
Patent Document 2 describes a structure in which a heater is provided in a housing incorporating a rolling bearing, which is a solid lubricated rolling bearing used in a vacuum. However, the patent document 2 does not describe the reason for providing the heater. In Patent Document 2, the heater is described only in the drawings and is not described in the specification, but it is considered to be used for heating during the test. In the first place, since the invention described in Patent Document 2 is intended for solid lubricated rolling bearings, it is clear that the heater is not intended to reduce rotational resistance by reducing the viscosity of grease.

FIG. 2 is a half sectional view showing a first example of an embodiment of the present invention. The relationship between the temperature of a double row rolling bearing unit with a rolling circle pitch circle diameter of 64 mm and a preload of 5.3 kN and the dynamic torque of this rolling bearing corresponding to the viscosity of the grease sealed in the rolling bearing unit is shown. Diagram. Sectional drawing which shows the 2nd example of embodiment of this invention. Sectional sectional drawing which shows the 3rd example. Sectional drawing which shows an example of the rolling bearing unit which has not applied this invention.

[First example of embodiment]
FIG. 1 shows a first example of an embodiment of the present invention corresponding to claims 1, 2, and 5. The feature of this example is that an electric heater 13 is installed on the outer peripheral surface of the outer ring 2 in order to keep the viscosity of the grease sealed in the bearing inner space 8 low immediately after the wheel support hub unit 1 is started. Is maintained (to increase the rotation resistance of the hub 3 to a level that can suppress the rotational resistance of the hub 3 while ensuring the necessary lubricity from the start of operation). The configuration and operation of the other parts are substantially the same as those of the conventionally known wheel support hub unit 1 described with reference to FIG. 5, for example, so the description of the equivalent parts is omitted or simplified. The description will focus on the characteristic part.

  In the case of this example, a sheet-like or belt-like electric heater 13 is installed on the outer peripheral surface of the outer ring 2 in a state of being attached (in the case of a sheet-like heater) or wound (in the case of a belt-like heater) to the outer ring 2. ing. In any case, the electric heater 13 can be energized from a solar power generation panel 14 installed on the roof surface of an automobile. The energization from the photovoltaic power generation panel 14 to the electric heater 13 is controlled (ON / OFF) based on the temperature of the grease so that the temperature of the grease is excessively high (the rotation resistance of the hub 3 can be suppressed). It will be prevented from rising so that the required lubricity cannot be secured. For this purpose, a temperature detector 15 such as a temperature sensor or a thermal relay is provided on the inner peripheral surface of the outer ring 2.

  An energization controller installed between the solar power generation panel 14 and the electric heater 13 controls energization from the solar power generation panel 14 to the electric heater 13 based on a detection signal of the temperature detector 15. The grease temperature is set appropriately (before the start of operation, the viscosity of the grease is low enough to suppress the rotational resistance of the hub 3 and high enough to ensure the required lubricity). )maintain. That is, the dynamic torque (rotational resistance of the hub 3) of the wheel supporting hub unit 1 changes as shown in FIG. 2, for example, as the viscosity of the grease changes as the temperature of the wheel supporting hub unit 1 changes. To do. Therefore, in consideration of the characteristics shown in FIG. 2, the electric heater 13 is used to raise the temperature of the wheel-supporting rolling bearing unit 1 and maintain the temperature until the dynamic torque is lowered to a preferable level. Controls energization to.

  According to the structure of the present example configured as described above, the viscosity of the grease sealed in the bearing internal space 8 is set to the rotational resistance of the hub 3 even before the automobile is stopped for a long time and restarted. It can be kept low enough to suppress For this reason, even when the automobile is stopped for a long time and then restarted, the rotational resistance of the wheel supported and fixed to the hub 3 is kept low, and the running performance centering on the acceleration performance and the fuel efficiency performance are improved. it can. In addition, in the case of the structure of the present example, the electric heater 13 is energized from the photovoltaic power generation panel 14, so that the load of the alternator is not increased as in the case of energizing from the battery, and the fuel efficiency performance is increased. The improvement effect can be sufficiently obtained.

  However, even when the amount of power generated by the solar power generation panel 14 cannot be secured, such as in an indoor parking lot, the electric heater 13 is energized from the battery so that the electric heater 13 can sufficiently heat the grease. You can also. In this case, if the photovoltaic power generation panel 14 is configured to charge the battery with the amount consumed by the electric heater 13 (during outdoor travel, etc.), an increase in the load on the alternator can be suppressed. The fuel efficiency improvement effect can be sufficiently secured. Alternatively, if a small battery dedicated to energizing the electric heater 13 is provided and the small battery is configured to be charged by the solar power generation panel 14, the electric heater 13 in a state where it is parked in an indoor parking lot or the like. It is possible to reliably prevent an increase in load on the alternator while ensuring energization of the generator.

[Second Example of Embodiment]
FIG. 3 also shows a second example of an embodiment of the present invention corresponding to claims 1, 2, and 5. In the case of this example, an electric heater 13 a is installed in the portion between the double row outer ring raceways 4, 4 on the inner peripheral surface of the outer ring 2. In the case of this example, since the electric heater 13a directly faces or contacts the grease sealed in the bearing internal space 8, the grease can be effectively heated. For this reason, even if the capacity of the electric heater 13a is kept lower than the capacity of the electric heater 13 of the first example of the above-described embodiment, the grease can be sufficiently heated to a desired temperature. However, in the case of this example, the electric heater 13a may directly contact the grease. Therefore, for safety reasons, it is necessary to consider that the grease does not ignite even if a failure such as a short circuit occurs in the electric heater 13a. Specifically, as the electric heater 13a, a band heater is used in which the heating element is covered with an insulating material such as silicon rubber so as to form a band. In addition, when there is a possibility that the silicon rubber is deteriorated by grease, a band heater in which a heating element is covered with a polyimide film instead of the silicon rubber can be used. In any case, the electric heater 13a as the band heater is fixed to the inner peripheral surface of the outer ring 2 by bonding. Needless to say, the amount of current applied to the band heater is suppressed to such an extent that the insulating material and the adhesive are not damaged.

  Such a structure of this example can sufficiently heat the grease in the bearing internal space 8 even if it is implemented alone. However, it can also be implemented in combination with the structure of the first example of the above-described embodiment (electric heaters 13 and 13a are provided on both inner and outer peripheral surfaces of the outer ring 2). Since the configuration and operation of the other parts are the same as in the first example, a duplicate description is omitted.

[Third example of embodiment]
FIG. 4 shows a third example of the embodiment of the present invention corresponding to the first, third, and fifth aspects. In the case of this example, the outer peripheral surface of the intermediate portion of the outer ring 2 located around the bearing inner space 8, and the bottom surface and inner periphery of the concave portion 16 formed at the center portion of the hub 3 and opened to the axial outer end surface. Heat insulation layers 17a and 17b are provided on the surfaces, respectively. These two heat insulating layers 17a and 17b are preferably those which do not contain water and deteriorate the heat insulating performance even when exposed to rainwater or the like. Specifically, a plate material (metal plate or metal plate) in which an air layer (heat insulating layer) is interposed between a ceramic coating layer, an organic sheet such as nitrile rubber wound, and the outer ring 2 or the peripheral surface of the recess 16. Non-metal plates) and coating layers (synthetic resin coating, plating, etc.) made of a material having a low heat transfer coefficient can be used.

  According to such a structure of this example, heat dissipation from the outer ring 2 and the hub 3 to the atmosphere can be suppressed. Accordingly, the grease in the bearing inner space 8 is agitated by the rolling of the balls 6 and 6 accompanying the relative rotation of the outer ring 2 and the hub 3, and the heat of the grease is transferred to the surroundings in the process of increasing the temperature of the grease. Difficult to diffuse. For this reason, when each of the balls 6 and 6 starts stirring the grease as the operation starts, the temperature of the grease rises quickly. As a result, the temperature of the grease becomes low enough to suppress the rotational resistance of the hub 3 in a very short time after the start of operation, and the running performance centering on the acceleration performance and the fuel consumption performance can be improved.

  In order to quickly increase the temperature of the grease after the start of operation, heat is dissipated through the mounting portion of the outer ring 2 with respect to the suspension device instead of the structure shown in FIG. 4 or together with the structure shown in FIG. It is also effective to suppress this. In this case, the axially inner side surface of the stationary flange 18 (see FIG. 5) provided on the outer peripheral surface of the outer ring 2 and the non-rotating support members such as knuckles, axle housings, and axle beams that constitute the suspension device. Made of a material that has sufficient strength and rigidity (buckling resistance) at the abutting portion with the outer surface in the axial direction and has a lower heat transfer coefficient than the material constituting the outer ring 2 (generally medium carbon steel). The spacer is interposed. Specifically, a washer made of SUS304, SUS420, SUS440, titanium, or an alloy thereof is sandwiched between the both side surfaces.

DESCRIPTION OF SYMBOLS 1 Wheel support hub unit 2 Outer ring 3 Hub 4 Outer ring raceway 5 Inner ring raceway 6 Ball 7 Cage 8 Bearing inner space 9 Seal ring 10 Cover 11 Rotating side flange 12 Inner ring 13, 13a Electric heater 14 Solar power generation panel 15 Temperature detector 16 Concave part 17a, 17b Thermal insulation layer 18 Static side flange

JP 2008-18822 A JP-A-3-172610

Claims (5)

  Rotation-side raceway and stationary-side raceway arranged concentrically with each other, rotation-side raceway surface and stationary-side raceway surface provided on the circumferential surfaces facing each other, and these rotation-side raceway surface and stationary-side raceway. A plurality of rolling elements installed between the side raceway surfaces so as to freely roll, a seal member for sealing an end opening of a bearing internal space in which the rolling elements are installed, and sealed in the bearing internal space. In the rolling bearing unit provided with the grease, the grease is heated by attaching a heater to at least one of the peripheral surface portion of the stationary side race and the bearing internal space portion. Rolling bearing unit characterized by being made possible.   The rolling bearing unit according to claim 1, wherein the heater is an electric heater, and the electric heater is energized by a photovoltaic power generation panel.   Rotation-side raceway and stationary-side raceway arranged concentrically with each other, rotation-side raceway surface and stationary-side raceway surface provided on the circumferential surfaces facing each other, and these rotation-side raceway surface and stationary-side raceway. A plurality of rolling elements installed between the side raceway surfaces so as to freely roll, a seal member for sealing an end opening of a bearing internal space in which the rolling elements are installed, and sealed in the bearing internal space. A heat-insulating layer on at least a portion of the surface of at least one of the rotating-side bearing ring and the stationary-side bearing ring that is in contact with outside air. A rolling bearing unit characterized by the provision of   Rotation-side raceway and stationary-side raceway arranged concentrically with each other, rotation-side raceway surface and stationary-side raceway surface provided on the circumferential surfaces facing each other, and these rotation-side raceway surface and stationary-side raceway. A plurality of rolling elements installed between the side raceway surfaces so as to freely roll, a seal member for sealing an end opening of a bearing internal space in which the rolling elements are installed, and sealed in the bearing internal space. In the rolling bearing unit provided with the grease, the heat transfer coefficient between the stationary bearing ring and the support member for fixing the stationary bearing ring is higher than that of the material constituting the stationary bearing ring. Rolling bearing unit characterized by interposing a spacer made of low material.   The rolling bearing unit is a wheel supporting hub unit for rotatably supporting the wheel with respect to the suspension device. The rolling bearing unit includes a rotating raceway surface arranged in a double row and a stationary raceway surface arranged in a double row. A plurality of rolling elements are arranged between both rows, and a pair of seal members are provided in a state of sealing both end openings of the bearing internal space. The rolling bearing unit according to any one of claims 1 to 4, wherein the rolling bearing unit does not rotate in a state of being coupled and fixed to the suspension device, and the rotating side race wheel rotates together with the wheel while supporting and fixing the wheel.

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