JP2012172818A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing, capable of reducing torque by reducing the agitation resistance caused by lubricant sealed in a bearing internal space.SOLUTION: The rolling bearing includes: annular bearing rings (inner ring 2, outer ring 4) opposed to each other so as to be relatively rotatable; a plurality of rolling bodies 6 aligned along between the bearing rings so as to be rollable; a retainer 8 for rotatably retaining each rolling body; and a sealing member 10 incorporated to both axial sides between the inner and outer rings to seal the bearing internal space from the outside of the bearing. The retainer is molded of a resin material and designed so that its capacity is at least 25% or more of the capacity of the bearing internal space.

Description

  The present invention relates to a rolling bearing capable of reducing torque by reducing agitation resistance due to a lubricant enclosed in a bearing internal space or a lubricant entering a bearing internal space.

  Conventionally, it is possible to reduce the agitation resistance due to the lubricant enclosed in the bearing inner space (the space surrounded by the outer inner ring and the sealing members on both sides thereof) or the lubricant entering the bearing inner space. Various bearings are known. As an example, in the rolling bearing shown in Patent Document 1, the agitation resistance associated with grease movement is achieved by feeding grease to the inner peripheral surface of the outer ring via the outer diameter surface side of the cage guided by the outer ring. Is suppressed.

JP 2008-240775 A

  By the way, in the conventional bearings as described above, and also in so-called oil-lubricated bearings, in order to prevent foreign matter (for example, water, dust, etc.) from entering the bearing internal space that may cause a reduction in bearing life. A sealing member may be provided to improve the sealing performance. In this case, there is a risk that the amount of lubricant is retained more than necessary in the bearing internal space, in which case the agitation resistance due to the lubricant enclosed in the bearing internal space increases, resulting in an increase in torque. Problem arises.

  The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a rolling bearing that can reduce torque by reducing agitation resistance due to a lubricant enclosed in the bearing internal space. Is to provide.

In order to achieve such an object, the rolling bearing of the present invention includes an annular race ring arranged to face each other so as to be relatively rotatable, and a plurality of rolling elements arranged so as to be freely rollable between the race rings, A cage that rotatably holds each rolling element and a sealing member that is incorporated on both sides in the axial direction between the inner and outer rings and seals the bearing inner space from the outside of the bearing. The cage is formed of a resin material. And the volume is designed to occupy at least 25% of the bearing internal space volume.
In the present invention, the bearing internal space volume is a value obtained by subtracting the sum of the volumes of a plurality of rolling elements from the space volume defined by the facing raceway ring and the sealing member.
In the present invention, the cage is formed of a polyamide resin having a specific gravity smaller than that of metal.
In the present invention, the cage is a rolling element guide cage that is configured so that neither the inner diameter side nor the outer diameter side of the cage touches the inner ring and the outer ring, and is rotationally guided only by a plurality of rolling elements. .

  ADVANTAGE OF THE INVENTION According to this invention, the rolling bearing which makes it possible to aim at reduction of a torque by reducing the stirring resistance by the lubricant enclosed by the bearing internal space is realizable.

(a) is sectional drawing which shows the structure of the rolling bearing which concerns on one Embodiment of this invention, (b) is the relationship between the rotational speed and rotational torque based on the measurement result of the bearing of this embodiment, and the conventional bearing. FIG. Sectional drawing which shows the other structure of the rolling bearing which concerns on one Embodiment of this invention.

Hereinafter, a rolling bearing according to an embodiment of the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1 (a), the rolling bearing of this embodiment rolls between an inner ring 2 and an outer ring 2 and an annular race ring (inner ring 2, outer ring 4) disposed opposite to each other so as to be relatively rotatable. A plurality of rolling elements 6 arranged freely, a cage 8 having a plurality of pockets 8p for rotatably holding each rolling element 6 one by one, and both axial sides between the inner and outer rings 2, 4 (a plurality of rolling elements And a sealing member 10 that is incorporated in the rolling body 6 and the cage 8 in the state where the moving body 6 is held by the cage 8 and seals the bearing internal space from the outside of the bearing. In the bearing internal space, a predetermined amount of lubricant (for example, oil, grease) is enclosed or supplied from the outside of the rolling bearing.

  The type of material constituting the bearing ring (inner ring 2, outer ring 4) is not particularly limited. For example, it is preferable to use bearing steel such as high carbon chrome steel (SUJ2), and particularly carburizing treatment or carbonitriding treatment. The bearing steel which gave is more preferable. Moreover, alloy steel such as silicon, manganese, chromium, molybdenum, or the like may be added to the medium carbon steel as necessary, and carburizing or carbonitriding treatment may be applied thereto. In particular, when the rolling bearing is used at high speed rotation in a high temperature environment, it is preferable to use an alloy steel that has been subjected to carburizing treatment or carbonitriding treatment to increase the amount of silicon added to the medium carbon steel. .

  As the rolling element 6, for example, balls, rollers, needles, and the like can be applied. In the drawings, balls are assumed as an example, and a ball bearing is configured thereby. In this case, the type of material constituting the rolling element (ball) 6 is not particularly limited, but for example, it is preferable to appropriately use bearing steel, ceramics, or the like.

  As the cage 8, both the inner diameter side and the outer diameter side of the cage 8 are the outer peripheral surface 2s of the inner ring 2 (hereinafter referred to as inner ring outer peripheral surface 2s) and the inner peripheral surface 4s of the outer ring 4 (hereinafter referred to as outer ring). It is preferable to apply a rolling element guide holder that is configured so as not to touch the inner peripheral surface 4 s and is guided to rotate only by the rolling elements (balls) 6. As the retainer 8, for example, a corrugated retainer, a combined retainer, a crown retainer, and the like can be applied. Assume a crown-shaped cage 8 in which a pocket 8p is opened and a peripheral surface 8a on the other side (the side opposite to the side where each pocket 8p is opened) is closed along the circumferential direction.

  Moreover, as a kind of material which comprises the holder | retainer 8, in order to enlarge the volume of the said holder | retainer 8, it is preferable to apply the resin material whose specific gravity is smaller than a metal. Here, the type of the resin material is not particularly limited as long as the cage 8 has the necessary strength, heat resistance, etc., but a polyamide-based material that can be injection-molded and has a low specific gravity is applied. It is preferable to do. Examples of the polyamide-based resin include nylon 46 and nylon 66. It is also preferable to use a synthetic resin such as polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), or polyether ether ketone (PEEK).

  In this case, since it is preferable that the weight of the cage 8 is smaller in a use environment in high-speed rotation of the bearing, reinforcing fibers (for example, glass fibers (GF), carbon fibers (CF), etc., which are blended into the resin material described above, are used. ) Is preferably set to be relatively less than usual (for example, about 3 to 25% by weight (mass)% of the total amount of the resin) in order to increase the specific gravity of the resin material.

  As the sealing member 10, various types such as a contact type or non-contact type seal (rubber seal, resin seal), a metal shield, and the like can be applied. FIG. 1 (a) shows, as an example, a ball bearing in which a non-contact seal 10 made of rubber 10b containing a mandrel 10a is incorporated. The sealing member (seal) 10 is attached with its base end 10 e fitted into a mounting groove 4 g formed on the inner peripheral surface 4 s of the outer ring 4, and its tip 10 t is attached to the outer peripheral surface 2 s of the inner ring 2. On the other hand, it is positioned in a non-contact state.

  In the ball bearing described above, the inner ring outer circumferential surface 2s is formed with an inner ring raceway surface 2m continuous in the circumferential direction, while the outer ring inner circumferential surface 4s is opposed to the inner ring raceway surface 2m. An outer ring raceway surface 4m continuous in the circumferential direction is formed. In this case, a plurality of rolling elements (balls) 6 roll between the inner ring raceway surface 2m and the outer ring raceway surface 4m in a state in which the rolling elements (balls) 6 are rotatably held one by one in the pockets 8p of the cage 8. Arranged freely.

  When the ball bearing is rotated in this state (the inner and outer rings 2 and 4 are relatively rotated), the plurality of rolling elements (balls) 6 roll along the inner ring raceway surface 2m and the outer ring raceway surface 4m. At this time, the cage 8 holds each rolling element (ball) 6 in each pocket 8p so that it can rotate one by one, together with each rolling element (ball) 6 between the inner and outer rings 2 and 4 (inside the bearing). Revolve along the (space).

  Here, the above-described bearing internal space refers to a space region defined by the inner ring 2 (inner ring outer peripheral surface 2s), the outer ring 4 (outer ring inner peripheral surface 4s), and a pair of sealing members (seal) 10. The bearing internal space volume is a plurality of rolling elements (balls) from a space volume defined by the inner ring 2 (inner ring outer peripheral surface 2s), the outer ring 4 (outer ring inner peripheral surface 4s), and the pair of sealing members 10. The value obtained by subtracting the total volume of 6 (value).

  In this case, in the rolling bearing of this embodiment, the cage 8 is formed of a polyamide-based resin material having a specific gravity smaller than that of metal (can be injection-molded), and the volume thereof is at least 25 of the bearing internal space volume. It is preferable that it is designed to occupy% or more.

  According to this, since the bearing internal space can be reduced, it is possible to reduce the amount of lubricant (for example, oil, grease) that is enclosed in the bearing internal space or that is supplied and retained from the outside. Further, the lubricant that is excessively present in the bearing internal space can be quickly discharged to the outside of the bearing. Thereby, the agitation resistance peculiar to the bearing sealed by the pair of sealing members (seal) 10 (that is, the agitation resistance by the staying lubricant) can be greatly reduced. As a result, the torque of the bearing (that is, rotational torque) can be dramatically reduced.

In addition, the rolling bearing according to the present embodiment that exhibits this effect is highly effective when used in an environment where the maximum rotational speed of the bearing is 150,000 or more in terms of a dmn value.
The dmn value indicates an allowable rotational speed calculated by the relational expression dm (bearing inner diameter: mm) × n (rotational speed (number): min ⁻¹ ).

Furthermore, the rolling bearing of the present embodiment that exhibits the above-described effect has a viscosity of 130 mm ² / s or more at 40 ° C., for example, when the viscosity of the lubricant used for lubrication is high in a low-speed use environment. The effect is also great when using this type of lubricating oil.

  Here, with respect to the effects described above, the bearings of the rolling bearing (the bearing of the present embodiment) provided with the resin cage 8 and the sealing member 10 described above and the conventional bearing provided with an iron cage are described. The relationship between the rotational speed of the motor and the rotational torque at that time was measured. In this measurement, the present bearing and the conventional bearing were different from each other only in the cage, and other parts and measurement conditions were the same. That is, the bearing size was a bearing inner diameter: 45φ, a bearing outer diameter: 100φ, a bearing width: 26φ, a measurement load was no load, an ambient temperature and a lubricating oil temperature were 40 ° C., and a lubricating oil level was a shaft center.

  FIG. 1B shows the relationship between the rotational speed and the rotational torque based on the measurement results of the present bearing and the conventional bearing. According to this, it has been found that the rotational torque of the bearing of the present case is always greatly lower from the low speed rotation to the high speed rotation as compared with the conventional bearing. According to this, the agitation resistance peculiar to the bearing sealed by the pair of sealing members (seal) 10 (that is, the agitation resistance by the staying lubricant) is greatly reduced, and the torque of the bearing (that is, the rotational torque) is reduced. It was confirmed that it can be drastically reduced.

  In the embodiment described above, both the inner ring raceway surface 2m and the outer ring raceway surface 4m are assumed to be rolling bearings that are positioned at the center with respect to the bearing width, but instead, as shown in FIG. The inner ring raceway surface 2m and the outer ring raceway surface 4m may be both rolling bearings that are offset (eccentric) with respect to the bearing width. In this case, the cage 8 applied to the rolling bearing is preferably designed so that its volume occupies 70% of the bearing internal space volume.

  According to the rolling bearing having such a configuration, the volume of the bearing internal space can be reduced more efficiently, so that the amount of lubricant (for example, oil, grease) retained and retained in the bearing internal space is further reduced. Can be made. Thereby, the agitation resistance peculiar to the bearing sealed by the pair of sealing members (seal) 10 (that is, the agitation resistance by the staying lubricant) can be greatly reduced. As a result, the torque of the bearing (that is, rotational torque) can be dramatically reduced. Since other effects are the same as those of the above-described embodiment, description thereof is omitted.

2 Inner ring (Raceway)
4 Outer ring (Raceway)
6 Rolling element 8 Cage 10 Sealing member

Claims (4)

An annular race ring arranged to be relatively rotatable, and
A plurality of rolling elements arranged to freely roll along the raceway,
A cage for rotatably holding each rolling element;
A sealing member that is incorporated on both axial sides between the inner and outer rings and seals the bearing inner space from the outside of the bearing,
A rolling bearing, wherein the cage is formed of a resin material, and the volume is designed to occupy at least 25% or more of the bearing internal space volume.   The bearing internal space volume is a value obtained by subtracting the sum of the volumes of a plurality of rolling elements from a space volume defined by the opposed raceway ring and the sealing member. Rolling bearings.   The rolling bearing according to claim 1 or 2, wherein the cage is formed of a polyamide resin having a specific gravity smaller than that of a metal.   The cage is a rolling element guide cage that is configured not to touch the inner ring and the outer ring on both the inner diameter side and the outer diameter side of the cage, and is rotationally guided only by a plurality of rolling elements. The rolling bearing according to any one of claims 1 to 3.

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