JP2012207699A - Ball bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball bearing which is high in durability and low in torque even in high-speed rotation.SOLUTION: The ball bearing is characterized in that: there is arranged a synthetic-resin made cage for rollingly holding a rolling body; a synthetic resin forming the cage is reinforced by a glass fiber (GF) whose tensile elasticity modulus is not lower than 5 GPa and not higher than 30 GPa, or a carbon fiber (CF); the cage has a plurality of pockets for rollingly holding balls which are aligned in the circumferential direction at an annular cage body; each pocket has a pair of ball-holding claw pieces at the end of an opening which is opened at the axial one end side of the cage body; a protrusion protruded toward the axial one end side is formed along the circumferential direction between the adjacent pockets at almost the same height as that of the claw piece, an axial thickness of the thinnest thin-thick part in the axial direction of the pock is not smaller than 20% of a diameter (Da) of the ball; and the cage has no thinned part substantially.

Description

  The present invention relates to a ball bearing which is a rolling bearing suitable for use in, for example, a motor support of a vehicle transmission, a hybrid vehicle, or a fuel cell vehicle or a gear support directly connected to the motor, and more particularly, a holding made of a synthetic resin (plastic). The present invention relates to a ball bearing provided with a vessel.

  In general, deep groove ball bearings used under oil lubrication, such as automobile transmissions, are SUJ2 for bearing steel and SCR420 for case-hardened steel as materials for balls, inner rings and outer rings as rolling elements. A steel material or the like equivalent to SCM420 is used. In addition, an iron corrugated press holder made of SPCC or a plastic crown holder is used as a holder for holding the balls so as to roll freely.

In recent years, due to increasing environmental problems, there is an increasing need for extremely low torque in bearing parts constituting automobile transmissions. Further, the ball bearing [(inner ring inner diameter dimension (mm) + outer ring outer diameter dimension (mm)) / 2] × rotational speed (min ⁻¹ ) has a dmn value of 650,000 or more and a low torque. There is a need to be.

The causes of friction loss torque of ball bearings are [1] rolling friction between inner and outer rings and balls, [2] sliding friction between inner and outer rings and balls, [3] sliding friction between balls and cages, [4]
Although there is a stirring resistance of the lubricating oil, as means for achieving a reduction in torque of the ball bearing, reduction of load conditions and size reduction of the bearing are generally used.

  However, in such a means, there are problems such as a decrease in bearing life and rigidity, or a restriction on a bearing mounting peripheral structure.

  In addition, from the viewpoint of the above [3], in recent years, plastic cages that are lightweight and have excellent self-lubricating properties are increasingly used for transmission ball bearings.

Further, from the viewpoint of the above [4], it is conceivable to reduce the amount of oil supplied to the bearing or to lower the viscosity of the lubricating oil. However, with these means, there are restrictions on the performance of the bearing and unit, Operating conditions (
For example, there is a problem that it is difficult to control in the above method because it is also affected by the number of rotations of the engine or other rotating members.

As conventional cages and bearings for ball bearings, there are crown-shaped configurations shown in FIGS. 3, 4, and 5 and rolling bearings including the cage (for example, Patent Document 1).
reference). 3 is a perspective view of the cage, FIG. 4 is a partially developed view of the cage of FIG. 3, and FIG. 5 is a cross-sectional view of the rolling bearing.

  The cage 31 is made of plastic and is formed into a so-called crown shape, and the annular cage body 32 opens on one axial surface in the axial direction so that the balls can roll and cannot be dropped. A plurality of pockets 35 to be held are arranged in the circumferential direction. The pockets 35 are equally spaced.

The opening end portions of these pockets 35 are formed by a pair of claw pieces 33a and 33b located on both sides of the pocket opening in the circumferential direction of the cage body, and the inner surface of the pocket 35 is spherical. Pocket 3
The claw pieces 33a and 33b on both sides of the No. 5 are shaped so that the tips approach each other, and the entrance diameter between the claw pieces 33a and 33b is smaller than the ball diameter.

  The assembly of the bearing is performed by a snap-on method in which the tips of the claw pieces 33a and 33b are slightly pushed by the balls 36. In other words, the claw pieces 33a and 33b formed on the cage 31 need to be freely deformed to some extent. If the rigidity is too high, the assembling property is lowered, or the cage 31 is damaged during the assembly, Due to the permanent deformation, the opening that is the ball insertion opening becomes large, and the cage 31 may be easily detached during rotation.

  Therefore, the general plastic retainer 31 has a recess 34 between the claw pieces 33a and 33b between the adjacent pockets 35, so that the claw pieces 33a and 33b can be elastically deformed. The cage 31 is provided with a meat stealing unit 19.

JP 2003-329045 A

  However, these claw pieces 33a and 33b have a complicated shape of projecting in different directions while curving from the cage main body 32, so that there is a problem that the lubricating oil is unnecessarily agitated when the bearing rotates.

  Therefore, if the ball diameter is reduced or the number of balls is reduced in order to reduce torque, the influence of the stirring resistance of the lubricating oil by the claw pieces 33a and 33b provided on the front side (pocket side) of the cage 31 is ignored. Can not. In particular, when the bearing has a large PCD (pitch circle diameter), the influence of the lubricating oil stirring resistance by the claw pieces 33a and 33b is large.

The object of the present invention is achieved by the following constitution.
A ball bearing,
An inner ring having an inner ring raceway surface;
An outer ring having an outer ring raceway surface;
Balls that are a plurality of rolling elements arranged in a relatively rotatable manner between the inner ring raceway surface and the outer ring raceway surface;
A cage made of a synthetic resin that holds the rolling element in a freely rollable manner,
The synthetic resin forming the cage is a resin reinforced with glass fiber (GF) or carbon fiber (CF) having a tensile modulus of elasticity of 5 GPa or more and 30 GPa or less, and the cage rolls balls onto the annular cage body. It has a plurality of pockets to be held movably arranged side by side in the circumferential direction, and the pockets open to one end side in the axial direction of the retainer body, and have a pair of claw pieces for holding balls at the open ends. ,
Between the adjacent pockets, a convex portion protruding toward the one end side in the axial direction is provided at substantially the same height as the claw piece along the circumferential direction,
The axial width in the axially thinnest portion of the pocket in the axial direction is 20% or more of the diameter (Da) of the ball,
The cage is a ball bearing characterized by having substantially no meat theft.

  The ball bearing of the present invention is a rolling bearing that may be used in particular with a dmn of 650,000 or more, or in particular in a region of dmn of 650,000 or more, preventing skidding, heat generation, seizure prevention, and cage damage prevention during high-speed rotation. In addition to being effective, it also has a torque reduction effect by reducing the stirring resistance of the lubricating oil.

It is a figure explaining the ball bearing of the present invention. It is a figure explaining the holder | retainer used for the ball bearing of this invention. It is a figure explaining the holder used for the conventional ball bearing. It is a figure explaining the holder used for the conventional ball bearing. It is a figure explaining the conventional ball bearing.

  An embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 is a diagram illustrating a ball bearing according to the present invention, and FIG. 2 is a diagram illustrating a ball bearing according to the present invention.

  The ball bearing 20 of the present invention includes an inner ring 11 having an inner ring raceway surface 16, an outer ring 12 having an outer ring raceway surface 18, and a plurality of relative rotation between the inner ring raceway surface 16 and the outer ring raceway surface 18. A ball 13 which is a rolling element and a cage 31 made of synthetic resin (plastic) are provided.

  Here, the synthetic resin forming the cage 31 made of synthetic resin is mixed with glass fiber (GF) having a tensile elastic modulus of 5 GPa to 30 GPa or carbon fiber (CF) having a tensile elastic modulus of 5 GPa to 30 GPa. It is a resin reinforced by the above. Therefore, even when the ball bearing 20 rotates at a high speed by inner ring rotation or outer ring rotation, the initial dimensional accuracy can be maintained with little deformation due to centrifugal force, and the ball can be held well.

  Further, the cage 31 has a plurality of pockets 35 arranged in a circumferential direction in the annular cage body 32 so as to hold the balls 13 in a freely rolling manner. And claw pieces 33a and 33b for holding the ball 13 at the opening end. The ball 13 is held by the pocket 35 and the claw pieces 33a and 33b. The type of the cage 31 is a so-called crown type cage.

  Further, a convex portion 17 projecting toward one end side in the axial direction is provided between the plurality of pockets 35 along the circumferential direction, and the height of the convex portion 17 is substantially the same as that of the claw pieces 33a and 33b. It is the same. That is, the retainer 31 has a shape with little unevenness in the circumferential cross section, except for the recesses between the pockets 35, the claw pieces 33a and 33b, and the projections 17. For this reason, even when the ball bearing 20 rotates at a high speed and the cage 31 also rotates at a high speed, it is possible to suppress the entrainment of lubricating oil in excess of the necessary amount or reduce the agitation resistance of the lubricating oil. Therefore, even during high-speed rotation, low heat generation and low torque can be maintained.

  Furthermore, the thinnest wall portion (FIG. 2) in the axial direction of the pocket 35 is at least 20% of the diameter (Da) of the ball. For this reason, the strength of the cage is further improved, and deformation due to centrifugal force or the like during high-speed rotation is difficult to occur.

  Further, in the cage 31 of the present invention, the meat stealing portion 19 (FIG. 5) is not provided. As a result, it is possible to further obtain the effect derived from the above-described “shape with less unevenness in the circumferential cross section”.

  The ball bearing of the present invention can be suitably used for supporting a rotating shaft of a motor of a vehicle transmission, a hybrid vehicle, a fuel cell vehicle, an electric vehicle or the like.

10, 20 Ball bearing 11 Inner ring 12 Outer ring 13 Ball (rolling element)
16 Inner ring raceway 17 Convex part 18 Outer ring raceway 19 Meat stealing part 31 Retainer 32 Annular retainer body 33a, 33b Claw piece 34 Recessed part 35 Pocket

Claims (1)

A ball bearing,
An inner ring having an inner ring raceway surface;
An outer ring having an outer ring raceway surface;
Balls that are a plurality of rolling elements arranged in a relatively rotatable manner between the inner ring raceway surface and the outer ring raceway surface;
A cage made of a synthetic resin that holds the rolling element in a freely rollable manner,
The synthetic resin forming the cage is a resin reinforced with glass fiber (GF) or carbon fiber (CF) having a tensile modulus of elasticity of 5 GPa or more and 30 GPa or less, and the cage rolls balls onto the annular cage body. It has a plurality of pockets to be held movably arranged side by side in the circumferential direction, and the pockets open to one end side in the axial direction of the retainer body, and have a pair of claw pieces for holding balls at the open ends. ,
Between the adjacent pockets, a convex portion protruding toward the one end side in the axial direction is provided at substantially the same height as the claw piece along the circumferential direction,
The axial width in the axially thinnest portion of the pocket in the axial direction is 20% or more of the diameter (Da) of the ball,
A ball bearing having substantially no meat theft in the cage.

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