JP3196443B2 - Roller bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The roller bearing according to the present invention can be used as a full-roller needle roller bearing for use in, for example, an automatic transmission for an automobile.

[0002]

2. Description of the Related Art For example, a roller bearing such as a full roller type needle roller bearing (a so-called needle bearing) is incorporated in a rotation supporting portion of a planetary gear mechanism of an automatic transmission for an automobile. In order to ensure the service life of such a roller bearing, the rolling surfaces of a plurality of rollers and the raceway surfaces formed on the peripheral surface of a mating member such as an outer raceway, an inner raceway or the like, where the rolling surfaces are in line contact with each other, are required. Are in line contact,
The lubrication state of the rolling parts needs to be good. In particular, in the case of a planetary gear mechanism for an automatic transmission, a sufficient amount of lubricating oil is not necessarily ensured to the roller bearing mounting portion, and therefore, consideration must be given to improving the lubrication state of the rolling portion.

Conventionally, the rolling surface and the raceway surface have been finished as smooth as possible to prevent metal contact between the roller and the mating member between the rolling surface and the raceway surface even with a small amount of lubricating oil. I was doing it.

[0004]

However, it has been pointed out that if the rolling surface and the raceway surface are simply finished to be smooth, the roller bearing may seize in a remarkable case. That is,
During operation of the roller bearing, a moment in a direction in which the central axis of each roller and the central axis of the mating member are made non-parallel (skew) may be applied to the plurality of rollers. When such a moment is applied, if the rolling surface and the raceway surface are simply smooth, each roller skews almost without opposing this moment.

[0005] When the rollers are skewed, the resistance to rotation of each roller is extremely large as compared to before the skew, and the amount of heat generated at the roller bearings is significantly increased. In a remarkable case, there is a possibility that the roller bearing portion is seized.

In order to prevent the skew which causes such inconvenience, for example, Japanese Patent Publication No. 57-61933 discloses that the roughness of an outer raceway is larger (rougher) than that of an inner raceway.
In addition, a technique is described in which the friction coefficient between the rolling surface of each roller and the outer raceway is larger than the friction coefficient between the rolling surface of each roller and the inner raceway. However, in such a conventional technique, the effect of preventing roller skew is not always sufficient, and when the moment is large, the roller skew cannot be sufficiently prevented. The roller bearing of the present invention has been invented in view of such circumstances.

[0007]

A roller bearing according to the present invention comprises a plurality of rollers having an outer peripheral surface as a rolling surface and a raceway surface having a peripheral surface in line contact with the rolling surface, similarly to a conventional roller bearing. And a mating member. In particular, in the roller bearing of the present invention, the surface roughness of the rolling surface in both the axial direction and the circumferential direction is 0.06 μmRa or less, and the surface roughness of the peripheral surface of the mating member is less than 0.06 μmRa. 0.08 to 0.1 in the axial direction
5 μm Ra, and is not more than 0.04 μm Ra in the circumferential direction.

[0008]

In the case of the roller bearing of the present invention configured as described above, even when a moment acting in the direction of skewing the roller acts, the roller bearing is positioned between the rolling surface of the roller and the raceway surface of the mating member.
The frictional force acting in the direction to prevent the skew of the roller acts, so that the roller does not skew.

This state will be described with reference to FIGS. FIGS. 1 to 3 show that the roller 1 is prevented from skew by devising a state of contact between a rolling surface 2 of the roller 1 and an inner raceway 4 which is a raceway surface provided on an outer peripheral surface of the inner race 3. Is what you do. In the case of the roller bearing of the present invention, as is apparent from FIGS. 1 to 3, the surface roughness of the inner raceway 4 is not changed in the axial direction (the left-right direction in FIGS. 1 and 2 and the left-right direction in FIG. 3). It is relatively rough (0.08 to 0.15 μm Ra) and relatively smooth (0.04 μm Ra or less) in the circumferential direction. That is,
The ratio of the surface roughness in the axial direction to the surface roughness in the circumferential direction (surface roughness in the axial direction / surface roughness in the circumferential direction) is 2 or more.

As described above, the roller 1 is rolled while the rolling surface 2 of the roller 1 is brought into contact with the inner raceway 4 having a difference between the surface roughness in the axial direction and the surface roughness in the circumferential direction. In this state, when a moment M in the direction of skewing the roller 1 acts on the roller 1, a force in the direction of preventing the roller 1 from skewing against the moment M is applied to the roller 1. Works.

That is, when the rollers 1 tend to skew, the friction state between the rolling surface 2 and the inner raceway 4 becomes a state in which not only rolling friction but also sliding friction is mixed. The sliding friction tends to cause friction in both the axial direction and the circumferential direction of the two surfaces 2 and 4 (the rolling surface 2 and the inner raceway 4; the same applies hereinafter). In the case of a roller bearing, the surface roughness of the inner raceway 4 in the axial direction is larger than the surface roughness of the inner raceway 4 in the circumferential direction. Is greater than the frictional force over Then, a relatively large sliding friction force in the axial direction generates a force against the moment 1 in the roller 1 to prevent the roller 1 from being skewed.

As described above, the effect of preventing the skew of the rollers 1 is that the surface roughness of the outer raceway formed on the inner peripheral surface of the outer race instead of (or together with the inner raceway 4) In the direction (the left-right direction in FIGS. 1 and 2 and the left-right direction in FIG. 3), it is relatively coarse (0.08 to 0.15 μmRa), and relatively smooth in the circumferential direction (0.04 μmRa). Below), the same can be obtained.

On the other hand, as shown in FIGS. 4 to 6, when the surface roughness of the inner raceway 4 (or the outer raceway) is substantially equal in the axial direction and the circumferential direction, the inner raceway 4 Irrespective of the degree of surface roughness of the roller 1, a force in the direction to prevent the skew of the roller 1 is not sufficiently generated. That is, when the surface roughness is small (smooth) in both the axial direction and the circumferential direction, the frictional force enough to generate a force for countering the skew is generated on the two surfaces 2 and 4. No skew of the roller 1 can be prevented without acting in the middle. When the surface roughness is large (rough) in both the axial direction and the circumferential direction, not only the sliding friction force in the axial direction but also the sliding friction force in the circumferential direction is increased. By frictional force in the circumferential direction,
The force to return the skewed roller to its original state is erased, and the effect of preventing the roller 1 from skew is lost. Further, when the surface roughness is increased in both directions, the lubricity between the two surfaces 2 and 4 is deteriorated, adversely affecting rolling fatigue occurs, and the life of the roller bearing is shortened.

[0014]

EXAMPLES In order to confirm the effects of the present invention, the results of experiments conducted by the present inventors will be described with reference to FIGS. 7 to 9 and Table 1.

FIG. 7 shows the apparatus used for the experiment. A hollow fixed shaft 6 is supported between a pair of holders 5a and 5b arranged concentrically and spaced apart from each other so as to span both holders 5a and 5b. This fixed shaft 6
The lubricating oil is fed into the inside from one of the holders 5 b, and the lubricating oil is discharged around the fixed shaft 6 through the discharge holes 7. The outer peripheral surface of the fixed shaft 6 is the inner raceway 4 which is the raceway surface.

On the other hand, an outer ring 8 is provided around the fixed shaft 6,
The fixed shaft 6 is supported concentrically and rotatably.
That is, a plurality of rollers 1 and 1 are provided between the outer raceway 9 formed on the inner peripheral surface of the outer race 8 and the inner raceway 4 so as to roll freely.
An outer ring 8 is rotatably supported around the fixed shaft 6. No retainer for retaining rollers 1 and 1 is provided.

A driven gear 10 is externally fitted and fixed to an outer peripheral surface of an end (right end in FIG. 7) of the outer ring 8.
The outer ring 8 is rotated at 16000 rpm by meshing with a drive gear 12 that is rotationally driven by a motor 11. In addition, a retaining ring 14 is provided around the outer ring 8 via a pair of angular type ball bearings 13, 13 which are combined back to back. And this retaining ring 14
, A radial load of 2500 N and a moment load of 14 N · m.

Using such a test apparatus, the inner raceway 4 on the outer peripheral surface of the fixed shaft 6 and the rolling surfaces 2, 2 of the rollers 1, 1 are used.
When the temperature of the inner ring raceway 4 was measured while changing the surface roughness of the above, the results shown in the following Table 1 were obtained. still,
In Table 1, the value of the surface roughness is the center line average roughness specified in JIS B 0601, and the unit is μmRa. The unit of the temperature of the inner raceway 4 is ° C.

Table 1

[Table 1]

As is clear from the description in Table 1, the roller bearing of the present invention can suppress the temperature rise of the inner ring raceway 4 portion lower than the conventional roller bearing. Further, in the case of the roller bearing of the present invention, the temperature change in the inner ring raceway 4 was very small as shown in FIG. On the other hand, in the case of the conventional roller bearing, as shown in FIG. 9, the temperature of the inner ring raceway 4 greatly changed.

The surfaces of the constituent members can be machined into desired properties by using appropriate abrasive grains and binders of the grindstone and devising a machining method such as centerless machining. For example, using a grindstone formed of fused alumina abrasive grains and a resinous binder, by appropriately setting the feed speed and the like of the workpiece and performing a grinding process, a member having a desired surface property can be obtained. can get.

[0022]

Since the roller bearing of the present invention is constructed and operates as described above, the amount of heat generated at the roller bearing portion can be reduced, and the risk of seizure of the roller bearing portion can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a roller bearing of the present invention.

FIG. 2 is a view similarly viewed from a circumferential direction.

FIG. 3 is a diagram viewed from the same axial direction.

FIG. 4 is a perspective view schematically showing a conventional roller bearing.

FIG. 5 is a view similarly viewed from a circumferential direction.

FIG. 6 is a diagram viewed from the axial direction.

FIG. 7 is a cross-sectional view of a test device performed to confirm the effects of the present invention.

FIG. 8 is a diagram showing a temperature change of a raceway surface of the roller bearing of the present invention.

FIG. 9 is a diagram showing a temperature change of a raceway surface of a conventional roller bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roller 2 Rolling surface 3 Inner ring 4 Inner ring track 5a, 5b Holder 6 Fixed shaft 7 Discharge hole 8 Outer ring 9 Outer ring track 10 Follower gear 11 Motor 12 Drive gear 13 Ball bearing 14 Retaining ring

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiyuki Yamamoto 11-1 Okuchicho, Takasaki City, Gunma Prefecture (72) Inventor Yasuyuki Shimazaki 646-1 Nakajuku, Annaka City, Gunma Prefecture (56) References 4-39412 (JP, A) JP-A-3-292416 (JP, A) JP-A-3-117725 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16C 19/00 -19/56 F16C 33/30-33/66

Claims (1)

(57) [Claims] 1. A roller bearing comprising: a plurality of rollers having an outer peripheral surface as a rolling surface; and a mating member having a peripheral surface as a raceway surface in linear contact with the rolling surface. The surface roughness in both the axial direction and the circumferential direction is 0.06 μmRa or less, and the surface roughness of the peripheral surface of the mating member is 0.08 to 0.15 μmRa in the axial direction. A roller bearing having a diameter of 0.04 μm Ra or less in a circumferential direction.