JP3062675B2 - Grease-filled rolling bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grease-filled rolling bearing for radial loads, which is widely used in automobiles and various electric appliances.

[0002]

2. Description of the Related Art Grease-filled rolling bearings, for example, ball bearings, are widely used for general parts such as electric parts of automobiles. In the prior art, the inner and outer rings are made of steel such as bearing steel, and between them, the same steel balls are inserted together with grease.

In recent years, in order to save energy, automobile parts have been required to be smaller, lighter and have higher performance, and the above-mentioned ball bearings have been subjected to severe conditions such as high load, high speed rotation and high temperature. It is intended to be used below.

[0004]

The conventional grease-filled ball bearings made of steel, under severe operating conditions such as those described above, cause peeling and other damages on the raceway surface due to metal fatigue, and decompose the grease due to high temperatures. Is promoted, and the deteriorated grease cannot exert a sufficient lubricating effect, so that the grease is liable to peel and a long life cannot be expected.

On the other hand, as a small, lightweight and high-performance bearing, there is a ceramic bearing, which is already used in some fields.

However, current ceramic bearings are:
Because the material is expensive, all components are not made of ceramics, only balls are made of ceramics. Still, the product price is high, so the range of use is limited,
It has not yet been adopted for general parts such as automobile parts.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to obtain a high performance equivalent to a ceramic bearing at the lowest possible cost by incorporating a ceramic part into a part of a grease-sealed rolling bearing made of steel.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a rolling bearing in which the inner and outer races are made of steel and grease is sealed between the inner and outer rings, wherein the rolling element comprises a steel rolling element and a ceramic rolling element. The rolling elements are distributed between the steel rolling elements so that at least one rolling element is always present in the radial load application region , and the ceramic
The diameter of the rolling element shall be less than the diameter of the steel rolling element when no load is applied.
Is set to be larger than the diameter at the time of breaking limit .

[0009]

[0010]

[Function] There is always a rolling element made of ceramics in the radial load area, which supports most of the large radial load. In particular, ceramic rolling elements are replaced by steel rolling elements.
Because the diameter is small, when the radial load is small,
Only the rolling elements made of steel contact the inner and outer rings,
Can support the load, but the radial load exceeds
The steel rolling elements are compressed and deformed by the load,
So that the hard ceramic rolling element contacts the inner and outer rings
The load is applied by the ceramic rolling element and steel rolling element.
Is shared and supported. Thus, high loads are
Evenly supported by moving body, load is applied to either rolling body
Because it is not concentrated, it can easily support high loads.

Further, since the rolling elements made of ceramic and the rolling elements made of steel having different contact states come into contact with each other alternately on the raceway surface, even if a minute flaw is generated on the raceway surface, the hard ceramic rolling element is formed. You will be trained by moving objects.

Further, since the heat capacity of the ceramic rolling element is large, the raceway does not rise in temperature, the decomposition of grease is suppressed, and the separation of the raceway surface due to a decrease in lubrication ability due to deterioration of the grease is suppressed. Become.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to one embodiment shown in FIGS. FIG. 1 is a longitudinal sectional view of a grease-sealed ball bearing, and FIG. 2 is a side view schematically showing a ball arrangement state. In the drawing, reference numeral 1 denotes an inner ring, 2 denotes an outer ring, 3A denotes a steel ball, 3B denotes a ceramic ball, 4 denotes a seal, and 5 denotes a retainer.

The inner ring 1 and the outer ring 2 are made of bearing steel (JIS SUJ-2) or the like, and grease is applied between them to be sealed with a seal 4.

The steel ball 3A is made of the same bearing steel as the inner and outer rings 1 and 2, and the ceramic ball 3B is made of a sintered body mainly composed of silicon nitride. Ceramic ball 3
The number of B may be three or more, but the optimal number is desirably approximately half of the total number of the balls 3, that is, approximately the same as the number of the steel balls 3A. In the embodiment, as shown in FIG.
Of the total number of seven, four are steel balls 3A and three are ceramic balls 3B.

In a general radial bearing, three balls are always present in the radial load application region, and these balls receive a radial load. In the present invention, the predetermined plurality of balls are used. By distributing the ceramic balls 3B between the steel balls 3A, at least one ceramic ball 3B is always present in the radial load application region.

The diameter of the ceramic ball 3B may be the same as the diameter of the steel ball 3A. However, in consideration of the compressive deformation of the steel ball 3A due to the radial load, the diameter of the steel ball 3A when no load is applied. It is desirable to make the diameter smaller, and the value is
What is necessary is just to set it as larger than the diameter at the time of the breaking limit of A. In short, it is desirable that the ceramic ball 3B be in contact with both raceway surfaces of the inner and outer rings 1 and 2 when the steel ball 3A is slightly compressed and deformed by the radial load within a range not broken by the radial load. .

In the above configuration, there are three balls 3 in the radial load area, one of which is always a ceramic ball 3B. This ceramic ball 3
Since B supports most of the large radial load, the stress of the steel ball 3A is reduced, and the use of the ball with a high load is enabled as a whole.

In this case, if the ceramic ball 3B has a smaller diameter than the steel ball 3A, when the radial load is small,
Only the steel ball 3A is in contact with the inner and outer rings 1 and 2, and the load is supported by the steel ball 3A alone. When the radial load exceeds a predetermined value, the steel ball 3A is compressed and deformed by the load. The hard ceramic balls 3B are
The ceramic ball 3B and the steel ball 3A bear the load and are supported. In this way, the high load is evenly supported by the two types of balls 3A and 3B, and the load is not concentrated on one of the balls, so that the high load can be supported without difficulty.

Further, the ceramic balls 3B and the steel balls 3A having different contact states due to differences in hardness, smoothness and the like come into contact with the raceways of the inner and outer rings 1 and 2 alternately. Therefore, even if a minute seizure or peeling occurs between the inner and outer rings 1 and 2 and the steel ball 3A of the same metal, these scratches will be smoothed by the contact of the ceramic ball 3B, Avoids major damage.

Further, since the ceramic balls 3B have a large heat capacity and a low thermal conductivity, the temperature of the inner and outer rings 1 and 2 does not rise. Therefore, decomposition of the grease is suppressed, the life of the grease is extended, and peeling of the raceway surface due to a decrease in lubrication ability due to deterioration of the grease is suppressed.

Tests for confirming the above-described effects have been conducted, and will be described. JIS standard number 6302 sealed type was used as a sample bearing.

There are three samples: (a) conventional product, (b) the present invention product, and (c) comparative product. In the conventional product, all seven balls are made of bearing steel (JIS standard SUJ-2). In the embodiment of the present invention, four balls are bearing steel and three are ceramics, and the arrangement is as shown in FIG. The diameter of this ceramic ball is 7.937, and the diameter of the steel ball is 7.942.
It is. In the comparative product, all seven balls are made of ceramics.

The material of the other parts of the sample is the same as that of the conventional product, the product of the present invention, and the comparative product.
UJ-2), the cage was 66 nylon, the seal was acrylic resin, and the grease used was synthetic oil grease.

Then, as a test condition, a radial load =
100kgf, rotation speed = 20000rpm, bearing temperature =
When the grease life (time) of each sample was measured at 150 ° C., the following results were obtained.

(A) Conventional product 543 hr (b) Product of the present invention 1370 hr (c) Comparative product 1500 hr From the test results, the decomposition of grease is suppressed in the product of the present invention. It is clear that the service life is as long as that of the comparative product made of all ball ceramics, and it is considered that the separation of the raceway surface due to the decomposition of the grease is effectively suppressed.

Although the grease-filled ball bearing has been described in the above embodiment, the present invention can also be applied to a grease-filled roller bearing, and the conditions applied to the above-mentioned ball may be applied to the roller as it is. .

[0028]

According to the present invention, since a part of the rolling elements is made of ceramic, a bearing having a long life under severe use conditions such as high load, high speed rotation and high temperature can be obtained. Since the number of the rolling elements is small, the cost is low, and the same high performance as a bearing in which all of the rolling elements are made of ceramic parts can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a grease-sealed ball bearing according to one embodiment of the present invention.

FIG. 2 is a side view schematically showing a ball arrangement state.

[Explanation of symbols]

 1 inner ring 2 outer ring 3A steel ball 3B ceramic ball

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 60-7422 (JP, U) JP-A 4-97115 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) F16C 33/66 F16C 19/06 F16C 33/32

Claims (1)

(57) [Claims] 1. A rolling bearing in which inner and outer races are made of steel and grease is sealed between the rolling elements, wherein the rolling elements are made of steel rolling elements and ceramic rolling elements, and the ceramic rolling elements are radially loaded. The ceramic rolling elements are distributed between steel rolling elements so that at least one rolling element is always present in the region.
The body diameter is less than the unloaded diameter of the steel rolling element,
A grease-enclosed rolling bearing, which is set to be larger than the limit diameter .