Ball bearing

Abstract

To provide a ball bearing having reduced weight, predetermined dynamic load rating, bearing ring strength, and bearing life.SOLUTION: When a ball diameter of the ball 4 is Dw, a radial minimum thickness of the inner ring 2 is Hi, and a radial minimum thickness of the outer ring 3 is Ho, a value of a ratio Dw / (Hi + Ho) of the ball diameter Dw to a sum Hi + Ho of both thicknesses is within a range of 1.55 or more and 2.4 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ball bearing. [Background technology]

[0002] Ball bearings (especially deep groove ball bearings) are widely used to support the rotating shafts of automobile prime movers (engines) and electric motors (motors). These ball bearings are required to have a certain dynamic load rating, raceway strength, bearing life, etc. For example, in the following Patent Document 1, a ball bearing with a large cross-sectional height H1 and a rolling element size D is used to support the rotating shaft of a high-speed motor or the like. W By using a ball bearing with a small diameter, the thickness of the raceway is ensured to be sufficient, increasing the strength (rigidity) of the raceway (see FIG. 1 in this document, etc.). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 1,1859,661 Summary of the Invention [Problem to be solved by the invention]

[0004] In particular, there is a demand for lighter components in automotive ball bearings to improve fuel economy. In the ball bearing described in Patent Document 1, the strength (rigidity) of the raceway is ensured by reducing the size of the rolling elements and ensuring a sufficient thickness of the raceway. This results in a problem of a larger mass than a ball bearing of the same cross-sectional height. While it is possible to reduce the weight by reducing the bearing size itself, this could result in a decrease in dynamic load rating and bearing life.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a ball bearing that is lightweight, has a predetermined dynamic load rating, race strength, and bearing life. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides: A ball bearing is configured (first configuration) having an inner ring, an outer ring provided radially outward of the inner ring, and a plurality of balls arranged between the inner ring and the outer ring, wherein when the ball diameter of the balls is Dw, the minimum radial thickness of the inner ring is Hi, and the minimum radial thickness of the outer ring is Ho, the ratio Dw / (Hi+Ho) of the ball diameter Dw to the sum Hi+Ho of both thicknesses is within the range of 1.55 to 2.4.

[0007] In this way, by keeping the ratio Dw / (Hi+Ho) (a measure of the ball occupancy) of the ball diameter Dw to the sum of the wall thicknesses of the inner and outer rings Hi+Ho within the above range while maintaining the bearing size (dimension series), it is possible to provide a ball bearing that is lightweight while also achieving the required dynamic load rating, raceway strength, and bearing life. If the ratio Dw / (Hi+Ho) is less than 1.55, the bearing mass will increase and the required dynamic load rating will not be achieved, while if it is more than 2.4, the required raceway strength (tensile strength, shear strength) may not be achieved.

[0008] In the first configuration, it is preferable to use a configuration (second configuration) in which the value of the ratio Dw / (Hi+Ho) is within the range of 1.9 to 2.4. By further limiting the range of the ratio in this way, it is possible to reliably achieve both weight reduction and a predetermined dynamic load rating, bearing ring strength, and bearing life.

[0009] The first configuration can be changed to a configuration (third configuration) in which the balls have a diameter larger than the standard ball diameter at which the ratio Dw / (Hi+Ho) is 1.5, but within a range of 5% to 10%, or a configuration (fourth configuration) in which the balls have a diameter larger than the standard ball diameter at which the ratio Dw / (Hi+Ho) is 1.5, but within a range of 10% to 18%. In this way, it is possible to reliably achieve both weight reduction and a predetermined dynamic load rating, raceway strength, and bearing life.

[0010] In the first to fourth configurations, a configuration (fifth configuration) can be used in which, when the axial width of the inner ring and the outer ring is B, the ratio Dw / B of the ball diameter Dw to the axial width B is within the range of 0.65 to 0.95. In this way, similar to the above, it is possible to fit the cage holding the balls within the range of the axial width of the bearing while achieving both weight reduction and a predetermined dynamic load rating, raceway strength, and bearing life.

[0011] The first to fifth configurations can be configured as an open type (sixth configuration) in which no seal members are provided at either end in the axial direction. In this way, the balls (retainer) can be positioned close to the axial ends of the bearing where the seal members would normally be provided, making it relatively easy to expand the diameter of the balls.

[0012] The first to sixth configurations can be configured as a seventh configuration, which further includes a cage that holds the plurality of balls at predetermined intervals in the circumferential direction, and the cage is a mated cage formed by combining a pair of split pieces from the axial direction. By using a mated cage in this way, the axial width can be made narrower than in a cantilever-type cage, making it possible to use balls with a larger diameter.

[0013] In the first to seventh configurations, a configuration (eighth configuration) can be used in which the ratio Hi / Ho of the minimum radial wall thickness Hi to the minimum radial wall thickness Ho is within the range of 0.9 to 1.1. In this configuration, the load on the wall thickness acting from the ball acts relatively evenly on both the inner ring and the outer ring, preventing a difference in strength due to a load being biased to one of the inner or outer ring.

[0014] The ball bearings according to the first to eighth configurations can be used to support the rotating shaft of an automotive prime mover, electric motor, or reducer (ninth configuration). By adopting the ball bearings according to the present invention, which combine lightweight design with a specified dynamic load rating, raceway strength, and bearing life, it is possible to improve the fuel economy, power consumption, and driving performance of an automobile. They are particularly useful as support bearings for the second shaft of a reducer, which is subjected to a relatively large load within limited size requirements. [Effects of the Invention]

[0015] In the ball bearing according to the present invention, where Dw is the diameter of the balls, Hi is the minimum radial thickness of the inner ring, and Ho is the minimum radial thickness of the outer ring, the ratio Dw / (Hi+Ho) of the ball diameter Dw to the sum of the two thicknesses Hi+Ho is between 1.55 and 2.4, making it possible to provide a ball bearing that is lightweight while also achieving a specified dynamic load rating, raceway strength, and bearing life.This allows for improved fuel efficiency through weight reduction and reduced environmental impact through reduced material use while still satisfying the requirements for a bearing. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view showing an embodiment of a ball bearing according to the present invention; [Figure 2] A schematic diagram showing an example in which the ball bearing shown in Figure 1 is used to support the rotating shaft of a reducer in an electric axle (e-Axle). DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of a ball bearing 1 according to the present invention will be described with reference to the drawings. As shown in Fig. 1, this ball bearing 1 is a deep groove ball bearing having an inner ring 2, an outer ring 3 provided coaxially on the radially outer side of the inner ring 2, and a plurality of balls 4 arranged between the inner ring 2 and the outer ring 3. An inner ring raceway groove 5 is formed on the outer diameter surface of the inner ring 2, and an outer ring raceway groove 6 is formed on the inner diameter surface of the outer ring 3, and the balls 4 roll along both raceway grooves 5, 6.

[0018] The multiple balls 4 are held at a predetermined interval in the circumferential direction by a cage 7. This cage 7 is a laminated cage made by combining, in the axial direction, divided pieces formed by stamping steel plate. In addition to steel plate, various resins such as polyamide resin, polyether ether ketone resin, and polyphenylene sulfide resin can also be used as the material for the cage 7. Furthermore, the type of cage 7 is not limited to a laminated cage, and various types of cages 7 can be used.

[0019] This ball bearing 1 is an open type ball bearing 1 with no sealing members at either axial end, and the balls 4 (retainer 7) are arranged up to the vicinity of the axial ends of the bearing where sealing members would normally be provided. In this embodiment, when the ball diameter of the balls 4 is Dw and the axial width of the inner ring 2 and outer ring 3 is B, the ratio Dw / B of the ball diameter Dw to the axial width B is 0.75. It is preferable to design the ball bearing 1 so that the value of this ratio Dw / B is within the range of 0.65 to 0.95. Note that if this ball bearing 1 is used in an environment where foreign matter such as muddy water is likely to enter, it can also be configured with sealing members at both axial ends.

[0020] Here, if the minimum radial thickness of the inner ring raceway groove 5 is Hi and the minimum radial thickness of the outer ring raceway groove 6 is Ho, the ratio Hi / Ho of these minimum thicknesses Hi and Ho is 1.0, that is, the minimum radial thickness Hi of the inner ring raceway groove 5 and the minimum radial thickness Ho of the outer ring raceway groove 6 are the same thickness. It is preferable to design the bearing so that the value of this ratio Hi / Ho is within the range of 0.9 to 1.1.

[0021] As shown in Table 1, in a conventional product, the ratio Dw / (Hi+Ho) of the ball diameter Dw to the sum of both thicknesses Hi+Ho is, for example, 1.5, and if the bearing size is an inner diameter of 35 mm, an outer diameter of 72 mm, and a width of 17 mm, the ball diameter Dw will be 11.1 mm. If the value of the ratio Hi / Ho is within the above range (the minimum radial thicknesses Hi and Ho of the inner and outer ring raceway grooves 5, 6 are roughly the same), then changing the ball diameter Dw will leave almost no change in the perimeter of the pitch circle, and therefore the number of balls 4 that can be installed between the inner and outer rings 2, 3 decreases as the ball diameter Dw increases.

[0022] The ball bearing 1 according to the present invention is designed so that the ratio Dw / (Hi+Ho) is in the range of 1.55 to 2.4, and more preferably in the range of 1.9 to 2.4. The ratio Dw / (Hi+Ho) can be increased by upgrading (increasing the diameter of) the balls 4 used in conventional products while maintaining the same bearing size (dimension series).

[0023] For example, as shown in Table 1, by changing the ball diameter Dw from the standard 11.1 mm used in conventional products to 11.9 mm, the ratio Dw / (Hi+Ho) can be increased from 1.5 to 1.8 (see invention product 1 of the present application). In this case, the ball diameter Dw can be determined based on the index of increasing the diameter by 5% to 10% relative to the standard ball diameter at which the ratio Dw / (Hi+Ho) becomes 1.5.

[0024] Furthermore, by changing the ball diameter Dw from the standard 11.1 mm used in conventional products to a 12.7 mm diameter, the ratio Dw / (Hi+Ho) can be increased from the original 1.5 to 2.2 (see Invention Product 2 of the present application). In this case, the ball diameter Dw can be determined based on the index of increasing the diameter by 10% to 18% relative to the standard ball diameter at which the ratio Dw / (Hi+Ho) becomes 1.5.

[0025] When replacing the balls with larger diameters (Dw) than the standard, the sum of the minimum radial thicknesses (Hi + Ho) of the inner and outer ring raceway grooves 5 and 6 must be reduced by the increase in ball diameter (Dw) to maintain the same bearing size as the conventional product. Therefore, as shown in Table 1, the ratio of the raceway thickness to the conventional product (raceway thickness ratio) decreases. Furthermore, increasing the ratio Dw / (Hi + Ho) increases the contact area between the balls 4 and the inner and outer ring raceway grooves 5 and 6, thereby increasing the dynamic load rating that can be applied to this ball bearing 1 relative to the conventional product (dynamic load rating ratio). Furthermore, by reducing the sum of the minimum radial thicknesses (Hi + Ho) of the inner and outer ring raceway grooves 5 and 6 by the increase in ball diameter (Dw), i.e., by thinning the inner and outer rings 2 and 3, the ratio of the bearing mass to the conventional product (bearing mass ratio) decreases.

[0026] On the other hand, since the sum Hi+Ho of the minimum radial thicknesses of the inner and outer ring raceway grooves 5, 6 becomes smaller, the ratio of the raceway strength to that of a conventional product (raceway strength ratio) tends to become smaller.

[0027] [Table 1]

[0028] Table 2 shows the evaluation results for dynamic load rating, bearing mass, and raceway strength when the ratio Dw / (Hi+Ho) value is changed between 1.5 and 2.5 for ball bearing 1 having the inner diameter, outer diameter, and width shown in Table 1. The symbols ◎ in the table mean that the required level is fully met, ○ means that the required level is met, and △ means that the required level cannot be said to be fully met. As a general trend, the larger the value of the ratio Dw / (Hi+Ho), the better the evaluation of dynamic load rating and bearing mass. On the other hand, the larger the value of the ratio Dw / (Hi+Ho), the worse the evaluation of raceway strength.

[0029] It was confirmed that by setting the ratio Dw / (Hi+Ho) within the range of 1.55 or more and 2.4 or less, very good or good ratings could be obtained for the dynamic load rating, bearing mass, and raceway strength, and in particular, by setting it within the range of 1.9 or more and 2.4 or less, very good ratings could be obtained for the dynamic load rating and bearing mass.

[0030] [Table 2]

[0031] In the above-described ball bearing 1, the ratio Dw / (Hi+Ho) of the ball diameter Dw of the balls 4 to the sum Hi+Ho of the minimum radial wall thicknesses of the inner and outer raceway grooves 5 and 6 is set within the range of 1.55 to 2.4, thereby providing a ball bearing 1 that achieves both lightweight and a desired dynamic load rating, raceway strength, and bearing life while maintaining the bearing size (dimension series). In particular, by setting the ratio Dw / (Hi+Ho) within the range of 1.9 to 2.4, lightweight and a desired dynamic load rating, raceway strength, and bearing life can be reliably achieved. Furthermore, by setting the ratio Dw / (Hi+Ho) within the range of 1.9 to 2.2, raceway strength can be improved. Furthermore, the weight reduction allows for a reduction in the amount of steel used in the inner and outer rings 2 and 3, thereby reducing manufacturing costs.

[0032] Furthermore, the above-mentioned ball bearing 1 is configured to use large diameter balls 4 within a range of 5% to 10% of the standard ball diameter at which the ratio Dw / (Hi+Ho) is 1.5, and in particular, to use large diameter balls 4 within a range of 10% to 18% of the standard ball diameter at which the ratio Dw / (Hi+Ho) is 1.5, thereby reliably achieving both lightweight design and a specified dynamic load rating, raceway strength, and bearing life.

[0033] Furthermore, the above-mentioned ball bearing 1 is configured so that when the axial width of the inner ring 2 and the outer ring 3 is B, the ratio Dw / B of the ball diameter Dw to the axial width B is within the range of 0.65 or more and 0.95 or less.As a result, as with the above, it is possible to achieve a balance between weight reduction and a specified dynamic load rating, raceway strength, and bearing life, while allowing the retainer 7 holding the balls 4 to be contained within the axial width range of the bearing.

[0034] Furthermore, the above-mentioned ball bearing 1 is configured such that the retainer 7 is a mating retainer formed by combining a pair of split pieces in the axial direction, so that the axial width can be made narrower compared to a cantilever-type retainer 7, making it possible to use balls 4 with a larger diameter.

[0035] Furthermore, in the above-described ball bearing 1, the ratio Hi / Ho of the minimum radial thickness Hi of the inner ring raceway groove 5 to the minimum radial thickness Ho of the outer ring raceway groove 6 is set to approximately 1 (within the range of 0.9 to 1.1), so that the load acting on the thickness from the balls 4 acts relatively evenly on both the inner ring 2 and the outer ring 3, preventing differences in strength due to the load being biased toward one of the inner and outer rings 2, 3.

[0036] Furthermore, the above-mentioned ball bearing 1 preferably has a width series of 8, 0, 1, 2, or 3. As shown in Table 2, as the ball diameter Dw increases (the ratio Dw / (Hi+Ho) increases), the minimum radial thicknesses Hi and Ho of the inner and outer raceway grooves 5 and 6 decrease, and the raceway strength decreases. However, compared with bearings with width series 4, 5, and 6, bearings with width series 8, 0, 1, 2, and 3 have a relatively large radial width relative to the bearing width, and therefore may be able to relatively suppress the decrease in raceway strength that occurs with an increase in ball diameter Dw.

[0037] As shown in Fig. 2, the above-described ball bearing 1 can be applied to, for example, an electric axle 8 (e-Axle) mounted on an electric vehicle. This electric axle 8 has a motor 9 and a reducer 11 that reduces the speed of the output of a motor shaft 10. The reducer 11 has a multi-stage rotating shaft 13 to which rotation is transmitted by a gear 12. The motor shaft 10 of the motor 9 and the rotating shaft 13 of the reducer 11 are supported by bearings 14. There are no particular limitations on the application location of the ball bearing 1 according to the present invention, but it can be applied, for example, to supporting the second-stage rotating shaft 13 of the reducer 11.

[0038] An automobile's electric axle 8 (reduction gear 11), prime mover, electric motor, etc., may be designed to be relatively resistant to muddy water splashed up from the road while the automobile is in motion, and therefore may not require a seal to prevent foreign matter from entering the bearing. In this case, as in the ball bearing 1 shown in Figure 1, the balls 4 (retainer 7) can be positioned axially up to the position where a seal would normally be provided (larger diameter balls 4 can be used), achieving both weight reduction and a specified dynamic load rating and raceway strength. Applying this ball bearing 1 to an automobile can improve its fuel economy, power consumption, and driving performance.

[0039] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0040] 2. Inner circle 3 outer ring 4 balls 5 Inner ring raceway groove 6 Outer ring raceway groove 7 Cage 11 Reducer 13 Rotation axis

Claims

1. A ball bearing comprising an inner ring (2), an outer ring (3) provided radially outward of the inner ring (2), and a plurality of balls (4) arranged between the inner ring (2) and the outer ring (3), wherein, when the ball diameter of the balls (4) is Dw, the minimum radial thickness of the inner ring (2) is Hi, and the minimum radial thickness of the outer ring (3) is Ho, the ratio Dw / (Hi+Ho) of the ball diameter Dw to the sum of the two thicknesses Hi+Ho is within the range of 1.55 to 2.

4.

2. 2. The ball bearing according to claim 1, wherein the value of the ratio Dw / (Hi+Ho) is within the range of 1.9 to 2.

4.

3. 2. A ball bearing according to claim 1, wherein the balls (4) have a diameter larger than the standard ball diameter at which the ratio Dw / (Hi+Ho) is 1.5, within a range of 5% to 10%.

4. 2. A ball bearing according to claim 1, wherein the balls (4) have a diameter larger than the standard ball diameter at which the ratio Dw / (Hi+Ho) is 1.5, within a range of 10% to 18%.

5. 2. The ball bearing according to claim 1, wherein when the axial width of the inner ring (2) and the outer ring (3) is B, the ratio Dw / B of the ball diameter Dw to the axial width B is within a range of 0.65 to 0.

95.

6. 2. A ball bearing according to claim 1, which is an open type having no seal members at either end in the axial direction.

7. 2. A ball bearing as described in claim 1, further comprising a retainer (7) that holds the plurality of balls (4) at predetermined intervals in the circumferential direction, the retainer (7) being a mating retainer formed by combining a pair of split pieces from the axial direction.

8. 2. The ball bearing according to claim 1, wherein a ratio Hi / Ho of the minimum radial thickness Hi to the minimum radial thickness Ho is within a range of 0.9 to 1.

1.

9. 9. The ball bearing according to claim 1, which is used to support a rotating shaft (13) of a prime mover, an electric motor, or a reducer (11) for an automobile.

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