Roller bearing

Abstract

To more reliably prevent the occurrence of galling when assembling a shell outer ring to a housing.SOLUTION: A roller bearing comprises an annular shell outer ring 10, a cage 20 incorporated into the shell outer ring 10, and rollers 30 retained in the cage 20. The shell outer ring 10 comprises an outer ring portion 13 forming a raceway surface 15 facing the rolling surfaces 31 of the rollers 30, a first flange portion 11 protruding from one axial end of the outer ring portion 13 toward the inner diameter side, a second flange portion 12 protruding from the other axial end of the outer ring portion 13 toward the inner diameter side, and curved portions 14 provided between the outer ring portion 13 and the first flange portion 11 and between the outer ring portion 11 and the second flange portion 12. An inner diameter r11 of an inner diameter side end 11a of the first flange portion 11 is set to be 80% or more and less than 95% of an outer diameter r20 of the maximum diameter portion of the cage 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a roller bearing and a shell outer ring used for the roller bearing.

Background Art

[0002] As a roller bearing, there is one provided with a shell-shaped outer ring. This type of roller bearing includes a shell outer ring formed of a metal plate-like member, a cage incorporated on the inner diameter side of the shell outer ring, and rollers as rolling elements held by the cage. The shell outer ring includes a cylindrical outer ring portion that forms a raceway surface facing the rolling surface of the rolling element, and flange portions that project inward in the diameter direction at both axial ends of the outer ring portion.

[0003] By the way, in the current automotive industry, from the perspective of improving fuel efficiency, the opportunity to use light alloy materials such as aluminum to reduce the weight of vehicles is increasing. Along with this, as the material of the housing (axle box) that supports the bearing, light alloy materials such as aluminum are often used. In a housing made of a light alloy, compared with a housing made of steel (iron), the risk of galling of the shell outer ring increases. For this reason, in the shell outer ring of Patent Document 1, a tapered portion is provided on the outer peripheral surface of one axial end of the outer ring portion, where the outer diameter gradually decreases from the inner side in the axial direction toward the outer side in the axial direction, and the taper angle with respect to the axial direction of the tapered portion is in the range of 0.5 degrees or more and less than 5 degrees to prevent the occurrence of galling.

[0004] Further, in the shell outer ring of Patent Document 2, a bent R portion is interposed on the outer surface of the ridge line portion between the outer ring portion and the flange portion, and a connection portion where both are smoothly connected is provided between the tapered portion on the outer peripheral surface of the outer ring portion and the bent R portion.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] As an advantage of a roller bearing using a shell outer ring, it can be applied in a compact size compared with other types of bearings such as ball bearings. In particular, in recent years, in electric vehicles, the demand for a power device “eAxle” in which an inverter, a motor, and a speed reducer including a differential are integrated has been increasing. In this type of power device, in order to reduce the size of the device while ensuring the load capacity, a shell bearing with a reduced bearing width and an increased outer diameter may be adopted.

[0007] By the way, as described above, a roller bearing using a shell outer ring is likely to cause galling with respect to a housing made of a light alloy. Further, the shell outer ring is formed by pressing. Therefore, as the outer diameter of the bearing increases, the machining accuracy of the shell outer ring may deteriorate. Further, due to an increase in the fitting area of the shell outer ring with respect to the housing, an increase in the press-fitting force is a concern. When galling or an excessive press-fitting force occurs, a situation such as deformation of the flange portion of the shell outer ring and pinching of internal components may occur.

[0008] According to the shell outer rings of Patent Documents 1 and 2, it is said that the occurrence of galling during press-fitting can be prevented. However, when the outer diameter of the shell outer ring increases, the force required for press-fitting into the housing increases. Therefore, a technique for more surely preventing the occurrence of galling during press-fitting is required.

[0009] Therefore, an object of the present invention is to more surely prevent the occurrence of galling when assembling a roller bearing provided with a shell outer ring to a housing.

Means for Solving the Problems

[0010] In order to solve the above problems, the present invention provides a roller bearing including an annular shell outer ring, a cage incorporated in the shell outer ring, and rollers held by the cage. The shell outer ring includes an outer ring portion forming a raceway surface facing the rolling surface of the rollers, a first flange portion protruding from one axial end of the outer ring portion toward the inner diameter side, a second flange portion protruding from the other axial end of the outer ring portion toward the inner diameter side, and curved portions provided between the outer ring portion and the first flange portion and between the outer ring portion and the second flange portion. The inner diameter of the inner diameter side end of the first flange portion is set to be 80% or more and less than 95% of the outer diameter of the maximum diameter portion of the cage (Configuration 1).

[0011] In Configuration 1, a configuration can be adopted in which the shell outer ring is press-fitted into the inner diameter of the housing, and the first flange portion is set as the tip side when press-fitting into the inner diameter of the housing (Configuration 2).

[0012] In Configuration 1 or Configuration 2, a configuration can be adopted in which the plate thickness of the first flange portion is set to be 45% or more and less than 70% of the plate thickness of the outer ring portion (Configuration 3).

[0013] Further, in Configuration 1, Configuration 2, or Configuration 3, an end portion on one axial end side of the outer ring portion has a plate thickness change portion in which the plate thickness gradually decreases from the plate thickness of the outer ring portion to the plate thickness of the first flange portion, and an inner surface of the plate thickness change portion is an inclined surface facing the outer diameter side at an angle of 25° or more and less than 35° with respect to the axial direction as it approaches the first flange portion. A configuration can be adopted (Configuration 4).

[0014] Further, in any of Configuration 1 to Configuration 4, a configuration can be adopted in which the hardness of at least the first flange portion of the shell outer ring is 600 HV or less (Configuration 5).

[0015] Further, in any one of Configuration 1 to Configuration 5, a configuration in which Rb>Ra≧Rc or Rb>Rc>Ra is satisfied among the outer diameter Ra at the axially other end of the opposing range of the outer ring portion with the rolling surface, the outer diameter Rb at the axial center of the opposing range of the outer ring portion with the rolling surface, and the outer diameter Rc at the axially one end of the opposing range of the outer ring portion with the rolling surface can be adopted (Configuration 6).

Advantages of the Invention

[0016] According to the present invention, when assembling the roller bearing provided with the shell outer ring into the housing, the occurrence of galling can be more reliably prevented.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0018] Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a roller bearing 1 according to this embodiment. FIGS. 2A and 2B are detailed views of a shell outer ring 10 used for the roller bearing 1. FIG. 3 is a sectional view showing the state where the roller bearing 1 is press-fitted and fixed in a housing H.

[0019] The roller bearing 1 includes an annular shell outer ring 10, a cage 20 incorporated in the shell outer ring 10, and cylindrical rollers 30 held by the cage 20. In the embodiment, as the rollers 30, needle rollers having a length in the cylindrical axial direction longer than the diameter (for example, a length of about 3 times or more and less than 10 times the diameter) are used. In the embodiment, a large roller bearing 1 with an outer diameter of φ60 or more and 100φ or less used in the power unit "eAxle" of an electric vehicle is assumed.

[0020] The cage 20 includes a pair of annular portions 21, 21 and a plurality of column portions 22 connecting the annular portions 21, 21 in the axial direction. The space between adjacent column portions 22, 22 in the circumferential direction serves as a pocket portion for holding the rollers 30. The rollers 30 are held so as not to fall off by a roller stopper portion (not shown) formed to protrude from the column portion 22.

[0021] The shell outer ring 10 includes an outer ring portion 13 forming a raceway surface 15 facing the rolling surface 31 of the rollers 30, a first flange portion 11 protruding from one axial end of the outer ring portion 13 toward the inner diameter side, and a second flange portion 12 protruding from the other axial end of the outer ring portion 13 toward the inner diameter side. Further, the first flange portion 11 and the second flange portion 12 each include a curved portion 14 connected to the outer ring portion 13.

[0022] The shell outer ring 10 is formed by bending a metal cylindrical member. The curved portion 14 on the other axial end side (the second flange portion 12 side) is formed by pressing the end of the cylindrical member. The curved portion 14 on one axial end side (the first flange portion 11 side) is formed by bending after the cage 20 and the rollers 30 are inserted into the outer ring portion 13. Hereinafter, the processing of the curved portion 14 on the other axial end side is referred to as pre-bending processing, and the processing of the curved portion 14 on one axial end side is referred to as post-bending processing.

[0023] Inside the shell outer ring 10 in which the second flange portion 12 is formed by pre-bending, the cage 20 and the roller 30 are inserted, and the first flange portion 11 is formed by post-bending, so that the cage 20 and the roller 30 are held inside the outer ring portion 13, and the roller bearing 1 is configured. Further, the roller bearing 1 is press-fitted and fixed to the inner diameter of the housing H having a hole with a circular cross-section. At this time, an interference fit of about 40 to 350 μm is set by the diameter difference. Note that a shaft (not shown) is inserted inside the rollers 30 arranged in parallel in the circumferential direction, that is, on the shaft center O side of the roller bearing 1, and the shaft is supported so as to be rotatable relative to the housing H about the axis.

[0024] In the embodiment, as the housing H, a shaft housing that supports the roller bearing 1 used in the power unit "eAxle" of an electric vehicle is assumed, but the housing H may be other than such a shaft housing in the "eAxle". The housing H is made of a light metal mainly composed of aluminum or another light metal other than aluminum. When the shell outer ring 10 is press-fitted into the inner diameter of the housing H, the first flange portion 11 side of the shell outer ring 10 is press-fitted first. That is, the first flange portion 11 side is set as the tip side at the time of press-fitting, and the second flange portion 12 side is set as the rear end side at the time of press-fitting.

[0025] The shell outer ring 10 is formed by cold rolling carbon steel for mechanical structures or stainless steel. For example, SPC, SCM, SUS, etc. may be mentioned. As the plate thickness t13 of the outer ring portion 13, for example, 0.5 or more and less than 2.5 mm is adopted. Note that the inner surface of the hole of the housing H in contact with the outer surface 17 of the outer ring portion 13 is processed to a predetermined average roughness or less.

[0026] As shown in FIG. 1, the outer diameter r20 of the maximum diameter portion of the cage 20 is larger than the inner diameter r11 of the inner diameter side end 11a of the first flange portion 11 and also larger than the inner diameter r12 of the inner diameter side end 12a of the second flange portion 12. Thereby, the axial movement of the cage 20 is restricted by the first flange portion 11 and the second flange portion 12. Note that the outer diameter of the shell outer ring 10 is denoted by the symbol R in FIG. 1.

[0027] Also, the inner diameter r11 of the inner diameter side end 11a of the first flange portion 11 is set to be 80% or more and less than 95% with respect to the outer diameter r20 of the maximum diameter portion of the cage 20. Thereby, an effect of preventing galling during press-fitting into the housing H can be expected. That is, if the press-fitting force of the roller bearing 1 with respect to the housing H is excessive, galling is likely to occur in the first flange portion 11 of the shell outer ring 10 and the mating housing H. However, by increasing the inner diameter of the first flange portion 11, which is the tip side during press-fitting, compared to the conventional one, the rigidity of the flange portion is reduced. As a result, smooth press-fitting is achieved by reducing the press-fitting force.

[0028] Here, when the ratio of the inner diameter r11 of the inner diameter side end 11a of the first flange portion 11 to the outer diameter r20 of the maximum diameter portion of the cage 20 is less than 80%, the rigidity of the shell outer ring 10 increases, and galling tends to occur. Also, when the roller bearing 1 is oil-lubricated, there may also occur a problem that smooth inflow and outflow of oil to the inside of the shell outer ring 10 are hindered. Conversely, when the ratio is 95% or more, when the cage 20 is tilted (when the axis of the cage 20 is inclined with respect to the axis of the shell outer ring 10), depending on the use conditions, the end portion of the cage 20 may be caught by the inner diameter side end of the shell outer ring 10, or a problem of dropping off of the cage 20 may also occur. Also in these respects, it is desirable that the ratio of the inner diameter r11 of the inner diameter side end 11a of the first flange portion 11 to the outer diameter r20 of the maximum diameter portion of the cage 20 is set to be 80% or more and less than 95%.

[0029] Further, the first flange portion 11 rises from one axial end of the cylindrical outer ring portion 13 toward the inner diameter side. The outer ring portion 13 has a constant thickness t13 over the entire axial length except for the thickness change portion 16 at one axial end. The thickness t11 of the first flange portion 11 is set to be smaller (thinner) than the thickness t13 of the outer ring portion 13. In the embodiment, the thickness t11 of the first flange portion 11 is set to be 45% or more and less than 70% of the thickness t13 of the outer ring portion 13. With this thickness setting, the effect of suppressing the occurrence of biting is further enhanced. That is, by setting the thickness t11 of the first flange portion 11 to be thinner than the thickness t13 of the outer ring portion 13, the rigidity of the flange portion is reduced, and smooth press fitting is realized. Further, since the first flange portion 11 is the flange portion on the post-bending side, such a thickness setting also contributes to facilitating the post-bending process.

[0030] Here, when the ratio of the thickness t11 of the first flange portion 11 to the thickness t13 of the outer ring portion 13 is less than 45%, a situation may occur where the shape of the first flange portion 11 is unstable during the press working of the shell outer ring 10. Also, if the thickness t11 of the first flange portion 11 is too thin, the first flange portion 11 may be deformed when the shell outer ring 10 is press-fitted into the housing H. Conversely, when the ratio is 70% or more, the rigidity of the shell outer ring 10 increases, and there is a tendency for biting to occur easily. Also in these respects, it is desirable that the ratio of the thickness t11 of the first flange portion 11 to the thickness t13 of the outer ring portion 13 is set to be 45% or more and less than 70%.

[0031] Note that, as shown in FIG. 2A, the inner diameter side end 11a of the first flange portion 11 is the portion that protrudes most toward the inner diameter side among the respective portions of the first flange portion 11. In the embodiment, the first flange portion 11 includes a first portion 11c connected to the inner diameter side of the curved portion 14 and a second portion 11d connected to the inner diameter side of the first portion 11c. The first portion 11c extends linearly along the radial direction of the roller bearing 1 from the inner diameter side end of the curved portion 14. The side surface 11b of the first portion 11c is the portion that protrudes most toward one axial end side of the shell outer ring 10. The second portion 11d extends in a direction that inclines slightly toward the other axial end side as it goes toward the inner diameter side from the inner diameter side end of the first portion 11c. The inner diameter side end 11a of the first flange portion 11 corresponds to the leading edge of the axial end side of this inclined second portion 11d.

[0032] The curved portion 14 on one axial end side is at the outer diameter side end of the first flange portion 11, and the first flange portion 11 is coupled to the outer ring portion 13. The outer surface 18 and the inner surface 19 of the curved portion 14 are concentric circles each formed by an arc of a single radius in any longitudinal section including the axis O of the roller bearing 1. Since the outer surface 18 of the curved portion 14 forms an arc-shaped ridge portion that bulges outward over the entire circumference of the shell outer ring 10, the press-fitting of the shell outer ring 10 into the housing H is smoother.

[0033] Here, it is preferable that the hardness of at least the first flange portion 11 of the shell outer ring 10 is 600 HV (Vickers hardness) or less in order to prevent the occurrence of galling. This is because if the hardness of the first flange portion 11 is too high (too hard), galling is likely to occur. Note that HV (Vickers hardness) is a method for determining the hardness of a test piece based on the size of the indentation area formed when a rigid body (indenter) made of diamond is pressed into the test piece. The measurement method is based on Japanese Industrial Standard JIS-Z 2244:2009. In the embodiment, the hardness of at least the first flange portion 11 is set to 600 HV or less. However, depending on the material and the intended use, the entire shell outer ring 10 may be set to 600 HV or less.

[0034] Further, the outer ring portion 13 has a thickness change portion 16 at one end in the axial direction thereof, where the thickness gradually decreases from the thickness t13 of the outer ring portion 13 to the thickness t11 of the first flange portion 11. In any longitudinal section including the axis of the shell outer ring 10, the inner surface 16a of the thickness change portion 16 includes an inclined surface that faces the outer diameter side as it approaches the first flange portion 11, and the inclined surface 16a forms an angle α (see FIG. 2B) with respect to the axial direction of the shell outer ring 10. This angle α is preferably 25° or more and less than 35°. By providing the thickness change portion 16 at one end in the axial direction of the outer ring portion 13, the post-bending process of the first flange portion 11 is facilitated. Here, if the angle α is less than 25 degrees, the shape may become unstable during the bending process of the first flange portion 11. Conversely, if the angle α is 35 degrees or more, the rigidity near the thickness change portion 16 is low, so the member may deform when the shell outer ring 10 is press-fitted into the housing H. Also in these respects, the angle α is preferably 25° or more and less than 35°.

[0035] In the embodiment, as shown in FIG. 2B, the inner surface 16a of the thickness change portion 16 is made smooth by forming the connection portion 16b to the outer ring portion 13 and the connection portion 16c to the inner surface 19 of the curved portion 14 in an arc shape, respectively. However, the forms of these connection portions 16b and 16c can be changed as appropriate. For example, the radii rb and rc of the arcs of each connection portion 16b and 16c may be made smaller than the state shown in FIG. 2B, or conversely, the radii rb and rc of the arcs of each connection portion 16b and 16c may be made larger than the state shown in FIG. 2B. Also, each connection portion 16b and 16c may be a combination of a plurality of arcs with different radii. Further, a linear inclined surface (taper surface) formed with a single gradient may be interposed in the middle of the inner surface 16a of the thickness change portion 16 as shown in FIG. 2B, or the inner surface 16a of the thickness change portion 16 without such a linear inclined surface may be used. When a linear inclined surface is not interposed in the inner surface 16a of the thickness change portion 16, the maximum angle among the angles (acute angles) with respect to the axial direction at each part of the inner surface 16a of the thickness change portion 16 may be defined as the above-mentioned angle α.

[0036] In addition, in the embodiment, the outer surface 18 and the inner surface 19 of the curved portion 14 are each a concentric circle formed by an arc having a single radius. However, the aspect of the curved portion 14 is not limited to this embodiment. Further, for example, a tapered surface that smoothly connects from the outer surface 17 side of the outer ring portion 13 to the outer surface 18 side of the curved portion 14 may be provided at one axial end of the outer surface 17 of the outer ring portion 13. In this case, in any longitudinal section including the axis O of the rolling bearing 1, the angle of the tapered surface with respect to the axial direction of the rolling bearing 1 can be, for example, an angle that gradually goes toward the inner diameter side at an angle of 0.5 degrees or more and less than 5 degrees as it goes toward the first flange portion 11 side.

[0037] Similarly, the second flange portion 12 rises from the other axial end of the cylindrical outer ring portion 13 toward the inner diameter side. The configuration of the curved portion 14 is the same as that of the first flange portion 11. Note that the side surface 12b of the second flange portion 12 extends linearly along the radial direction of the rolling bearing 1 from the inner diameter side end of the curved portion 14. The space between the side surface 12b of the second flange portion 12 and the side surface 11b of the first flange portion 11 corresponds to the axial width A of the shell outer ring 10. Note that the second flange portion 12 side is the rear end side during press fitting, and the plate thickness t12 of the second flange portion 12 is less likely to be a factor in the occurrence of galling during press fitting. Further, since the outer ring portion 13 forming the raceway surface 15 is formed by deep drawing, the plate thickness t12 of the second flange portion 12 may be set to be larger than the plate thickness t13 of the outer ring portion 13.

[0038] In this embodiment, with respect to the outer diameter R of the shell outer ring 10 shown in FIG. 1, by adopting the following configuration, the effect of preventing galling during press-fitting into the housing H is further enhanced. That is, as shown in FIG. 3, among the axial widths A of the shell outer ring 10, the outer diameter Ra at the axial other end 13a of the facing range B with the rolling surface 31 of the roller 30 in the outer ring portion 13, the outer diameter Rb at the axial center 13b of the facing range B, and the outer diameter Rc at the axial one end 13c of the facing range B, it is preferable that Rb>Ra≧Rc or Rb>Rc>Ra holds. Also, the difference between Rb and Ra, and the difference between Rb and Rc are each preferably about 10 to 30 μm. FIG. 3 shows the shell outer ring 10 in a state press-fitted into the housing H. However, the numerical values of the outer diameter Ra, outer diameter Rb, and outer diameter Rc shown in each of the above expressions of Rb>Ra≧Rc and Rb>Rc>Ra are the numerical values of the outer diameters at each position of the shell outer ring 10 before press-fitting, respectively.

[0039] FIG. 4 schematically shows the shell outer ring 10 in a state press-fitted into the inner diameter of the housing H. The pressing force in the inner diameter direction centered on the axis O indicated by the symbol X and the pressing force in the outer diameter direction indicated by the symbol Y are each suppressed to be smaller than before.

[0040] The disclosed embodiments should be considered illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of claims rather than the above description, and it is intended that all modifications within the meaning and scope equivalent to the scope of claims are included.

Explanation of Reference Numerals

[0041] 1 Roller bearing (bearing) 10 Shell outer ring 11 First flange portion 12 Second flange portion 13 Outer ring portion 14 Curved portion 15 Raceway surface 16 Plate thickness change portion 16a Inner surface (inclined surface) 20 Cage 30 Roller 31 Running surface r11 Inner diameter of the inner diameter side end r20 Outer diameter of the maximum diameter part t11, t13 Plate thickness R, Ra, Rb, Rc Outer diameter

Claims

1. A roller bearing comprising an annular shell outer ring (10), a cage (20) incorporated in the shell outer ring (10), and rollers (30) held by the cage (20). The shell outer ring (10) includes an outer ring portion (13) that forms a raceway surface (15) facing the rolling surface (31) of the roller (30), a first flange portion (11) that projects inward from one axial end of the outer ring portion (13), a second flange portion (12) that projects inward from the other axial end of the outer ring portion (13), and curved portions (14) provided between the outer ring portion (13) and the first flange portion (11) and between the outer ring portion (13) and the second flange portion (12). A roller bearing in which the inner diameter (r11) of the inner diameter side end (11a) of the first flange portion (11) is set to be 80% or more and less than 95% of the outer diameter (r20) of the maximum diameter portion of the cage (20).

2. The roller bearing according to claim 1, wherein the shell outer ring (10) is press-fitted into the inner diameter of a housing, and the first flange portion (11) is set as the tip side when press-fitting into the inner diameter of the housing.

3. The roller bearing according to claim 1 or 2, wherein the plate thickness (t11) of the first flange portion (11) is set to be 45% or more and less than 70% of the plate thickness (t13) of the outer ring portion (13).

4. The roller bearing according to claim 1 or 2, having a plate thickness changing portion (16) at one axial end of the outer ring portion (13), where the plate thickness gradually decreases from the plate thickness (t13) of the outer ring portion (13) to the plate thickness (t11) of the first flange portion (11), and the inner surface (16a) of the plate thickness changing portion (16) is an inclined surface that faces outward at an angle of 25° or more and less than 35° with respect to the axial direction as it approaches the first flange portion (11).

5. The roller bearing according to claim 1 or 2, wherein the hardness of at least the first flange portion (11) of the shell outer ring (10) is 600 HV or less.

6. The outer diameter Ra at the other axial end (13a) of the outer ring portion (13) within the range facing the rolling surface (31), The outer diameter Rb at the axial center (13b) of the outer ring portion (13) within the range facing the rolling surface (31), The outer diameter Rc at one axial end (13c) of the outer ring portion (13) within the range facing the rolling surface (31), The roller bearing according to claim 1 or 2, in which Rb > Ra ≥ Rc, or Rb > Rc > Ra is satisfied.

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