Method for assembling a wheel bearing device and wheel bearing device

Abstract

The axial bearing clearance of the third-generation wheel bearing device is precisely set to the desired negative clearance. [Solution] The method includes an inner ring press-fitting step in which the axial bearing gap is set to a negative gap by pressing an outer ring 11, which is arranged radially outside the cylindrical portion 12a of the hub ring 12 together with a plurality of balls 14 (14A, 14B), in the axial direction, and bringing one end face 13a of the inner ring 13, which is press-fitted against the outer circumferential surface of the cylindrical portion 12a of the hub ring 12, into contact with the shoulder surface 12c of the hub ring 12. Based on the measurement results of the axial displacement of the inner ring 13 and the axial displacement of the outer ring 11, which are measured individually during the execution of the inner ring press-fitting step, the axial position of the inner ring 13 at which the axial bearing gap becomes zero and the gap width of the axial bearing gap resulting from the negative gap are determined.

Description

Technical Field

[0001] The present invention relates to a method for assembling a wheel bearing device that rotatably supports a wheel with respect to a vehicle body.

Background Art

[0002] Wheel bearing devices include the first generation that uses a combination of double-row rolling bearings, the second generation in which a flange for vehicle body mounting is integrally provided on the outer ring of the double-row rolling bearing, and the third generation in which an inner raceway surface (one of two inner raceway surfaces) is formed on the outer circumferential surface of a hub wheel having a flange for wheel mounting.

[0003] FIG. 6 shows a configuration example of a third-generation wheel bearing device. The wheel bearing device 10 shown in the figure includes an outer ring 11 integrally having a cylindrical portion 11a with a first outer raceway surface 15A and a second outer raceway surface 15B formed on an inner circumferential surface thereof, and a flange portion 11b for vehicle body mounting; a hub wheel (also referred to as an "axle") 12 integrally having a cylindrical portion 12a with a first inner raceway surface 16A formed on an outer circumferential surface thereof, and a flange portion 12b for wheel mounting; an inner ring 13 with a second inner raceway surface 16B formed on an outer circumferential surface thereof; and a plurality of balls 14 interposed respectively in a first ball track 17 formed between the first outer raceway surface 15A and the first inner raceway surface 16A, and a second ball track 18 formed between the second outer raceway surface 15B and the second inner raceway surface 16B, and rotatably supporting the hub wheel 12 and the inner ring 13 with respect to the outer ring 11.

[0004] The ball 14 interposed in the first ball track 17 (hereinafter also referred to as "ball 14A") makes angular contact with both raceway surfaces 15A and 16A at a predetermined contact angle, and the ball 14 interposed in the second ball track 18 (hereinafter also referred to as "ball 14B") makes angular contact with both raceway surfaces 15B and 16B. With this structure, the wheel bearing device 10 is capable of supporting radial loads and axial loads in both directions. The wheel bearing device 10 having the above configuration is mounted on the vehicle in a horizontal position with its axis aligned with the vehicle width direction, such that the first ball track 17 and the second ball track 18 are positioned on the outside (outboard side) and inside (inboard side) of the vehicle width direction, respectively.

[0005] In the wheel bearing device 10 shown in Figure 6, the inner ring 13 is press-fitted against the outer circumferential surface of the cylindrical portion 12a of the hub ring 12, while the end face 13a on one axial side (outboard side) of the inner ring 13 is brought into contact with the shoulder surface 12c of the hub ring 12, thereby applying axial preload and setting the axial bearing clearance to a negative clearance. This makes it possible to realize a quiet bearing device with excellent bearing rigidity and suppression of vibration and noise during operation. In addition to the above preload application structure, as shown in Figure 7, for example, the end on the other axial side (inboard side) of the cylindrical portion 12a of the hub ring 12 may be plastically bent to form a crimping portion 19 that clamps the inner ring 13 from both axial sides between it and the shoulder surface 12c of the hub ring 12. In this case, the amount of preload applied to the wheel bearing device 10 can be increased. Furthermore, creating a negative axial clearance is equivalent to elastically compressing and deforming at least one of the components involved in forming the axial clearance—the outer ring 11, hub ring 12, inner ring 13, and ball 14—in the axial direction during the assembly of the wheel bearing device 10. It does not mean creating an axial clearance between the components that can be visually observed.

[0006] However, if the amount of preload applied to the wheel bearing device 10 is excessive, it is likely to cause problems such as increased rotational torque and reduced bearing life. Therefore, the amount of preload to be applied to the bearing device 10 must be properly managed.

[0007] For example, Patent Document 1 below describes a method for measuring preload (axial bearing clearance) in a wheel bearing device having the structure shown in Figure 6. Specifically, when pressing the inner ring onto the outer circumferential surface of the cylindrical portion of the hub ring, the pressing of the inner ring is temporarily stopped when the axial bearing clearance is positive, the bearing clearance (Δa') is measured, and then the pressing of the inner ring is completed. After that, the amount of axial movement of the inner ring from the state where the pressing was temporarily stopped to the state where the pressing is completed is measured, and the difference between this measured value and the measured value of the bearing clearance (Δa') is determined as the negative bearing clearance (Δa) after the assembly is completed.

[0008] Furthermore, Patent Document 2, described below, describes a method for measuring the clearance of a wheel bearing device, in which the amount of ball displacement is calculated from the difference in the axial position of the ball (the ball interposed in the ball track located on the inboard side of the two ball tracks; in the bearing device 10 shown in Figure 6, this refers to ball 14B) measured before and after axial preload is applied, and this amount of displacement is defined as the negative axial bearing clearance. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 2866282 [Patent Document 2] Japanese Patent Publication No. 2018-21613 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] In Patent Document 1, the press-fitting (preliminary press-fitting) of the inner ring is temporarily stopped when the axial bearing clearance is positive, and the axial bearing clearance (clearance width) is measured. However, when the axial bearing clearance is positive, that is, when there is an axial clearance between the outer ring and the balls, the outer ring can move freely, which means that the outer ring may tilt relative to the hub ring and the inner ring (and its axis). Even if the axial bearing clearance (Δa') is measured in this state, an error will occur in the measurement value, so the axial bearing clearance after assembly will not be the target negative clearance, and the bearing rigidity of the bearing device may be insufficient.

[0011] On the other hand, in Patent Document 2, the axial position of the ball is directly measured by bringing a measuring jig into contact with the ball before and after axial preload is applied, so it is thought that the axial bearing clearance consisting of a negative gap can be measured (estimated) with high accuracy. However, • The ball may get scratched when the measuring jig is brought into contact with it. When the measuring jig is inserted into the internal space of the bearing (the annular space formed on the inner circumferential surface of the outer ring), lubricants such as grease that are pre-sealed inside the bearing may leak out of the bearing. Problems such as those mentioned above may arise, which can lead to a decrease in bearing performance and bearing life.

[0012] In view of the above circumstances, the present invention aims to provide a technical means that can accurately set the axial bearing clearance to be provided in a so-called third-generation wheel bearing device to a target negative clearance without causing problems that lead to a decrease in bearing performance or bearing life. [Means for solving the problem]

[0013] The present invention, devised to achieve the above objectives, A method for assembling a wheel bearing device comprising: an outer ring having first and second outer raceway surfaces formed on its inner circumferential surface; a hub ring having a cylindrical portion with a first inner raceway surface formed on its outer circumferential surface; an inner ring having a second inner raceway surface formed on its outer circumferential surface; a plurality of balls interposed in a first ball track between the first outer raceway surface and the first inner raceway surface, and a second ball track between the second outer raceway surface and the second inner raceway surface, wherein the plurality of balls interposed in the first ball track make angular contact with the first outer raceway surface and the first inner raceway surface, and the plurality of balls interposed in the second ball track make angular contact with the second outer raceway surface and the second inner raceway surface; The process includes an inner ring press-fitting step in which an outer ring, arranged radially on the outer side of the cylindrical portion of the hub ring along with multiple balls, is pressed in the axial direction, while one end face of the inner ring, which is pressed against the outer circumferential surface of the cylindrical portion of the hub ring, is brought into contact with the shoulder surface of the hub ring, thereby setting the axial bearing clearance to a negative clearance. The method is characterized by identifying the axial position of the inner ring where the axial bearing clearance becomes zero, and the clearance width of the axial bearing clearance resulting from a negative clearance, based on the measurement results of the axial displacement of the inner ring and the axial displacement of the outer ring, which are measured individually during the inner ring press-fitting process.

[0014] In the assembly method of the wheel bearing device (third-generation wheel bearing device) according to the present invention, when an inner ring press-fitting step is performed in which the inner ring is pressed into the cylindrical portion of the hub ring while applying axial pressure to the outer ring, which is arranged radially outside the cylindrical portion of the hub ring together with a plurality of balls, the displacement pattern of the outer ring relative to the inner ring can be made different from when the axial bearing gap is in a positive gap state (a state in which there is an axial gap between the balls and the raceway surface) until it becomes zero, and after the axial bearing gap becomes zero (after the axial bearing gap transitions to a negative gap). Therefore, by individually measuring the axial displacement of the inner ring and the outer ring during the execution of this step, the axial position of the inner ring when the axial bearing gap becomes zero can be easily and accurately determined. Furthermore, the gap width of the axial bearing gap consisting of a negative gap can be accurately determined by the amount of displacement (press-fit amount) of the inner ring from the position where the axial gap becomes zero.

[0015] In this invention, which measures the axial displacement of the inner and outer rings individually, it is not necessary to measure (actually measure) the axial bearing gap (gap width) in the pre-press-fit state of the inner ring, where the axial bearing gap is a positive gap, as in the conventional method described in Patent Document 1. Therefore, it is possible to avoid problems such as the axial bearing gap not becoming the target negative gap due to the influence of measurement errors. Furthermore, in this invention, the target of axial displacement measurement is the inner and outer rings, and it is possible to prevent as much as possible the occurrence of problems such as scratching of the balls and external leakage of lubricant, which are concerns when measuring the displacement of the balls with a measuring jig that is in contact with the balls (Patent Document 2). In addition, if the outer ring is pressed axially during the inner ring press-fit process, it is possible to prevent as much as possible the deterioration of the positional accuracy of the outer ring (such as the coaxiality of the outer ring with respect to the inner ring and hub ring), making it easier to set the axial bearing gap to the target negative gap.

[0016] During the inner ring press-fitting process, the direction of pressure applied to the outer ring may be opposite to the direction of press-fitting the inner ring, or it may be in the same direction as the direction of press-fitting the inner ring.

[0017] The wheel bearing device obtained by the assembly method of the present invention described above has the characteristics of having an axial bearing clearance set to the target negative clearance, low vibration and low noise, and excellent bearing rigidity. [Effects of the Invention]

[0018] As described above, according to the present invention, it is possible to accurately set the axial bearing clearance to be provided in a so-called third-generation wheel bearing device to the target negative clearance without causing problems that lead to a decrease in bearing performance or bearing life. [Brief explanation of the drawing]

[0019] [Figure 1] This is a schematic longitudinal cross-sectional view of an assembly device used when carrying out an assembly method for a wheel bearing device according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view taken along the line AA in Figure 1. [Figure 3] This is a view of the assembly apparatus shown in Figure 1, taken from an oblique angle above. [Figure 4] Schematic vertical cross-sectional views for explaining an assembling method according to an embodiment of the present invention, wherein Figure (a) shows a state where an axial bearing clearance of a wheel bearing device is positive (positive clearance), and Figure (b) shows a state where an axial bearing clearance of the wheel bearing device is zero to negative (negative clearance). [Figure 5] Schematic vertical cross-sectional views for explaining an assembling method according to another embodiment of the present invention, wherein Figure (a) shows a state where an axial bearing clearance of a wheel bearing device is positive (positive clearance), and Figure (b) shows a state where an axial bearing clearance of the wheel bearing device is zero to negative (negative clearance). [Figure 6] It is a schematic vertical cross-sectional view of an existing wheel bearing device, and also a schematic vertical cross-sectional view of a wheel bearing device obtained by applying the assembling method according to the present invention. [Figure 7] It is a schematic vertical cross-sectional view of an existing wheel bearing device according to a modified example. MODE FOR CARRYING OUT THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0021] First, with reference to FIG. 6, an example of a wheel bearing device (third-generation wheel bearing device) 10 obtained by applying the assembling method according to the present invention will be described. The "axial direction", "radial direction" and "circumferential direction" referred to in the following description are respectively the direction along the axis of the wheel bearing device 10, the radial direction and the circumferential direction of a circle centered on said axis. In addition, hereinafter, when the wheel bearing device 10 is mounted on an automobile, the side arranged on the outer side in the vehicle width direction (outboard side) is referred to as "one axial side", and the side arranged on the inner side in the vehicle width direction (inboard side) is referred to as "the other axial side". In FIG. 6, the lower side of the drawing is the above-mentioned "one axial side".

[0022] As mentioned above, the wheel bearing device 10 shown in Figure 6 mainly comprises an outer ring 11, a hub ring 12, an inner ring 13, a plurality of balls 14, and a cage (not shown). Although not shown, the annular space formed between the inner circumferential surface of the outer ring 11 and the outer circumferential surfaces of the hub ring 12 and the inner ring 13 is filled with a lubricant such as grease. To prevent external leakage of this lubricant and the intrusion of foreign matter into the annular space, the end openings on one axial side and the other side of the outer ring 11 are sealed by sealing members (not shown).

[0023] The outer ring 11 integrally comprises a cylindrical tube portion 11a and a flange portion 11b for vehicle body mounting that extends radially outward from the outer circumferential surface of the tube portion 11a. On the inner circumferential surface of the tube portion 11a, a first outer raceway surface 15A and a second outer raceway surface 15B, which have a circular arc cross-section, are formed at axial intervals. Although not shown in the figures, the flange portion 11b has a plurality of bolt mounting holes formed at circumferential intervals that penetrate it axially, and the outer ring 11 is attached to a vehicle body (not shown) using bolt members fitted into each bolt mounting hole.

[0024] The hub wheel 12 integrally comprises a cylindrical portion 12a having a first inner raceway surface 16A with a circular arc cross-section and a cylindrical inner ring mounting surface 12d formed on its outer circumference, and a flange portion 12b for wheel mounting that extends radially outward from the outer circumference of the cylindrical portion 12a on one axial side of the first inner raceway surface 16A. The inner ring mounting surface 12d is located radially inward of the first inner raceway surface 16A and is connected to the first inner raceway surface 16A via an annular stepped surface (shoulder surface) 12c. The shoulder surface 12c is provided so as to be located between the axial directions of the first outer raceway surface 15A and the second outer raceway surface 15B provided on the outer ring 11, but it does not have to be located between the two raceway surfaces 15A and 15B. Although not shown in the illustration, the flange portion 12b has multiple bolt mounting holes formed at circumferential intervals, and the hub wheel 12 is attached to a wheel (not shown) using bolt members fitted into each bolt mounting hole. The shaft portion of the outer joint member constituting a constant velocity universal joint is connected to the central hole of the hub wheel 12 in a manner that allows for torque transmission.

[0025] A second inner raceway surface 16B, having a circular arc cross-section, is formed on the outer circumferential surface of the inner ring 13. The balls 14 are interposed in the first ball track 17, which is provided between the first outer raceway surface 15A of the outer ring 11 and the first inner raceway surface 16A of the hub ring 12, and in the second ball track 18, which is provided between the second outer raceway surface 15B of the outer ring 11 and the second inner raceway surface 16B of the inner ring 13, thereby rotatably supporting the hub ring 12 and the inner ring 13 with respect to the outer ring 11. The balls 14 interposed in the first ball track 17 (hereinafter also referred to as "ball 14A") make angular contact with the first outer raceway surface 15A and the first inner raceway surface 16A at a predetermined contact angle, and the balls 14 interposed in the second ball track 18 (hereinafter also referred to as "ball 14B") make angular contact with the second outer raceway surface 15B and the second inner raceway surface 16B. With this structure, the wheel bearing device 10 is capable of supporting radial loads and axial loads in both directions.

[0026] The inner ring 13 is fixed to the hub ring 12 by press-fitting its inner circumferential surface against the outer circumferential surface (inner ring mounting surface 12d) of the cylindrical portion 12a of the hub ring 12. In this fixed state, one end surface 13a of the inner ring 13 is pressed against the shoulder surface 12c of the hub ring 12. This applies axial preload to the wheel bearing device 10 (inside the bearing), and the axial bearing clearance is set to a negative clearance.

[0027] The assembly of the wheel bearing device 10 having the above configuration is completed by first creating an assembly 1 (see Figure 1, etc.) which is made by arranging the outer ring 11, a plurality of balls (balls held by a cage not shown) 14A, 14B and the inner ring 13 on the radially outer side of the cylindrical portion 12a of the hub ring 12 so that the axial bearing gap is a positive gap (there is an actual axial gap between the balls 14 and the inner and outer raceway surfaces), as shown in Figures 1 and 4(a), etc., and then press-fitting the inner ring 13 to a predetermined axial position of the cylindrical portion 12a of the hub ring 12 (specifically, a position where the axial bearing gap can be set to the target negative gap). The process of press-fitting the inner ring 13 into the hub ring 12, which is a characteristic configuration of the present invention, will be described in detail below.

[0028] Figure 1 is a schematic longitudinal cross-sectional view showing the overall configuration of the assembly device 20 used in the inner ring press-fitting process described above, Figure 2 is a cross-sectional view taken along the line AA in Figure 1, and Figure 3 is a schematic perspective cross-sectional view of the assembly device 20 (a view of Figure 1 taken from diagonally above). The assembly device 20 comprises a workpiece mounting table 30 and an upper unit that is removablely set on the workpiece mounting table 30. The upper unit comprises a hub ring press-fitting section 40, an inner ring press-fitting section 50, an outer ring press-fitting section 60, a first measuring instrument 21, and a second measuring instrument 22.

[0029] The workpiece mounting table 30 includes a support table 31 that contacts and supports one axial end of the assembly (the hub wheel 12 that constitutes it) from below, a lifting table 32 that can move up and down above the support table 31 while maintaining a horizontal position parallel to the support table 31, a plurality of guide shafts 33 that guide the lifting movement of the lifting table 32, and a plurality of coil springs 34 fitted around the outer circumference of each guide shaft 33 and capable of elastic expansion and contraction deformation in the vertical direction. Each coil spring 34 is interposed between the support table 31 and the lifting table 32 and supports the lifting table 32 from below. Therefore, the lifting table 32 moves up and down in accordance with the elastic expansion and contraction deformation of the coil springs 34.

[0030] The central part of the lifting table 32 is provided with a hole 32a that opens on both the upper and lower sides. During the inner ring press-fitting process, the cylindrical portion 11a of the outer ring 11 is positioned on the inner circumference of the hole 32a, and the flange portion 11b of the outer ring 11 is supported by contact from below by the lifting table 32.

[0031] The hub wheel pressurizing section 40 includes a pressurizing member 41 that pressurizes the hub wheel 12 of the assembly 1 downward, a member to be measured 42 positioned above the pressurizing member 41, and a connecting shaft 43 that connects the pressurizing member 41 and the member to be measured 42 with a predetermined distance between them.

[0032] The inner ring pressurizing section 50 is arranged coaxially with the pressurizing member 41 of the hub ring pressurizing section 40 and includes a cylindrical pressurizing member 51 that pressurizes the inner ring 13 of the assembly 1 downward, a pressurized plate 52 positioned above the pressurizing member 51, a connecting shaft 53 that connects the pressurizing member 51 and the pressurized plate 52 with a predetermined distance between them, and a measuring instrument holding plate 54 that is mounted horizontally on the upper end of the pressurizing member 51 and holds the first measuring instrument 21 in a fixed position. The first measuring instrument 21 employs a dial gauge equipped with a measuring probe 21a that measures the amount of displacement in the vertical direction (which is also the axial direction of the wheel bearing device 10; the same applies hereinafter), and the lower end of the measuring probe 21a is in contact with the pressurizing member 41 of the hub ring pressurizing section 40. Therefore, the first measuring instrument 21 can measure the amount of relative vertical displacement of the inner ring 13 with respect to the hub ring 12.

[0033] A coil spring 55 that is elastically expandable and contractible in the vertical direction is interposed between the measuring instrument holding plate 54 of the inner ring pressurizing section 50 and the pressurizing member 41 of the hub ring pressurizing section 40.

[0034] The outer ring pressurizing section 60 is arranged coaxially with the pressurizing member 41 of the hub ring pressurizing section 40 (and the pressurizing member 51 of the inner ring pressurizing section 50) and includes a cylindrical pressurizing member 61 that pressurizes the outer ring 11 of the assembly 1 downward, a measuring instrument holding plate 62 that is attached horizontally to the upper end of the pressurizing member 61 and holds the second measuring instrument 22 in a fixed position, a plurality of guide shafts 63 that extend upward from the upper end of the pressurizing member 61 and guide the vertical movement of the pressed plate 52 of the inner ring pressurizing section 50, and a coil spring 64 that is fitted around the outer circumference of each guide shaft 63 and interposed between the pressurizing member 61 and the pressed plate 52 of the inner ring pressurizing section 50 in an elastically compressed and deformed state, and constantly biases the pressed plate 52 upward.

[0035] The second measuring instrument 22, like the first measuring instrument 21, employs a dial gauge equipped with a measuring probe 22a capable of measuring vertical displacement, and the lower end of the measuring probe 22a is in contact with the upper end surface of the member to be measured 42 of the hub ring pressurizing section 40. Therefore, the second measuring instrument 22 is capable of measuring the vertical relative displacement of the outer ring 11 with respect to the hub ring 12.

[0036] The assembly apparatus 20 has generally the above configuration and is used as follows.

[0037] First, as shown in Figures 1 and 3, the assembly 1 is held on the workpiece holder 30 such that the hub wheel 12 is supported from below by the support table 31 and the outer ring 11 is supported from below by the lifting table 32.

[0038] Furthermore, the upper unit of the assembly device 20 is set on the assembly 1. Specifically, as shown in Figures 1 and 3, the pressurizing members 41 of the hub ring pressurizing section 40, 51 of the inner ring pressurizing section 50, and 61 of the outer ring pressurizing section 60 are placed on the other end face of the hub ring 12, the other end face of the inner ring 13, and the other end face of the flange portion 11b of the outer ring 11, respectively. Then, when a downward vertical pressure (one side in the axial direction) is applied to the pressurized plate 52 of the inner ring pressurizing section 50, this pressure is transmitted to the inner ring 13 via the connecting shaft 53 and the pressurizing members 51, so that the inner ring 13 is pushed downward and the pressurizing of the inner ring 13 into the cylindrical portion 12a of the hub ring 12 begins [see the white arrow in Figure 4(a)]. The downward pressure applied to the pressurized plate 52 is also applied to the hub wheel 12 via the connecting shaft 53, pressurizing member 51, measuring instrument holding plate 54, coil spring 55, and the pressurizing member 41 of the hub wheel pressurizing section 40, thereby pressing the hub wheel 12 against the support table 31. This minimizes the reduction in the posture accuracy of the hub wheel 12, and consequently the coaxial accuracy between the hub wheel 12 and the inner wheel 13 (and outer wheel 11), during the inner wheel press-fitting process, making it possible to press-fit the inner wheel 13 into the hub wheel 12 with high accuracy.

[0039] The pressure applied to the pressurized plate 52 is also applied to the outer ring 11 via the coil spring 64 and the pressurizing member 61 of the outer ring pressurizing section 60. However, the lifting table 32, which contacts and supports the outer ring 11 from below, is constantly subjected to the elastic restoring force of the coil spring 34, i.e., an upward force in the vertical direction, as shown by the black arrow in Figure 4(a). In this embodiment, the coil spring 34 is used which has a spring force (elastic restoring force) that does not compress or deform until the press-fitting of the inner ring 13 into the hub ring 12 has progressed to a certain extent. Therefore, as shown in Figure 4(a), at the start of the press-fitting of the inner ring 13, the outer ring 11 is located on the other axial side (here, the upper side of the paper) than at the stage when the press-fitting of the inner ring 13 is completed (the stage when the assembly of the wheel bearing device 10 is completed: see Figure 6), and contacts the inner ring 13 via the ball 14B.

[0040] Therefore, even as the downward vertical pressure applied to the inner ring 13 gradually increases, causing the inner ring 13 to be pressed into the hub ring 12, the outer ring 11 and inner ring 13 will continue to descend together until the balls 14A make angular contact with the first outer raceway surface 15A of the outer ring 11 and the first inner raceway surface 16A of the hub ring 12, that is, as long as the axial bearing gap (gap width) of the assembly 1 (wheel bearing device 10) is positive.

[0041] Meanwhile, as the inner ring 13 is pressed into the hub ring 12, the balls 14A make angular contact with the first outer raceway surface 15A of the outer ring 11 and the first inner raceway surface 16A of the hub ring 12, and the balls 14B make angular contact with the second outer raceway surface 15B of the outer ring 11 and the second inner raceway surface 16B of the inner ring 13, resulting in zero axial bearing clearance. The downward displacement of the outer ring 11 stops when the axial bearing clearance becomes zero. Subsequently, as the inner ring 13 is pushed downward until one end surface 13a of the inner ring 13 contacts the shoulder surface 12c of the hub ring 12, axial preload is applied to the assembly 1 (wheel bearing device 10), and the outer ring 11 is displaced due to deflection etc. caused by this preload.

[0042] Therefore, by performing the inner ring press-fitting process in the above manner, the displacement patterns of the inner ring 13 and outer ring 11 (the ratio of the displacement of the outer ring 11 to the displacement of the inner ring 13) can be made different depending on whether the axial bearing gap of the wheel bearing device 10 is positive, as shown in Figure 4(a), or whether the axial bearing gap of the wheel bearing device 10 transitions from zero to negative, as shown in Figure 4(b). For this reason, if the displacement amounts of the inner ring 13 and outer ring 11 are measured individually by the first measuring instrument 21 and the second measuring instrument 22, respectively, during the execution of the inner ring press-fitting process, the axial position of the inner ring 13 where the axial bearing gap of the bearing device 10 becomes zero can be identified based on the measurement results. In addition, the gap width of the axial bearing gap consisting of a negative gap can be accurately determined by the amount of displacement of the inner ring 13 from the position where the axial bearing gap becomes zero.

[0043] In this invention, the axial displacement of the inner ring 13 and the outer ring 11 is measured individually by first and second measuring instruments 21 and 22. Unlike the conventional method described in Patent Document 1, it is not necessary to measure the axial bearing gap (gap width) in the temporary press-fit state of the inner ring where the axial bearing gap is a positive gap. Therefore, problems such as the axial bearing gap not becoming the target negative gap due to the influence of measurement errors can be avoided. Furthermore, in this invention, the objects of measurement for axial displacement are the inner ring 13 and the outer ring 11, and problems such as scratching of the balls and external leakage of lubricant, which are concerns when measuring the displacement of balls with a measuring jig that is in contact with the balls (Patent Document 2), can be prevented as much as possible.

[0044] As described above, according to the present invention, it is possible to accurately set the axial bearing clearance to be provided in the so-called third-generation wheel bearing device 10 to the target negative clearance without causing problems that lead to a decrease in bearing performance or bearing life. As a result, it is possible to realize a highly reliable wheel bearing device 10 that can stably exhibit high bearing performance over a long period of time.

[0045] The assembly method of the wheel bearing device 10 according to an embodiment of the present invention has been described above, but the embodiments of the present invention are not limited thereto.

[0046] For example, in the embodiment described above, when performing the inner ring press-fitting process in which the inner ring 13 is press-fitted into the cylindrical portion 12a of the hub ring 12, the outer ring 11 is pressurized in the opposite direction (upward) to the press-fitting direction of the inner ring 13, as schematically shown in Figures 4(a) and 4(b). However, when performing the inner ring press-fitting process, the outer ring 11 may be pressurized in the same direction as the press-fitting direction of the inner ring 13, as schematically shown in Figures 5(a) and 5(b). By pressurizing the outer ring 11 in the opposite direction (upward) to the press-fitting direction of the inner ring 13, the balls 14B make angular contact with the outer ring 11 and the inner ring 13, and the inner ring 13 can be press-fitted into the hub ring 12 in a more stable position for the outer ring 11 and the inner ring 13. By applying pressure to the outer ring 11 in the same direction (downward) as the press-fitting direction of the inner ring 13, the balls 14B make angular contact with the outer ring 11 and the hub ring 12, allowing the inner ring 13 to be press-fitted into the hub ring 12 in a more stable position for the outer ring 11 and the hub ring 12.

[0047] When the outer ring 11 is pressed in the same direction (downward) as the press-fitting direction of the inner ring 13, as shown in Figure 5(a), from the start of the press-fitting of the inner ring 13, the outer ring 11 is in contact with the hub ring 12 via the balls 14A in the press-fitting direction of the inner ring 13 (axial direction of the bearing). Therefore, the outer ring 11 does not displace in the axial direction at least while the axial bearing clearance is positive, that is, until the balls 14B make angular contact with the second outer raceway surface 15B of the outer ring 11 and the second inner raceway surface 16B of the inner ring 13. On the other hand, as the press-fitting of the inner ring 13 progresses, as shown in Figure 5(b), after the axial bearing clearance becomes zero due to the balls 14B making angular contact with the second outer raceway surface 15B of the outer ring 11 and the second inner raceway surface 16B of the inner ring 13, the outer ring 11 is slightly displaced in the axial direction due to deflection caused by the application of axial preload.

[0048] Therefore, similar to the embodiment described above with reference to Figures 1 to 4, if the displacement amounts of the inner ring 13 and the outer ring 11 are individually measured by the first measuring instrument 21 and the second measuring instrument 22, respectively, during the inner ring press-fitting process, the axial position of the inner ring 13 where the axial bearing gap of the bearing device 10 becomes zero can be identified based on the measurement results. Furthermore, the gap width of the axial bearing gap consisting of a negative gap can be accurately determined by the displacement amount of the inner ring 13 from the position where the axial bearing gap becomes zero.

[0049] The assembly method according to the present invention described above is also applicable to the assembly of a wheel bearing device of a type in which a crimping portion 19 (see Figure 7) is additionally formed at the other axial end of the cylindrical portion 12a of the hub ring 12, between it and the shoulder surface 12c of the hub ring 12, to clamp the inner ring 13 from both axial sides.

[0050] The present invention is not limited in any way to the embodiments described above, and can be implemented in various other forms without departing from the spirit of the invention. [Explanation of Symbols]

[0051] 10 Wheel bearing device 11 Outer ring 12 hub wheels 12a Cylinder part 12c shoulder surface 12d Inner ring mounting surface 13 Inner circle 13a One end face 14 balls 20 Assembly equipment 21,22 Measuring instruments 30 Workpiece mounting stand 40 Hub wheel pressurization section 50 Inner ring pressurizing section 60 Outer ring pressurizing section

Claims

1. A method for assembling a wheel bearing device comprising: an outer ring having first and second outer raceway surfaces formed on its inner circumferential surface; a hub ring having a cylindrical portion with a first inner raceway surface formed on its outer circumferential surface; an inner ring having a second inner raceway surface formed on its outer circumferential surface; a plurality of balls interposed in a first ball track between the first outer raceway surface and the first inner raceway surface, and a second ball track between the second outer raceway surface and the second inner raceway surface, wherein the plurality of balls interposed in the first ball track make angular contact with the first outer raceway surface and the first inner raceway surface, and the plurality of balls interposed in the second ball track make angular contact with the second outer raceway surface and the second inner raceway surface, The process includes an inner ring press-fitting step in which the axial bearing clearance is set to a negative clearance by pressing the outer ring, which is arranged radially outside the cylindrical portion of the hub ring together with the plurality of balls, in the axial direction, while bringing one end face of the inner ring, which is press-fitted against the outer circumferential surface of the cylindrical portion of the hub ring, into contact with the shoulder surface of the hub ring, thereby applying axial pressure to the outer ring, which is arranged radially outside the cylindrical portion of the hub ring, and bringing the inner ring into contact with the shoulder surface of the hub ring. A method for assembling a wheel bearing device, characterized by determining the axial position of the inner ring at which the axial bearing clearance becomes zero, and the clearance width of the axial bearing clearance consisting of the negative clearance, based on the measurement results of the axial displacement of the inner ring and the axial displacement of the outer ring, which are measured individually during the execution of the inner ring press-fitting process.

2. The assembly method for a wheel bearing device according to claim 1, wherein, during the inner ring press-fitting step, the outer ring is pressurized in the opposite direction to the press-fitting direction of the inner ring.

3. The assembly method for a wheel bearing device according to claim 1, wherein, during the inner ring press-fitting step, the outer ring is pressurized in the same direction as the inner ring press-fitting direction.

4. A wheel bearing device assembled by the assembly method described in claim 1.

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