JP7524804B2 - Rolling Bearing Device - Google Patents

Description

The present invention relates to a rolling bearing device.

A rolling bearing device called a hub unit bearing is used to rotatably support the wheels of an automobile. Figures 5 and 6 show the structure described in JP 2008-75837 A (Patent Document 1) as an example of a rolling bearing device used to rotatably support and rotate the wheels (drive wheels) of heavy vehicles such as trucks and buses.

The rolling bearing device 100 rotatably supports the hub wheel 102 around the axle tube 101. A drive shaft 103 is inserted inside the axle tube 101. A flange 104 is provided at the end of the drive shaft 103, and the hub wheel 102 is fixed to the flange 104. A drive wheel 105 and a braking rotor 106 are fixed to the hub wheel 102. With this configuration, the drive wheel 105 and the braking rotor 106 are rotatably supported relative to the axle tube 101, and torque from the drive shaft 103 can be transmitted to the drive wheel 105 and the braking rotor 106.

As shown in Figure 6, the rolling bearing device 100 is a double-row tapered roller bearing, and includes an outer ring 107 that rotates when in use, a pair of inner rings 108a, 108b that do not rotate when in use, a plurality of rolling elements 109a, 109b, a sealing member 110, and a connecting ring 111.
With regard to the rolling bearing device 100, the axially outer side is the left side in Figure 6, which is the outer side in the width direction of the vehicle when assembled to the vehicle, and the axially inner side is the right side in Figure 6, which is the central side in the width direction of the vehicle when assembled to the vehicle.

The outer ring 107 has double-row outer ring raceways 112a, 112b on its inner circumferential surface. The outer ring 107 is fitted into the hub ring 102 with an interference fit.

Each of the pair of inner rings 108a, 108b has a single-row inner ring raceway 113a, 113b on its outer circumferential surface. The pair of inner rings 108a, 108b are fitted onto the axle tube 101 with their opposing small diameter end faces butted against each other.

The rolling elements 109a, 109b are tapered rollers, and are arranged between the outer ring raceways 112a, 112b and the inner ring raceways 113a, 113b, with multiple elements in each row, so that they can roll freely.

The seal member 110 is made of an O-ring and is disposed radially inside the butt joint 114 between the pair of inner rings 108a, 108b. The seal member 110 prevents foreign matter such as differential oil and muddy water present inside the axle tube 101 from entering the internal space of the rolling bearing device 100 through the butt joint 114.

In the rolling bearing device 100 for supporting the hub wheel 102 rotatably around the axle tube 101, a pair of inner rings 108a, 108b are fitted around the axle tube 101 with a clearance fit to allow the rolling bearing device 100 to be attached and detached to the axle tube 101. In addition, since the internal space of the axle tube 101 is connected to the internal space of the differential case (not shown), differential oil may enter the gap between the inner peripheral surface of the inner rings 108a, 108b and the outer peripheral surface of the axle tube 101. In addition, muddy water may flow from the outside into the gap between the inner peripheral surface of the inner rings 108a, 108b and the outer peripheral surface of the axle tube 101. Therefore, the seal member 110 is disposed radially inside the butt portion 114 to prevent foreign matter such as differential oil and muddy water from entering the internal space of the rolling bearing device 100.

The connecting ring 111 is annular in shape and has a U-shaped cross section. The connecting ring 111 has a cylindrical connecting portion 115 and a pair of outward flange-shaped locking portions 116. With the connecting portion 115 covering the seal member 110 from the radially inner side, the pair of locking portions 116 are locked into the locking grooves 117a, 117b provided on the inner peripheral surfaces of the pair of inner rings 108a, 108b, respectively. As a result, the connecting ring 111 connects the pair of inner rings 108a, 108b in the axial direction. When the rolling bearing device 100 is assembled to the axle tube 101, friction acting on the inner rings 108a, 108b prevents the pair of inner rings 108a, 108b from separating from each other, and prevents the inner ring 108a, which is positioned on the axially outer side, from coming out of the axle tube 101 in the axial direction due to a collision between the inner ring 108a and the axle tube 101.

JP 2008-75837 A

The conventional rolling bearing device 100 described in JP 2008-75837 A has room for further improvement in the following areas:

In the rolling bearing device 100 of the conventional structure, in order to ensure sufficient sealing of the butt joint 114, it is necessary to crush the seal member 110, which is made of an O-ring, to some extent between the small diameter end faces of the pair of inner rings 108a, 108b. However, since a considerable force is required to crush the seal member 110, if the pair of inner rings 108a, 108b are connected by the connecting ring 111 before the rolling bearing device 100 is installed on the vehicle, a gap may occur at the butt joint 114 due to the elasticity of the seal member 110. This makes it difficult to guarantee the axial clearance using conventionally known measurement methods.

Specifically, it is known that the axial clearance of a double row rolling bearing is measured by the method shown in FIG. 7. First, as shown in FIG. 7(A), the small diameter end faces of a pair of inner rings 108x, 108y are butted against each other, and rolling elements 109x, 109y are arranged around the pair of inner rings 108x, 108y. In this state, one inner ring 108x (or 108y) is placed on a reference surface 118 with the other inner ring 108y (or 108x) facing upward. Then, the axial height from the reference surface 118 to the large diameter end face of the upper inner ring 108y (or 108x) is measured with a displacement meter 119 such as a dial gauge, and the measured value is used as the reference value (the dial is set to 0).

Next, as shown in FIG. 7B, the rolling elements 109x and the inner ring 108x of one side row are assembled to the outer ring 107x, and the inner ring 108x is placed facing upward on the reference surface 118. Then, the axial height (Hout) from the reference surface 118 to the large diameter side end face of the inner ring 108x is measured by the displacement gauge 119. Similarly, although not shown, the rolling elements 109y and the inner ring 108y of the other side row are assembled to the outer ring 107x, and the inner ring 108y is placed facing upward on the reference surface 118. Then, the axial height (Hin) from the reference surface 118 to the large diameter side end face of the inner ring 108y is measured by the displacement gauge 119. Finally, the two axial dimensions (Hin, Hout) are summed, and the sum [-(Hin + Hout)] is taken as the axial clearance.

In the above-described method of measuring the axial clearance, as shown in FIG. 7A, the axial height from the reference surface 118 to the large diameter end face of the upper inner ring 108y (or 108x) when the small diameter end faces of a pair of inner rings 108x, 108y are butted against each other is used as the reference value. Therefore, if a gap occurs at the butted portion 114 due to the elasticity of the seal member 110, as in the rolling bearing device 100 of the conventional structure, it becomes difficult to accurately measure the axial clearance, and the axial clearance cannot be guaranteed.

The present invention has been made to solve the above problems, and aims to provide a rolling bearing device that can ensure sealing at the butted portion of a pair of inner rings and guarantee the axial clearance.

A rolling bearing device according to one aspect of the present invention includes an outer ring, a pair of inner rings, a plurality of rolling elements, a seal member, and a connecting ring.
The outer ring has a double row outer ring raceway on its inner circumferential surface.
The pair of inner rings each have a single-row inner ring raceway on an outer circumferential surface.
The rolling elements are disposed between the outer ring raceway and the inner ring raceway.
The seal member seals the butted portion of the pair of inner rings.
The connecting ring connects the pair of inner rings.
In one embodiment of the rolling bearing device of the present invention, the pair of inner rings have a dovetail-shaped seal retaining groove on the radially outer side of the butt portion, the groove having a pair of inner groove surfaces that are inclined in the axial direction toward each other as they move radially outward.
The sealing member is made of an elastic material, has an overall annular shape, and has an outer diameter side seal portion that is positioned outside the seal retaining groove, and an inner diameter side seal portion that is positioned inside the seal retaining groove and has a cross-sectional shape different from that of the outer diameter side seal portion, and has a pair of inclined outer surfaces that are inclined in the axial direction toward each other as they move radially outward.
The seal member abuts the inner surfaces of both axial sides of the outer diameter side seal portion against the outer peripheral surfaces of the pair of inner rings, and abuts each of the pair of inclined outer surfaces against each of the pair of groove inner surfaces, and has a radial gap between the inner surface of the inner diameter side seal portion and the groove bottom surface of the seal retaining groove.

In one aspect of the rolling bearing device of the present invention, the inner diameter side seal portion can have a seal groove on the inner circumferential surface.

In one embodiment of the rolling bearing device of the present invention, the hardness of the seal member can be set to Hs85 or more and Hs95 or less (Hs90±5).

The present invention makes it possible to realize a rolling bearing device that can ensure sealing at the butted portion between a pair of inner rings and guarantee the axial gap.

FIG. 1 is a cross-sectional view showing a drive wheel support device incorporating a rolling bearing device according to a first embodiment. FIG. 2 is a partial cross-sectional view showing a rolling bearing device according to a first embodiment. FIG. 3 is a partially enlarged view of FIG. FIG. 4 is a diagram showing a second example of the embodiment, and corresponds to FIG. FIG. 5 is a cross-sectional view showing a drive wheel support device incorporating a rolling bearing device of a conventional structure. FIG. 6 is a partial cross-sectional view showing a rolling bearing device of a conventional structure. 7A and 7B are cross-sectional views for explaining a conventionally known method for measuring an axial gap in order of steps.

[First Example of the Embodiment]
A first embodiment of the present invention will be described with reference to Figures 1 to 3. In this embodiment, a rolling bearing device of the present invention is applied to a drive wheel support device for a heavy large vehicle such as a truck or a bus.

[Overall configuration of the drive wheel support device]
1, the driving wheel support device 1 includes a rolling bearing device 2, an axle tube 3, a hub wheel 4, and a driving shaft 5. The driving wheel support device 1 rotatably supports a driving wheel 6, such as a rear wheel of a truck, and a braking rotor 7, and transmits driving torque to the driving wheel 6 and the braking rotor 7, and has a fully floating configuration.

With respect to the drive wheel support device 1, the axially outer side is the left side in FIG. 1, which is the outer side in the width direction of the vehicle when assembled to the vehicle, and the axially inner side is the right side in FIG. 1, which is the center side in the width direction of the vehicle when assembled to the vehicle.

The rolling bearing device 2 rotatably supports the hub wheel 4 around the axially outer end of the axle tube 3. The rolling bearing device 2 is disposed between the outer peripheral surface of the axle tube 3 and the inner peripheral surface of the hub wheel 4.

The axle tube 3 is also called an axle housing, and has a cylindrical shape, with its axially inner end connected to a differential case (not shown). For this reason, the axle tube 3 does not rotate even when in use. The internal space of the axle tube 3 is connected to the internal space of the differential case. The axle tube 3 has a cylindrical surface portion 8 on the axially outer side of its outer peripheral surface. The axle tube 3 also has a step surface 9 facing axially outward on the portion of its outer peripheral surface adjacent to the axially inner side of the cylindrical surface portion 8, and has a male thread portion 10 with a smaller diameter than the cylindrical surface portion 8 on the portion adjacent to the axially outer side of the cylindrical surface portion 8. A nut 11 for applying preload to the rolling bearing device 2 is screwed onto the male thread portion 10.

The drive shaft 5, also known as the axle shaft, is solid and inserted inside the axle tube 3. The drive shaft 5 is arranged coaxially with the axle tube 3. The axially inner end of the drive shaft 5 is connected to a differential gear (not shown). Therefore, the drive shaft 5 rotates when in use. The drive shaft 5 has an outward flange-shaped flange 12 at the axially outer end protruding from the axle tube 3. The hub wheel 4 is fixed to the flange 12 by a number of bolts 13.

The hub wheel 4 has a circular ring shape. The hub wheel 4 has a cylindrical mating surface 14 on its inner circumferential surface, and a rotating flange 15 at the axially middle portion of its outer circumferential surface. The driving wheel 6 is fixed to the rotating flange 15 by a connecting member 16 such as a hub bolt or a stud. The braking rotor 7 is fixed to the axially inner side of the hub wheel 4 by a bolt 13.

The drive wheel support device 1, with the above configuration, supports the drive wheels 6 and the braking rotors 7 rotatably relative to the axle tube 3, and is capable of transmitting torque from the drive shaft 5 to the drive wheels 6 and the braking rotors 7. Furthermore, in the fully floating drive wheel support device 1, the vehicle load is not supported by the drive shaft 5, but by the axle tube 3. The drive shaft 5 is only responsible for transmitting torque.

The specific structure of the rolling bearing device 2 of this embodiment will be described below with reference to FIGS.
With regard to the rolling bearing device 2, the axially outer side is the left side in Figures 2 and 3, which is the outer side in the width direction of the vehicle when assembled to the vehicle, and the axially inner side is the right side in Figures 2 and 3, which is the central side in the width direction of the vehicle when assembled to the vehicle.

<Rolling bearing device>
The rolling bearing device 2 is a back-to-back type double row tapered roller bearing and is an outer ring rotating type. The rolling bearing device 2 includes an outer ring 17 that rotates when in use, a pair of inner rings 18a, 18b that do not rotate when in use, a plurality of rolling elements 19a, 19b, a seal member 20, and a connecting ring 21.

Paddle Wheel
The outer ring 17 is made of, for example, bearing steel and has an annular shape. The outer ring 17 has a cylindrical surface on its outer circumferential surface and double-row outer ring raceways 22a, 22b with conical concave surfaces on its inner circumferential surface. When the rolling bearing device 2 is mounted on a vehicle, the outer ring 17 is fitted and fixed to the fitting surface 14 provided on the inner circumferential surface of the hub wheel 4 by an interference fit. Therefore, the outer ring 17 rotates together with the hub wheel 4.

Inner Circle
Each of the pair of inner rings 18a, 18b is made of, for example, bearing steel and has a circular ring shape. Each of the pair of inner rings 18a, 18b has a single-row inner ring raceway 23a, 23b with a conical convex surface at the axial middle of the outer circumferential surface. Each of the pair of inner rings 18a, 18b has a large flange portion 24a, 24b and a small flange portion 25a, 25b on both axial sides of the inner ring raceway 23a, 23b. Therefore, the outer diameter of the large diameter side end portion including the large flange portion 24a, 24b of each of the pair of inner rings 18a, 18b is larger than the outer diameter of the small diameter side end portion including the small flange portion 25a, 25b.

The pair of inner rings 18a, 18b each have a locking groove 26a, 26b with a substantially triangular cross-sectional shape on the inner circumferential surface of the small diameter end. The locking groove 26a, 26b is open only to the inner circumferential surface of the inner ring 18a, 18b, and is provided around the entire circumference of the inner ring 18a, 18b. The inner circumferential surface of the inner ring 18a, 18b has a cylindrical small diameter surface portion 27a, 27b in the portion deviating from the locking groove 26a, 26b toward the large diameter end face in the axial direction, and has a cylindrical large diameter surface portion 28a, 28b with an inner diameter larger than the small diameter surface portion 27a, 27b in the portion deviating from the locking groove 26a, 26b toward the small diameter end face in the axial direction.

The pair of inner rings 18a, 18b are arranged coaxially with the outer ring 17, radially inside the outer ring 17, with their small diameter end faces butted against each other. The pair of inner ring raceways 23a, 23b are arranged in double rows, radially facing the double row outer ring raceways 22a, 22b.

When the rolling bearing device 2 is installed on a vehicle, the pair of inner rings 18a, 18b are fitted with a clearance fit onto the cylindrical surface portion 8 provided on the outer circumferential surface of the axle tube 3. The pair of inner rings 18a, 18b are also sandwiched in the axial direction between the nut 11 and a stepped surface 9 provided on the outer circumferential surface of the axle tube 3. This applies a predetermined preload to the rolling bearing device 2. For example, the amount of screwing (screwed position) of the nut 11 is set so that the axial internal gap of the rolling bearing device 2 is zero or a slight positive or negative value.

In this example, the pair of inner rings 18a, 18b are made of the same material and are arranged in opposite axial directions. Therefore, the shape and dimensions of each part of the pair of inner rings 18a, 18b are the same as each other, except that they are oriented in opposite axial directions. However, when implementing the present invention, it is also possible to use materials whose parts have different shapes and dimensions as the pair of inner rings.

As shown in FIG. 3, of the pair of inner rings 18a, 18b, the inner ring 18a, which is disposed on the axially outer side, has a first abutment surface 29a and a first annular groove 30a on its small diameter side end face, which is its axially inner end face.

The first abutment surface 29a is a flat surface that exists on a virtual plane perpendicular to the central axis of the inner ring 18a, and is provided on the radially inner half of the axially inner end face of the inner ring 18a.

The first annular groove 30a is located radially outward from the first abutting surface 29a and is provided in the radially outer half of the axially inner end face of the inner ring 18a. The first annular groove 30a opens to both the outer peripheral surface and the axially inner end face of the inner ring 18a and has a substantially trapezoidal cross-sectional shape. In the illustrated example, the radial bottom surface, which is the outer peripheral surface of the first annular groove 30a, is composed of a cylindrical surface and a tapered surface, which is located axially inward of the cylindrical surface and has an outer diameter that decreases toward the axially inner side.

The axial bottom surface, which is the axial side surface of the first annular groove 30a, is a conical cylindrical surface inclined with respect to an imaginary plane perpendicular to the central axis of the inner ring 18a. Specifically, the axial bottom surface of the first annular groove 30a is inclined in a direction toward the axial inside as it moves radially outward. In the illustrated example, the axial bottom surface of the first annular groove 30a is inclined at about 45° with respect to the central axis of the inner ring 18a. The radial bottom surface and the axial bottom surface of the first annular groove 30a are connected via a corner portion having a cross-sectional arc shape.

The inner ring 18a, which is arranged on the axially outer side, has a first annular groove 30a formed therein, and is provided with a first protrusion 31a having a triangular cross-sectional shape on the radially outer side of the axially inner end. The inner peripheral surface of the first protrusion 31a is formed by the axial bottom surface of the first annular groove 30a.

Of the pair of inner rings 18a, 18b, the inner ring 18b, which is located on the axially inner side, has a second abutment surface 29b and a second annular groove 30b on its small diameter side end face, which is the axially outer end face.

The second abutting surface 29b is a flat surface that exists on a virtual plane perpendicular to the central axis of the inner ring 18b, and is provided on the radially inner half of the axially outer end face of the inner ring 18b. The outer and inner diameter dimensions of the second abutting surface 29b are the same as the outer and inner diameter dimensions of the first abutting surface 29a.

The second annular groove 30b is located radially outward from the second abutment surface 29b and is provided in the radially outer half of the axially outer end face of the inner ring 18b. The second annular groove 30b opens to the outer peripheral surface and the axially outer end face of the inner ring 18b, and has a substantially trapezoidal cross-sectional shape. The radial bottom surface, which is the outer peripheral surface of the second annular groove 30b, is composed of a cylindrical surface and a tapered surface, which is located axially outward from the cylindrical surface and has an outer diameter that decreases toward the axially outer side.

The axial bottom surface, which is the axial side surface of the second annular groove 30b, is a conical cylindrical surface inclined with respect to a virtual plane perpendicular to the central axis of the inner ring 18b. Specifically, the axial bottom surface of the second annular groove 30b is inclined in the axially outward direction as it moves radially outward. In the illustrated example, the axial bottom surface of the second annular groove 30b is inclined at about 45° with respect to the central axis of the inner ring 18b. The radial depth and axial depth of the second annular groove 30b are the same as the radial depth and axial depth of the first annular groove 30a. The radial bottom surface and the axial bottom surface of the second annular groove 30b are connected via a corner portion having a circular arc-shaped cross section. When implementing the present invention, the radial depth and axial depth of the first annular groove and the radial depth and axial depth of the second annular groove can be made different from each other. In addition, the radial bottom surfaces of the first and second annular grooves may be made up of only a cylindrical surface or a tapered surface, or may be made up of a surface having another generatrix shape.

The inner ring 18b, which is arranged on the axially inner side, has a second annular groove 30b formed therein, and is provided with a second protrusion 31b having a triangular cross-sectional shape on the radially outer side of the axially outer end. The inner peripheral surface of the second protrusion 31b is formed by the axial bottom surface of the second annular groove 30b.

The rolling bearing device 2 forms an abutment portion 32 by abutting the first abutment surface 29a of the inner ring 18a arranged on the axially outer side with the second abutment surface 29b of the inner ring 18b arranged on the axially inner side in surface contact. In addition, with the abutment portion 32 formed, the first annular groove 30a and the second annular groove 30b are connected in the axial direction to form a seal retaining groove 33 that is open only radially outward. Therefore, the pair of inner rings 18a, 18b have a seal retaining groove 33 that axially straddles the inner rings 18a, 18b.

The seal retaining groove 33 is configured as a dovetail groove having a cross-sectional shape that is approximately isosceles trapezoidal, and is disposed radially outward of the butting portion 32. The seal retaining groove 33 has a groove bottom surface 33a that is composed of the radial bottom surface of the first annular groove 30a and the radial bottom surface of the second annular groove 30b. The seal retaining groove 33 also has a pair of groove inner surfaces 33b that are composed of the axial bottom surface of the first annular groove 30a and the axial bottom surface of the second annular groove 30b. The pair of groove inner surfaces 33b are inclined in a direction that approaches each other in the axial direction as they move radially outward.

Rolling Body
Each of the rolling elements 19a, 19b is a tapered roller, made of, for example, bearing steel or ceramic. Each of the rolling elements 19a, 19b is arranged between the outer ring raceways 22a, 22b and the inner ring raceways 23a, 23b in a state of being held by cages 34a, 34b so as to be freely rollable. Each of the rolling elements 19a in the axially outer row has a part of its axially outer end face in contact with the large rib portion 24a, and a part of its axially inner end face closely facing the small rib portion 25a. Each of the rolling elements 19b in the axially inner row has a part of its axially inner end face in contact with the large rib portion 24b, and a part of its axially outer end face closely facing the small rib portion 25b.

<Sealing material>
The seal member 20 is for sealing an abutting portion 32 between the pair of inner rings 18 a, 18 b, and is disposed radially outward of the abutting portion 32 .

As shown in FIG. 3, in the rolling bearing device 2 of this embodiment, the cross-sectional contour shape of the seal member 20 is not circular as described in JP 2008-75837 A, but is roughly an eight-shape with a narrowed radial middle portion.

The seal member 20 is made of an elastic material and is configured to have an overall annular shape. The seal member 20 is made of a material having a hardness of Hs85 to Hs95 ( Hs90 ±5), such as acrylonitrile butadiene rubber (NBR, high hardness nitrile), so that the seal member 20 can maintain the annular shape to some extent before being attached to the seal retaining groove 33. In this example, the hardness of the seal member 20 is set to about Hs90.

The seal member 20 has an outer diameter side seal portion 35 and an inner diameter side seal portion 36.

The outer diameter side seal portion 35 constitutes the radially outer half of the seal member 20 and has a generally rectangular cross-sectional shape. The outer diameter side seal portion 35 is disposed outside the seal retaining groove 33 when the seal member 20 is attached to the seal retaining groove 33. In other words, the outer diameter side seal portion 35 protrudes radially outward from the seal retaining groove 33.

The axial width of the outer diameter side seal portion 35 is greater than the axial width of the opening of the seal retaining groove 33. The outer diameter side seal portion 35 has a cylindrical inner peripheral surface on both axial sides. When the seal member 20 is attached to the seal retaining groove 33, the inner peripheral surfaces of both axial sides of the outer diameter side seal portion 35 abut (make surface contact) against the outer peripheral surfaces of the small flanges 25a, 25b of the pair of inner rings 18a, 18b over the entire circumference. This allows the seal member 20 to be positioned radially and covers the opening of the seal retaining groove 33 over the entire circumference.

In this example, the radial width of the outer diameter side seal portion 35 is approximately the same as the radial width of the seal retaining groove 33 and the radial width of the inner diameter side seal portion 36, and is given a certain degree of thickness. This prevents the outer diameter side seal portion 35 from twisting. The outer diameter side seal portion 35 has chamfered portions on both axial sides of the outer peripheral surface.

The inner diameter side seal portion 36 constitutes the radially inner half of the seal member 20 and has a cross-sectional shape that is a substantially isosceles trapezoid that is substantially the same as the cross-sectional shape of the seal retaining groove 33. The inner diameter side seal portion 36 is disposed inside the seal retaining groove 33 when the seal member 20 is attached to the seal retaining groove 33. Specifically, the inner diameter side seal portion 36 is held inside the seal retaining groove 33 without any rattling.

The inner seal portion 36 has an inner peripheral surface 37 in the form of a cylindrical surface. The inner seal portion 36 also has a pair of inclined outer surfaces 38 in the form of a conical cylinder, which are inclined on both sides in the axial direction in a direction that approaches each other in the axial direction as they move radially outward. Therefore, the axial width of the inner seal portion 36 becomes smaller as they move radially outward. The axial width of the portion of the inner seal portion 36 where the axial width is the largest is approximately the same as the axial width of the outer seal portion 35. The inclination angle of the inclined outer surface 38 with respect to the central axis of the seal member 20 is slightly smaller than the inclination angle of the groove inner surface 33b with respect to the central axis of the inner rings 18a and 18b. In the illustrated example, the inclined outer surface 38 is inclined at about 40° with respect to the central axis of the seal member 20. Each of the pair of inclined outer surfaces 38 and the inner peripheral surface 37 is not directly connected, but is connected via a chamfered portion.

In the free state of the seal member 20, the axial distance between the pair of inclined outer surfaces 38 is slightly larger, at least in a portion of the inclined outer surfaces 38, than the axial distance between the pair of groove inner surfaces 33b when the pair of inner rings 18a, 18b are connected by the connecting ring 21. In the illustrated example, the axial distance between the pair of inclined outer surfaces 38 at the radial inner portion of the inclined outer surfaces 38 is slightly larger than the axial distance between the pair of groove inner surfaces 33b. The axial distance between the pair of inclined outer surfaces 38 from the radial outer portion to the radial middle portion of the inclined outer surfaces 38 is slightly smaller than the axial distance between the pair of groove inner surfaces 33b.

When the seal member 20 is attached to the seal retaining groove 33, the pair of inclined outer surfaces 38 (in the illustrated example, the radially inner parts) of the inner diameter side seal portion 36 are in contact with the pair of groove inner surfaces 33b of the seal retaining groove 33 over the entire circumference. In this example, when the pair of inclined outer surfaces 38 are in contact with the pair of groove inner surfaces 33b, the pair of inclined outer surfaces 38 (inner diameter side seal portion 36) are slightly elastically deformed in the axial and radial directions.

The seal member 20 has a cross-sectional shape of the outer diameter side seal portion 35 and a cross-sectional shape of the inner diameter side seal portion 36 that are different from each other. This makes it impossible to attach the seal member 20 to the seal retaining groove 33 when the seal member 20 is inverted in the radial direction, i.e., when the outer diameter side seal portion 35 faces radially inward and the inner diameter side seal portion 36 faces radially outward. Specifically, the outer diameter side seal portion 35 cannot be positioned inside the seal retaining groove 33.

The seal member 20 has engagement grooves 39a, 39b with a triangular cross section in the radially intermediate portion (diametrical middle portion) between the outer diameter side seal portion 35 and the inner diameter side seal portion 36 on both axial sides.

When the seal member 20 of this example is attached to the seal retaining groove 33, the inner peripheral surfaces of both axial sides of the outer diameter side seal portion 35 abut (surface contact) radially against the outer peripheral surfaces of the small flanges 25a, 25b of the pair of inner rings 18a, 18b, and the pair of inclined outer surfaces 38 of the inner diameter side seal portion 36 abut against the pair of groove inner surfaces 33b of the seal retaining groove 33. In other words, when the seal member 20 of this example is attached to the seal retaining groove 33, the first protrusion portion 31a and the second protrusion portion 31b engage with the engagement recess grooves 39a, 39b without any play in the radial and axial directions. This allows the seal member 20 to be positioned relative to the pair of inner rings 18a, 18b. That is, the seal member 20 is prevented from moving radially and axially relative to the pair of inner rings 18a, 18b.

With the seal member 20 positioned, a minute radial gap 40 is formed around the entire circumference between the inner circumferential surface 37 of the inner diameter side seal portion 36 and the groove bottom surface 33a of the seal retaining groove 33. In this example, the groove bottom surface 33a is composed of the radial bottom surface of the first annular groove 30a and the radial bottom surface of the second annular groove 30b, each of which is composed of a cylindrical surface and a tapered surface, so the radial gap 40 is not constant in the axial direction and is largest at the axial center.

In this example, with the seal member 20 attached, the inner peripheral surfaces of both axial sides of the outer diameter side seal portion 35 are in contact with the outer peripheral surfaces of the small flange portions 25a, 25b over the entire circumference, and each of the pair of inclined outer surfaces 38 is in contact with each of the pair of groove inner surfaces 33b over the entire circumference. Therefore, according to the rolling bearing device 2 of this example, foreign matter such as differential oil present inside the axle tube 3 and muddy water from the external space can be prevented from entering the gap between the outer peripheral surface of the axle tube 3 and the inner peripheral surfaces of the inner rings 18a, 18b, and then entering the internal space of the rolling bearing device 2 through the butt portion 32. Therefore, deterioration of the grease sealed inside the rolling bearing device 2 can be prevented.

Linking Ring
The connecting ring 21 is for connecting the pair of inner rings 18a, 18b in the axial direction and is made of a metal plate. The connecting ring 21 is annular as a whole and has a substantially U-shaped cross section. The connecting ring 21 has a cylindrical connecting portion 41 in the axial middle portion and a pair of locking portions 42a, 42b, each of which has a substantially L-shaped cross section, at both axial ends.

The connecting ring 21 is fitted into the pair of inner rings 18a, 18b so as to straddle the pair of inner rings 18a, 18b in the axial direction. The connecting ring 21 engages the pair of locking portions 42a, 42b with the locking grooves 26a, 26b provided on the inner peripheral surfaces of the pair of inner rings 18a, 18b. Specifically, the outer surface of the locking portion 42a on the axially outer side is abutted against the inner surface of the locking groove 26a of the axially outer inner ring 18a without any axial rattle. The outer surface of the locking portion 42b on the axially inner side is abutted against the inner surface of the locking groove 26b of the axially inner inner ring 18b without any axial rattle. As a result, the connecting ring 21 connects the pair of inner rings 18a, 18b in the axial direction. Therefore, with the rolling bearing device 2 of this example, it is possible to prevent the pair of inner rings 18a, 18b from separating from each other due to friction acting on the inner rings 18a, 18b when assembling the rolling bearing device 2 to the axle tube 3, and to prevent the inner ring 18a, located on the axially outer side, from coming out of the axle tube 3 in the axial direction due to a collision between the inner ring 18a and the axle tube 3.

The outer diameter and inner diameter of the connecting portion 41 are constant in the axial direction, and when the connecting ring 21 is in a free state, the outer diameter is the same as or slightly larger than the inner diameter of the large diameter surface portions 28a, 28b. Therefore, when the connecting ring 21 is attached (fitted) to the pair of inner rings 18a, 18b, the outer peripheral surface of the connecting portion 41 is in contact with the inner peripheral surfaces of the large diameter surface portions 28a, 28b.

Sealing device
As shown in Figures 1 and 2, the rolling bearing device 2 of this example further includes a pair of sealing devices 43a, 43b for sealing the openings on both axial sides of the internal space existing between the inner peripheral surface of the outer ring 17 and the outer peripheral surfaces of the pair of inner rings 18a, 18b. One sealing device 43a is disposed between the axially outer side of the inner peripheral surface of the outer ring 17 and the outer peripheral surface of the large flange portion 24a constituting the inner ring 18a disposed on the axially outer side. The other sealing device 43b is disposed between the axially inner side of the inner peripheral surface of the outer ring 17 and the outer peripheral surface of the large flange portion 24b constituting the inner ring 18b disposed on the axially inner side. These sealing devices 43a, 43b prevent the grease sealed in the internal space of the rolling bearing device 2 from leaking to the external space, and prevent foreign matter such as muddy water present in the external space from entering the internal space.

According to the rolling bearing device 2 of this embodiment as described above, the sealing performance of the butted portion 32 between the pair of inner rings 18a, 18b can be ensured, and the axial gap can be guaranteed.
That is, in this example, with the seal member 20 attached to the seal retaining groove 33 provided on the radial outside of the butt portion 32, the inner peripheral surfaces of both axial sides of the outer diameter side seal portion 35 are brought into contact with the outer peripheral surfaces of the small flange portions 25a, 25b of the pair of inner rings 18a, 18b, respectively, and the pair of inclined outer surfaces 38 of the inner diameter side seal portion 36 are brought into contact with the pair of groove inner surfaces 33b of the seal retaining groove 33, respectively. Therefore, the seal member 20 can ensure the sealing performance of the butt portion 32.

In addition, according to the structure of this example, it is possible to ensure the sealing of the butt joint 32 by only slightly elastically deforming each of the pair of inclined outer surfaces 38, and it is not necessary to crush the seal member and greatly elastically deform it in order to ensure the sealing of the butt joint, as in the conventional structure described in JP 2008-75837 A. This makes it possible to prevent the contact pressure (surface pressure) between the pair of inclined outer surfaces 38 and the pair of groove inner surfaces 33b from becoming high. Therefore, according to the structure of this example, it is possible to sufficiently reduce the elastic force (component force) in the axial direction acting from the seal member 20 on the pair of inner rings 18a, 18b. As a result, it is possible to prevent gaps from occurring in the butt joint 32.

In addition, in this example, a radial gap 40 is formed between the inner peripheral surface 37 of the inner diameter side seal portion 36 and the groove bottom surface 33a of the seal retaining groove 33. This prevents a part of the seal member 20 (the radial inner part) from being pinched by the butt joint 32. In addition, in this example, the groove bottom surface 33a of the seal retaining groove 33 is composed of the radial bottom surface of the first annular groove 30a and the radial bottom surface of the second annular groove 30b, each of which is composed of a cylindrical surface and a tapered surface, so that the radial distance (the size of the radial gap 40) from the butt joint 32 to the inner peripheral surface 37 can be secured large. This effectively prevents a part of the seal member 20 from being pinched by the butt joint 32.

As a result, according to the rolling bearing device 2 of this example, even when the pair of inner rings 18a, 18b are connected by the connecting ring 21 to measure the axial clearance by the conventionally known measurement method as shown in FIG. 7, it is possible to prevent a gap from being generated at the butt joint 32 due to the elasticity of the seal member 20 or the seal member 20 being pinched by the butt joint 32. Therefore, the rolling bearing device 2 of this example can accurately measure the reference value of the axial clearance by the conventionally known measurement method. Therefore, the axial clearance can be accurately measured, and the axial clearance can be guaranteed. This also makes it possible to apply an appropriate preload to the rolling bearing device 2.

[Second Example of the Embodiment]
A second embodiment will be described with reference to FIG.

The rolling bearing device 2a of this example differs from the structure of the first embodiment only in the structure of the seal member 20a for sealing the butt joint 32 between the pair of inner rings 18a, 18b.

The seal member 20a of this example is composed of an outer diameter side seal portion 35 arranged on the outside of the seal holding groove 33 and an inner diameter side seal portion 36a arranged on the inside of the seal holding groove 33 when the seal member 20a is attached to the seal holding groove 33. The structure of the outer diameter side seal portion 35 is the same as the structure of the outer diameter side seal portion 35 constituting the seal member 20 of the first example of the embodiment.

The inner seal portion 36a has a pair of inclined outer surfaces 38 in the form of a conical cylinder on both axial sides, which are inclined in a direction approaching each other in the axial direction as they move radially outward. The inner peripheral surface 37a of the inner seal portion 36a is not cylindrical, and has a seal groove 44 in the axial middle portion, which is recessed radially outward, over the entire circumference. The seal groove 44 has a cross-sectional shape that is approximately an isosceles trapezoid. As a result, the inner seal portion 36a has a pair of fin-shaped (thin) lip portions 45 on both axial sides of the seal groove 44. The seal groove 44 is located radially outward of the butt portion 32. Each of the pair of lip portions 45 is located in a portion that is axially off from the butt portion 32. When implementing the present invention, the cross-sectional shape of the seal groove is not limited to a trapezoid shape, and other shapes such as a triangular shape and a semicircular shape can also be adopted. Additionally, the number of seal grooves formed on the inner circumferential surface of the inner diameter seal portion is not limited to one, and multiple seal grooves can be formed.

In the above-described embodiment, the seal groove 44 is formed in the axial middle portion of the inner peripheral surface 37a of the inner diameter side seal portion 36a, and the fin-shaped lip portions 45 are provided on both axial sides of the inner diameter side seal portion 36, so that each of the pair of inclined outer surfaces 38 can be easily elastically deformed. Therefore, the contact pressure between the pair of inclined outer surfaces 38 and the pair of groove inner surfaces 33b can be further reduced compared to the structure of the first embodiment. In addition, since the seal groove 44 is formed on the inner peripheral surface 37a of the inner diameter side seal portion 36a, the radial gap 40a formed between the bottom surface of the seal groove 44 and the groove bottom surface 33a can be made large. Therefore, it is possible to effectively prevent a part of the seal member 20a from being pinched by the butt portion 32.
The other configurations and effects are the same as those of the first embodiment.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and can be modified as appropriate without departing from the technical concept of the invention. Furthermore, the structures of each example of the embodiment can be combined as appropriate as long as no contradiction occurs.

When implementing the present invention, the shapes of the outer diameter side seal portion and the inner diameter side seal portion that constitute the seal member are not limited to the shapes shown in the examples of the embodiments, and can be modified as appropriate. In addition, when implementing the present invention, the structure of the connecting ring is not limited to the structures in the examples of the embodiments, and can be modified as appropriate. Furthermore, the rolling bearing device of the present invention can be incorporated into the rotation support portion of various mechanical devices and can be used not only in drive wheel support devices.

REFERENCE SIGNS LIST 1 Drive wheel support device 2, 2a Rolling bearing device 3 Axle tube 4 Hub wheel 5 Drive shaft 6 Drive wheel 7 Braking rotor 8 Cylindrical surface portion 9 Step surface 10 Male thread portion 11 Nut 12 Flange 13 Bolt 14 Fitting surface 15 Rotating flange 16 Coupling member 17 Outer ring 18a, 18b Inner ring 19a, 19b Rolling element 20, 20a Seal member 21, 21a Connecting ring 22a, 22b Outer ring raceway 23a, 23b Inner ring raceway 24a, 24b Large flange portion 25a, 25b Small flange portion 26a, 26b Locking groove 27a, 27b Small diameter surface portion 28a, 28b Large diameter surface portion 29a First abutting surface Description of the Related Art 29b second abutment surface 30a first annular groove 30b second annular groove 31a first protrusion portion 31b second protrusion portion 32 abutment portion 33 seal retaining groove 33a groove bottom surface 33b groove inner surface 34a, 34b cage 35 outer diameter side seal portion 36, 36a inner diameter side seal portion 37, 37a inner circumferential surface 38 inclined outer surface 39a, 39b engagement groove 40, 40a radial gap 41 connecting portion 42a, 42b engaging portion 43a, 43b sealing device 44 seal groove 100 rolling bearing device 101 axle tube 102 hub wheel 103 drive shaft 104 flange 105 drive wheel 106 braking rotor REFERENCE SIGNS LIST 107, 107x Outer ring 108a, 108b, 108x, 108y Inner ring 109a, 109b, 109x, 109y Rolling element 110 Sealing member 111 Connecting ring 112a, 112b Outer ring raceway 113a, 113b Inner ring raceway 114 Butt portion 115 Joint portion 116 Locking portion 117a, 117b Locking groove 118 Reference surface 119 Displacement gauge

Claims (3)

an outer ring having a double row outer ring raceway on an inner circumferential surface;
A pair of inner rings each having a single-row inner ring raceway on an outer circumferential surface thereof;
A plurality of rolling elements disposed between the outer ring raceway and the inner ring raceway;
a seal member that seals an abutting portion between the pair of inner rings;
a connecting ring connecting the pair of inner rings,
the pair of inner rings each have a dovetail-shaped seal retaining groove on the radially outer side of the butted portion, the dovetail-shaped seal retaining groove including a pair of groove inner surfaces inclined in a direction approaching each other in the axial direction as they extend radially outward,
The seal member is made of an elastic material, has an overall annular shape, and includes an outer diameter side seal portion disposed outside the seal retaining groove, and an inner diameter side seal portion disposed inside the seal retaining groove and having a cross-sectional shape different from that of the outer diameter side seal portion, the inner diameter side seal portion including a pair of inclined outer surfaces inclined in a direction approaching each other in the axial direction as they extend radially outward,
The seal member has inner peripheral surfaces of both axial sides of the outer diameter side seal portion abutted against outer peripheral surfaces of the pair of inner rings, and has the pair of inclined outer surfaces abutted against the pair of groove inner surfaces, and has a radial gap between the inner peripheral surface of the inner diameter side seal portion and a groove bottom surface of the seal retaining groove.
Rolling bearing device. The rolling bearing device according to claim 1, wherein the inner diameter side seal portion has a seal groove on the inner circumferential surface. A rolling bearing device according to any one of claims 1 to 2, in which the hardness of the sealing member is Hs85 or more and Hs95 or less.

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