JP2002127706A - Automobile hub unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automobile hub unit 1a with sufficient durability by surely preventing an inner ring 3a from rotating about a hub body 2 and preventing the wearing out of a fitting section of the hub body 2 and the inner ring 3a. SOLUTION: An outer end surface 20 of the inner ring 3a is positioned axially outside the intersection of extensions α, β of generating lines on first and second outer ring races 14, 15 formed in the inner peripheral surface of an outer ring 4. Fitting strength of the hub body 2 and the inner ring 3a is thereby increased enough to meet the needs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an automobile hub unit for rotatably supporting a wheel of an automobile with respect to a suspension device, and to prevent the inner ring from rotating with respect to the hub body. It is intended to prevent the fitting portion between the hub body and the inner ring from being worn and to improve the durability.

[0002]

2. Description of the Related Art The wheels of an automobile are rotatably supported on a suspension system by rolling bearings. In addition, a heavy vehicle wheel is rotatably supported with respect to a suspension device by a vehicle hub unit incorporating double-row tapered roller bearings. FIG. 3 shows an example of an automobile hub unit used in such a case, which is described in Japanese Utility Model Laid-Open Publication No. 56-119015. First, the automobile hub unit 1 described in this publication will be described.

The hub unit 1 for an automobile includes a hub body 2, an inner ring 3 fitted and fixed to the hub body 2, an outer ring 4 disposed around the hub body 2 and the inner ring 3, A plurality of tapered rollers 5a and 5b are provided between the outer peripheral surface of the inner ring 3 and the inner peripheral surface of the outer ring 4.
Outer end of the hub body 2 (outside in the axial direction)
Is the outer side in the width direction when assembled to a car, and is the left side of each figure. Conversely, with respect to the axial direction, the right side portion of each drawing, which is the center in the width direction when assembled to an automobile, is referred to as “inside”. Same throughout this specification. ) At the outer ring 4
A first flange 6 for supporting the wheel is formed on the outer peripheral surface of the portion exposed from the outside. On the outer peripheral surface of the intermediate portion of the hub body 2, there is provided a tapered convex shaped inclined surface in which the outer diameter becomes smaller toward the inner side in the axial direction for forming the first row of tapered roller bearings 7. One inner raceway 8 is directly formed. Further, a small-diameter step portion 9 is provided on the outer peripheral surface of the inner end portion of the hub main body 2. The outer peripheral surface of the small-diameter step portion 9 is a cylindrical surface concentric with the hub body 2. The illustrated example shows a vehicle hub unit 1 for supporting driving wheels. For this purpose, a spline hole 10 is provided in the center of the hub body 2 so as to be attached to a constant velocity joint (not shown). The end of the drive shaft is freely splined.

[0004] The inner race 3 is a second conical convex inner raceway which is inclined in such a manner that the outer diameter becomes smaller toward the outside in the axial direction in order to constitute the second row of tapered roller bearings 11. 12 is formed on the outer peripheral surface of the intermediate portion.
Is externally fitted and fixed to the small-diameter step portion 9. Further, a small-diameter flange portion 27 is formed at the outer end of the outer peripheral surface of the inner ring 3, and a large-diameter flange portion 28 is formed at the inner end similarly. The inner end of the inner ring 3 projects slightly beyond the inner end surface of the hub body 2 with the outer end surface of the inner ring 3 abutting against the step surface 13 of the small-diameter step portion 9. In the assembled state to the automobile, the inner end face of the inner ring 3 protruding from the hub body 2 in this way hits the outer end face of the constant velocity joint and the like, and the inner ring 3 comes out of the small diameter step portion 9. To prevent.

On the inner peripheral surface of the outer ring 4, the first
First and second outer raceways 14 and 15 for forming the second row of tapered roller bearings 7 and 11 are formed. The inclination directions of the first and second outer raceways 14 and 15 are opposite to each other in accordance with the first and second inner raceways 8 and 12. That is, the first and second outer raceways 14, 15
Have a conical concave shape, and are inclined in such a direction that the inner diameter decreases as they approach each other (as they approach the axial center portion of the outer ring 4). A second flange 16 for fixing the outer ring 4 to a suspension (not shown) is provided at an axially intermediate portion of the outer peripheral surface of the outer ring 4.

A part of the plurality of tapered rollers 5a, 5b (the left half in FIG. 3) 5a is held by the first holder 17 so as to be able to roll freely. Are disposed between the inner raceway 8 and the first outer raceway 14. On the other hand, the plurality of tapered rollers 5a,
Tapered roller 5b of the remaining part (right half of FIG. 3) of 5b
The second inner raceway 12 and the second outer raceway 15 are held rotatably by a second cage 18.
And between them. Also, the remaining tapered rollers 5b
Are partially opposed to the inner surfaces of the small-diameter flange portion 27 and the large-diameter flange portion 28 provided at both ends of the outer peripheral surface of the inner ring 3, respectively.

Further, seal rings 19a and 19b are provided between the openings at both ends of the outer ring 4 and the outer peripheral surface of the intermediate portion of the hub body 2 and the outer peripheral surface of the inner end of the inner ring 3, so that the first row is provided. The space in which the second row of tapered roller bearings 7 and 11 are installed is isolated from the outside. The grease sealed in this space is prevented from leaking outside, and foreign matter is prevented from entering this space.

[0008]

In the case of the conventional automobile hub unit 1 shown in FIG. 3, a fitting length L between the inner ring 3 and the hub body 2 constituting the inner second row of tapered roller bearings 11 is shown. ₃ is not always sufficient, and the inner ring 3 may creep (the inner ring 3 rotates with respect to the hub body 2) with respect to the hub body 2 depending on the load conditions at the time of using the vehicle hub unit 1. was there. That is, the inner ring 3
Is externally fitted to the hub body 2 by a light interference fit. Fitting strength between inner ring 3 and the hub body 2, when the same diameter of the fitting portion is proportional to the product of the interference and the fitting length L ₃ of both members 3,2 . And
Among these, the interference is to prevent the initial tensile stress from being generated in the second inner raceway 12 from the viewpoint of controlling the preload of the hub unit 1 for the automobile, suppressing the increase in the manufacturing cost, and further. In view of securing the rolling life of the second inner raceway 12, the length cannot be made too large. On the other hand, it is difficult to increase the diameter of the fitting part in consideration of prevention of size increase and securing of the thickness of the inner ring 3.

[0009] Therefore, in the case of the conventional structure the fitting length L ₃ is not sufficiently large, it is difficult to sufficiently increase the fitting strength, there is a possibility that creep occurs as described above Was. When creep occurs, one or both of the inner peripheral surface of the inner race 3 and the outer peripheral surface of the hub main body 2 gradually wears, and after a long-term use, the inner race 3 moves with respect to the hub main body 2. It will rattle. The present invention has been made in view of such circumstances to increase the fitting strength between the inner ring 3 and the hub body 2.

[0010]

An automobile hub unit according to the present invention comprises a hub body and an inner ring externally fitted to and fixed to the hub body, as in the case of the above-described conventionally known automobile hub unit. An outer ring disposed around the hub body and the inner ring; and a plurality of tapered rollers provided between the outer peripheral surface of the hub body and the inner ring and the inner peripheral surface of the outer ring. Of these, the hub main body is provided with a first flange for supporting the wheel on the outer peripheral surface of the outer end portion, and is formed inward in the axial direction for forming the first row of tapered roller bearings on the outer peripheral surface of the intermediate portion. A first conical convex inner raceway is formed directly inclining in such a direction that the outer diameter becomes smaller as it goes, and a small-diameter step is provided on the outer peripheral surface of the inner end. In addition, the inner ring is configured such that a second row of tapered roller bearings is formed on the outer peripheral surface of the intermediate portion. A small-diameter flange portion is formed on the outer peripheral surface of the outer end, and a large-diameter flange portion is formed on the outer peripheral surface of the inner end portion. Further, the outer ring has a first and second rows of tapered roller bearings on an inner peripheral surface thereof, each of which has a tapered concave shape and is inclined in a direction in which the inner diameter becomes smaller as approaching each other. And a second flange for supporting and fixing the outer ring to a suspension device is formed on the outer peripheral surface of the outer ring raceway.

In particular, in the automobile hub unit according to the present invention, the outer end surface of the inner race is located axially outward from a position where the extended lines of the buses of the first and second outer raceways intersect. Exists. In general, the inclination angles of the generatrix of these first and second outer raceways are equal to each other. Therefore, the position where the extended lines of the bus cross each other is generally the center position of the portion between the first and second outer raceways. Further, the length of shifting the outer end surface position of the inner ring outward from the intersecting position is within a range that does not impair the strength and function of the first inner ring raceway formed on the outer peripheral surface of the intermediate portion of the hub body. ,
Make it as large as possible. Therefore, the above-mentioned length is preferably secured at least 2 mm, more preferably at least 5 mm.

[0012]

According to the present invention constructed as described above, the fitting length between the inner race and the hub body is longer than in the case of the conventional structure. In addition, since the small-diameter flange portion and the large-diameter flange portion are respectively formed on the outer peripheral surfaces at both ends of the inner ring, the average thickness of the inner ring is increased. For this reason, the diameter of the fitting portion between the inner ring and the hub body can be increased without lowering the strength of the inner ring as compared with a structure in which the flanges are not formed on the outer peripheral surface of the inner ring. Can be. As a result, according to the present invention, it is possible to effectively prevent the inner ring from creeping on the hub main body, prevent the outer peripheral surface of the hub main body from rubbing against the inner peripheral surface of the inner race, Wear can be prevented, and the durability of the automobile hub unit can be improved.

[0013]

FIG. 1 shows a first embodiment of the present invention corresponding to claims 1 and 2. The feature of the present invention, by increasing the engagement length L _3a of the inner ring 3a relative to the hub body 2, to ensure the engagement strength between these hub body 2 and the inner ring 3a, the inner ring 3a is the hub body 2 To prevent creep. Since the basic structure of the vehicle hub unit 1a is the same as the conventional structure shown in FIG. 3 described above, the same parts are denoted by the same reference numerals, and redundant description is omitted or simplified.
The following description focuses on the features of the present invention.

In the hub unit 1a for an automobile according to the present invention, the outer end surface 20 of the inner ring 3a is formed on the inner peripheral surface of the outer ring 4 by the bus lines α and β of the first and second outer ring raceways 14 and 15.
Are located axially outward by ΔL from the position O where the extension lines of In the case of this example, the inclination angles of the generatrix of the first and second outer raceways 14 and 15 are equal to each other. Therefore, the position where the extended lines α and β of the bus cross each other is the center position between the first and second outer raceways 14 and 15.

The position of the outer end surface 20 of the inner ring 3a is
Length shifted axially outward from the intersecting position O.
L is made as large as possible without impairing the strength and function of the first inner raceway 8 formed on the outer peripheral surface of the intermediate portion of the hub body 2. In the case of the present example, the flange portion 21 is formed at the small diameter side end portion (inner ring portion) of the first inner ring raceway 8, but the length ΔL can secure the strength of the flange portion 21. About as long as possible. In this case, in a state where the automobile hub unit 1a is assembled and further assembled to the automobile, the outer end surface 20 of the inner ring 3a is strongly pressed against the inner side surface 22 of the flange portion 21 to back up the flange portion 21. I do. Therefore, the axial length of the flange portion 21 may be any length that can secure the strength at the time of machining, and is made smaller than that of the conventional structure, and the length ΔL can be increased accordingly.

According to the present invention configured as described above, the fitting strength between the hub body 2 and the inner ring 3a can be increased by the length ΔL. Moreover, since the small-diameter flange 27 and the large-diameter flange 28 are respectively formed on the outer peripheral surfaces at both ends of the inner ring 3a, the average thickness of the inner ring 3a in the diametric direction is increased. For this reason, compared to a structure in which the both flange portions 27 and 28 are not formed on the outer peripheral surface of the inner ring 3a,
Without reducing the strength of the inner ring 3a,
The diameter of the fitting portion between the hub and the hub body 2 can be increased. As a result, according to the present invention, the hub body 2
In contrast, the inner ring 3a is effectively prevented from creeping, the outer peripheral surface of the hub body 2 is prevented from rubbing against the inner peripheral surface of the inner ring 3a, and both peripheral surfaces are prevented from being worn. Thus, the durability of the automobile hub unit 1a can be improved. In addition, unlike the case of this example, the first inner raceway 1
In addition to omitting the flange 21 from the small diameter side end of No. 4, the small diameter side end of the first inner raceway 14 and the step surface 13 can be directly connected. In this case, a part of the end face of each of the rollers 5a, 5a constituting the first row of tapered roller bearings 7 is directly opposed to a portion of the outer end face 20 of the inner ring 3a, which is abutted against the step surface 13, near the outer diameter. Thus, the small-diameter flange 27 formed at the outer end of the inner ring 3a serves as a flange at the small-diameter side end of the tapered roller bearings 7 in the first row. In the case of such a configuration, the structure of the hub main body 2a is simplified, and the processing of the hub main body 2a can be facilitated.

Next, FIG. 2 corresponds to claims 1 to 3,
9 shows a second example of the embodiment of the present invention. In the case of the vehicle hub unit 1b of this example, not only the inner ring 3b but also the axial dimensions of the hub body 2a and the outer ring 4a are increased, and the first row of tapered roller bearings 7 and the second row of tapered roller bearings. The distance from the reference numeral 11 is increased. And the inner ring 3
The position of the outer end surface 20 of the outer ring 4b is located more axially outward than the position O where the extended lines of the buses α and β of the first and second outer ring raceways 14 and 15 formed on the inner peripheral surface of the outer ring 4a intersect. The length △ L ′ to be shifted is made larger than in the case of the first example described above.

The outer half of the inner ring 3b has a function as an encoder. For this reason, the second inner raceway 12 is formed by the outer half of the inner race 3b made of magnetic metal such as bearing steel.
Gear-shaped irregularities on the outer peripheral surface of the part located outside than
It is formed by an appropriate processing method such as broaching and rolling. The magnetic properties of the outer peripheral surface of the outer half of the inner ring 3b are changed alternately at regular intervals in the circumferential direction. Therefore, the outer peripheral surface of the outer half portion of the inner ring 3b functions as a detected portion of the encoder constituting the rotation speed detecting device.

On the other hand, at the intermediate portion of the outer ring 4a,
Mounting hole 2 formed between second outer raceways 14 and 15
3, a sensor 24 constituting the rotation speed detecting device is inserted, and a detection surface provided at a tip portion (a lower end portion in FIG. 2) of the sensor 24 is minutely attached to an outer peripheral surface of an outer half portion of the inner ring 3b. They face each other with a gap 25 therebetween. An O-ring 26 engaged with the outer peripheral surface of the intermediate portion of the sensor 24 seals between the outer peripheral surface of the sensor 24 and the inner peripheral surface of the mounting hole 23. Foreign matter such as rainwater is prevented from entering the inner diameter side.

When the hub body 2a and the inner ring 3b rotate together with the wheels in a state of being mounted on the automobile, the vicinity of the detection surface of the sensor 24 constitutes irregularities formed on the outer peripheral portion of the outer half of the inner ring 3b. The concave portions and the convex portions pass alternately. As a result, the density of the magnetic flux flowing in the sensor 24 changes at a frequency proportional to the rotation speed of the wheel.
Therefore, if the detection signal of the sensor 24 is sent to a controller (not shown), the rotation speed of the wheel is obtained, and the control of the antilock brake system (ABS) and the traction control system (TCS) can be performed.

If only the rotation speed detection by the sensor 24 is considered, it is conceivable that an encoder and an inner ring which are independent from each other are externally fitted to the inner half of the hub main body 2a. However, when such a structure is adopted, it is difficult to secure the fitting strength between the hub body 2a and the inner ring, and creep may occur between the hub body 2a and the inner ring. . When such creep occurs, not only does this cause rattling at the fitting portion between the hub body 2a and the inner ring, but also the independent encoder rotates with respect to the hub body 2a. there's a possibility that. When the encoder rotates with respect to the hub body 2a, the rotational speed of the wheel cannot be measured accurately. Other configurations and operations are the same as those in the first example described above, and therefore, the same reference numerals are given to the same parts, and the duplicate description will be omitted.

[0022]

Since the present invention is constructed and operates as described above, the inner ring is reliably prevented from rotating with respect to the hub body, and the fitting portion between the hub body and the inner ring is worn. Thus, an automobile hub unit having sufficient durability can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first example of an embodiment of the present invention.

FIG. 2 is a sectional view showing the second example.

FIG. 3 is a cross-sectional view showing one example of a conventional structure.

[Explanation of symbols]

 1, 1a, 1b Automobile hub unit 2, 2a Hub body 3, 3a, 3b Inner ring 4, 4a Outer ring 5a, 5b Tapered roller 6 First flange 7 First row of tapered roller bearing 8 First inner ring raceway 9 Small diameter Step portion 10 Spline hole 11 Second row of tapered roller bearings 12 Second inner raceway 13 Step surface 14 First outer raceway 15 Second outer raceway 16 Second flange 17 First retainer 18 Second retainer Containers 19a, 19b Seal ring 20 Outer end surface 21 Flange 22 Inner surface 23 Mounting hole 24 Sensor 25 Micro gap 26 O-ring 27 Small diameter flange 28 Large diameter flange

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16C 35/063 F16C 35/063

Claims (3)

[Claims] 1. A hub body, an inner ring externally fitted to and fixed to the hub body, an outer ring arranged around the hub body and the inner ring, and an outer peripheral surface of the hub body and the inner ring and an inner peripheral surface of the outer ring. A plurality of tapered rollers provided in the hub body, of which the hub body is provided with a first flange for supporting the wheel on the outer peripheral surface of the outer end, and a first row of tapered rollers on the outer peripheral surface of the intermediate portion. To form a bearing, the first inner ring raceway of a conical convex shape is formed directly on the outer surface of the conical surface, which is inclined in such a manner that the outer diameter becomes smaller as it goes inward in the axial direction, and a small diameter step is provided on the outer peripheral surface of the inner end. The inner ring is configured such that a second row of tapered roller bearings is formed on the outer peripheral surface of the intermediate portion. Inner ring raceway, small-diameter flange on outer end outer peripheral surface, large-diameter flange on inner end outer peripheral surface The outer ring is formed on the inner peripheral surface of the first and second rows of tapered roller bearings, each having a tapered concave shape. An automobile in which first and second outer raceways which are inclined in a direction in which the inner diameter becomes smaller as approaching each other, and second flanges for supporting and fixing the outer race to a suspension device are formed on the outer peripheral surface, respectively. In the hub unit for an automobile, the outer end surface of the inner race is located axially outward from a position where the extended lines of the generatrix of the first and second outer raceways cross each other. unit. 2. An outer peripheral portion of an intermediate portion of the hub main body, wherein a length of shifting an outer end surface position of the inner race to an axially outward position from a position where extended lines of the generatrix of the first and second outer raceways cross each other. The automobile hub unit according to claim 1, wherein the hub unit is made as large as possible without impairing the strength and function of the first inner raceway formed on the surface. 3. A detection portion of an encoder constituting a rotation speed detecting device is provided on an outer peripheral surface of a portion located outside of a second inner raceway in an outer half portion of the inner race. The hub unit for an automobile according to any one of the above.