Wheel Bearing Apparatus For A Vehicle

• US 20110206307A1
• Filed: 05/04/2011
• Published: 08/25/2011
• Est. Priority Date: 11/05/2008
• Status: Active Grant

• Current Assignee: NTN Corporation
• Original Assignee: NTN Corporation
• Inventors: Komori, Kazuo
• Granted Patent: US 8,794,844 B2
• Time in Patent Office: Days
• US Class Current: 384/512
• CPC Class Codes: B60B 27/0005 with ball bearings
• CPC Class Codes: B60B 27/0084 caulking to fix inner race
• CPC Class Codes: B60B 27/0094 one or more of the bearing races are formed by the hub
• CPC Class Codes: C21D 1/42 Induction heating
• CPC Class Codes: C21D 1/63 for bath quenching
• CPC Class Codes: C21D 2211/005 Ferrite
• CPC Class Codes: C21D 2221/02 Edge parts
• CPC Class Codes: C21D 2221/10 Differential treatment of inner with respect to outer regions, e.g. core and periphery, respectively
• CPC Class Codes: C21D 9/40 for rings; for bearing races
• CPC Class Codes: C22C 38/04 containing manganese
• CPC Class Codes: F16C 19/186 with three raceways provided integrally on parts other than race rings, e.g. third generation hubs
• CPC Class Codes: F16C 2240/80 Pitch circle diameters [PCD]
• CPC Class Codes: F16C 2326/02 Wheel hubs or castors
• CPC Class Codes: F16C 33/62 Selection of substances
• CPC Class Codes: F16C 43/04 Assembling rolling-contact bearings
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

A vehicle wheel bearing apparatus has an outer member; an inner member and double row balls freely rollably contained between outer raceway surfaces and inner raceway surfaces. An inner ring is axially secured relative to a wheel hub by a caulked portion. The caulked portion is formed by plastically deforming the cylindrical portion radially outward. The wheel hub is formed from medium-high carbon steel including carbon of 0.40-0.80% by weight and with a ferrite grain size number selected larger than #3.

Claims

1. A vehicle wheel bearing apparatus comprising:

an outer member formed with double row outer raceway surfaces on its inner circumference;

an inner member including a wheel hub and at least one inner ring, the wheel hub is integrally formed with a wheel mounting flange on its one end, the wheel hub outer circumference has an axially extending cylindrical portion, the inner ring is press-fit onto the cylindrical portion of the wheel hub, via a predetermined interference, the inner ring outer circumference includes an inner raceway surface that opposes the inner side outer raceway surface of the outer member;

double row balls are freely rollably contained between the outer raceway surfaces and inner raceway surfaces, respectively, of the outer member and the inner member;

the inner ring is axially secured relative to the wheel hub by a caulked portion, the caulked portion is formed by plastically deforming the cylindrical portion radially outward; and

the wheel hub is formed of medium-high carbon steel including carbon of 0.40-0.80% by weight and with a ferrite grain size number that is selected larger than #3.

2. The vehicle wheel bearing apparatus of claim 1, wherein the wheel hub is formed from medium-high carbon steel including C:

0.50-0.70 wt %, Mn;

0.1-2.0 wt %, Cr;

1.0 wt % or less and residues;

Fe and inevitable impurities.

3. The vehicle wheel bearing apparatus of claim 2, further comprising S in the wheel hub in the amount limited to 0.02 wt % or less.

4. The vehicle wheel bearing apparatus of claim 2, further comprising Si in the wheel hub in an amount limited to 0.2 wt % or less.

5. The vehicle wheel bearing apparatus of claim 1, wherein draft (La−

Lb)/La of the caulking work is set at 0.55 or less, “

La”

is an amount of projection from the larger end face of the inner ring before caulking of the cylindrical portion and “

Lb”

is a height of the caulked portion.

6. The vehicle wheel bearing apparatus of claim 1, wherein the wheel hub is directly formed on its outer circumference with one inner raceway surface that opposes the outer side outer raceway surface of the double row outer raceway surfaces, the inner raceway surface and a region from the inner side base of the wheel mounting flange to the cylindrical portion are hardened by induction hardening to have a surface hardness of 58-64 HRC, the caulked portion is not hardened and remained as is after forging to have a surface hardness of 13-30 HRC.

7. The vehicle wheel bearing apparatus of claim 1, wherein a pitch circle diameter of the outer side ball group is set larger than a pitch circle diameter of the inner side ball group.

8. The vehicle wheel bearing apparatus of claim 7, wherein a number of the outer side balls of the double row balls is set larger than a number of the inner side balls.

9. The vehicle wheel bearing apparatus of claim 7, wherein an outer diameter of each ball of the outer side ball group of the double row balls is set smaller than an outer diameter of each ball of the inner side ball group.

10. The vehicle wheel bearing apparatus of claim 8, wherein an outer diameter of each ball of the outer side ball group of the double row balls is set smaller than an outer diameter of each ball of the inner side ball group.