Wheel Bearing Apparatus

• US 20180209482A1
• Filed: 03/23/2018
• Published: 07/26/2018
• Est. Priority Date: 09/25/2015
• Status: Active Grant

• Current Assignee: NTN Corporation
• Original Assignee: NTN Corporation
• Inventors: Suma, Hiroto
• Granted Patent: US 10,641,336 B2
• Time in Patent Office: Days
• CPC Class Codes: B60B 27/0068 the element being a sensor
• CPC Class Codes: B60B 27/0073 characterised by sealing means
• CPC Class Codes: B60B 35/02 Dead axles, i.e. not transmitting torque
• 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 2226/30 Material joints in general B23K
• CPC Class Codes: F16C 2233/00 Monitoring condition, e.g. temperature, load, vibration
• CPC Class Codes: F16C 2326/02 Wheel hubs or castors in general B60B
• CPC Class Codes: F16C 33/723 Shaft end sealing means, e.g. cup-shaped caps or covers
• CPC Class Codes: F16C 33/768 between relatively stationary parts, i.e. static seals
• CPC Class Codes: F16C 33/7813 for tapered roller bearings
• CPC Class Codes: F16C 33/783 of the mounting region
• CPC Class Codes: F16C 33/7833 Special methods of manufacture
• CPC Class Codes: F16C 41/007 Encoders, e.g. parts with a plurality of alternating magnetic poles
• CPC Class Codes: Y02T 10/86 Optimisation of rolling resistance, e.g. weight reduction

Abstract

A wheel bearing apparatus has a magnetic encoder 14 mounted on an inner ring 5 opposing the rotational speed sensor 16, via the cap 10 and an air gap. The cap 10 has a cylindrical fitting part 10a press-fit into an inner circumference of an end of the outer member 2. A shielding part 10c extends radially inward from the fitting part 10a and has an annular disc shape. A detection part 16a of the rotational speed sensor 16 is arranged close to or in contact with a side surface of the shielding part 10c. The cap 10 is formed of austenitic stainless steel sheet based on SUS 304. The carbon (C) content is reduced and the nickel (Ni) content is increased. A difference of magnetic flux density between a martensitic transformation part and non-martensite part is 1.4 mT or less.

Claims

1. A wheel bearing apparatus comprising:

an outer member integrally 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 integrally formed with a wheel mounting flange on its one end and having an axially extending cylindrical part, the inner ring press fit onto the cylindrical part of the wheel hub, the inner member formed, on its outer circumference, with double row inner raceway surfaces opposing the double row outer raceway surfaces;

double row rolling elements accommodated between the inner raceway surfaces and outer raceway surfaces, respectively, of the inner member and outer member;

a magnetic encoder mounted on the outer circumference of the inner ring;

a cap fit into an inner-side end of the outer member to seal an annulus opening formed by the outer member and the inner ring;

a rotational speed sensor opposing the magnetic encoder via the cap and an air gap;

the cap formed into a cup-shape so that it has a cylindrical fitting part press-fit into an inner circumference of an end of the outer member, a shielding part extends radially inward from the fitting part and has an annular disc shape, a detection part of the rotational speed sensor arranged close to or in contact with a side surface of the shielding part; and

the cap is formed of austenitic stainless steel sheet based on SUS 304 with a reduced carbon (C) content and an increased nickel (Ni) content, and a difference of magnetic flux density between a martensitic transformation part and non-martensite part is 1.4 mT or less.

2. The wheel bearing apparatus of claim 1, wherein the C content of the steel sheet being a blank of the cap is set at 0.030 wt % or less and the Ni content is set at 9.00 to 13.00 wt %.

3. The wheel bearing apparatus of claim 1, wherein the sheet thickness of the cap is 0.2 to 1.0 mm.

4. The wheel bearing apparatus of claim 1, wherein the cap further comprises a radially reduced part, a shielding part, bottom part and cylindrical part, the radially reduced part formed at an end of the fitting part, the shielding part extending radially inward from the radially reduced part, and the bottom part extending from the shielding part via the cylindrical part for closing the inner-side end of the inner member;

and wherein a sealing member, of synthetic rubber, is secured on an outer circumference of the radially reduced part, the sealing member comprising an annular part and an annularly projected part projecting radially outward from the annular part, an outer diameter of the annular part being smaller than that of the fitting part of the cap, an outer diameter of the annularly projected part being larger than that of the fitting part of the cap so that the annularly projected part can be pressed against the inner circumference of the outer member.