Full-type rolling bearing and roller cam follower for engine

• US 20040079310A1
• Filed: 10/17/2003
• Published: 04/29/2004
• Est. Priority Date: 10/17/2002
• Status: Active Grant

• Current Assignee: NTN Corporation
• Original Assignee: NTN Corporation
• Inventors: Maeda, Kikuo, Fujii, Yukio, Ichikawa, Kenichi, Suzuki, Tadatoshi
• Granted Patent: US 7,490,583 B2
• Time in Patent Office: Days
• US Class Current: 123/90.41
• CPC Class Codes: C23C 8/32 of ferrous surfaces
• CPC Class Codes: F01L 1/146 Push-rods
• CPC Class Codes: F01L 1/18 Rocking arms or levers
• CPC Class Codes: F01L 1/181 Centre pivot rocking arms
• CPC Class Codes: F01L 1/185 Overhead end-pivot rocking arms
• CPC Class Codes: F01L 2301/00 Using particular materials
• CPC Class Codes: F01L 2303/00 Manufacturing of components used in valve arrangements
• CPC Class Codes: F01L 2305/00 Valve arrangements comprising rollers
• CPC Class Codes: F01L 2305/02 Mounting of rollers
• CPC Class Codes: F16C 13/02 Bearings
• CPC Class Codes: F16C 2240/18 Stress
• CPC Class Codes: F16C 2360/18 Camshafts
• CPC Class Codes: F16C 33/30 Parts of ball or roller bearings
• CPC Class Codes: F16C 33/34 Rollers; Needles
• CPC Class Codes: F16C 33/62 Selection of substances
• CPC Class Codes: F16C 33/64 Special methods of manufacture
• CPC Class Codes: F16H 53/06 Cam-followers F16H53/08 takes precedence
• CPC Class Codes: Y10T 74/1828 Cam, lever, and slide
• CPC Class Codes: Y10T 74/2101 Cams

Abstract

A full-type rolling bearing that can be used under the conditions of high-speed, heavy-load and lowered viscosity of lubricating oil is provided. The full-type rolling bearing is formed of an outer ring, an inner ring and rollers made of steel, at least one of the outer ring, inner ring and rollers has a carbonitrided layer in its surface layer, and the austenite crystal grain size number of the surface layer is larger than 10.

Claims

1. A full-type rolling bearing formed of an outer ring, an inner ring and rollers that are made of steel, wherein

at least one of said outer ring, inner ring and rollers has a carbonitrided layer in its surface layer, and the austenite crystal grain size number of the surface layer is greater than 10.

2. The full-type rolling bearing according to claim 1, wherein

at least one of said outer ring, inner ring and rollers is carbonitrided at a carbonitriding temperature equal to or higher than the A1 transformation temperature, cooled to a temperature lower than the A1 transformation temperature and then heated to a quenching temperature lower than said carbonitriding temperature and thereby quenched.

3. The full-type rolling bearing according to claim 2, wherein

said quenching temperature is in a temperature range at which carbide and/or nitride and an austenite phase coexist in the carbonitrided surface layer of the steel.

4. The full-type rolling bearing according to claim 2, wherein

said quenching temperature is 790°

C.-830°

C.

5. The full-type rolling bearing according to claim 2, wherein

at least one of said outer ring, inner ring and rollers is cold-worked before being carbonitrided.

6. The full-type rolling bearing according to claim 1, wherein

in at least one of said outer ring, inner ring and rollers, a compression residual stress of at least 500 MPa is generated.

7. A roller cam follower of an engine comprising:

an outer ring being in rolling contact with a cam shaft of the engine;

a roller shaft located inside said outer ring and fixed to a cam follower body; and

bearing elements placed between said outer ring and said roller shaft, wherein

at least one of said outer ring, roller shaft and bearing elements has a carbonitrided layer, and austenite crystal grains in at least a surface layer are made fine to have a grain size number greater than 10.

10. The roller cam follower of an engine according to claim 7, wherein

said cam follower body is mounted on one end of a rocker arm, said rocker arm is pivotably attached to a rotational shaft located between said one end and the other end, one end of an open/close valve of said engine abuts on said other end, said cam follower body on said one end has a bifurcated roller supporting portion, and said roller shaft is fixed to said bifurcated roller supporting portion.

13. The roller cam follower of an engine according to claim 7, wherein

said cam follower body is mounted between one end and the other end of a rocker arm, said roller shaft is fixed in a roller hole extending between two sidewalls of the rocker arm, an end of an open/close valve of said engine abuts on said one end of said rocker arm, and a pivot abuts on said other end.

16. The roller cam follower of an engine according to claim 7, wherein

a rocker arm is pivotably attached to a rotational shaft located between one end and the other end of said rocker arm, an end of an open/close valve of said engine abuts on said one end, said other end abuts on one end of an interlocking rod transmitting a stress from said cam, said cam follower body is mounted on the other end of said interlocking rod, said one end and said other end of said interlocking rod being located respectively on said rocker arm and said cam, and said roller shaft is attached to said cam follower body and abuts on said cam.

19. The roller cam follower of an engine according to claim 7, wherein

said bearing elements are full type needle bearings.

22. The roller cam follower of an engine according to claim 7, wherein

said roller shaft has its end with a hardness lower than that of its central portion.

25. The roller cam follower of an engine according to claim 7, wherein

said roller shaft has its end which is caulked.

28. The roller cam follower of an engine according to claim 7, wherein

said cam follower is entirely press-formed.

8. A roller cam follower of an engine comprising:

an outer ring being in rolling contact with a cam shaft of the engine;

a roller shaft located inside said outer ring and fixed to a cam follower body; and

bearing elements placed between said outer ring and said roller shaft, wherein

at least one of said outer ring, roller shaft and bearing elements has a carbonitrided layer and has a fracture stress of at least 2650 MPa.

11. The roller cam follower of an engine according to claim 8, wherein

said cam follower body is mounted on one end of a rocker arm, said rocker arm is pivotably attached to a rotational shaft located between said one end and the other end, one end of an open/close valve of said engine abuts on said other end, said cam follower body on said one end has a bifurcated roller supporting portion, and said roller shaft is fixed to said bifurcated roller supporting portion.

14. The roller cam follower of an engine according to claim 8, wherein

said cam follower body is mounted between one end and the other end of a rocker arm, said roller shaft is fixed in a roller hole extending between two sidewalls of the rocker arm, an end of an open/close valve of said engine abuts on said one end of said rocker arm, and a pivot abuts on said other end.

17. The roller cam follower of an engine according to claim 8, wherein

a rocker arm is pivotably attached to a rotational shaft located between one end and the other end of said rocker arm, an end of an open/close valve of said engine abuts on said one end, said other end abuts on one end of an interlocking rod transmitting a stress from said cam, said cam follower body is mounted on the other end of said interlocking rod, said one end and said other end of said interlocking rod being located respectively on said rocker arm and said cam, and said roller shaft is attached to said cam follower body and abuts on said cam.

20. The roller cam follower of an engine according to claim 8, wherein

said bearing elements are full type needle bearings.

23. The roller cam follower of an engine according to claim 8, wherein

said roller shaft has its end with a hardness lower than that of its central portion.

26. The roller cam follower of an engine according to claim 8, wherein

said roller shaft has its end which is caulked.

29. The roller cam follower of an engine according to claim 8, wherein

said cam follower is entirely press-formed.

9. A roller cam follower of an engine comprising:

an outer ring being in rolling contact with a cam shaft of the engine;

a roller shaft located inside said outer ring and fixed to a cam follower body; and

bearing elements placed between said outer ring and said roller shaft, wherein

at least one of said outer ring, roller shaft and bearing elements has a carbonitrided layer and has a hydrogen content of at most 0.5 ppm.

12. The roller cam follower of an engine according to claim 9, wherein

said cam follower body is mounted on one end of a rocker arm, said rocker arm is pivotably attached to a rotational shaft located between said one end and the other end, one end of an open/close valve of said engine abuts on said other end, said cam follower body on said one end has a bifurcated roller supporting portion, and said roller shaft is fixed to said bifurcated roller supporting portion.

15. The roller cam follower of an engine according to claim 9, wherein

said cam follower body is mounted between one end and the other end of a rocker arm, said roller shaft is fixed in a roller hole extending between two sidewalls of the rocker arm, an end of an open/close valve of said engine abuts on said one end of said rocker arm, and a pivot abuts on said other end.

18. The roller cam follower of an engine according to claim 9, wherein

a rocker arm is pivotably attached to a rotational shaft located between one end and the other end of said rocker arm, an end of an open/close valve of said engine abuts on said one end, said other end abuts on one end of an interlocking rod transmitting a stress from said cam, said cam follower body is mounted on the other end of said interlocking rod, said one end and said other end of said interlocking rod being located respectively on said rocker arm and said cam, and said roller shaft is attached to said cam follower body and abuts on said cam.

21. The roller cam follower of an engine according to claim 9, wherein

said bearing elements are full type needle bearings.

24. The roller cam follower of an engine according to claim 9, wherein

said roller shaft has its end with a hardness lower than that of its central portion.

27. The roller cam follower of an engine according to claim 9, wherein

said roller shaft has its end which is caulked.

30. The roller cam follower of an engine according to claim 9, wherein

said cam follower is entirely press-formed.