US4905538A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Camshaft
Assignee: Nissan Motor Co Ltd
•
Filing: 1989-01-24
•
Granted: 1990-03-06
•
Expires: 2009-01-24
Abstract
Abstract A camshaft of a valve operating system for an internal combustion engine, is formed of iron-based alloy casting and has cam sections, each of which is in slidable contact with a heat resistant tip of a rocker arm. The cam section is formed at its surface portion with a surface hardened layer formed of an air-cooled chilled structure. The surface hardened layer is formed by remelting a part of the surface of the casting after preheating. An intermediate hardened layer of a heat affected zone is formed in contact with the surface hardened layer and has a thickness ranging from 0.5 to 2.0 mm. The intermediate hardened layer is formed of a mixed structure of bainite transformation phase and troostite and is formed by being thermally affected during the remelting.
Inventors
- 👤 Koji Watanabe
- 👤 Makoto Kano
- 👤 Shigeoki Sawada
- 👤 Ryoji Makino
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 02:36
CPC Classifications
C; C21; C21D; C21D9/00; C21D9/30; F; F01; F01L; F01L1/00; F01L1/02; F01L1/04; F01L1/047; F01L2301/00; F01L2303/00; F01L2820/00; F01L2820/01; Y; Y10; Y10S; Y10S148/00; Y10S148/902; Y10S148/903; Y10S148/904; Y10T; Y10T74/00; Y10T74/21; Y10T74/2101
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
113 words
A camshaft formed of iron-based alloy casting, comprising: a cam section; a first hardened layer of air-cooled chilled structure and formed in at least a part of said cam section, said first layer forming at least a part of surface of the said cam section and being formed by remelting the iron-based alloy casting after preheating; and a second hardened layer of a heat affected zone and in contact with said first hardened layer, said second hardened layer having a thickness ranging from 0.5 to 2.0 mm and being formed of a mixed structure of bainite transformation phase and troostite, said heat affected zone being formed by being thermally affected under said remelting.
Claim 2
Dependent Claim
113 words
A camshaft formed of iron-based alloy casting, comprising: a cam section; a first hardened layer of air-cooled chilled structure and formed in at least a part of said cam section, said first layer forming at least a part of surface of the said cam section and being formed by remelting the iron-based alloy casting after preheating; and a second hardened layer of a heat affected zone and in contact with said first hardened layer, said second hardened layer having a thickness ranging from 0.5 to 2.0 mm and being formed of a mixed structure of bainite transformation phase and troostite, said heat affected zone being formed by being thermally affected under said remelting.
Claim 3
Dependent Claim
36 words
A camshaft as claimed in claim 1, wherein said chilled structure is formed by radiation of high density heat energy onto the iron-based alloy casting after the preheating and thereafter by cooling the casting in air.
Claim 4
Dependent Claim
32 words
A camshaft as claimed in claim 2, wherein said high density heat energy is generated by one selected from the group consisting of TIG arc, plasma arc, laser beam and electron beam.
Claim 5
Dependent Claim
22 words
A camshaft as claimed in claim 1, wherein said preheating is carried out at a temperature ranging from 200° to 300° C.
Claim 6
Dependent Claim
108 words
A camshaft as claimed in claim 1, wherein said iron-based alloy casting consists essentially of carbon in an amount ranging from 3.0 to 3.5% by weight, chromium in an amount ranging from 0.5 to 1.0% by weight, molybdenum in an amount ranging from 0.1 to 0.3% by weight, nickel in an amount ranging from 0.1 to 0.3% by weight, manganese in an amount ranging from 0.5 to 1.0% by weight, phosphorus in an amount not more than 0.1% by weight, sulfur in an amount not more than 0.1% by weight, silicon in an amount ranging from 1.5 to 2.5% by weight, with the balance being iron and impurities.
Claim 7
Independent Claim
117 words
A method of producing a camshaft having a cam section and formed of iron-based alloy casting, said method comprising the following steps in the sequence set forth: preheating the iron-based alloy casting; radiating high density heat energy onto the casting to remelt at least a part of surface of the cam section so as to form a remelting part, in which a heat affected zone is formed in contact with said remelting part, said heat affected zone having a thickness ranging from 0.5 to 2.0 mm and formed of a mixed structure of bainite transformation phase and troostite; and cooling said remelting section in air so as to form an air-cooled chilled structure in said remelting part.
Claim 8
Independent Claim
117 words
A method of producing a camshaft having a cam section and formed of iron-based alloy casting, said method comprising the following steps in the sequence set forth: preheating the iron-based alloy casting; radiating high density heat energy onto the casting to remelt at least a part of surface of the cam section so as to form a remelting part, in which a heat affected zone is formed in contact with said remelting part, said heat affected zone having a thickness ranging from 0.5 to 2.0 mm and formed of a mixed structure of bainite transformation phase and troostite; and cooling said remelting section in air so as to form an air-cooled chilled structure in said remelting part.
Claim 9
Dependent Claim
22 words
A method as claimed in claim 6, wherein said preheating is carried out at a temperature ranging from 200° to 300° C.
Claim 10
Dependent Claim
29 words
A method as claimed in claim 6, wherein said radiating high density heat energy is carried out onto the casting at a temperature ranging from 200° to 300° C.
Claim 11
Dependent Claim
32 words
A method as claimed in claim 6, wherein said high density heat energy is generated by one selected from the group consisting of TIG arc, plasma arc, laser beam, and electron beam.
References Cited (Backward Citations)
JPS55148772A
Cited
JPS60184694A
Cited
JPS60234167A
Cited
JPS60234168A
Cited
JPS60234169A
Cited
EP0161624A2
Cited
JPS60258426A
Cited
JPS61522A
Cited
US4686349A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-05 | 1993-09-04 | 1994-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-05 | 1997-09-04 | 1998-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-05 | 2001-09-04 | 2002-03-06 | $7700.00 | Window Closed / Lapsed |