Engine part

• US 20060026952A1
• Filed: 08/04/2005
• Published: 02/09/2006
• Est. Priority Date: 08/06/2004
• Status: Active Grant

• Current Assignee: Yamaha Hatsudoki Kabushiki Kaisha (Yamaha Corporation)
• Original Assignee: Yamaha Hatsudoki Kabushiki Kaisha (Yamaha Corporation)
• Inventors: Takahashi, Naohisa
• Granted Patent: US 7,726,121 B2
• Time in Patent Office: Days
• US Class Current: 60/299
• CPC Class Codes: C25D 5/12 at least one layer being of nickel or chromium
• CPC Class Codes: C25D 5/14 two or more layers being of nickel or chromium, e.g. duplex or triplex layers
• CPC Class Codes: C25D 5/611 Smooth layers
• CPC Class Codes: C25D 5/617 Crystalline layers
• CPC Class Codes: C25D 5/619 Amorphous layers
• CPC Class Codes: C25D 5/627 Electroplating characterised by the visual appearance of the layers, e.g. colour, brightness or mat appearance
• CPC Class Codes: C25D 7/04 Tubes; Rings; Hollow bodies
• CPC Class Codes: F01N 13/16 Selection of particular materials
• CPC Class Codes: Y10T 29/49345 Catalytic device making

Abstract

An engine part has a construction which prevents the surface discoloration/deterioration associated with a high-temperature exhaust gas, irrespective of the type of Cr used in the formation of a chromium plating layer (hexavalent chromium or trivalent chromium). The engine part includes a metal substrate, a chromium plating layer covering at least a region of a surface of the metal substrate, the region being heated to a temperature of about 350° C. or more, and an intermediate plating layer provided between the metal substrate and the chromium plating layer. The chromium plating layer has a thickness of about 0.2 μm or more in the region.

Claims

1. An engine part comprising:

a metal substrate;

a chromium plating layer covering at least a region of a surface of the metal substrate, the region being heated to a temperature of about 350°

C. or more; and

an intermediate plating layer provided between the metal substrate and the chromium plating layer;

wherein

the chromium plating layer has a thickness of about 0.2 μ

m or more in the region.

2. The engine part of claim 1, wherein the chromium plating layer has a thickness in a range from about 0.2 μ

m to about 0.9 μ

m in the region.

3. The engine part of claim 1, wherein the chromium plating layer has a thickness in a range from about 0.2 μ

m to about 0.5 μ

m in the region.

4. The engine part of claim 1, wherein the metal substrate is a metal tube defining a passage through which an exhaust gas from an engine travels.

5. The engine part of claim 4, wherein the chromium plating layer covers an outer side surface of the metal tube.

6. The engine part of claim 5, wherein,

the metal tube has a bent portion;

and

the region is a convex surface defined by the bent portion.

7. The engine part of claim 5, wherein,

the metal tube includes a manifold section having a plurality of branch pipes connected thereto;

and

the region is an outer surface of the manifold section.

8. The engine part of claim 5, wherein,

the metal tube has a catalyst accommodating section accommodating a catalytic apparatus arranged to decompose at least one component in the exhaust gas;

the region is an outer surface of the catalyst accommodating section.

9. The engine part of claim 1, wherein the chromium plating layer includes decorative chromium plating.

10. The engine part of claim 1, wherein the intermediate plating layer includes at least one of C and S.

11. The engine part of claim 7, wherein the intermediate plating layer further includes Ni.

12. The engine part of claim 1, wherein the intermediate plating layer includes a metal having a hardness lower than that of a type of Cr composing the chromium plating layer.

13. The engine part of claim 1, wherein the intermediate plating layer includes nickel plating.

14. The engine part of claim 1, wherein the metal substrate includes a material containing Fe, Al, Zn, Mg, or Ti as a main component.

15. The engine part of claim 1, wherein the chromium plating layer is formed by using a hexavalent chromium plating bath.

16. The engine part of claim 1, wherein the chromium plating layer is formed by using a trivalent chromium plating bath.

35. An engine comprising the engine part of claim 1.

17. An engine part comprising:

a metal substrate;

a chromium plating layer covering at least a portion of a surface of the metal substrate; and

an intermediate plating layer provided between the metal substrate and the chromium plating layer;

wherein

a type of Cr composing the chromium plating layer substantially has an amorphous structure, and an Fe content in the chromium plating layer is about 2 mass % or less.

18. The engine part of claim 17, wherein the chromium plating layer has a color tone such that an L* value measured according to CIE (Commision Internationale de l'"'"'Eclairage) 1976 is in a range from 68 to 80.

19. The engine part of claim 17, wherein the chromium plating layer covers a region of the surface of the metal substrate, the region being heated to a temperature of about 350°

C. or more, and the chromium plating layer has a thickness in a range from about 0.2 μ

m to about 0.6 μ

m in the region.

20. The engine part of claim 17, wherein the metal substrate is a metal tube defining a passage through which an exhaust gas from an engine travels.

21. The engine part of claim 20, wherein the chromium plating layer covers at least a portion of an outer side surface of the metal tube.

22. The engine part of claim 21, wherein,

the metal tube has a bent portion;

and

the region is a convex surface defined by the bent portion.

23. The engine part of claim 21, wherein

the metal tube includes a manifold section having a plurality of branch pipes connected thereto;

and

the region is an outer surface of the manifold section.

24. The engine part of claim 21, wherein,

the metal tube has a catalyst accommodating section accommodating a catalytic apparatus for decomposing at least one component in the exhaust gas;

the region is an outer surface of the catalyst accommodating section.

25. The engine part of claim 17, wherein the chromium plating layer includes decorative chromium plating.

26. The engine part of claim 17, wherein the intermediate plating layer includes at least one of C and S.

27. The engine part of claim 26, wherein the intermediate plating layer further includes Ni.

28. The engine part of claim 17, wherein the intermediate plating layer includes a metal having a hardness lower than that of a type of Cr composing the chromium plating layer.

29. The engine part of claim 17, wherein the intermediate plating layer includes nickel plating.

30. The engine part of claim 17, wherein the metal substrate includes a material containing Fe, Al, Zn, Mg, or Ti as a main component.

36. An engine comprising the engine part of claim 17.

31. An exhaust pipe comprising:

a metal tube having a bent portion; and

a decorative chromium plating layer arranged so as to cover at least an outer convex surface being defined by a portion of the bent portion, the decorative chromium plating layer having a thickness of about 0.2 μ

m or more.

32. The exhaust pipe of claim 31, wherein,

the metal tube includes a manifold section having a plurality of branch pipes connected thereto, and a catalyst accommodating section accommodating a catalytic apparatus;

and

the decorative chromium plating layer further covers an outside of the manifold section and the catalyst accommodating section.

33. The exhaust pipe of claim 32, wherein the chromium plating layer has a thickness in the range from about 0.2 μ

m to about 0.5 μ

m.

34. The exhaust pipe of any of claims 31, wherein the chromium plating layer has a color tone such that an L* value measured according to CIE (Commision Internationale de l'"'"'Eclairage) 1976 is in a range from 68 to 80.

37. A transportation apparatus comprising the exhaust pipe of claim 31.

38. A method of producing an engine part, comprising the steps of:

placing a metal substrate in a plating apparatus;

forming an intermediate plating layer on the metal substrate; and

using a chromium plating bath, performing plating while placing the metal substrate with the intermediate plating layer formed thereon in such a manner that a chromium plating layer having a thickness of about 0.2 μ

m or more is formed in a region of a surface of the metal substrate, the region being heated to a temperature of about 350°

C. or more.

39. The engine part producing method of claim 38, wherein an Fe content in the chromium plating layer is suppressed to about 2 mass % or less by controlling an Fe content in the chromium plating bath to be substantially zero.

40. The engine part producing method of claim 39, wherein the chromium plating bath does not contain any additive having an Fe component.

41. The engine part producing method of claim 38, wherein Fe contained in the chromium plating bath is removed by using a cation exchange resin.