Common rail for diesel engines

a diesel engine and common rail technology, applied in the direction of fuel injection apparatus, charge feed system, metal-working apparatus, etc., can solve the problems of applying auto-frettage, achieve excellent durability, increase the fatigue strength of inner pressure, and high compressive residual stress

US20060260124A1Inactive Publication Date: 2006-11-23USUI KOKUSAI SANGYO KAISHA LTD
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2006-11-23
Estimated Expiration
Not applicable · inactive patent

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Abstract

A common rail for a diesel engine has a main pipe rail with an axial flow passage. Branch holes are made in the main pipe rail and communicate with the axial flow passage. The main pipe rail is worked to decrease stress concentration near the branch holes. The whole inner peripheral surface of the main pipe rail and the branch holes then is subjected to autofrettage processing to generate a compressive residual stress on the entire inner peripheral surface of the main pipe rail and the branch holes for increasing fatigue strength.
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Description

[0001] This application is a divisional U.S. patent application Ser. No. 10 / 653,477, filed Sep. 2, 2003.BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a common rail, such as high-pressure fuel manifolds, block rails, or the like, in a fuel injection system for diesel engines, and more particularly, to a common rail for diesel engines, in which portions of a branch hole or holes on a main pipe rail and a whole inner peripheral surface of the main pipe rail are enhanced in fatigue strength for inner pressures.

[0004] 2. Description of the Related Art

[0005] A common rail in a fuel injection system for diesel engines is shown in FIG. 7, and has a circular main pipe 11. The main pipe 11 has an internal flow passage 11-1. A branch hole 11-2 is provided in a peripheral wall of the main pipe 11 and communicates to the internal flow passage 11-1. The branch hole 11-2 leads to an outwardly opened pressure-receiving seat surface 11-3. A cy...

Examples

Embodiment Construction

[0032] In the invention, reference numeral 1 denotes a main pipe rail, 1-1 a flow passage, 1-2 a branch hole, 1-3 a pressure-receiving seat surface, 1-4 a boss portion, 1-4a a male thread, 1-5 a flattened surface, 2 a branch pipe, 2-1 a flow passage, and 2-2 a projection.

[0033] The main pipe rail 1 or common rail shown in FIGS. 1 to 4 is a forging of a material S45C or the like. The main pipe rail 1 has a tubular portion, which is relatively thick-walled to have, for example, a diameter of 28 mm and a wall thickness 9 mm. An axial interior is subjected to machining, such as boring, gun drilling, or the like, to make the flow passage 1-1, and boss portions 1-4 are provided on a peripheral wall to be axially spaced from one another.

[0034] In the common rail shown in FIGS. 1 and 2, branch holes 1-2 having a predetermined diameter are formed in the boss portions 1-4 which are integral with the main pipe rail 1 The branch holes 1-2 communicate with the flow passage 1-1 of the main pipe...