Fuel Rail End Cap Structure to Prevent Boundary Load Concentration
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Solution Overview
Problem
Conventional gasoline direct injection rails with U-shaped end caps experience excessive load concentration at the boundary between the rail body and end cap due to a large level difference, leading to potential damage under high pressure.
Innovation Solution
A gasoline direct injection rail design featuring an end cap with a circumferential wall placed in a depression of the rail body's inner circumference, ensuring no level difference at the boundary, and maintaining a h/T ratio of 0<h/T≤0.25 to distribute pressure evenly, preventing load concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the circumferential wall of the end cap has a large thickness, then the end cap has sufficient strength, but a large level difference is formed at the boundary part between the rail body and end cap, causing load concentration and potential damage
Solution Approach 1:
The patent applies local quality by creating a depression (local structural modification) in the rail body at the boundary region. This depression allows the thick circumferential wall of the end cap to be recessed into the rail body, maintaining the strength-providing thickness of the circumferential wall while eliminating the level difference that causes load concentration. The local structural change confines the thick wall within the depression, preventing stress concentration at the boundary.
2Stress or pressure
If the circumferential wall of the end cap has a large thickness, then the end cap can withstand high pressure, but the boundary part between rail body and end cap experiences excessive load concentration
Solution Approach 1:
The depression creates a localized structural feature that accommodates the thick circumferential wall without creating a protruding boundary. This local modification allows the end cap to maintain its pressure resistance through the thick circumferential wall while the depression ensures the boundary region does not become a stress concentration point, preserving the strength of the boundary part.
3Ease of manufacture
If the circumferential wall of the end cap is placed on the inner circumference of the rail body, then manufacturing is simplified, but a level difference is formed at the boundary part causing load concentration
Solution Approach 1:
The depression is pre-formed in the rail body before the end cap is installed. This preliminary action creates a prepared receptacle that guides the circumferential wall into the correct position, simplifying the manufacturing and assembly process. The depression ensures that when the end cap is placed, the circumferential wall is already recessed, eliminating the level difference and preventing load concentration without requiring additional machining or adjustment during assembly.
Data Source
AI summary
To obtain a gasoline direct injection rail in which a large load is unlikely to be concentrated on a boundary part between a rail body and an end cap, and damage to the boundary part can be prevented, even when high pressure is applied to the inside of the rail body. The gasoline direct injection rail comprises an end cap 4 composed of a top plate 5 and a circumferential wall 6, and a rail body 1 having an end part 2 in which the circumferential wall 6 of the end cap 4 is inserted and placed, wherein an inner circumference of the end part 2 of the rail body 1 has a depression 3, the circumferential wall 6 is placed in the depression 3, and there is no level difference at a boundary part 12 between an inner circumferential surface 11 of the circumferential wall 6 and an inner circumferential surface 10 of the rail body 1.