High-Pressure Fuel Pump Bore Segmentation for Stress Reduction
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Solution Overview
Problem
High-stress concentrations at the intersection of boreholes in high-pressure fuel injection systems, particularly at acute angles, lead to material failure under varying pressure conditions, and existing solutions to reduce hoop stresses are costly and sensitive to manufacturing tolerances due to the need for drilling from both sides of the component.
Innovation Solution
A central bore is drilled through the component with a first section extending over the intersection and a second section, where secondary bores only extend along the first section as blind holes, reducing the number of holes to be drilled and minimizing stress peaks by aligning the secondary bores with the central bore, either in the same plane or with a spherical or conical end to reduce stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If secondary bores are introduced to increase the cross section of the central bore at the intersection area, then hoop stresses are reduced and structural integrity is improved, but the number of drilling operations increases and manufacturing complexity increases
Solution Approach 1:
The central bore is segmented into two distinct sections: a first section with enlarged cross-section formed by the intersection of the central bore and secondary bores, and a second section with the original cross-section. This segmentation allows the structure to have optimized stress distribution only where needed (at the intersection area) while maintaining simpler geometry elsewhere, thus improving structural integrity without unnecessarily increasing manufacturing complexity throughout the entire component.
Solution Approach 2:
The cross-sectional enlargement of the central bore is applied locally only in the area where secondary bores open into it, rather than throughout the entire length of the central bore. This local quality change ensures that hoop stresses are reduced precisely at the critical intersection area where secondary bores connect, while avoiding unnecessary complexity in regions where stress reduction is not required.
2Manufacturing precision
If the central bore and secondary bores are drilled from both sides of the component, then stress distribution is optimized and manufacturing precision is improved, but the number of drilling operations increases and production time increases
Solution Approach 1:
Instead of drilling all bores (central and secondary) from both sides of the component as in conventional designs, the invention inverts the approach by drilling the central bore through the entire component from one side to the other, while secondary bores are drilled only from one side as blind holes. This inversion reduces the total number of drilling operations from potentially eight (four bores × two sides) to six (one through-bore + three blind holes from one side), significantly reducing production time while maintaining adequate manufacturing precision.
3Reliability
If the cross section of the central bore is enlarged at the intersection area, then stress concentrations are reduced and reliability is improved, but the amount of material removed increases and manufacturing costs increase
Solution Approach 1:
The cross-sectional enlargement of the central bore is applied locally only in the specific area where secondary bores open into it, creating a stepped configuration. This localized material removal reduces stress concentrations precisely at the critical intersection points where reliability is most compromised, while minimizing the total amount of material removed from the component compared to uniform cross-sectional enlargement throughout the entire central bore length.
Data Source
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AI summary
In a component (1), in particular a housing of a high-pressure fuel pump, in which at least one first high-pressure channel (4) and one second high-pressure channel (5) are present, the longitudinal axis of the first channel (4) is at an acute or right angle to the longitudinal axis of the second channel (5), wherein the second channel (5) leads into the first channel (4), such that an intersection is formed. The first channel (4) is formed by a central bore (10) and at least one secondary bore (11) that enlarges the cross-section of the central bore (10), wherein the longitudinal axis of the secondary bore (11) and the longitudinal axis of the central bore (10) extend parallel to one another. The central bore (10) passes through ugh the component (1) and consists of a first segment (8) extending over the intersection and a second segment (9) connected to the first segment, wherein the at least one secondary bore (11) extends only along the first segment (8) and no secondary bore is provided along the second segment (9).