Housing Intersecting Passages Stress Concentration Reduction
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Solution Overview
Problem
High pressure fatigue issues arise in engineering components with intersecting passages due to stress concentrations, which are not adequately reduced by existing shaping methods in high-pressure pump applications like common rail diesel engine pumps, leading to potential failure.
Innovation Solution
A housing design with intersecting passages featuring a region with substantially flat surfaces aligned with the boundaries of the enlarged diameter, along with radiused and tangential surfaces, which reduces stress concentrations by avoiding interference with hoop stress planes, thereby minimizing fatigue and failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional passage intersection design is used, then manufacturing is simple, but stress concentrations arise leading to fatigue failure
Solution Approach 1:
The invention applies different surface geometries (flat surfaces, radiused surfaces, tangential surfaces) to different regions of the passage intersection. The flat surfaces are positioned to avoid intersecting hoop stress planes, radiused surfaces smooth transitions to reduce stress concentrations, and tangential surfaces align with the first drilling circumference. This localized application of different geometric qualities optimizes stress distribution while maintaining manufacturing feasibility.
2Ease of manufacture
If passage intersection is simplified, then manufacturing is easier, but stress concentrations increase causing component failure
Solution Approach 1:
The invention incorporates radiused surfaces at the passage intersection to replace sharp corners and abrupt transitions. These curved surfaces smooth the stress flow paths and eliminate stress concentration points that would otherwise lead to fatigue failure. The radiused surfaces are integrated into the intersection region geometry, maintaining manufacturability while significantly improving structural strength and fatigue resistance.
3Reliability
If flat surfaces are aligned with boundaries, then stress concentrations are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The invention employs asymmetric positioning of flat surfaces relative to the passage intersection boundaries. Rather than requiring symmetric alignment with multiple boundaries, the flat surfaces are oriented to avoid intersecting critical hoop stress planes in an asymmetric configuration. This approach reduces stress concentrations while being more tolerant of manufacturing variations, as it does not require precise symmetric alignment across multiple reference surfaces.
Data Source
AI summary
A housing for use in high pressure fluid applications comprises a first drilling having a region of enlarged diameter bounded by an upper boundary in a first plane and a lower boundary in a second plane; and a second drilling intersecting with the first drilling via an intersection region. The intersection region includes a first substantially flat surface which defines a ceiling of the intersection region and which intersects the upper boundary of the region of enlarged diameter, and a second substantially flat surface which is opposed to the first substantially flat surface and which defines a floor of the intersection region and intersects the lower boundary of the region of enlarged diameter. As the flat surfaces are in alignment with a region of maximum hoop stress they do not act as a significant stress raiser at the intersection.