Calotte-Shaped Fuel Pump Rod Reduces Contact Forces
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Solution Overview
Problem
Existing high-pressure fuel pump and engine valve designs experience significant contact forces due to Hertzian stress, transverse forces, and angle errors, leading to wear and increased production costs when attempting to mitigate these forces through close tolerances and longer guide lengths.
Innovation Solution
A high-pressure fuel pump design featuring a piston with a calotte-shaped end region and a traverse with a corresponding calotte-shaped recess, eliminating the angle error and reducing transverse forces by shifting the contact point closer to the rod axis, thereby minimizing contact forces without excessive production cost increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If close tolerances are applied to reduce contact forces, then wear is reduced, but production costs increase
Solution Approach 1:
The patent applies a calotte-shaped (spherical cap) design to the rod end and corresponding recess in the traverse. This curved geometry replaces the conventional flat or cylindrical contact surfaces, allowing the contact point to self-align and reduce transverse forces. The spherical geometry inherently compensates for angular deviations and guide axis misalignments, reducing wear without requiring tighter manufacturing tolerances on the guide axes and mounting positions.
2Reliability
If longer guide lengths are used to reduce angle errors, then transverse forces are reduced, but device complexity increases
Solution Approach 1:
The calotte-shaped rod end and recess create a spherical contact interface that automatically compensates for angular deviations between the rod axis and plunger guide axis. The curved geometry allows the contact point to migrate along the spherical surface, maintaining optimal force transmission angles without requiring excessively long guide lengths to constrain angular errors.
3Force
If the contact point is shifted closer to the rod axis, then transverse forces are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The spherical cap geometry inherently positions the contact point close to the rod axis through its curved profile. The calotte shape ensures that the normal force at the contact point passes through or near the rod axis, minimizing transverse force components. The self-aligning nature of the spherical interface compensates for manufacturing variations in contact point positioning.
Solution Approach 2:
The calotte-shaped recess in the traverse is designed with asymmetric curvature relative to the rod end, creating an optimal contact geometry that naturally guides the contact point to a position that minimizes transverse forces while accommodating manufacturing tolerances.
Data Source
AI summary
The present disclosure relates to a device for pressure control, including a rod and a plunger. The rod has a first end region delimiting a pressurized space and is movable along an axis between a top dead center and a bottom dead center. The plunger has a traverse substantially perpendicular to a plunger axis transmitting kinetic energy from a plunger drive to the rod in a contact region between a traverse surface and a second end region of the rod arranged opposite the first end region. The rod includes a calotte-shaped end region in the contact region of the rod and the traverse includes a calotte-shaped recess in the contact region of the traverse.