Piston Pump Roller Rim Geometry for Wear Reduction
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Solution Overview
Problem
High-pressure fuel pumps in internal combustion engines face issues with axial movement and twisting of rollers leading to corner contact, which causes wear and potential operational failures due to high surface pressure.
Innovation Solution
Designing rims and rollers with specific conical shapes and surface treatments to prevent corner contact, promoting line contact and reducing wear, with angles between 0.1° to 10° and radii between 1 mm to 40 mm, and incorporating a one-piece cam section and hardenable materials for increased wear resistance and reduced friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the roller is allowed to move axially and twist freely, then the operation is flexible, but corner contact occurs leading to high surface pressure, wear, and potential operational failures
Solution Approach 1:
The patent applies parameter changes by specifying precise geometric parameters for the rim and roller surfaces. The rim is designed with a conical shape having an opening inclination angle (α) between 5° and 15°, while the roller has a convex curvature with radius (r) between 2mm and 10mm. These parameter specifications transform the contact from point/corner contact to line contact, distributing the load and preventing high surface pressure that causes wear and operational failures.
Solution Approach 2:
The patent employs spheroidality by giving the roller end face a convex curvature instead of a flat or sharp edge. This curved surface, combined with the conical rim shape, ensures that contact occurs along a line rather than at a corner or point. The curvature radius (r) is specifically controlled between 2mm and 10mm to optimize the contact geometry and prevent stress concentration.
2Manufacturing precision
If the rim and roller have sharp edges for precise positioning, then the positioning is accurate, but edge breaks occur leading to operational failures
Solution Approach 1:
The patent resolves this contradiction by replacing sharp edges with curved surfaces. The roller end face has a convex curvature with radius (r) between 2mm and 10mm, which eliminates sharp edges that are prone to breaking. Despite the curvature, the conical rim shape with angle (α) between 5° and 15° maintains precise positioning by guiding the roller along a defined path, thus achieving both edge strength and positioning precision.
Solution Approach 2:
The patent changes the geometric parameters of the rim and roller from sharp-edged configurations to curved configurations with specific parameter ranges. The opening inclination angle (α) of 5°-15° and curvature radius (r) of 2mm-10mm are optimized to maintain positioning precision while eliminating stress concentration at edges, thereby preventing edge breaks and operational failures.
3Device complexity
If the roller contacts the rim at a single point for simple design, then the design is simple, but point contact causes high surface pressure and wear
Solution Approach 1:
The patent maintains design simplicity while improving reliability by using curved surfaces instead of complex distributed contact mechanisms. The conical rim shape with angle (α) between 5° and 15° combined with the convex roller curvature (r = 2mm-10mm) naturally creates line contact geometry. This curved surface approach is simpler than adding multiple contact points or complex suspension systems, yet it distributes the load effectively to prevent wear.
Solution Approach 2:
The patent transforms the contact geometry by changing key parameters: the rim opening inclination angle (α) is set between 5° and 15°, and the roller curvature radius (r) is set between 2mm and 10mm. These parameter changes convert point contact into line contact, distributing the surface pressure and reducing wear, while maintaining the simplicity of the overall design without adding complex mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively minimizes wear and chipping, reduces the risk of operational failures, and ensures reliable operation by preventing corner contact and promoting idler return to its original position through optimized geometries and surface treatments.
Implementation Method 1
The roller is caused to rotate by the friction that occurs when it runs against one of the rims, if it is not already rotating due to the rolling friction between the cam section and the roller
Data Source
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AI summary
The invention relates to a piston pump, in particular a high-pressure fuel pump, comprising a housing (1), a piston and a drive shaft (2) having a cam section (3) on which the piston is at least indirectly supported via a guide roller (5) that is rotatably mounted in a roller plunger (4), wherein laterally on either of the two sides of the cam section (3) a rim (6) is provided that protrudes in the radial direction beyond the cam section (3), wherein the rim (6) tapers on one front face directed towards the guide roller (5) to an outer circumference of the rim (6), wherein the rim (6) is in particular conical, so that an angular opening results, wherein the cam roller comprises a convex curvature directed towards the rim (6), preferably with a radius (r). Alternatively, also the rim can have a convex curvature and the roller can taper conically.