Roller Shoe Groove Segmentation for Fuel Pump Cost Reduction
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Solution Overview
Problem
Conventional high pressure fuel pumps have high manufacturing costs due to complex dimensional requirements of the roller assembly, which complicates the conversion of rotational movement into reciprocal movement.
Innovation Solution
A roller assembly design featuring a roller shoe with a semicircular and straight groove, a cylindrical roller, and a tappet body with specific diameters and undercuts, allowing for a press-fit assembly that converts rotational movement into reciprocal movement while reducing manufacturing costs through deformation of the groove and interference fit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional roller assembly design with a circular arc groove is used, then the roller assembly can convert rotational movement into reciprocal movement, but the manufacturing cost is high due to complex dimensional requirements
Solution Approach 1:
The groove is segmented into two distinct portions: a semicircular portion and a straight portion. This segmentation allows each portion to be manufactured with simpler, more standardized dimensions, reducing overall manufacturing complexity and cost while maintaining the required functional precision for roller retention and movement conversion.
2Reliability
If the groove dimensions are precisely controlled to retain the roller, then the roller assembly functions properly, but the manufacturing complexity increases
Solution Approach 1:
Dividing the groove into semicircular and straight portions simplifies the manufacturing process for each segment while ensuring proper roller retention. The semicircular portion provides smooth roller engagement, while the straight portion offers precise dimensional control, together achieving reliable retention without excessive overall complexity.
Solution Approach 2:
Different portions of the groove have different geometric qualities optimized for their specific functions. The semicircular portion is optimized for roller engagement and smooth motion, while the straight portion is optimized for precise dimensional control and cost-effective manufacturing. This local optimization reduces overall device complexity while maintaining reliability.
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 converts rotational movement into reciprocal movement, reducing manufacturing costs and maintaining sufficient running clearance for the roller assembly, thus enhancing the efficiency and cost-effectiveness of high pressure fuel pumps.
Implementation Method 1
deforming a groove in the cylindrical roller in response to the radial force generated at the interface between the first portion of the cylindrical roller and the inner bore of the tappet body
Implementation Method 2
retaining the roller shoe in the cylindrical roller in response to deforming the groove, and retaining the roller shoe in a fully inserted position with the cylindrical roller protruding
Data Source
AI summary
A roller assembly, comprising a roller shoe having a bottom surface, and a groove at the bottom surface, the groove having a semicircular portion and a straight portion extending from the semicircular portion, the semicircular portion having a first diameter and the straight portion having a first width, and a cylindrical roller positioned in the roller shoe groove, the cylindrical roller having a second diameter, wherein the first width is greater than or equal to the first diameter and the second diameter is less than the first width.