High-Pressure Fuel Pump Retainer Projection Design
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Solution Overview
Problem
In high-pressure fuel pumps, the clearance between the plunger and retainer decreases over time due to environmental factors, leading to a loss of fixing force and potential sticking or breakage of the plunger, especially under side forces.
Innovation Solution
A high-pressure fuel pump design featuring a protruding projection on the retainer with a smaller clearance between the retainer and tappet, a spherical surface, and reduced surface hardness, integrated by press molding, to maintain consistent clearance and prevent sticking and breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a close fit is used to fix the plunger to the retainer, then initial fixing force is adequate, but the fixing force decreases over time due to environmental factors and wear
Solution Approach 1:
The retainer is divided into two functional zones: an outer peripheral portion that contacts the tappet and an inner portion that receives the plunger. This segmentation allows the outer portion to maintain clearance and prevent side forces, while the inner portion provides secure plunger retention, resolving the contradiction between initial fixing strength and long-term durability
Solution Approach 2:
Different regions of the retainer are given different properties: the outer peripheral portion has a larger clearance with the tappet to prevent side force transmission, while the inner portion maintains a close fit with the plunger for secure retention. This local differentiation allows each region to optimize its function, preventing overall failure while maintaining initial fixing effectiveness
2Volume of moving object
If the clearance between the retainer and tappet becomes small, then the structure is compact, but side forces cause bending moments that lead to plunger sticking or breakage
Solution Approach 1:
The retainer implements local quality by creating a larger clearance specifically at the outer peripheral portion where it contacts the tappet. This localized clearance prevents side forces from being transmitted to the plunger, while the inner portion maintains adequate structural integrity. The differential clearance design directly addresses the contradiction between compactness and durability
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 design ensures that the clearance between the retainer and tappet remains consistent, reducing the risk of plunger sticking and breakage even under side forces, enhancing the reliability and durability of the pump.
Implementation Method 1
reduced surface hardness
Implementation Method 2
The spherical surface...maintain consistent clearance and prevent sticking and breakage
Implementation Method 3
integrated by press molding
Data Source
AI summary
A high-pressure fuel pump includes a pump body, a plunger, a retainer, a spring that is configured to energize the plunger in a direction opposite to a direction of the pressurizing chamber, and a tappet covering the retainer from a side of an end portion of the retainer and the plunger. The retainer is provided with a projection portion protruding to a side of the tappet. The projection portion is separated from the tappet by a predetermined distance along an axial direction of the plunger.