Fuel Pump Piston Sealing Structure for Low-Leakage Machining
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Solution Overview
Problem
Existing high-pressure fuel pumps face challenges in sealing efficiency and cost due to complex machining requirements and potential for leakage, which affects their operational reliability and manufacturing costs.
Innovation Solution
A high-pressure fuel pump design featuring a machined, injection-molded sealing device with two radially inward circumferential sealing sections, optimized geometry, and a perfluoroalkoxy material, which reduces undercuts, improves machinability, and enhances sealing effectiveness while minimizing leakage and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex sealing device with multiple sealing sections is used, then sealing efficiency is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The sealing device is divided into exactly two sealing sections positioned at axially distant end regions, which is the minimum number needed to seal both fuel-side and oil-side areas. This segmentation provides sufficient sealing efficiency while avoiding the complexity of having more sections.
Solution Approach 2:
The sealing device is implemented as a single integrated injection-molded part that combines both sealing sections into one component. This merging approach reduces manufacturing complexity compared to assembling multiple separate sealing components, while still providing effective sealing at both ends.
2Reliability
If traditional machining methods are used for the sealing device, then sealing effectiveness is achieved, but manufacturing cost and time increase
Solution Approach 1:
The sealing device is pre-formed using injection molding to create the basic geometry and integrated structure before any machining operations. This preliminary action allows subsequent machining to focus only on critical sealing surfaces rather than creating the entire component from scratch, reducing both cost and time.
Solution Approach 2:
The invention transitions from traditional full machining to a hybrid approach where injection molding parameters are optimized to create the sealing device's basic form. This parameter change in the manufacturing process significantly reduces machining requirements while maintaining sealing effectiveness.
3Manufacturing precision
If multiple undercuts are designed in the sealing device, then sealing sections can be positioned, but machinability deteriorates
Solution Approach 1:
The sealing device uses exactly two sealing sections, which minimizes the number of undercuts required in the injection mold. This segmentation into two sections provides sufficient sealing coverage while keeping the number of complex mold features to a minimum, thereby improving machinability.
4Ease of manufacture
If a one-piece injection-molded sealing device is used, then manufacturing cost is reduced, but sealing precision may deteriorate
Solution Approach 1:
The injection molding process is used to pre-form the sealing device with high precision, creating accurate geometries for both sealing sections before any machining. This preliminary precision forming allows subsequent minimal machining to achieve the required sealing precision while keeping overall manufacturing cost low.
Solution Approach 2:
The invention optimizes injection molding parameters to achieve the required sealing precision directly in the molding process. By changing from a purely machined approach to an injection-molded approach with optimized parameters, the patent reduces manufacturing cost while maintaining or improving sealing precision.
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 provides improved sealing efficiency, reduced wear, and lower manufacturing costs by simplifying the sealing device's geometry and material selection, leading to enhanced operational reliability and cost-effectiveness.
Implementation Method 1
The necessary return force of the piston is generated by a compression spring
Implementation Method 2
the sealing device seals the high-pressure fuel pump against a liquid medium at a radially outer surface of the piston
Data Source
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AI summary
The invention relates to a high-pressure fuel pump (28) comprising a piston (30) which has, arranged on its end section oriented toward a drive, a sealing device (74) which radially surrounds the piston (30), wherein the piston (30) can be displaced relative to the sealing device (74) along a longitudinal axis (64). According to the invention, the sealing device (74) has a first and a second radially inner circumferential sealing section (78), wherein the first and second sealing sections (78) are arranged at mutually separated axial end regions of the sealing device (74), and wherein the sealing sections (78) are present on an injection-molded part (77) that has been reworked in a chip-removing manner.