Fuel Pump Plunger Seal Assembly for Fuel-Oil Leakage Control
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Solution Overview
Problem
High pressure fuel pumps in internal combustion engines experience significant fuel to oil and oil to fuel transfer rates due to clearance between the plunger and sleeve, leading to reduced oil filter life and fuel combustibility.
Innovation Solution
A fuel pump with an annular seal assembly around the plunger to minimize fluid transfer, featuring a seal retainer housing and double lip seals to prevent leakage, and a configuration allowing for easy serviceability of the seal assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a clearance is provided between the plunger and plunger sleeve inner wall to enable the plunger to slide therein, then the plunger can move smoothly for fuel pumping, but fuel leaks from the clearance into the oil cavity and oil leaks into the fuel, increasing fuel to oil transfer rate and oil to fuel transfer rate
Solution Approach 1:
The plunger assembly is segmented into distinct functional zones: a fuel-exposed tip portion for pumping, a sealed intermediate portion with annular seals preventing fluid transfer, and an oil-exposed base portion for lubrication. This segmentation allows the plunger to maintain sliding motion while preventing fuel-oil mixing through the clearance.
Solution Approach 2:
Annular seals are introduced as intermediary elements between the plunger and plunger sleeve. These seals act as mediators that permit the plunger to slide within the clearance while blocking the leakage path for both fuel and oil, thus enabling smooth motion without substance loss.
2Reliability
If fuel leaks from the clearance into the oil cavity, then the fuel to oil transfer rate increases, but the useful life of the oil filter decreases due to fuel contamination
Solution Approach 1:
Annular seals serve as intermediary barriers that prevent fuel from leaking into the oil cavity. By blocking the leakage path at the plunger-sleeve interface, these seals protect the oil filter from fuel contamination while maintaining reliable fuel pumping through the controlled clearance.
Solution Approach 2:
The plunger is divided into zones with different sealing requirements. The intermediate portion features annular seals that specifically address fuel-to-oil transfer, thereby protecting the oil filter system without compromising the fuel pumping reliability of the tip portion.
3Ease of operation
If oil leaks from the clearance into the pump head, then the oil to fuel transfer rate increases, but the combustibility of the fuel decreases due to oil mixing
Solution Approach 1:
Annular seals act as intermediary barriers that prevent oil from leaking into the fuel chamber. These seals maintain the plunger's reciprocating motion capability while blocking the leakage path that would otherwise allow oil to contaminate the fuel and reduce combustibility.
Solution Approach 2:
The plunger assembly is segmented to include a sealed intermediate portion with annular seals that specifically prevent oil-to-fuel transfer. This segmentation allows the plunger to maintain smooth reciprocating motion while protecting fuel combustibility from oil contamination.
4Reliability
If the plunger and barrel are permanently assembled to the seal assembly, then sealing effectiveness is maintained, but serviceability of the seal assembly and fuel pump is reduced
Solution Approach 1:
The fuel pump assembly is segmented into serviceable modules: the plunger assembly with integrated annular seals can be removed as a unit for maintenance, while the barrel and pump housing remain in place. This segmentation maintains sealing effectiveness during operation while enabling easy serviceability by allowing removal and replacement of the seal assembly without dismantling the entire pump.
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
Significantly reduces fluid transfer rates, extending oil filter life and maintaining fuel combustibility by effectively sealing the plunger and barrel within the annular seal assembly.
Implementation Method 1
an annular seal assembly arranged around the circumference of the plunger to limit the transfer rate between oil and fuel or fuel and oil
Data Source
AI summary
A fuel pump for an internal combustion engine comprising a barrel having a longitudinal axis that spans between a proximal end and a distal end and a central bore therein. A plunger is disposed at least partially in the central bore and is configured to move along the longitudinal axis. An annular seal assembly is arranged around the circumference of the plunger wherein the annular seal assembly includes a seal retainer housing and a first seal and the seal retainer housing also retains the proximal end of the barrel thereon to form a second seal wherein the first and the second seals reduce the fuel to oil transfer rate and the oil to fuel transfer rate. The plunger and barrel are configured to be removed from and re-assembled with the annular seal assembly to enable service of these parts and the fuel pump.