Spring-Loaded Adaptor for High Pressure Fuel Pump Axial Stability
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Solution Overview
Problem
High pressure diesel fuel pumps face issues with axial movement and seal fretting due to small spigot diameters, which interfere with the assembly of driving gears and compromise the 'tell-tale' function, leading to potential seal failure and distorted pump geometry.
Innovation Solution
A spring-loaded adaptor with a wave spring mechanism is used between the spigot and engine block, minimizing axial movement and maintaining the tell-tale leak path, allowing for a larger bore diameter for gear assembly while preventing seal fretting and failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the diameter of the spigot is increased to allow pre-assembly of the driving gear, then the driving gear can be assembled to the fuel pump before location in the engine block, but the spigot interferes with the screws that fix the pump front plate to the pump housing
Solution Approach 1:
An adaptor is introduced as an intermediary component between the spigot and the engine block bore. The adaptor has a first portion that fits over the spigot and a second portion that interfaces with the engine block bore, allowing the spigot to remain small for easy screw fixation while enabling the driving gear to be pre-assembled on a larger bore diameter
2Ease of manufacture
If the spigot diameter is kept small to avoid interfering with fixing screws, then the pump front plate can be easily fixed to the pump housing, but the driving gear cannot be assembled to the fuel pump before location in the engine block
Solution Approach 1:
The adaptor is segmented into two distinct portions: a first portion that fits over the small spigot diameter and a second portion that interfaces with the larger engine block bore. This segmentation allows each portion to fulfill its specific function - the first portion maintains compatibility with the spigot and fixing screws, while the second portion enables pre-assembly of the driving gear
3Reliability
If the adaptor design causes axial movement to minimize, then seal fretting and failure are prevented, but the tell-tale function may be compromised
Solution Approach 1:
The adaptor incorporates local quality variations with a stepped configuration - a first portion with a first diameter for fitting over the spigot and a second portion with a second diameter for interfacing with the engine block bore. This local variation in diameter allows the adaptor to provide axial positioning for seal retention while maintaining a flow path that preserves the tell-tale function
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 spring-loaded adaptor reduces axial movement, prevents seal fretting, and maintains the tell-tale function, enabling efficient assembly and reducing the risk of seal failure, while allowing for a larger bore diameter without interfering with the pump's geometry.
Implementation Method 1
a spring means adapted to be located at a bottom end of the collar between said collar and the front plate
Implementation Method 2
the spring means is configured to apply an axial load to the front plate when compressed
Implementation Method 3
an outer seal for location between the collar and the engine block, and an inner seal for location between the collar and the locaton spigot
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A high pressure diesel fuel pump (20) comprising a pump housing (21), a location spigot (24) protruding from a front plate (23), and a driveshaft (22) protruding from the location spigot (24), the driveshaft (22) being adapted for assembly with a driving gear (31) and said location spigot (24) being adapted to be located in a bore (32) relative to an engine block (30). The pump (20) comprises an adaptor (40) for location around said location spigot (24) between the front plate (23) and the engine block (30). The adaptor (40) comprises a collar (43), an outer seal (45) for location between the collar (43) and the engine block (30), and an inner seal (47) for location between the collar (43) and the location spigot (24). The adaptor (40) comprises a spring means (49) adapted to be located at a bottom end (41) of the collar (43) between said collar (43) and the front plate (23).