High Pressure Fuel Pump Turret Assembly Segmentation
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Solution Overview
Problem
High pressure fuel pumps face challenges in precise machining of lengthy guiding bores and annular grooves, leading to clearance issues and costly machining processes, which affect sealing and fuel-oil separation.
Innovation Solution
A tubular turret assembly is added to the pump head, with a through bore that aligns coaxially with the blind bore, reducing clearance to 2.5 μm and incorporating a coil spring and sealing means to enhance sealing, while a fuel return line manages leaking fuel through a counter-shape geometry and channel to a low pressure line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a lengthy guiding bore is used in the pump head, then the piston can be reciprocally displaced through the turret, but the machining precision becomes difficult to achieve and clearance control becomes problematic
Solution Approach 1:
The guiding bore is divided into two separate components: a blind bore in the pump head and a through bore in the turret assembly. This segmentation allows each component to be machined independently with shorter, more controllable bore lengths, improving manufacturing precision and clearance control to 2.5 μm while maintaining the overall functional length.
2Ease of manufacture
If an annular groove is machined in the pump head for fuel return, then fuel leakage can be collected, but the machining process becomes difficult and costly
Solution Approach 1:
The fuel return function is segmented from the pump head to the turret assembly. The annular groove is machined in the turret's disc face rather than the pump head, simplifying the pump head machining while maintaining fuel collection capability. The groove geometry becomes easier to manufacture with standard machining operations.
Solution Approach 2:
The turret assembly acts as an intermediary component that provides the fuel return groove function. By placing the groove in the turret's disc face, the system achieves fuel collection without requiring complex machining in the pump head, reducing manufacturing difficulty and cost.
3Device complexity
If the turret is made integral with the pump head, then assembly is simplified, but machining precision and clearance control become more difficult
Solution Approach 1:
The turret is segmented from the pump head as a separate assembly. This allows the blind bore in the pump head and through bore in the turret to be machined independently with precise clearance control (2.5 μm). The separate assembly maintains functional integration while improving manufacturing precision through independent machining of each component.
Data Source
AI summary
A fuel pump unit includes a pump head provided with an axial blind bore within which is arranged a piston extending from an inner end, inside the bore, to an outer end, outside the head, the outer end cooperating with a cam follower and a cam of which rotations reciprocally displace the piston. The pump unit also includes a coil spring axially compressed between pump head and the cam follower and a tubular turret assembly extending toward the cam and provided with a through bore through which extends the piston, the final spirals of the spring being slipped around the outer surface of the turret. The turret is an added part, non-integral to the pump head and, arranged in abutment against an under face of the pump head, the blind bore being coaxial to the through bore arranged in the turret.