Fuel Pump Assembly Angular Offset Design
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Solution Overview
Problem
Existing common rail fuel pump designs face challenges in terms of width and length, making them unsuitable for certain engine layouts, with radial pumps being too wide and in-line pumps being too long, and both having complex and costly manufacturing processes.
Innovation Solution
A fuel pump assembly with at least two pump heads offset angularly along the drive shaft, allowing overlap in the axial direction, and cams offset by the same or different amounts to achieve evenly or unevenly spaced pumping events, reducing the overall length and accommodating various engine layouts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If radial pump design with three plungers arranged around cam is used, then high pressure fuel delivery is achieved, but overall pump width becomes large
Solution Approach 1:
The patent transitions from a radial arrangement (plungers around cam) to an in-line arrangement (pump heads along drive shaft), changing the spatial dimension from radial to axial. This allows the pump to achieve high pressure fuel delivery while reducing overall width by extending along the shaft axis instead of spreading radially.
Solution Approach 2:
The pump is divided into separate pump heads (first and second pump heads) that can be independently positioned along the drive shaft. Each pump head contains its own plunger and pump chamber, allowing modular arrangement that reduces width while maintaining pumping capability.
2Area of stationary object
If in-line pump design with plungers arranged side by side axially is used, then pump width is reduced, but overall pump length becomes excessive
Solution Approach 1:
The patent offsets the pump heads angularly around the drive shaft rather than arranging them in a straight line. The second pump head is positioned at an angular offset from the first, allowing axial overlap in projection while maintaining spatial separation. This nesting-like arrangement reduces the overall axial length while keeping width compact.
Solution Approach 2:
The pump heads are arranged asymmetrically around the drive shaft with angular offsets, rather than symmetrically in a straight line. This asymmetric angular positioning allows the pump heads to occupy overlapping axial regions from different angular perspectives, reducing the total length required along the shaft axis.
3Ease of manufacture
If common monobloc pump head with all pumping chambers is used, then manufacturing is simplified, but the monobloc becomes complicated and expensive to make
Solution Approach 1:
Instead of a single monobloc pump head containing all pumping chambers, the patent divides the pump into separate pump heads (first and second pump heads). Each pump head can be manufactured independently with simpler internal structures, avoiding the complexity of a large integrated monobloc while maintaining assembly efficiency.
4Ease of manufacture
If multiple separate pump heads arranged side by side in line are used, then manufacturing of individual heads is simplified, but overall pump length becomes excessive
Solution Approach 1:
The separate pump heads are positioned with angular offsets that create axial overlap in their projected positions along the drive shaft. This nesting-like arrangement allows the individual easily-manufactured pump heads to be compactly arranged, reducing overall length while preserving the manufacturing simplicity of individual heads.
Solution Approach 2:
The pump heads are arranged in an angular pattern around the drive shaft rather than in a straight line. This changes the spatial arrangement from one-dimensional linear spacing to two-dimensional angular distribution, allowing axial overlap and reducing the overall length while maintaining the simplicity of individual pump head manufacturing.
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 angular offset design reduces the overall length of the pump assembly while maintaining efficient fuel pressurization and delivery, accommodating different engine layouts without increasing manufacturing complexity or cost.
Implementation Method 1
at least two cams provided on the drive shaft, each of which is associated with a respective one of the pump heads to effect a plunger pumping cycle as the drive shaft is driven
Data Source
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AI summary
A fuel pump assembly for a fuel injection system comprises a drive shaft (14), at least two pump heads (28, 30) each of which is axially displaced along the drive shaft, each pump head (28, 30) having a respective plunger (32) for pressurising fuel within a respective pump chamber (38), and at least two cams (20, 22) provided on the drive shaft (14), each of which is associated with a respective one of the pump heads (28, 30). Adjacent pump heads (28, 30) are offset angularly from one another by an amount sufficient to allow a region of overlap (R), in an axial direction along the drive shaft (14), between said adjacent pump heads (28, 30).