Diesel Fuel Pump Shoe Guide Layout for Higher Stroke Capacity
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Solution Overview
Problem
High pressure diesel fuel pumps face a challenge in increasing pump capacity without increasing the height of the hydraulic head, as current methods result in larger pumps that do not fit within tight engine bay constraints.
Innovation Solution
The design incorporates a shoe guide with a pair of tangs that reduces its effective length, allowing the cam to extend into the space occupied by the guide, thereby increasing the stroke length and pump capacity without elevating the hydraulic head, while maintaining compact dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the height of the hydraulic head is increased to increase pump capacity, then the stroke length is improved, but the overall pump size increases which violates engine bay constraints
Solution Approach 1:
The shoe guide is designed with a tilted bore relative to the pumping axis, creating a geometric transformation that converts vertical space into extended stroke length. The tangs extend laterally to support the roller while the tilted bore allows the shoe to travel along an inclined path, effectively using dimensional transformation to increase pump capacity without increasing vertical height.
Solution Approach 2:
The cam is positioned to extend into the space traditionally occupied by the shoe guide body, utilizing the lateral extensions (tangs) of the shoe guide to support the roller. This nesting arrangement allows the cam to reach further along the pumping axis while the shoe guide's tangs provide structural support, effectively one component occupying the space of another to achieve compact design.
2Length of moving object
If the shoe guide effective length is reduced to allow cam extension, then the stroke length is improved, but the structural support for the roller must be maintained
Solution Approach 1:
The shoe guide is segmented into a main body and lateral tangs, where the main body contains the tilted bore and the tangs provide lateral support for the roller. This segmentation allows the main body to be shortened along the pumping axis while the tangs extend laterally to maintain roller support capability, resolving the contradiction between reduced effective length and maintained structural strength.
Solution Approach 2:
The support function is shifted from the vertical dimension to the lateral dimension through the tangs. Instead of extending the shoe guide body vertically to support the roller throughout the entire stroke, the tangs extend laterally to provide support at the necessary points, allowing the vertical effective length to be reduced while maintaining strength.
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
This configuration enhances the stroke length and pump capacity while minimizing the dimensions of the pump, reducing drive torque and CO2 emissions, and allowing for a more compact design that fits within existing engine bay constraints.
Implementation Method 1
a roller (7) mounted and retained within an aperture (not shown) provided at a lower end of the shoe (5) and slides within the bore (6a, 62) with the shoe (5) wherein the roller (7) contacts a surface of a cam (8)
Implementation Method 2
A plunger return spring (3) is seated around the head (1) and extends to the top of a spring seat (4) fixed near a lower end (2a) of the plunger (2)
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~4
AI summary
A high pressure diesel fuel pump comprises a pumping assembly and a drivetrain assembly. The pumping assembly comprises a plunger (20) extending from a pump head (10) along a pumping axis (A-A'). The drivetrain assembly comprises a drive shaft (100) and a cam (80) within a cambox, a shoe (50) for contact with a lower end (22) of the plunger (20), a roller (70) mounted within a cavity (52) of the shoe (50) for contact with the cam (80), and a shoe guide (60) mounted within a guide chamber substantially between the cam (80) and the plunger (20) and adapted to receive the shoe (50) and roller (70) within a bore (62). The shoe guide (60) comprises a pair of tangs (68) extending from a lower end (61) of a main body (64) of the she guide (60) to support the roller (70).