Fuel Injection Pump Cam Lobe Accommodation
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Solution Overview
Problem
Common rail fuel injection pumps are limited by the geometry of their pump body, constraining the maximum plunger lift and thus the fuel supply capacity.
Innovation Solution
A modified fuel pump design featuring a cam assembly with increased stroke, a body assembly with a groove for a seal cap, and an inlet valve assembly, allowing for a larger cam lobe installation and enhanced sealing to increase fuel supply volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump body geometry is increased to accommodate a larger cam lobe for higher fuel supply, then the fuel supply volume increases, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The pump body is segmented into a body portion and a cover portion that cooperatively form the cavity. This segmentation allows the larger cam lobe to be accommodated while maintaining manageable manufacturing complexity, as each portion can be manufactured separately and then assembled together.
Solution Approach 2:
The seal cap is nested within the groove formed in the engagement surface of the cover portion. This nested structure provides enhanced sealing for the larger cam lobe configuration without adding external complexity to the pump body structure.
2Productivity
If the cam lobe size is increased to enhance fuel supply capacity, then the fuel output increases, but the sealing requirements become more difficult to maintain
Solution Approach 1:
A seal cap is introduced as an intermediary component between the cam lobe and the pump body cavity. The seal cap receives the cam lobe and provides sealing surfaces that maintain reliable sealing even with the larger cam lobe size required for enhanced fuel output.
Solution Approach 2:
The seal cap includes an internal wall and external wall that form flexible sealing surfaces. These walls can adapt to the larger cam lobe geometry while maintaining effective sealing, preventing fuel leakage in the high-output configuration.
3Productivity
If the plunger lift is increased to improve fuel delivery, then the fuel injection volume increases, but the pump body bore diameter must be increased which complicates manufacturing
Solution Approach 1:
Dividing the pump body into body and cover portions allows the cavity to be formed with the necessary dimensions for increased plunger lift without requiring a single large-bore machining operation. Each portion can be manufactured with standard bore sizes and then assembled to achieve the overall larger cavity volume.
Data Source
AI summary
A fuel pump comprises a cam assembly having a lobe, and a body assembly including a cavity for receiving the cam assembly. The body assembly includes both a body portion and a cover portion that cooperatively form the cavity. The body portion includes a lobe cavity, an engagement surface and an opening at the cavity, with the cover portion including a respective engagement surface and opening. The engagement surfaces are mated together with the cam assembly disposed in the cavity and extending through the openings, and is configured to rotate in the cavity with the lobe disposed in the lobe cavity. A groove is formed in one of the engagement surfaces of the body portion or cover portion for receiving a seal cap at least partially therein adjacent the lobe cavity.