Asymmetric Cam Ridge High-Pressure Fuel Pump for Unequal Interval Timing
Solution Overview
Problem
In unequal interval two-cylinder internal combustion engines, existing high-pressure fuel pumps face challenges in setting pressurization timing at unequal intervals, leading to irregular cam lift characteristics and vibration issues due to flat parts in cam lift profiles, which affect the accuracy and performance of the engine.
Innovation Solution
A reciprocating high-pressure fuel pump with a plunger driving cam having cam ridges formed at 180° intervals and a crossing angle of approximately 67.5° to 90°, ensuring continuous and regular plunger operation without flat parts, allowing for precise control of pressurization timing and reduced spring load, thus improving engine performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cam ridges are unevenly distributed to set pressurization timing at unequal intervals, then pressurization timing accuracy is improved, but flat parts are generated in cam lift characteristics causing irregular plunger movement
Solution Approach 1:
The patent applies asymmetry by distributing cam ridges at unequal angular intervals (e.g., 120° and 240° instead of equal 180° intervals) to match the unequal interval two-cylinder engine configuration. This asymmetric arrangement enables precise pressurization timing that corresponds to the specific intake stroke timing requirements of each cylinder, resolving the timing accuracy issue while maintaining continuous cam lift characteristics through careful profile design.
2Measurement precision
If cam ridges are unevenly distributed to set pressurization timing at unequal intervals, then pressurization timing accuracy is improved, but vibration associated with fuel transfer becomes irregular
Solution Approach 1:
The patent applies local quality by designing specific cam lift profiles for each cam ridge position. The cam lift characteristics are locally optimized at each ridge to ensure smooth plunger acceleration and deceleration patterns, which reduces irregular vibrations in the fuel transfer system while maintaining the unequal interval timing required for accurate pressurization synchronization with each cylinder's intake stroke.
3Measurement precision
If plunger moves in two steps due to flat part in cam lift characteristics, then pressurization timing is set at unequal intervals, but followability of pulsation damper deteriorates
Solution Approach 1:
The patent applies continuity of useful action by designing cam lift profiles that eliminate flat parts and ensure continuous, smooth plunger movement throughout the pressurization cycle. This continuous motion pattern allows the pulsation damper to effectively follow and suppress fuel pressure fluctuations, maintaining reliable operation while achieving accurate unequal interval pressurization timing through asymmetric cam ridge distribution.
Data Source
AI summary
In a reciprocating high-pressure fuel pump that operates a plunger while facing a cam ridge of a plunger driving cam provided on a camshaft to which power of a crankshaft of an internal combustion engine is transmitted, the cam ridge includes a cam curved surface including two apexes at a cam angle interval of 180° and two valley bottoms at a cam angle interval of 180° and alternately connecting the apexes and the valley bottoms, and a crossing angle between a first virtual line connecting the two apexes and a second virtual line connecting the two valley bottoms is not a right angle as viewed in a direction of a camshaft axis.