Asymmetrical Cam Contour for High-Pressure Pump Suction Optimization
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Solution Overview
Problem
High-pressure pumps for fuel injection devices in common-rail systems often have cam contours optimized only for the pumping phase, leading to unfavorable filling behavior and fuel delivery variations during the suction phase, resulting in increased drive torque and consumption.
Innovation Solution
A high-pressure pump with an asymmetrical cam contour that follows a sinusoidal curve during the suction phase and a combination of sinusoidal and linear curves during the delivery phase, optimizing both phases to improve fuel delivery and reduce drive torque and consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If symmetrical cam contours are used to reduce part variety, then manufacturing complexity is reduced, but suction phase filling behavior deteriorates
Solution Approach 1:
The cam contour is designed with asymmetrical geometry where the suction phase profile differs from the delivery phase profile. Specifically, the suction phase uses a sinusoidal curve while the delivery phase uses a different curve shape, allowing optimization of filling behavior during suction while maintaining adequate performance during delivery.
Solution Approach 2:
Different portions of the cam contour are optimized for different functions: the suction phase portion is optimized for maximum fuel filling with sinusoidal motion, while the delivery phase portion is optimized for fuel compression and delivery. This local optimization resolves the contradiction between manufacturing simplicity and suction phase performance.
2Device complexity
If cam contours are optimized only for pumping phase, then device complexity is reduced, but fuel delivery variations increase
Solution Approach 1:
The cam contour employs asymmetrical design with distinct optimization for both suction and delivery phases. The suction phase portion is optimized for complete chamber filling, while the delivery phase portion is optimized for stable fuel compression and delivery, thereby reducing fuel delivery variations across different operating speeds.
Solution Approach 2:
The cam contour parameters (rise profile, fall profile, duration, timing) are specifically adjusted to optimize both phases. The suction phase uses a sinusoidal profile with specific timing to ensure complete filling, while the delivery phase parameters are tuned to maintain stable fuel delivery quantity across varying engine speeds.
3Ease of manufacture
If conventional cam contours are used, then manufacturing simplicity is maintained, but drive torque increases
Solution Approach 1:
The asymmetrical cam contour with sinusoidal suction phase profile optimizes the timing and progression of piston movement during both suction and delivery phases, reducing peak drive torque requirements while maintaining manufacturing feasibility through standardized camshaft production processes.
Solution Approach 2:
The sinusoidal curve portion of the cam contour provides smooth, curved transitions during the suction phase, eliminating abrupt changes in piston acceleration and reducing peak drive torque demands on the camshaft drive system.
Data Source
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AI summary
The invention relates to a high-pressure pump for a fuel injection device of an internal combustion engine, in particular for a common-rail system, comprising a cam power train, wherein the rotational movement of a cam shaft is transformed by means of at least one cam into a stroke movement of a pump piston of the high-pressure pump, wherein a cam contour of the cam is designed in a way such that during a suction phase of the high-pressure pump in a range from a top dead center to a bottom dead center, in which fuel is sucked into a pump working chamber, the stroke of the pump piston follows a sinusoidal course as a function of the cam rotational angle.