High-Pressure Pump Sealing Surface Stiffness Equalization
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Solution Overview
Problem
High-pressure pumps in common rail injection systems face issues with flow erosion and fretting at sealing surfaces due to cyclical pressure changes, leading to potential cracking and component failure, exacerbated by differences in component stiffness and machining processes.
Innovation Solution
The design ensures equal radial expansion of annular sealing surfaces by adjusting component stiffness and creating an intermediate space with a larger cross-sectional area, allowing for rolling instead of sliding, and using increased material thickness and grinding to optimize stress distribution and reduce angular exaggeration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing surfaces are designed to ensure sealing under high pressure, then sealing effectiveness is improved, but flow erosion and fretting occur due to cyclical pressure changes and relative movements
Solution Approach 1:
The patent changes the geometric parameters of the sealing surfaces by introducing angular exaggeration (conical surfaces) and optimizing the sealing point geometry. This modifies the pressure distribution and stress state at the sealing interface, reducing cyclic stress amplitude and preventing fretting while maintaining sealing effectiveness under high pressure conditions.
Solution Approach 2:
The patent applies different geometric characteristics to different regions of the sealing surfaces. The angular exaggeration is localized at specific areas where stress concentration occurs, creating locally optimized sealing zones that resist flow erosion and fretting while maintaining overall sealing performance.
2Reliability
If the sealing surfaces are designed with angular exaggeration to improve sealing, then sealing pressure distribution is improved, but stress peaks and dimensional variability increase leading to cracking
Solution Approach 1:
The patent optimizes the angular exaggeration parameters within specific ranges to achieve the right balance. By controlling the angle and extent of the conical surfaces, the design improves pressure distribution while preventing excessive stress peaks that would lead to cracking and dimensional variability.
3Adaptability or versatility
If the valve carrier and pump cylinder have different stiffness to accommodate functional requirements, then functional adaptability is improved, but relative movements and fretting occur at the sealing surfaces
Solution Approach 1:
The patent creates a localized stiffening effect at the sealing surfaces through angular exaggeration and geometric optimization. This local reinforcement equalizes the effective stiffness at the sealing interface without changing the overall stiffness characteristics of the valve carrier and pump cylinder, thus maintaining functional adaptability while preventing fretting.
4Ease of manufacture
If standard machining processes are used on the pump cylinder to improve manufacturability, then ease of manufacture is improved, but surface quality and stress distribution are degraded leading to sealing failures
Solution Approach 1:
The patent specifies optimized geometric parameters for the sealing surfaces, including angular exaggeration and surface finish requirements. These parameter specifications guide the machining process to achieve the necessary surface quality and stress distribution while remaining compatible with standard manufacturing capabilities.
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 approach prevents fretting and reduces stress peaks, enhancing the durability and reliability of high-pressure pump components by homogenizing surface pressure and minimizing dimensional variability.
Implementation Method 1
the sealing point between the valve carrier and the pump cylinder is cyclically loaded by pressure changes. The load occurs with each pumping process, with the amplitude of the load corresponding to a change in pressure from the supply pressure of the high-pressure pump (2,000 bar). Due to the cyclical change in pressure, there is a risk that with each pumping process fuel will partially penetrate the high-pressure sealing surface and this will result in flow erosion. Furthermore, due to the cyclical change in pressure, cyclical component expansions occur
Data Source
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AI summary
In the case of a component which conducts high-pressure medium, comprising a first component (13) with at least one pressure duct (29) and a second component (2) with a pressure chamber (30), wherein an annular sealing surface (32), which surrounds the mouth(s) of the at least one pressure duct (29), of the first component (13) and an annular sealing surface (33), which surrounds the rim of the pressure chamber (30), of the second component (2) interact areally with one another to form a sealing point, wherein the cross-sectional area of the pressure duct (29) is smaller than the cross-sectional area of the pressure chamber (30), the pressure-induced radial expansion of the annular sealing surfaces (32, 33) is substantially equal.