Fuel Injector Control Valve Annular Grooves for Closing Time Stability
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Solution Overview
Problem
Existing fuel injectors experience non-constant closing times of the control valve due to flow-related effects and back-reflected pressure waves, particularly at medium rail pressures, which affects injection quantity accuracy and engine performance.
Innovation Solution
Optimizing the control valve geometry by using annular groove-shaped depressions with specific edge angles and conical surfaces to reduce the influence of pressure waves and stabilize the vapor phase, ensuring a constant closing time of the valve element, independent of system pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional valve geometry is used, then the structure is simple, but the closing time becomes non-constant due to flow-related effects and pressure waves
Solution Approach 1:
The patent applies local quality by introducing specific geometric features (conical side walls with angles of 45-135 degrees, annular grooves, and stepped structures) at critical locations within the valve body and valve element. These localized geometric modifications create specific flow conditions that stabilize pressure waves and ensure constant closing time, while maintaining simplicity in other areas of the valve structure.
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the conical angle (45-135 degrees) of side walls and the dimensions of annular grooves. By optimizing these geometric parameters, the flow characteristics are modified to reduce turbulence and pressure wave reflections, thereby achieving constant closing time across different operating conditions without overly complicating the overall valve design.
2Reliability
If the edge angle is reduced to less than 130 degrees, then flow turbulence increases and vapor phase stabilizes, but manufacturing becomes more difficult
Solution Approach 1:
The patent specifies a precise parameter range for the edge angle (less than 130 degrees, preferably 45-135 degrees for conical side walls). This parameter optimization creates sufficient flow turbulence to stabilize the vapor phase and prevent cavitation, while remaining within manufacturable limits for standard machining processes.
Solution Approach 2:
The patent employs curved and conical surfaces instead of sharp edges, using annular grooves and stepped structures that guide flow smoothly. These curved geometries reduce flow separation and stabilize vapor phases while being more tolerant to manufacturing variations compared to sharp angular features.
3Manufacturing precision
If the diameter at the edge is limited to maximum 120% of the valve seat diameter, then pressure wave reflection is reduced, but the flow cross-section is restricted
Solution Approach 1:
The patent creates local expansion zones with controlled diameter ratios (maximum 120%) at specific locations where pressure waves reflect. These localized geometric features are positioned to dampen pressure waves without significantly restricting the overall fuel flow cross-section, maintaining injection quantity accuracy while preserving adequate flow rates.
Solution Approach 2:
The patent incorporates nested annular grooves and stepped structures within the valve body. These nested features create multiple flow paths and expansion zones that manage pressure waves through successive reflections and dissipations, allowing the system to maintain both pressure wave control and sufficient fuel flow capacity.
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 optimization results in increased injection quantity accuracy, particularly for closely timed injections, and enables improved engine operation with reduced emissions.
Implementation Method 1
A minimum edge angle of less than 130 degrees in connection with the sharpest possible edge with minimal rounding ensures that the flow does not attach to the contour of the valve piece, but rather to the contour of the valve element on the corresponding end face of the valve element. As a result, the flow is more turbulent and not directed directly into the diversion path.
Implementation Method 2
the transmission of pressure waves to the valve element is dampened by the vapor below the face of the valve element
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a fuel injector (100) having a control valve (1; 1a), which is arranged in a housing (10) and can be actuated by an electromagnet (12), for controlling the flow of a pressure medium from a control chamber (44) into a low-pressure chamber (56), wherein the control valve (1; 1a) has a valve element (22; 22a), which can be moved by the electromagnet (12) in the direction of a longitudinal axis (18), wherein a valve chamber (50) connected to the control chamber (44) adjoins the valve element (22; 22a) and the valve element (22a; 22a) interacts with a seat face (40) formed on a valve body (36; 36a) in order to open and close a terminating connection (52) connecting the valve chamber (50) and the low-pressure chamber (56), and wherein an end face (62) of the valve element (22; 22a) has first ring-groove-shaped recess (63; 63a) and the valve piece (36; 36a) has a second ring-groove-shaped recess (64).