Fuel Injector Control Valve Crown Ring Thermal Compensation
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Solution Overview
Problem
Fuel injectors for internal combustion engines with control valves face challenges due to complex armature stroke settings, leading to high tolerance-related deviations and reduced robustness under temperature variations, affecting the overall functionality and reliability.
Innovation Solution
The fuel injector design incorporates a crown ring between the valve piece and magnet assembly to maintain a constant armature lift over temperature, minimizing tolerance errors and thermal stresses, with a cylindrical guide surface for the armature and a rolling element for low-friction operation, and a non-magnetic material for the crown ring to avoid electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a complex armature stroke adjustment mechanism is used, then the armature stroke can be precisely adjusted, but the tolerance variations during assembly increase and the system becomes more sensitive to thermal expansion
Solution Approach 1:
The patent extracts the complex adjustment mechanism and replaces it with a simple thickness-adjustable washer positioned between the armature and magnet assembly. This washer can be selectively manufactured with different thicknesses to compensate for tolerance variations, eliminating the need for complex mechanical adjustment mechanisms while maintaining precise armature stroke control.
Solution Approach 2:
The patent changes the parameter of the washer thickness to adjust the armature stroke. By manufacturing washers with different thicknesses based on measured tolerance deviations of individual components, the system achieves precise stroke adjustment through a simple parameter change rather than a complex mechanism.
2Adaptability or versatility
If multiple components are involved in armature stroke adjustment, then flexibility in adjustment is improved, but tolerance errors accumulate during series production assembly
Solution Approach 1:
The patent merges the adjustment function into a single washer component rather than using multiple separate adjustment elements. This single washer absorbs all tolerance variations from the armature, valve seat, and magnet assembly, preventing tolerance accumulation while maintaining adjustment flexibility through selective thickness variation.
3Ease of operation
If the armature stroke is defined by multiple components, then assembly flexibility is improved, but thermal expansion causes significant changes in armature stroke with temperature
Solution Approach 1:
The patent applies thermal expansion compensation by selecting materials with appropriate expansion coefficients. The washer is made from a material whose thermal expansion characteristics compensate for the combined thermal expansion of the armature and magnet assembly, maintaining constant armature stroke across temperature variations.
4Stability of the object's composition
If a crown ring is clamped between the valve piece and magnet assembly, then the armature stroke is stabilized across temperatures, but the device complexity increases
Solution Approach 1:
The crown ring serves multiple functions simultaneously: it stabilizes the armature stroke against thermal expansion, provides a mounting surface for the magnet assembly, and acts as a structural support element. By combining multiple functions into a single component, the patent minimizes the increase in device complexity while achieving thermal stability.
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 design ensures a robust and consistent fuel injection process by maintaining a constant armature lift and reducing thermal stresses, enhancing the fuel injector's reliability and longevity while minimizing friction and electromagnetic interference.
Implementation Method 1
The control valve includes a solenoid assembly, an armature, a valve stem, and a valve seat formed on the valve stem. The armature includes an armature plate, which is actuated by the solenoid assembly.
Implementation Method 2
The two fixed positions for the armature stroke are thus easily defined, and tolerance variations are accordingly minimized. Therefore, to adjust the armature stroke across operating temperatures, primarily only the coefficients of thermal expansion of the armature and crown ring need to be considered.
Data Source
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AI summary
The invention relates to a fuel injector (100) for injecting fuel into the combustion chamber of an internal combustion engine. The fuel injector (100) comprises a control valve (1) and an injection valve element (11). The injection valve element (11) bounds a control chamber (15) and is guided in the fuel injector (11) in such a way that the injection valve element can be moved longitudinally. The injection valve element (11) opens and blocks at least one injection opening (13) into the combustion chamber by means of the motion of the injection valve element. The control valve (1) controls the pressure in the control chamber (15). The control valve (1) comprises a magnet assembly (2), an armature (5), a valve piece (4), and a valve seat (7) formed on the valve piece (4). The armature (5) comprises an armature plate (50), which can be controlled by the magnet assembly (2). The armature (5) interacts at least indirectly with the valve seat (7) in order to relieve the control chamber (15). A crown ring (20) is clamped between the valve piece (4) and the magnet assembly (2).