Single-Stage Flapper Servovalve Housing for Thermal Fit Stability
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Solution Overview
Problem
Existing single stage flapper type servovalves face challenges in maintaining precise nozzle positioning and interference fit at elevated temperatures due to differences in thermal expansion coefficients between aluminum housings and stainless steel nozzles, leading to performance degradation.
Innovation Solution
The servovalve housing and nozzles are made from stainless steel with similar thermal expansion coefficients, and a lattice-like structure is used to reduce weight, with additive manufacturing enabling complex shapes and improved assembly, and a separate tube is used for fluid sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If aluminum housing is used with stainless steel nozzles, then weight is reduced and ease of manufacture is improved, but manufacturing precision deteriorates due to thermal expansion differences at elevated temperatures
Solution Approach 1:
The patent applies homogeneity by making both the valve housing and nozzles from the same stainless steel material. This eliminates the thermal expansion coefficient mismatch between dissimilar materials (aluminum housing with stainless steel nozzles), ensuring that both components expand and contract uniformly with temperature changes, thereby maintaining precise nozzle positioning and interference fit at elevated temperatures.
2Manufacturing precision
If stainless steel housing is used instead of aluminum, then manufacturing precision is improved through consistent thermal expansion, but weight increases
Solution Approach 1:
The patent uses homogeneous stainless steel material for both the housing and nozzles, which improves manufacturing precision through consistent thermal expansion behavior. While stainless steel is heavier than aluminum, the patent accepts this weight increase as necessary to maintain precise nozzle positioning and interference fit under thermal conditions, particularly in high-temperature applications where material compatibility is critical.
3Reliability
If tight tolerances are used for nozzle positioning, then reliability is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent uses identical stainless steel material for both the housing and nozzles, ensuring uniform thermal expansion characteristics. This homogeneity allows the interference fit between nozzles and housing to remain stable across temperature variations, maintaining reliable valve functioning without requiring excessively tight manufacturing tolerances that would complicate assembly.
4Weight of moving object
If complex lattice structure is used to reduce weight, then ease of manufacture is improved through additive manufacturing, but device complexity increases
Solution Approach 1:
The patent employs additive manufacturing technology to produce the valve housing with complex lattice structures, internal channels, and optimized geometries that would be difficult or impossible to achieve with traditional manufacturing methods. This parameter change in manufacturing approach enables weight reduction through optimized material distribution while managing structural complexity through digital design and fabrication 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
The solution allows operation at higher temperatures and pressures with reduced weight and improved fit, expanding application range and facilitating manufacturing by allowing looser tolerances and complex designs.
Implementation Method 1
The valve housing and the nozzles may be made from stainless steels having the same or a similar coefficient of thermal expansion
Data Source
Figure 1
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Figure 4~5
AI summary
A single stage flapper type servovalve comprises a valve housing (4) comprising a bore (8), a pair of opposed nozzles (10) arranged in the bore (8) and a flapper element (12) arranged between the pair of nozzles (10). The valve housing further comprises a plurality of fluid ports (14, 16, 18) for communicating a working fluid to and from the nozzles (10) and in fluid communication with the housing bore (8). The valve housing (4; 104; 204) and the nozzles (10) are both made from a stainless steel material.