Inline Pneumatic Valve Piston With Internal Bushing for Wear Control
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Solution Overview
Problem
Modern gas turbine engines and other systems face challenges in providing a valve piston that can withstand increasing pressures and temperatures, as materials with high strength limits for high temperatures often lack wear resistance when sliding along support tubes.
Innovation Solution
The inline valve design incorporates a radially inner sliding portion with a bushing made of a wear-resistant material, such as Stellite, and a radially outer stop portion made of a high-temperature, high-pressure resistant material like Nickel-based alloys, with the bushing being strategically located in low-stress areas to maintain structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a valve piston is made of high-temperature, high-pressure resistant material, then it can withstand increasing pressures and temperatures, but it lacks wear resistance when sliding along support tubes
Solution Approach 1:
The piston is constructed with different materials for different functional regions: the radially inner sliding portion that contacts the support tube is made of wear-resistant material, while the radially outer stop portion is made of high-temperature, high-pressure resistant material. This local differentiation allows each region to have the specific material properties needed for its function.
Solution Approach 2:
The piston employs a composite construction combining two distinct materials: a wear-resistant material for the sliding portion and a high-temperature, high-pressure resistant material for the stop portion. This composite approach allows the single component to simultaneously achieve both wear resistance and high-temperature strength.
2Reliability
If the radially inner sliding portion is made of wear-resistant material, then wear resistance is improved, but the material has lower resistance to high temperature and pressure
Solution Approach 1:
The wear-resistant material is strategically placed only in the radially inner sliding portion where it is needed for friction resistance, while the high-temperature resistant material is placed in the radially outer stop portion where structural strength is critical. This localized material assignment optimizes performance for each specific functional requirement.
Solution Approach 2:
The piston is segmented into two distinct material zones: the inner sliding portion made of wear-resistant material and the outer stop portion made of high-temperature resistant material. This segmentation allows independent optimization of material properties for each functional region without compromising the other.
3Ease of manufacture
If a single material is used for the entire piston, then manufacturing is simpler, but the piston cannot simultaneously achieve wear resistance and high-temperature strength
Solution Approach 1:
The piston uses a composite material construction with two distinct materials: wear-resistant material for the sliding portion and high-temperature resistant material for the stop portion. This composite approach prioritizes functional performance over manufacturing simplicity, as the dual-material construction enables the piston to simultaneously achieve both wear resistance and high-temperature strength.
Solution Approach 2:
Different material properties are assigned to different regions of the piston based on functional requirements. The radially inner sliding portion uses wear-resistant material while the radially outer stop portion uses high-temperature resistant material, creating local quality variations that optimize overall piston performance.
Data Source
Figure 1A~1B
Figure 1C
Figure 2
AI summary
An inline valve includes a sliding piston (21) having a radially outer stop portion (27) with a forward end. A radially inner sliding portion (24) is connected to the radially outer stop portion by an arm (23). A housing (25) includes an outer housing body surrounding the piston (21). The housing (25) has a stop surface (38, 39) selectively in contact with the forward end of the radially outer stop portion of the piston (21) to block flow for a housing inlet to a housing outlet. The radially inner sliding portion (24) slides on a support tube. At least a portion of the radially inner sliding portion (24) is formed of a first material having better wear resistance than a second material forming the outer stop portion of the piston (21). The second material has a greater resistance to high temperature and pressure than the first material. A vent valve for a compressor is also disclosed.