Ceramic Piston Ring and Sleeve Assembly for Lower-Weight Pump Wear
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Solution Overview
Problem
Traditional positive displacement piston pumps used in aerospace applications face challenges due to the heavy and dense nature of Tungsten Carbide cylinder barrels and tool steel piston components, which affect weight and wear resistance.
Innovation Solution
The pump assembly incorporates a cylinder block made of tool steel, with sleeves and piston rings made of ceramic materials like partially stabilized zirconia (PSZ) or silicon nitride (Si3N4), which provide improved wear resistance and reduced weight compared to traditional WC and tool steel combinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Tungsten Carbide cylinder barrels and tool steel piston components are used, then wear resistance is improved, but weight increases
Solution Approach 1:
The patent applies composite materials by combining ceramic materials (such as silicon nitride or partially stabilized zirconia) with metallic materials (such as tool steel or aluminum alloys) to create hybrid piston components and sleeves. This composite approach maintains the wear resistance benefits of ceramics while reducing the overall weight compared to solid Tungsten Carbide construction, directly resolving the technical contradiction between wear resistance and weight.
Solution Approach 2:
The patent implements local quality by applying ceramic materials specifically to the wearing surfaces (piston rings, piston ends, and sleeve inner surfaces) while using lighter metallic materials for the bulk structure of pistons and sleeves. This localized application of hard, wear-resistant ceramic coatings or inserts provides the necessary wear protection only where contact occurs, while the majority of the component mass uses lighter materials, thereby reducing overall weight while maintaining wear resistance.
2Reliability
If Tungsten Carbide cylinder barrels are used, then wear resistance is improved, but density increases
Solution Approach 1:
The patent replaces dense Tungsten Carbide with composite structures combining low-density ceramic materials (silicon nitride, zirconia) with metallic materials. These ceramic-metal composites provide comparable wear resistance to Tungsten Carbide but with significantly lower density, reducing the quantity of substance while maintaining protective functionality.
Solution Approach 2:
The patent applies ceramic materials locally to wearing surfaces within the cylinder barrel assembly rather than using solid Tungsten Carbide throughout. This localized ceramic application provides the necessary wear resistance at contact points while the overall structure uses lighter materials, reducing the total quantity of dense substance required.
Data Source
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AI summary
A pump assembly (100) includes a cylinder block (102) defining a piston bore (104) therein extending in an axial direction. A sleeve (106) lines the piston bore (104). A piston (108) is included in the piston bore (104), configured to reciprocate along a stroke in the axial direction within the sleeve (106). A piston ring (110) is engaged circumferentially about the piston. The piston ring (110) is fixed to the piston (108) and is slidingly engaged to an inner surface (112) of the sleeve (106).