Frusto-Conical Rotor Surface for Rotary Piston Efficiency
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Solution Overview
Problem
Rotary piston and cylinder devices face inefficiencies due to the geometry of the rotor surface interacting with the shutter disc, leading to increased inertia, fluid volume in the outlet port, and reduced volumetric and pumping efficiency, especially at high speeds.
Innovation Solution
The rotor features a substantially frusto-conical outer surface, which reduces the port volume, minimizes material usage, and enhances manufacturing accuracy, allowing for faster operation and improved sealing performance through strategically placed shoulders and grooves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor outer surface is made curved to match the shutter disc geometry, then sealing performance is improved, but the rotor inertia increases and manufacturing complexity increases
Solution Approach 1:
The rotor surface is divided into different zones with different geometries: a frusto-conical portion for the majority of the circumference and a curved portion only where needed for shutter disc interaction. This local differentiation maintains sealing performance at the critical interface while minimizing overall rotor mass and inertia.
Solution Approach 2:
The rotor outer surface is segmented into distinct geometric portions (frusto-conical and curved sections) rather than using a single continuous curved surface. This segmentation allows optimization of each zone for its specific function while reducing overall complexity and mass.
2Reliability
If the rotor outer surface is made curved to match the shutter disc geometry, then sealing performance is improved, but manufacturing complexity and inspection difficulty increase
Solution Approach 1:
Instead of making the entire rotor surface curved (which would be complex to manufacture and inspect), only the specific portion that interacts with the shutter disc is made curved. The majority of the rotor surface uses a simpler frusto-conical geometry that is easier to manufacture and inspect.
Solution Approach 2:
The rotor surface is segmented into manufacturable zones with different geometries, allowing each portion to be manufactured using appropriate processes while simplifying overall quality control and inspection procedures.
3Reliability
If the rotor outer surface is made curved to match the shutter disc geometry, then sealing performance is improved, but the device complexity increases
Solution Approach 1:
The complex curved geometry is localized only to the portion of the rotor that interacts with the shutter disc, while the rest of the rotor maintains a simpler frusto-conical shape. This reduces overall device complexity while maintaining necessary sealing performance.
4Ease of manufacture
If the rotor outer surface is made frusto-conical, then manufacturing simplicity and inspection ease are improved, but sealing performance with the curved shutter disc may be compromised
Solution Approach 1:
The rotor incorporates a localized curved surface portion that specifically matches the shutter disc geometry for sealing, while the rest of the rotor maintains simple frusto-conical geometry for ease of manufacture. This ensures sealing performance is not compromised at the critical interface.
Solution Approach 2:
The rotor surface is segmented into frusto-conical and curved portions, allowing the curved section to provide necessary sealing while the frusto-conical sections maintain manufacturing simplicity.
Data Source
AI summary
In a rotary piston and cylinder device (1) having a stator and a rotor, in which the stator at least partially defines an annular cylinder space and the rotor includes at least one piston that extends from the rotor into the cylinder space, and in which, during use, the piston moves through the annular cylinder space on rotation of the rotor relative to the stator, wherein at least part of an outer surface (30) of the rotor (22) is a substantially frusto-conical shaped surface.