Rotary Engine Variable Compression Ratio Port Control
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Solution Overview
Problem
Rotary engines, such as Wankel engines, face challenges in optimizing their operation to achieve higher volumetric compression ratios while ensuring effective purging of exhaust gases, which affects cycle efficiency and power output.
Innovation Solution
The method involves controlling air input by strategically opening and closing primary and secondary inlet ports in relation to the exhaust port during different engine operational stages, such as start-up, idle, and high power conditions, to optimize air-fuel mixture and exhaust gas purging, utilizing a compound cycle engine system with a compressor and turbine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inlet and exhaust ports are designed mechanically to allow minimum overlap during intake and exhaust portions, then the exhaust cavity is purged effectively, but the range of volumetric compression ratio is limited
Solution Approach 1:
The patent applies dynamic control of port opening/closing timing based on real-time operating conditions (engine speed, load, temperature). The control system adjusts the effective port timing dynamically rather than using fixed mechanical design, allowing the engine to achieve both effective purging and high compression ratios under different operating conditions
Solution Approach 2:
The patent changes the timing parameters of port opening and closing based on operating conditions. By varying the effective duration and timing of inlet and exhaust port communication with the rotor cavity, the system optimizes both purging effectiveness and compression ratio adaptability across different engine operating ranges
2Productivity
If the primary inlet port is closed during start-up, then higher volumetric compression ratio is achieved, but air input control complexity increases
Solution Approach 1:
The system dynamically adjusts which inlet ports are open or closed based on engine operating conditions. During start-up, the control system closes the primary inlet port while opening the secondary inlet port to achieve higher compression ratios. This dynamic switching capability is managed through electronic control that monitors engine state and actuates appropriate port valves
Solution Approach 2:
The patent employs multiple inlet ports (primary and secondary) that can serve different functions depending on operating conditions. The same port structure provides both high compression ratio operation during start-up and normal operating conditions, eliminating the need for separate mechanical systems for different functions
3Reliability
If the secondary inlet port is opened during high power demand, then exhaust gas purging is maximized, but air-fuel mixture control complexity increases
Solution Approach 1:
The control system uses feedback from engine sensors (exhaust gas composition, oxygen levels, power demand) to determine when to open or close the secondary inlet port. This feedback mechanism allows the system to automatically optimize purging efficiency without requiring complex manual intervention or overly sophisticated control mechanisms
Solution Approach 2:
The secondary inlet port operation follows periodic patterns based on engine cycle detection and operating condition thresholds. The control system activates purging mode when specific conditions are met (high power demand, elevated exhaust gas levels), creating a rhythmic control pattern that simplifies the overall control strategy while maintaining effectiveness
Data Source
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AI summary
A method and apparatus for controlling an air input in a rotary engine (410), includes selectively controlling a plurality of inlet ports (440, 442) communicating with an internal combustion cavity (20) of the engine. The ports are located serially downstream of the exhaust port (44) relative direction of a revolution of a rotor (24) of the engine. The inlet ports (440, 442) are controlled to alter air intake at various engine operational stages, such as start up, idle, etc., to allow for varying operational requirements to be met. For example: when a power demand on the engine lower than a predetermined threshold, control may be effected by opening a primary inlet port (440) and closing a secondary inlet port (442); and, when the power demand exceeds the predetermined threshold, control may be effected by opening the primary inlet port (440) and opening the secondary inlet port (442), the secondary inlet port (442) being located such as to be in communication with the exhaust port (44) throughout portions of the revolution of the engine to purge exhaust gases of the engine.