Opposed-Piston Engine Cold-Start Air Heating Strategy
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Solution Overview
Problem
Compression-ignition opposed-piston engines face challenges in starting quickly and efficiently in cold ambient conditions without adding complexity or expense, as the air drawn into the engine may be too cold to support combustion, and existing solutions like glow plugs or intake heaters increase complexity and cost.
Innovation Solution
A cold-start strategy for opposed-piston engines that involves controlling mass air flow and fuel injection through specific schedules, using a starter motor, backpressure valve, and supercharger to heat air by compression before fuel injection, and gradually increasing charge air flow to achieve an idling state, with engine control mechanization managing these processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glow plugs, block heaters, intake heaters, or ether injection are used to facilitate cold start-up, then the engine can start under cold conditions, but the complexity and expense of the engine construction and operation increase
Solution Approach 1:
The opposed-piston engine utilizes its own compression mechanism to generate the necessary heat for cold starting, without requiring external heating devices. The two-stroke cycle and opposed-piston architecture enable the engine to compress air to ignition temperature through its normal operating cycle, making the system self-sufficient for cold starts.
Solution Approach 2:
The invention changes the operating parameters during cold start by adjusting the compression ratio and timing to maximize heat generation. The control system modifies fuel injection timing and air-fuel mixture ratios to ensure reliable ignition under cold conditions while maintaining the simplicity of the base engine design.
2Reliability
If the engine cranks for long periods to raise combustion chamber temperature, then combustion can be supported, but the time required for starting increases
Solution Approach 1:
The engine performs preliminary compression strokes without fuel injection to preheat the air in the combustion chamber before actual combustion begins. This preliminary action raises the temperature to the ignition point, allowing combustion to start immediately when fuel is introduced, thereby reducing overall cranking time.
Solution Approach 2:
The opposed-piston two-stroke engine maintains continuous compression and scavenging actions during the cold start sequence, ensuring that heat is continuously generated in the combustion chamber. This continuous useful action prevents heat loss and maintains combustion chamber temperature throughout the starting process.
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
Enables quick and efficient starting of opposed-piston engines in cold conditions by effectively heating the air and ensuring successful ignition with minimal added complexity or expense, maintaining engine efficiency and reducing pollution.
Implementation Method 1
air in a cylinder is continually heated by compression while cranking the engine
Data Source
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AI summary
A strategy to cold-start an opposed-piston engine includes, before injecting fuel, preventing air flow through the engine while cranking the engine to heat air retained in the engine, followed by controlling mass air flow through and fuel injection into a cylinder of the engine according to cold-start schedules so as to create and preserve heat for stable engine firing and transition to an idling state of operation.