An air start engine utilizes compressed air to initiate the combustion cycle and get the engine running. This starting method is commonly found in large engines, such as those in heavy machinery, ships, or power generators, where traditional electric starters might be impractical or insufficient due to the engine's size and required starting torque.
The core principle involves using stored energy in the form of compressed air to turn the engine's crankshaft until it can run under its own power.
The Mechanism of an Air Start Engine
The process relies on an air motor powered by high-pressure compressed air. Here's a breakdown of the key components and how they interact:
- Compressed Air Source: A tank or reservoir stores compressed air, typically at high pressure.
- Air Motor: This is a specialized motor designed to run on compressed air. It's robust and capable of delivering significant torque.
- Connection to Flywheel: The air motor is connected to the engine's flywheel. The flywheel is a heavy wheel attached to the engine crankshaft, which helps smooth out engine rotation and stores rotational energy.
When the starting system is activated, the following sequence occurs:
- Air Flow: Compressed air flows through the motor.
- Motor Activation: The flow of compressed air causing the motor shaft to turn.
- Flywheel Engagement: The spinning motor shaft is mechanically linked (often via a gear) to the engine's flywheel, which in-turn drives the flywheel.
- Crankshaft Rotation: Since the flywheel is attached to it, turning the flywheel consequently the engine crankshaft.
As the crankshaft turns, the engine's pistons move, intake valves open, air is drawn in, and eventually, fuel is injected. Once the engine reaches a sufficient speed, combustion begins, and the engine takes over, running on its own power. The air motor then disengages.
Why Use Air Starting?
Air starting offers several advantages, particularly for large engines:
- High Torque: Air motors can provide very high starting torque needed to turn over massive engines.
- Reliability: Compared to large electric starters, air start systems can be simpler mechanically and less susceptible to issues like battery drain in cold weather.
- Cost-Effective for Large Applications: For extremely large engines, an air start system can be more cost-effective and practical than designing and installing an equivalent electric starter and battery bank.
In summary, an air start engine works by directing compressed air through an air motor, which is coupled to the engine's flywheel, thereby turning the crankshaft and initiating the combustion process.
