Volvo Patented Two-Stroke Engine for Trucks | Piataauto.md
Summary of the Volvo Two-Stroke Engine Innovation
This text details a novel two-stroke engine design by Volvo, aiming to overcome the traditional limitations of two-stroke engines. Here’s a breakdown of the key features and how it works:
Key Innovations & Differences from Traditional Two-Stroke Engines:
* Direct Fuel Injection & Intake Ports: unlike traditional two-strokes where the fuel mixture is drawn through the cylinder wall, this engine utilizes intake valves at the top of the cylinder and direct fuel injection after the exhaust port is closed. this prevents fuel from escaping during the exhaust phase.
* Separate Lubrication System: It employs a dedicated oil pump and oil circulation system, similar to a four-stroke engine, eliminating the need to mix oil with the fuel. Piston segments also contribute to lubrication.
* Exhaust Valves for Engine Braking: This is the most significant innovation. The engine includes exhaust valves, but thay are normally inactive. They are only activated when the engine is decelerating and engine braking is desired. This allows for a “sterile” air compression cycle, creating a braking force not possible with conventional two-strokes.
* Valve Control Versatility: Volvo is considering various valve control methods – mechanical cams, hydraulic actuators, or fully electronic control via the engine computer. Precise timing of both intake and exhaust valves is crucial.
How the Engine Works (Combustion Cycle):
- Intake: Air enters through intake valves.
- Fuel Injection & Compression: Fuel is injected after the exhaust port is closed. The piston compresses the air-fuel mixture.
- Combustion: Spark plug ignites the mixture, driving the piston down.
- Exhaust: The piston uncovers the exhaust port, and exhaust gases are expelled, aided by the exhaust valve opening and turbine intake pressure.
- Repeat: The cycle repeats with each piston movement, resulting in a combustion event per stroke.
Engine Braking Mechanism:
When engine braking is needed:
- Air Intake Only: The engine stops injecting fuel but continues to intake air.
- Compression of Air: The piston compresses this air.
- Valve Activation: The exhaust valves open at the appropriate time (similar to normal combustion timing).
- Braking Force: Compressing air and then releasing it through the valves creates a braking force.
Volvo’s design aims to combine the power-to-weight ratio benefits of a two-stroke engine with the efficiency, lubrication, and braking capabilities traditionally associated with four-stroke engines.