Upcoming diesel engine emission regulations will require significant reductions in NOx and CO2. The key to achieving this is maintaining the aftertreatment temperature in a sweet spot and maximizing the engine's thermodynamic efficiency. Eaton has developed several variable valve actuation technologies for medium- and heavy-duty engines addressing both needs:
Eaton’s deactivating roller technology can be employed to modulate the intake valve to achieve either early or late valve closing. LIVC makes effective compression ratio lower than expansion ratio, increasing efficiency while increasing exhaust temperature.
By deactivating the valves on one or more cylinders, the overall air/fuel ratio is reduced. The amount of injected fuel is similar while the airflow is reduced proportionally to the number of deactivated cylinders. This works to increase the exhaust temperatures and ultimately to improve emissions through improved catalyst efficiency. Simultaneously, a fuel efficiency benefit is possible. Eaton has developed a strategy for maximizing the CDA benefit while maintaining acceptable noise, vibration, and harshness (NVH). This strategy comprises deactivating variable numbers of cylinders depending on the engine's speed and load.
About emission benefits and how to manage NVH with our CDA technology
EATON study of the two technologies on 11L commercial engine.
Eaton’s capsule technology can be employed to modulate the exhaust valve to achieve early exhaust valve opening. By opening the exhaust valve earlier, halfway through the expansion event, a larger part of the combustion energy goes into heat, instead of mechanical work, to increase the exhaust temperature.
Depending on the application and customer requirements, our VVA solutions can have hydraulic or electro-mechanical actuation
The switching element of the VVA rocker is controlled via oil pressure. An oil control valve is used to change the pressure in the control circuit hence activating and deactivating the system.
The switching element of the VVA rocker is actuated via a stationary electro-mechanical actuator, connected to the rocker arm by a shaft. In its simplest form, the actuator has two positions, but it is possible to have a multi-step actuator that enables controlling multiple VVA functions with a single shaft and motor.
The VVA solutions presented above are indeed an application of two basic technologies of Eaton: the mechanical capsule and the split rocker. By combining these two technologies, a wide variety of VVA strategies can be realized, even beyond those presented here.
These two technologies have been picked vs alternatives, being the optimal combination of: