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Diesel variable valve actuation

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:

  • Early / Late Intake Valve Closing (EIVC / LIVC) or "Miller" cycle
  • Cylinder Deactivation (CDA)
  • Early Exhaust Valve Opening (EEVO)
Whatever the variable valvetrain need, Eaton has a solution that can meet the requirements.

LIVC - Late Intake Valve Closing

Eaton’s capsule 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.

  • Improves fuel economy by 1-2%
  • Enables higher compression ratio
  • Keeps the aftertreatment warm
    (+40°C at low load)
  • Eaton mechanical capsule technology enables full switch in one cam revolution and high lift fidelity

Learn more about our Late Intake Valve Closing

CDA - Cylinder Deactivation

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. 

  • Reduces NOx in low load cycle by around 40% while reducing CO2 by 5-8%
  • NOx reduction up to 90% when combined with advanced aftertreatment
  • Activation and deactivation within
    1 cam revolution
  • Enables 1.5 and 2 stroke engine brake strategies
  • Compatible with Dynamic Skip Fire (DSF)

Learn more about our Cylinder Deactivation

Learn more about emission benefits and how to manage NVH with our CDA technology

EEVO - Early Exhaust Valve Opening

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.

  • Gets aftertreatment hot fast at cold start without the need of an external heating system
  • Can open one or two valves
  • Compatible with engine brake and other VVA strategies
  • Can be activated at any temperature and 0 rpm, when combined with Eaton electro-mechanical actuation technology

Actuation options

Depending on the application and customer requirements, our VVA solutions can have hydraulic or electro-mechanical actuation


Hydraulic 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.

Electro-mechanical actuation

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:

  • Robustness and reliability
  • Fast response time and immediate switching between mode (no intermediate positions)
  • Maximum stiffness and lift fidelity