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Diesel Variable Valve Actuation

Eaton Variable Valve Actuation (VVA) solutions for medium- and heavy-duty diesel engines enable combustion strategies such as Miller cycle (EIVC / LIVC), Early Exhaust Valve Opening (EEVO), and Cylinder Deactivation (CDA). Variable Valvetrain functions reduce fuel consumption and increase the exhaust temperature for improved catalyst efficiency and lower emissions.

Diesel Variable Valve Actuation

Modular and flexible design

Our VVA capsule approach provides flexibility which enables modifications to the basic cam profile on the fly.  Oil commands to different valves can force the valve open or keep them closed when needed, reducing the amount of air going through the cycle, increasing exhaust temperature and improving thermal efficiency.

The LIVC capsule can keep the intake valve open a longer time, which improves the air flow at high engine load. The same type of capsule on the exhaust valve can open it early for higher temperature, or pulse open it during a compression stroke for engine braking.

This modular and flexible allows the same capsule with different oil commands achieve multiple functions allowing OEMs flexibility and choice in the design space. In addition, these solutions are more cost effective than additional aftertreatment.

Diesel engine variable valve actuation processes

Cylinder Deactivation

By deactivating the valves on one or more cylinders, the working cylinders are forced to operate at lower Air/Fuel Ratios. This works to increase the exhaust temperatures and ultimately improve emissions through improved catalyst efficiency. Simultaneously, a fuel efficiency benefit is possible.

Eaton’s deactivation technology is available for medium- and heavy-duty diesel engines applications and all valvetrain types.

Eaton diesel engine variable valve actuation cylinder deactivation

Watch this video

Learn how Eaton cylinder deactivation works to reduce NOx and CO2 to help diesel engines achieve 2024 and 2027 emissions reduction targets

Learn more about our Cylinder Deactivation

Cylinder Deactivation (CDA) on commercial vehicle engines increases the exhaust temperature by approximately 150°C, maintaining high NOx conversion efficiency of the SCR at low load. Cylinder Deactivation is realized by de-activating the fuel injection as well as the intake and exhaust valve motion via deactivating rockers. The Eaton CDA split rocker enables fast and reliable deactivation and reactivation of the valves, in a compact and flexible packaging.

Early Intake Valve Closing and Late Intake Valve Closing

Eaton’s capsule technology can be employed to modulate the intake valve to achieve either early or late valve closing.

Changing the duration of the intake event enables the powertrain engineer to deploy Miller cycle combustion and achieve their fuel economy objectives.

Eaton diesel VVA EIVC LIVC curve

Learn more about our Late Intake Valve Closing

Late Intake Valve Closing (LIVC) allows improving the efficiency of the engine, contributes to aftertreatment thermal management at partial loads and enables higher compression ratios. In the Eaton LIVC system, a standard intake rocker is combined with a switchable rocker. While the standard rocker realizes the regular intake valve lift, the switchable LIVC rocker runs on a secondary cam with increased duration. When the LIVC rocker is active, the valve closing motion is controlled by secondary cam and therefore is delayed.

Early Exhaust Valve Opening

Eaton’s capsule technology can be employed to modulate the exhaust valve to achieve early exhaust valve opening during a firing event.

Opening the exhaust valve early hotter exhuast gases into the exhaust system. This can be used in the vehicle's thermal management strategy to optimize catalyst efficiency and emissions.

Eaton diesel VVA EEVO.png

Benefits: thermal management and fuel efficiency

Thermal Management

  • Significant improvements in raising exhaust gas temperatures
  • Achieves fuel efficiency and emissions reductions

Fuel Efficiency

  • Improves Brake Thermal Efficiency (BTE)
  • Advantages with early or late intake valve closing
    • EIVC can improve BTE up to 4%
    • LIVC can improve BTE up to 3%
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