Our innovative Switching Roller Finger Follower (SRFF) technology for type II overhead camshaft engines enables a variety of variable valve lift strategies including cylinder deactivation to help engine manufacturers achieve emissions and fuel economy regulations.
In spark ignition, engines reduced pumping losses result in increased fuel economy.
Early Intake Valve Closing (EIVC) closes the intake before bottom dead center (BDC) to decrease pumping loss at the valve. We use low lift event for most of low speed operation and it’s always used with cam phasing for optimum timing of low lift.
Cylinder deactivation closes intake and exhaust valves on specific cylinders and forces the remaining cylinders to perform higher specific work. These higher loads force the throttle to be opened more, reducing pumping loss in the active cylinders and improving fuel economy.
Friction is a known contributor to the efficiency and fuel economy of modern internal combustion engines. Eaton continues to provide advancements in this area. Our three roller SRFF design offers significant friction reduction (up to 80%) over current state-of-the-art slider pad valvetrain solutions resulting in real-world fuel economy increases.
In order to meet future CO2 and NOx regulations, engines will need to rely on advanced combustion processes. Our switching roller finger followers enable powertrain engineers to select combustion process for their particular application.
Single roller SRFF is used in cylinder deactivation (CDA).
The three roller switching roller finger follower design enables a variety of combustion processes:
Our full lift lost motion, single roller SRFF design provides cylinder deactivation (CDA) when full engine power is not needed, so that remaining, active cylinders run in a higher efficiency mode, increasing fuel economy. This works by reducing throttling losses or pumping work on the active cylinders.
You can find more information about this feature in our cylinder deactivation area.
There are three actuation methods for cylinder deactivation on the Eaton full lift lost motion SRFF: hydraulic, electro-mechanical, and
E-Latch.
Mode | Engine Speed (rpm) | Oil Temperature (degrees Celsius) | OCV Signal | Switching Port Pressure (bar) | Latch Position |
---|---|---|---|---|---|
Standard Lift | 0 to 7200 | -40 to 150 | De-Enegized | 2 to 4 | Extended (engaged with inner arm) |
CDA (No Lift) | Idle to 3500 | -20 | Energized | 20 | Reactivated (disengaged with inner arm) |
See the Eaton hydraulic actuated, single roller SRFF cylinder deactivation in action.
For improved fuel economy, performance and drivability in internal combustion engines, Eaton switching roller finger followers enable two modes of operation, allowing gas exchange to be optimized. This is a achieved by a dual lift rocker arm that is actuated by a camshaft with separate cams with low-lift and high-lift profiles.
Three roller SRFFs use Hydraulic, Electro-mechanical and E-Latch actuation technologies.
Watch the 3-Roller SRFF iEGR application in action.
See our high lost motion SRFF in action.
Watch the electro-mechanical variable valve lift (VVL) in action.
Our switching roller finger followers can be activated by a variety of methods including hydraulic, electro-mechanical and electric or E-Latch technology, all of which can be tailored to specific requirements along with increasing efficiency and fuel economy.
Hydraulic actuation is a tried and true technology that reduces switching pressures to support low displacement oil pumps. Electro-mechanical and E-Latch technology enable instant and reliable switching even at very low temperature conditions.
Hydraulic actuation is a proven technology but it has limitations due to temperature pressure dependencies of engine oil. Electro-Mechanical and E-Latch technologies overcome these challenges by enabling a much larger operating envelope. Additionally, they provide improved onboard diagnostic capabilities and zero rpm switching.
Hydraulic Switching | Electro-Mechanical | Electric or E-Latch | |
---|---|---|---|
Oil Temp working range (Deg. C) | -20 to >150 | -30 to >120 | -30 to >120 |
Min Oil Pressure (Bar) | 1.5 to >2 | N/A | N/A |
Actuators/Rocker arms | 1 actuator/ 4 SRFF | 1 actuator/6 SRFF | 1 actuator/ 1 Rocker arm |
OBD | No direct OBD feedback | Bank position feedback | Individual rocker arm feedback |
Minimum RPM Switching | Above Idle | 0 RPM | 0 RPM |
Response Time | ≈ 15ms | < 15ms | ≈ 5ms |
Rolling activation | Very Difficult | Possible | Possible |
Oil Pump Impact | Added leakage | No impact | No impact |
Eaton’s single roller finger follower cylinder deactivation is proven technology with many options to fit the application.
Eaton’s three roller finger follower can enable iEGR or LIVC with a through-axle architecture.
Eaton’s high lost motion three roller SRFF technology is designed for the most challenging variable valve lift functions.