Diesel Dynamic Skip Fire

Dynamic Skip Fire for Diesel Engines (dDSF™) enables diesel engines to be both clean and green

How Diesel Dynamic Skip Fire (dDSF™) works

Tula’s dDSF technology carefully controls the number and sequence of combustion events in a diesel engine using patented algorithms to ensure the engine operates near peak efficiency. Due to the higher cylinder load, dDSF also increases exhaust gas temperatures to continue keeping the aftertreatment system at operating temperature, especially under low-load conditions.

dDSF™ in real world situations

High Torque
Merging On to the Freeway

When high torque is needed, dDSFTM activates all cylinders.

Medium Torque
Highway Cruise

As torque demand moderates, cylinders are dynamically skipped based on demand.

Low Torque
Low Speed Cruise

At slower speeds, maximum fuel efficiency is maintained by skipping more cylinders, even skipping all cylinders during deceleration.

Simultaneous CO2 and NOx benefits from optimal combustion
and greater conversion efficiency

Dynamic Skip Fire
Engine Controls
Higher Catalyst
Temperatures
Fuel Consumption (CO2)
and NOx Reduction

Optimal Combustion

Reduced CO2

dDSF improves fuel efficiency by firing all events at the most efficient air to fuel ratio, allowing optimal combustion at all engine output levels.

Conversion Efficiency

Reduced NOX

Cylinder deactivation reduces excess engine airflow and increases exhaust temperatures. This allows for more efficient conversion of pollutants in the catalyst and reduced NOx - at the same aftertreatment system cost.

Test results show 74% NOx and 5% CO2 reduction

Results shown are mapped for appropriate firing densities. The improvement in turbine outlet temperature is dramatic, allowing effective aftertreament control.

Temp (°C)
Baseline 6-cyl. Map
dDSF 6-cyl. Map

Valve Train Deactivation Mechanizations for Diesel Engines

Light Duty

Deactivation
Finger Follower

Source: Schaeffler
Medium/Heavy Duty

Deactivation
Rocker Arm

Source: Eaton
Medium/Heavy Duty

Deactivation
Pushrod Cartridge

Source: JVS
Medium/Heavy Duty

Deactivation
Valve Bridge

Source: JVS
Light Duty

Deactivation
Roller Lifter

Source: Delphi Technologies

Global regulations are becoming increasingly stringent for heavy-duty diesel NOX and CO2 emissions. dDSF simultaneously reduces NOX and CO2 emissions at a low cost.

Unique simultaneous NOx & CO2 reduction
Up to 75% lower toxic NOx emissions
Up to 10% fuel consumption benefit
Up to 11 tons annual CO2 + NOx emissions reduction per vehicle

Tula has developed one of the essential technologies
for reaching fuel efficiency mandates

Click to learn more about Tula and our dedication to a cleaner Earth

SAE International: SAE WCX (World Congress) 2021 paper
Vienna Motor Symposium 2020 Cummins-Tula paper
Future Diesel Engine Summit (China 2019) paper
CV Global Regulations and Technologies - A Whitepaper

Dynamic Efficiency
Starts with Tula

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