Jacobs Partners with Tula on Cylinder Deactivation for Diesel Engines

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Heavy Duty Trucking (HDT)  /  August 7, 2019

Cylinder deactivation technology is likely to be a major design change in the next generation of heavy-duty diesel engines looking to meet stricter greenhouse gas/fuel efficiency regulations. As its work on this technology progresses, Jacobs Vehicle Systems has entered into a collaboration agreement with Tula Technology, an internal combustion controls company. The two businesses will work together to enable Jacobs to further develop cylinder deactivation technologies, which reduce engine fuel consumption and emissions.

Jacobs announced its Cylinder Deactivation (CDA) technology for medium- and heavy-duty commercial vehicle engines in 2018. Tula has licensed its Dynamic Skip Fire (DSF) technology for major automotive OEM gasoline applications.

According to Jacobs, the new partnership will use Tula’s DSF controls technology to support Jacobs’ expertise in diesel deactivation hardware development.

“Vehicle manufacturers are looking for new and improved technologies to comply with stricter legal limits on CO2 and NOx emissions," explained Robb Janak, director, new technology, Jacobs Vehicle Systems. "New test measures, such as Real Driving Emissions and CARB Low Load Cycle for heavy-duty trucks, are encouraging the adoption of smarter technologies that address these requirements. Cylinder deactivation is a great solution, technically proven, and cost effective.”

Jacobs’ CDA, cylinder deactivation mechanisms, originally designed for the company’s High Power Density (HPD) engine brake, are used in the valvetrain to disable the opening of the intake and exhaust valves. The hydraulically activated mechanism is integrated in a collapsing valve bridge system for overhead camshaft engines or with a collapsing pushrod system for cam-in-block engines. When this is combined with disabled injection in selected cylinders, multiple cylinders can be deactivated as needed. At low engine loads with three of six cylinders deactivated, fuel consumption can be improved by up to 20%. 

Jacobs said its CDA technology reduces emissions by achieving higher exhaust temperatures, thus maintaining aftertreatment temperatures for optimal efficiency of SCR (selective catalytic reduction) systems, even when the engine is in idle or low load operation. CDA also enables faster warm-up after engine start-up of the aftertreatment system and minimizes cooling of aftertreatment during coasting. CDA additionally reduces camshaft friction, reduces pumping losses in part-load conditions, and can reduce or eliminate use of the intake throttle, all of which yields overall improvements in fuel consumption while increasing exhaust temperatures.

Tula has developed an infinitely variable cylinder deactivation system, integrating advanced digital signal processing and software with sophisticated engine control algorithms. This technology reduces fuel consumption of gasoline engines by 6-15% on real world drive cycles; the collaboration with Jacobs aims to enable Jacobs to develop and demonstrate deactivation hardware required for diesel engines.

The Tula DSF system makes dynamic firing decisions based on how much torque is requested and then selectively choosing which cylinders will be active or deactivated to meet performance demand. When more torque is required, the firing density increases, and when there is less demand for torque, firing density decreases. This means the control algorithm effectively creates an engine with optimal displacement for the torque required.

Tula’s control system also ensures production level noise, vibration and harshness in a vehicle, the company said. By having the ability to select which cylinders are fired every engine cycle, and by taking into account the frequencies and amplitudes of vibration produced by cylinder combinations, the control algorithm determines the cylinder firing sequences that deliver smooth operation and reduced cost at the fuel pump.

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Jacobs teams up with Tula Technology

Transport Engineer  /  August 8, 2019

Jacobs Vehicle Systems is partnering with internal combustion control business Tula Technology on the development of cylinder deactivation (CDA) technologies, which reduce engine fuel consumption and emissions.

The new partnership, say the companies, will use Tula’s Dynamic Skip Fire controls technology to support Jacobs’ developments in diesel deactivation hardware.

Jacobs introduced its CDA (pictured) system for medium- and heavy-duty commercial vehicle engines in 2018. CDA mechanisms are used in the valvetrain to disable the opening of the intake and exhaust valves.

The hydraulically-activated mechanism is integrated in a collapsing valve bridge system for overhead camshaft engines, or with a collapsing pushrod system for cam-in-block engines. When combined with disabled injection in selected cylinders, multiple cylinders can be deactivated as needed. At low engine loads with three of six cylinders deactivated, says Jacobs, fuel consumption can be improved by up to 20%.

Tula’s Dynamic Skip Fire system makes firing decisions based on how much torque is requested, choosing which cylinders will be active or deactivated to meet performance demand. When more torque is required, the firing density increases; when there is less demand for torque, firing density decreases.

Robb Janak, director new technology, Jacobs Vehicle Systems, says: “Vehicle manufacturers are looking for new and improved technologies to comply with stricter legal limits on CO₂ and NOx emissions... Cylinder deactivation is a great solution, technically proven and cost effective.”

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Jacobs Says Cylinder Deactivation Saves Fuel, Reduces NOx

Jim Park, Heavy Duty Trucking (HDT)  /  February 26, 2020

Jacobs Vehicle Systems has completed testing to quantify the fuel savings and emissions benefits of Jacobs’ Cylinder Deactivation (CDA) technology. Test results showed that CDA reduced fuel consumption by 5% over the baseline in the Hot Federal Test Procedure cycle while increasing exhaust temperatures and limiting the cool-down of the selective catalytic reduction emissions system.

Testing was conducted by an internationally known third-party laboratory and funded by the Environmental Protection Agency on a 13L Navistar engine equipped with CDA.  The announcement was made in Atlanta during the Annual Meeting of the American Trucking Associations' Technology & Maintenance Council.

CDA reduces NOx output by creating higher exhaust temperatures in the operating cylinders for optimal SCR operation.

High temperatures necessary for optimal aftertreatment performance are maintained even when the engine is in low-load operation. With three cylinders of a six-cylinder engine deactivated, high exhaust gas temperatures can be maintained in the three operating cylinders. CDA also enables faster warm-up of the aftertreatment system after engine startup and minimizes cooling of aftertreatment substrate during coasting.

To demonstrate the capability of the CDA system, the proposed California Air Resources Board "Low Load" cycle was evaluated, and CDA was found to raise the exhaust temperatures by about 50 degrees C, reducing tail-pipe NOx emissions by 86%. Fuel consumption (and CO2) was reduced by 12%. SCR NOx conversion increased from 48% (baseline) to 95% (CDA).

Laboratory tests focused on the extent to which Jacobs’ CDA reduces NOx emissions during the low-load cycles representative of real-world driving conditions such as cold startups and frequent low-load and idle conditions that typically cause the most pollution due to a cool aftertreatment system. Testing also sought to quantify CO2 improvements at the same time.

CDA is already proven to increase fuel economy and reduce tailpipe emissions in heavy-duty diesel engines, but Jacobs said it welcomed the opportunity to have these benefits independently measured. More extensive tests and results will be published under a joint paper at the April 2020 SAE World Congress.

In November 2018, the EPA announced the need for additional nitrogen oxide (NOx) reductions in its Cleaner Trucks Initiative. This is especially important in areas of the U.S. with elevated levels of air pollution, a focus in California for the same reasons. Current heavy-duty truck rules for NOx, adopted in 2010, are expected to be replaced by new rules in the future.

Jacobs introduced CDA technology last year in a new application of proprietary components originally designed for the company’s High Power Density engine brake. HPD employs mechanisms in the valve train to disable the opening of the intake and exhaust valves. Jacobs is now involved in numerous CDA development and demonstration projects on commercial vehicle powertrains around the world.

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Jacobs’ Technology Demonstrates Fuel Economy, After-treatment Efficiency

Heavy Duty Trucking (HDT)  /  June 18, 2020

Jacobs Vehicle Systems’ cylinder deactivation technology (CDA) combined next-generation diesel engines has delivered performance-enhancing benefits, according to recent independent validation tests.

The engines, currently under development, are being designed to meet the upcoming round of new U.S. Environmental Protection Agency’s Phase 2 Greenhouse Gas Emissions standards for heavy-duty diesel engines manufactured from 2021-2027.

Independent engine tests have been conducted on Navistar and Cummins engines by Tula Technology, a California-based company that specializes in combustion control and software technology. These tests have confirmed that the Jacobs’ CDA engine systems can deliver improved fuel economy while keeping diesel exhaust after-treatment systems operating at optimal temperatures, supporting the reduction of NOx and CO₂ emissions.

“Jacobs’ CDA features a hydraulically-activated mechanism integrated into a collapsing valve bridge system for overhead camshaft engines, or with a collapsing pushrod system for cam-in-block engines,” said Robb Janak, director new technologies for Jacobs. “When this is combined with disabled injection in selected cylinders, any combination of cylinders can be deactivated as needed.”

Jacobs’ CDA can be used to shut down engine cylinders at highway cruising speeds, or very low engine loads to improve fuel economy and still keep exhaust after-treatment systems hot and operating at optimal temperatures to limit NOx emissions, explained Janak.

In the most recent tests with the Cummins engine, Jacobs’ CDA hardware combined with Tula’s Dynamic Skip Fire (DSF) algorithm improved the control of these thermal management modes to simultaneously maximize exhaust temperatures and CO₂ reductions.

“At 1,000 rpm, diesel DSF shows an increase in exhaust temperature of nearly 100⁰ C while still improving fuel consumption by 25%,” as stated in a paper presented to the International Vienna Motor Symposium, along with similar improvements at other operating conditions.

“The Jacobs’ CDA system has been developed over the past 10 years and was specifically designed for the heavy-duty trucking market,” added Janak. “We believe these systems are ready for the market and we are excited with how technologies such as these will improve drivability, emissions and fuel economy.”