Better fuel economy and lower emissions, already proven in extensive tests by Jacobs, have been independently measured
Jacobs Vehicle Systems has completed testing with an internationally known third-party laboratory, funded by the US Environmental Protection Agency (EPA), to quantify the fuel savings and emissions benefits of Jacobs’ Cylinder Deactivation (CDA) technology. The tests were conducted on a 13-litre Navistar engine equipped with CDA.
Results from these tests showed that fuel consumption was improved by 5% over the baseline in the Hot FTP cycle, while increasing exhaust temperatures and limiting the cool-down of the SCR system. To demonstrate the capability of the CDA system, the proposed CARB Low Load cycle was evaluated, and CDA was found to raise the exhaust temperatures so that tail pipe NOx emissions were reduced by 86%.
CO2 and fuel consumption was reduced by 12%. SCR NOx conversion increased from 48% (baseline) to 95% (CDA). More extensive tests and results will be published under a joint paper at the April 2020 SAE World Congress.
CDA is already proven to increase fuel economy and reduce tailpipe emissions in heavy-duty diesel engines, but Jacobs welcomed the opportunity to have these benefits independently measured.
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 US 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.
New regulations are expected to place greater emphasis on measuring emissions in real-world driving conditions, in the same way that regulators’ methods for measuring automobile emissions have changed in the US and Europe in recent years. Laboratory tests focused on the extent to which Jacobs’ CDA reduces NOx emissions during the low-load cycles representative of real-world driving. These include cold start-ups, frequent low load and idle conditions that typically cause the most pollution, due to a cool aftertreatment system, while also looking to quantify CO2 improvements at the same time.
While decreasing fuel consumption lowers greenhouse gases, CDA additionally reduces NOx output by creating higher exhaust temperatures in the operating cylinders for optimal SCR (Selective Catalytic Reduction) operation. Crucially, the high temperatures necessary for after-treatment are maintained even when the engine is in low load operation. CDA also enables faster warm-up of the after-treatment system after engine start-up and minimises cooling of after-treatment during coasting.
Jacobs is the world’s leading manufacturer of heavy-duty diesel engine retarding systems and valve actuation systems. The company introduced CDA technology last year in a new application of proprietary components originally designed for the company’s High Power Density (HPD) engine brake, which employs mechanisms in the valve train to disable the opening of the intake and exhaust valves. Now Jacobs is involved in numerous CDA development and demonstration projects on commercial vehicle powertrains around the world.
The hydraulically activated mechanism for CDA 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, any combination of cylinders can be deactivated as needed.
For more information: www.jacobsvehiclesystems.com