Jacobs Vehicle Systems, one of the leading manufacturers of valve actuation systems and heavy-duty diesel engine retarding systems is planning to launch its Cylinder Deactivation (CDA) technology in Euope at IAA 2018. The event is slated to be held from September 20 to 27 in Hanover, Germany.
CDA uses Jacobs’ High Power Density (HPD) engine brake for a new purpose and in a new application. The main benefit that HPD offers is that it can equal or exceeds the braking capabilities of a driveline retarder at a minimal cost. CDA, on the other hand offers better fuel economy and lower reduced tailpipe emissions. Both CDA and HPD technologies are modular and can be integrated into an engine either individually or together.
In the case of CDA, cylinder deactivation mechanisms which were originally designed for HPD applications are used in the valvetrain to disable the opening of the intake and exhaust valves. The mechanism which is hydraulically activated is integrated in a collapsing valve bridge system for overhead camshaft engines. It can also be used with a collapsing pushrod system for cam-in-block engines. When used in tandem with disabled injection in selected cylinders, the deactivated cylinders function as a gas spring and return the compressed energy of the air back to the crank. Since higher exhaust temperatures are reached in the operating cylinders, CDA reduces emissions. Thus, it is possible to maintain aftertreatment temperatures when the engine is in low load operation. Another benefit is faster warm-up of the aftertreatment system after the engine is started. There is also less cooling during coasting. Temperature increases of 100-200 C are achieved in low load conditions and 250 C is consistently maintained at loads of approximately 15 kW or more.
CDA makes it possible for large engines to have the fuel economy of smaller engines as it increases the exhaust temperatures for optimal SCR (Selective Catalytic Reduction) operation, reduces camshaft friction, reduces pumping losses in part-load conditions and can reduce or even eliminate use of the intake throttle. Depending on the requirements, one, two or three cylinders can be deactivated. At the lowest engine loads and with three of six cylinders deactivated, fuel consumption improves by up to 20 percent. When the vehicle is coasting, CDA can be applied to some or all cylinders. This will reduce the air mass flow going through the aftertreatment system to reduce the cooling, and reduce engine pumping losses. Thus, the vehicle can coast further with less fuel.
CDA thus offers the twin benefits of lower emissions and higher fuel economy, which were earlier considered to be mutually exclusive. Alternative technologies for lowering emissions by raising aftertreatment temperatures have normally affected fuel efficiency badly.
Jacobs’ Cylinder Deactivation mechanism has proven its effectiveness and reliability in evaluation programs on seven different engine platforms with manufacturers in North America, Europe, China, Japan and Korea. During these trials, CDA hardware has been subjected to over 4,300 hours of durability testing, more than 1.2 billion component cycles, and 500 million cycles of fatigue and overload testing. These tests have shown that CDA is production-ready.
Steve Ernest, Vice-President of Engineering & Business Development at Jacobs Vehicle Systems, said that CDA is likely to draw the interest of OEMs who are keen on reducing emissions through improved after-treatment performance, without compromising fuel efficiency. He said that the dual benefits offered by the new technology will become more important in the near future, with vehicle manufacturers struggling to meet tougher emissions norms while increasing fuel economy.
United States is planning to tighten NOx emissions rules for low-load drive cycles in 2024. Regulatory bodies in China and Europe are also expected to do the same. So, CDA is definitely a technology that automotive manufacturers should consider.
Hamid Moaref has always been fascinated by cars and the automotive industry. His family has a longstanding association with the industry and has been in the tire business for the past 35 years. Raised in Dubai, Hamid attended Capilano University in Vancouver where he graduated with a BBA in marketing before attending an intensive course in magazine publishing in 2005. He has been the publisher and chief editor of Tires & Parts magazine for the past ten years.
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