Jacobs Vehicle Systems, known for its diesel engine retarding systems and valve actuation systems, has a new cleaner Jake Brake for Europe. It is introducing its new Cylinder Deactivation (CDA) technology to the European market at IAA Commercial Vehicles 2018, next week.
The CDA uses the componentry of Jacobs’ High Power Density (HPD) engine brake, but in a new application and for a new purpose. It’s benefits are claimed to be reduced tailpipe emissions plus better fuel economy. CDA and HPD technologies are modular and can be integrated into an engine individually or together.
For CDA, cylinder deactivation mechanisms originally designed for HPD applications are used in the valve train 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, the deactivated cylinders act as a gas spring and return the compressed energy of the air back to the crank.
CDA reduces emissions by achieving higher exhaust temperatures in the operating cylinders. This makes it possible to maintain after-treatment temperatures when the engine is in low load operation. It also enables faster warm-up of the after-treatment system after engine start-up and minimises cooling during coasting. Temperature increases of 100-200°C are achieved in low load conditions and 250°C is consistently maintained.
According to Jacobs, CDA simultaneously enables large engines to have the fuel economy of smaller engines because it increases exhaust temperatures for optimal SCR (Selective Catalytic Reduction) operation; reduces camshaft friction; reduces pumping losses in part-load conditions; and can reduce or eliminate use of the intake throttle.
One, two or three cylinders can be deactivated as needed. At the lowest engine loads and with three of six cylinders deactivated, fuel consumption improves by up to 20 per cent. During vehicle coasting conditions, CDA can be applied to some or all cylinders to further reduced the air mass flow going through the after treatment system to both reduce the cooling, and also reduce engine pumping losses, allowing the vehicle to coast further with less fuel.