Engine Modularity: Streamlining engine platforms and adjusting for global markets
Engine and Vehicle OEMs are faced with a difficult question. How do they streamline their engine platform and adjust it for global markets – each with its own emissions regulations and power requirements?
In the last few years, the market is becoming more consolidated with partnerships between Daimler and Cummins for the supply of medium duty engines, Daimler and Volvo’s fuel-cell joint venture, and the Traton and Navistar merger. To allow for more flexibility, Jacobs’ engineers have been working on the concept of “future-proofing” with in-engine modular technologies to allow engine platforms to be adjusted to varying global markets.
“What we are doing is creating a modular valvetrain. A valvetrain that can do it all--I’ll call it a Swiss Army Knife valvetrain. A valvetrain that can do engine braking. It can do Cylinder Deactivation. It can do Late Intake Valve Closing to improve fuel economy. It can do decompression for start-stop cycles. Having a valvetrain that is modular and can meet all of the OEM’s requirements as the emissions get tighter and tighter over the next 10 years.”
- Gabe Roberts, Director, Product Development, Jacobs Vehicle Systems
Engine Braking – Scaling Up or Down
As the commercial vehicle industry continues to evolve, so does the Jacobs Engine Brake®. For over 60 years, Jacobs has been developing, designing, and producing engine brakes for most of the world’s vehicle OEMs, and the technology has evolved to meet very specific requirements for each market such as the U.S., Europe, China, and India. The Compression Release engine brake is the standard in the Heavy Duty industry and is applied not only to commercial vehicles but in Agricultural and other Off-Road applications as well.
With the ever-increasing globalization of our customers, where the engine platforms are used all over the world and only customized on emission technology and general performance per market area, OEMs are looking for flexibility on the technologies provided.
Up- and downscaling is of importance with minimum impact on the basic elements of the engine. Jacobs’ answer to that trend is to supply “future-proofed” valvetrain designs right from the start of the engine design. This means that within the same hardware space claim several technology steps can be realized: standard Compression Release braking for markets that just need that, or upscale towards High Power Density (HPD) in markets or applications that require more performance or are looking at optimization of the complete drivetrain by eliminating the need for driveline retarders. Jacobs accommodates this by making sure these steps are easy to integrate, even in the future, so development and validation efforts are minimized.
Emissions – Meeting Ever-tightening Regulations
To help OEMs meet various emission regulations, Jacobs’ engineers have worked to solve this issue inside the engine with a modular technology approach. In fact, many of the emission-related technologies from Jacobs makes use of our well-proven engine brake technology and are just applied in a different way to offer in-valvetrain emission technologies. One example is Cylinder Deactivation (CDA), which makes use of the same collapsing valve bridge hardware that is also used for HPD. Using the same logic, CDA offers deactivation of several cylinders when engine loads are low, effectively enabling a six-cylinder engine to run as a 3-cylinder (or less) engine, providing important fuel economy benefits and NOx reduction. CDA is a technology that is expected to play an important role in NOx reduction for the next U.S. emission regulations and is part of Jacobs’ “Keep It Hot” aftertreatment strategy.
While NOx reduction is what North American regulations are focusing on, in Europe CO2 reduction is what matters most for upcoming emission regulations. The differences between these two markets have evolved from the duty-cycle standards that have been developed separately in both markets, creating a challenge for OEMs – how to accommodate a technology that meets both regulations within the same global engine platform. Jacobs’ answer to that is a modular system. Late Intake Valve Closing (LIVC), or any form of Variable Valve Actuation (VVA) can be integrated into that same valvetrain as well. VVA falls within Jacob’s “Get It Hot” strategy and allows for simplification of the aftertreatment systems downstream of the engine. In short: whether the engine needs to be optimized towards NOx reductions by using CDA, or reducing CO2 by using VVA, both are designed by Jacobs’ engineers at the start of the engine’s development.
Yet another technology that can be combined within the valvetrain is Active Decompression Technology (ADT), which is focused on start-stop applications. This is a technology that sees interest not only from Heavy Duty applications (also non-road) but also Medium Duty and Light Duty applications where it enables further levels of driveline electrification.
Demand for Fuel Economy
OEMs are progressively taking an overall vehicle system approach when looking for further fuel consumption reductions. This is important as all components work together; if one element of the system is overlooked, it may work against other improvements that depend on that element. The engine is just part of that system, as is the after-treatment system, the transmission, the axles, etc. When looking for every little drop of fuel to be saved, one must look at the overall system interaction. Jacobs takes a system approach, and when we design our modular technologies, we make sure we understand how it works together with the rest, and what can be done downstream of Jacobs’ technology to make it even better.
Most of the technologies discussed above have a focus on the emission levels coming out of the exhaust pipe, and they do offer fuel economy improvements to certain levels as well. CDA is the best example of that, but also ADT can provide fuel consumption reductions when applied correctly. But it doesn’t stop there. From a system perspective, minimizing friction within the engine is one thing that is talked about a lot, and a way to achieve this is by specifying lower viscosity engine oils. This seems like an easy thing to do, but as engine oil is the main medium for valvetrain actuation, suppliers such as Jacobs must make sure that the functionality, performance, and durability of these technologies are not jeopardized. With our in-house solenoid developments and advanced simulation and testing capabilities, Jacobs is making sure to follow suit. As all of Jacobs’ technology is concentrated on in-valvetrain solutions, further optimization and weight reduction of the overall vehicle is possible too (another element of the “system”), yet again allowing for further fuel consumption reduction.
Valvetrains that are consistent in their performance over the lifespan of the vehicle are important as well: any deterioration due to part wear that negatively impacts either emission levels or fuel consumption must be minimized. An example of technology that allows for that is Jacobs’ lashless technology. Already mainstream on passenger cars, lashless valvetrains eliminate the need to set lash on the valves by introducing Hydraulic Lash Adjusters (HLAs). The advantage of such is system is a very consistent engine operation, during the full life. Previously incompatible with an engine brake, Jacobs has designed a Fulcrum Bridge technology that now opens the door to HLA introduction in heavy and medium duty engines for any application.