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MCE-5 DEVELOPMENT provides R&D results, materials and industrial solutions for mass production to the automotive industry. The company designs and produces variable compression ratio engine blocks for car manufacturers to replace fixed compression ratio engine blocks.
Automotive original equipment manufacturers (OEMs), suppliers and research institutes are working around the clock to come up with the cleaner and greener automotive engine. One research company in Lyon, France, MCE-5 DEVELOPMENT SA, is in the midst of developing an innovative engine block, the new MCE-5 VCRi, a promising research and development (R&D) project that just might provide the decisive competitive edge that combines ideal gas engine performance with requisite eco-friendliness.
It seems that the automotive industry agrees that variable compression ratio (VCR) is one of the most reliable solutions to get the most out of gasoline engines. Saab and FEV Motorentechnik took the first steps with this exciting technology in 2000. Both companies demonstrated that VCR is the ultimate tool for spark ignition engines to meet market expectations.
But producing VCR engines represents a real technological challenge and requires rather large changes to the mechanical definition of the engine. Different VCR prototypes have confirmed the technology’s potential, but they also revealed that designing VCR engines that meet mass-production requirements is a tremendous technological feat. So the next step is to study and identify a design that fulfils all the necessary features for a mass-produced engine in terms of functionality, robustness, reliability and durability at a reasonable production cost.
VCR technology adjusts internal combustion engine cylinder compression ratios on the fly. This is done to increase fuel efficiency under varying loads. Higher compression ratios are key to increasing fuel efficiency in internal combustion engines because, as a general rule, the higher the compression ratio the better the thermal efficiency of an engine. The objective is to increase the compression ratio without causing knocking.
By constantly adapting the compression ratio to the driving conditions, the VCR engine can provide a 5 to 7 percent reduction in fuel consumption. Another advantage of the VCR engine is that it reduces the engine capacity as well its fuel consumption without sacrificing performance. This is called downsizing. It aims to replace a large engine with a smaller engine with the same power. Downsizing is of interest because it reduces engine pumping losses as well as thermal and friction losses, all of which significantly affect fuel consumption.
Combining downsizing and VCR can translate to both powerful and efficient engines. VCR engines automatically adapt the compression ratio to the supercharging pressure, making the most of downsizing.
Controlling the compression ratio involves controlling the position of the engine’s high-loaded components, including moving parts, engine block and cylinder heads. But with today’s highly complex engines containing multi-link mechanisms, moving cylinder heads, hydraulic pistons, eccentric-mounted crankshafts and various connecting rods, there are many different avenues of research that have been explored, all with advantages and drawbacks. And that is why MCE-5 VCRi technology is so interesting.
The MCE-5 VCRi behaves as if it were a conventional engine with a cylinder head gasket of variable thickness. Its piston kinematics remains identical to that of a conventional engine regardless of the compression ratio. The MCE-5 VCRi compression ratio can be controlled from 6:1 to 15.5:1. Thanks to its operational stability, the MCE-5 VCRi allows engine designers to make the most of their conventional engine know-how to design VCR engines.
The MCE-5 VCRi comes in an all-in-one engine block integrating both innovative components that transmit power from the piston to the crankshaft, and exclusive actuators, which control the engine compression ratio. The MCE-5 VCRi engine block is a combination of two principles: gears and a rod-crank mechanism. The MCE-5 VCRi engine block is a hybrid resulting in the crossing of an engine with a gearbox.
With the supply chain becoming increasingly involved in the development process, automotive OEMs and their partners and suppliers are aligning their working processes and counting more and more on validated simulation models prior to prototyping.
So it is logical that virtual prototypes have to be modeled very early in the process to confirm performance and reliability expectations. Members of MCE-5 DEVELOPMENT needed to assess the engine’s behavior without developing a full-scale prototype. As a result, they started to investigate the hydraulic circuit and mechanical parts, including the control jack, control rack, gear wheel and piston rack. Since they are not experts in hydraulic systems modeling, they wanted a tool that integrated real hydraulic expertise and would let them model their own unique technology to develop customized models in a simple way.
Another piece to the puzzle was that the VCR system required a specific hydraulic circuit that doesn’t exist in any classical engine. MCE-5 DEVELOPMENT needed to model the mechanical and hydraulic parts that controlled the engine compression rate by regulating the pressure throughout the entire hydraulic circuit and correctly distributing it throughout the chambers of the control rack. This involved analyzing different components, such as valves and accumulators, to correctly size the system to achieve the required performances.
After evaluating several system simulation tools, MCE-5 DEVELOPMENT selected Simcenter Amesim™ software of the Simcenter portfolio from Siemens Digital Industries Software to design its engine block prototype. Using Simcenter Amesim let them create a detailed engine simulation model to better understand and optimize the hydraulic actuation system design, which controls the compression ratio.
Using “Simcenter Amesim provides MCE-5 DEVELOPMENT with the necessary tools to rapidly model and analyze how design changes influence reliability, durability and production costs. The ultimate goal is to reduce the number of physical prototypes.
“Simcenter Amesim was considered by MCE-5 DEVELOPMENT to be the best-in-class tool for simulating and analyzing the engine hydraulic circuit, providing not only a numerically powerful, user-friendly platform that provides fast results, but also very rich and application-oriented libraries that encapsulate expertise on hydraulic engineering domains and technical data in the validated model itself. MCE-5 DEVELOPMENT especially appreciated the thorough hydraulic and mechanical libraries because they integrated not only mathematic formulas, but also technological data, like oil compressibility and valve friction loss.
The multiphysics capabilities of “Simcenter Amesim enabled seamless coupling between hydraulic and mechanical parts. This was crucial to study the interaction between pistons racks, gear wheels, connecting rods and the crankshaft. Moreover, MCE-5 engineers used the IFP-C3D package for “Simcenter Amesim to simulate in 3D the chemically-reacting two-phase spray flows in the piston engines. The tool allowed them to use the primary collected data as entry parameters to analyze the kinematic and control subsystems of the engine.
The simulation stage is very important in the MCE-5 DEVELOPMENT process, and the use of “Simcenter Amesim significantly sped up hydraulic control system development time by enabling the accurate sizing of components, from valves to accumulators as well as mechanical parts. In one week, MCE-5 engineers had already obtained the first results of their unique system without a single physical prototype. Even after the first test sessions, the results appeared to be good. The primary model helped them tune and adjust the parameters very precisely to fit customer expectations.
Additional training from Simcenter™ Engineering services made for a comprehensive and focused knowledge transfer to the MCE-5 engineers, and helped guarantee the first results within days.
““Simcenter Amesim has gained a reputation for excellence in hydraulic simulation over the years,” says Vincent Collèe, the manager of simulation, testing and measurements at MCE-5 DEVELOPMENT. “The software is considered the standard in this field. “Simcenter Amesim helped make us hydraulic experts thanks to advanced, application-oriented models and components.”
MCE-5 DEVELOPMENT engineers particularly appreciated “Simcenter Amesim because the system simulation software is an easy-to-use tool that helps them optimize the model during the early design stages and assess a variety of subsystems in multiple physical domains. The flawless communication between component libraries and accurate modeling of physical phenomena makes it possible to design the MCE-5 VCRi engine block and its related subsystems on a single platform.
“Simcenter Amesim Hydraulics solution proved to be the best technical choice for MCE-5 because Siemens Digital Industries Software has extensive experience in fluids, as is obvious from its robust component libraries,” says Yves Miehe, R&D engineer in system and engine simulation at MCE-5 DEVELOPMENT. “The solution assists both expert and nonexpert users in modeling fluids systems from the functional to the detailed model level.”
“Indeed, what is crucial for us is to identify and study a VCR mechanism that conforms to VCR engine mass production requirements,” says Vianney Rabhi, director of strategy and development at MCE-5 DEVELOPMENT. “Simcenter Amesim helps us clarify our project in terms of tangible costs and time saving.”