Balancing driveability, NVH, and fuel consumption on automotive powertrains using integrated simulation techniques

Abstract

The engine downsizing approach can be considered as state-of-the-art automotive propulsion system. However, future trends are also indicating a trend to a further reduction of the number of engine architectures, normally accompanied with a reduction of the number of cylinders in internal combustion engines, including prospective use of alternative fuels such as compressed natural gas or the downsized engine embedded in a powertrain with electrically driven propulsion systems. Hitherto, different simulation approaches are employed to evaluate the trade-off between noise, vibration and harshness, driveability, and fuel consumption. This paper presents the coupling of two simulation tools, each one an established tool in its discipline, namely a 1D-gas-dynamics tool for a downsized internal combustion engine including a dedicated boost-pressure control approach, and a multibody dynamics tool to simulate the powertrain and vehicle dynamics, using the functional mock-up interface. Using this approach as an industry first application, a significant reduction of development time while avoiding duplication of powertrain subsystem modeling, is achieved. This enables a transient simulation and supports a fast analysis of different powertrain architectures. It, furthermore, allows a detailed look at the impact of powertrain subsystems like the architecture of the internal combustion engine, flywheel, and driveline design on relevant vehicle attributes. Moreover, the transient simulation approach allows the investigation of lag effects caused by the air-path characteristics of the internal combustion engine, or transient effects brought up with the advent of hybrid powertrain architectures. The application case of this tool chain presented in this paper revealed that engine architecture reduction should be carried out carefully in order to not compromise driveability of the engine later on. This could bear the risk of sacrificing fuel economy due to a higher lugging limit, often linked to a reduced firing order of the engine, caused by a reduction of the number of cylinders. The paper finally discusses prospective solutions in terms of conventional mechanical solutions and added electrified propulsion including potential limitations to overcome this issue.

A Numerical Study of a Compressed Air Engine with Rotating Cylinders

“…The model includes both mechanical and kinematic joints. Simpack is a widely used MBS software package that can render models of various mechanical systems, including simplified subsystems of vehicles, such as engines [39] and gearboxes [40,41], parts of chassis and suspension systems, entire vehicles [42,43], and sets of vehicles or other mechanisms [44,45]. Simpack works using numerical methods in which a mathematical model describing the dynamic behavior of a mechanical system can be derived automatically.…”

Mechanism Study and Reduction of Minivan Interior Booming Noise during Acceleration

“…People start to turn to the vibration sources and the paths through which vibration energy can penetrate the cavity. But the automobile chassis is a very complex system as it contains a variety of mechanical components and excitations [18][19][20][21][22][23][24], and what's more, early in the minivan development process, manufacturers did not pay enough attention on this problem, so the generation mechanism of interior booming noise remains unclear. is is also the reason why various methods have been tried in solving the booming noise problem by minivan manufacturers, but no satisfactory effect is reached.…”

Identification of firefly algorithm-based fluctuation coefficient of the exciting torque for vehicle driveline

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