Passenger car powertrain mounts must meet many requirements and, therefore, always represent a compromise between various objectives such as durability, drivability, package, weight, costs, and the desired vibro-acoustic behavior. Particularly in light of current development trends such as downsizing and cylinder deactivation, the mount design is a challenging task. The boundary conditions for mount design are also becoming increasingly complex due to the growing space requirements for the installation of alternative drive concepts. On the one hand, the small installation space requirements and the desire for agile handling require a stiff mount concept. On the other hand, soft powertrain mounts with low damping are necessary in order to achieve high vibration isolation. In this context, a well-designed development process and smart development tools are absolutely indispensable.
The definition phase represents the first phase of a NVH-related development process for the powertrain mount. Here, target values are defined and technical specifications are set based on global vehicle parameters. FEV’s comprehensive data base, which contains the results of many diverse benchmark tests, is the basis for this process. These global target values are then broken down into component-specific target values, from which the individual desired mount parameters can be derived.
Simulation and Early Prototype Parts
The second step is the conceptual design of the mount system. To support the design, FEV provides various simulation development tools that, among others, include the use of the “Powertrain Mount Designer” – an interactive tool for concept design. This tool provides immediate information on the influence of modified mount parameters, such as position or stiffness. In doing so, the “Powertrain Mount Designer” covers various standard analyses, including kinetic energy distribution, mode distribution and separation, and interior vehicle noise. This enables rapid determination of many mount characteristics, which are used as the basis for the manufacturing of initial prototype parts by the mount manufacturer. The progressive detailing of the mount concept results in refined multi-body simulation models that are then used in the “FEV Virtual Engine” software. This is usually an important element of the prototype phase, during which the definition of the final specifications takes place. The highest simulation precision is required here.
From Validation to Series Manufacturing
The last step is the validation of the prototype parts with regard to drivability, package requirements, and acoustic behavior. This validation is done on a vehicle on a 4-post installation or on a rough road circuit, for instance. Series manufacturing is prepared through the switch from the one-caliber tool to the multi-caliber series tool.
The overall activity shows the necessity of a comprehensive collaboration between the OEM and the mount manufacturer. As a development service provider for the automotive industry, FEV provides support for every development stage with a variety of software tools, tests, and benchmark data bases.
>> AS A DEVELOPMENT SERVICE PROVIDER, FEV PROVIDES SUPPORT DURING EVERY DEVELOPMENT STAGE WITH ITS OWN SOFTWARE TOOLS, TESTS, AND BENCHMARK DATA BASES