Viscous damper robotic automated production incorporating statistical process control ensures consistent quality of this vital powertrain component.
Design engineers are challenged to deliver emissions compliant and more fuel efficient powertrains without sacrificing performance and reliability. An essential component to help meet these needs remains a quality torsional vibration damper to protect engine internals and improve efficiency. Invented by Vibratech TVD (formally Houdaille) in 1946, the viscous torsional damper continues to evolve and help OEMs demonstrate their market leadership and commitment to the environment.
Engineers of high power diesel engines have long preferred a viscous damper over tuned elastomer
types to reduce internal wear and achieve a longer engine life. The broadband damping design is capable of protecting across multiple frequencies and orders. It also becomes more effective as vibration amplitude increases. Featuring a sealed housing to prevent contamination and excellent
heat dispersion properties, a viscous damper is capable of a very long life cycle in demanding high power applications.
Finite element analysis software determines damper stress points under load application and rpm range.
Implementing sophisticated turbo charging systems, high pressure fuel injection and computer controlled optimized combustion techniques to rigorously reduce nitrogen oxide (NOx) and particulate matter (PM) by raising cylinder mean effective pressure in turn generates greater torsional vibration amplitude at the crankshaft. For OEM powertrain teams to maintain reliability and performance more importance is being placed on the viscous torsional damper. Partnering with an expert such as Vibratech TVD leverages their 65 plus years of torsional vibration analysis and damper development experience to jointly achieve the best solution for each specific application.
The way organizations collaborate today to develop a viscous damper has changed significantly. Standardized computer simulation software and telecommunications provide design teams the flexibility to work together effectively regardless of location. Complex computer simulation testing and predicted modeling of a damper design now takes place before any prototypes are made. Combined with the advent of rapid prototyping to confirm envelope specifications, the time involved during the development phase is reduced. This allows an OEM to bring new engines and technologies to market at a much faster pace over just 10 years ago.
Basic viscous damper design incorporates a free rotating inertia ring surrounded by viscous fluid inside a sealed housing. As torsional vibration resonates the inertia ring it moves independently in-and-out of phase with the outer housing rpm. The resulting shearing action of the inertia ring through the fluid transforms the vibration into heat, which dissipates rapidly through the housing. Cleaner in-cylinder combustion by raising mean effective pressure puts a tougher demand on the viscous damper to provide the necessary damping control. The inertia ring inside a viscous damper has to compensate predictably and quickly to keep amplitude within a range the crankshaft will tolerate and
prevent frequency orders from ‘stacking’.
To meet these demands, yet keep a simple and cost effective solution, much research and development has been placed on the internal components of the damper. The fluid used today
between the inertia ring and the outer housing is capable of holding viscosity tolerances through extreme temperature ranges. In addition, improvements in non-metallic bearings also reduce internal damper friction and minimize wear particles over traditional metallic ones. Both advances have
also contributed to a longer damper service or replacement life cycles.
[Top]: Computerized balancing of internal inertia ring. [Bottom]: Automated assembly line inspection check.
While new advances in performance have put more responsibility on the viscous damper to protect the crankshaft; overall engine size constraints, improved fuel economy, noise reduction and
longer service interval requirements are contributing factors to include a viscous damper on the camshaft(s) as well. The addition of a small viscous damper mounted to the camshaft system can help improve valve timing efficiency, reduces chain slap and gear chatter, and quiet down the overall valve train system.
Likewise, improving the reliability of the drivetrain and noise reduction has also furthered the development of driveline viscous dampers. Determining driveline vibration frequencies requires a comprehensive analysis of the system. Once optimum operating parameters are determined, a viscous damper is constructed to reduce individual shaft noise before a resonance point is reached. The benefit is reduced noise and component wear.
Achieving precise functional parameters, as described above, with the amplitude flexibility and long life of a traditional viscous damper is accomplished with today’s precision CNC machining. Multi-axis CNC lathes and mills are also capable of incorporating complex features into the outer housing for pulley features and system assembly configurations, such as provisions for power take offs. Finally, through advancements in machining technology complex internal configurations can be used to provide for higher rpm requirements.
To achieve required high quality standards and meet just-in-time inventory demands, Vibratech TVD implemented an ISO 9001 quality systems certified strategy and invested in the future of American manufacturing at their Buffalo, New York area headquarters and production facility. Today, the manufacturing of viscous dampers is transformed into a near fully automated process created by a workforce of highly skilled CNC machinists and programmers. Robotic automated production utilizing various laser capabilities improves productivity and focuses the attention on delivering consistent high quality across scalable quantity.
Engineers are increasingly requesting viscous dampers, for their proven benefits and
new flexibilities, in smaller size diesel engines. Meanwhile the industries that move our
economy, such as on-highway, off-highway, rail and mass transit, agriculture, marine and
energy continue to increasingly depend on the viscous torsional damper in new ways to
meet future emission regulations and achieve greater fuel efficiency.
On the engine or in the driveline, the viscous damper will continue to play an important role
in the performance and reliability of future diesel and alternative fuel hybrid powertrains in
over-the-road and off-highway equipment.