Horvath R., Flowers G.

Automatic, passive self-balancing systems are an important tool for reducing the effects of synchronous vibration in a variety of rotating machinery. Much of the work in this area that has been reported to-date has focused on ball-balancer systems. However, for applications where a high level of balancing precision is needed and dry (non-lubricated) operation is required, systems that use pendulums rather than rolling balls may offer distinctly better performance due to their lower sensitivity to dry friction. This investigation seeks to provide additional insight into the performance and expected behavior of such systems. A simulation model is developed for a two-pendulum balancer system with isotropic supports and analyzed in detail. The influence of mass differential between the two pendulums is considered in the singular-point determination and stability analysis. Three different types of singular points have been identified, with explicit closed form solutions developed for all three types. The stability characteristics of each were analyzed in detail, both for the two operating speed domains (sub and supercritical) and the three constructional domains (relatively undersized, sufficiently and insufficiently oversized). The conclusions and observations from the analysis and simulation studies are also demonstrated and tested in a series of experimental studies.