This work describes an analytical investigation of the eects of gravity on the dynamics and performance of centrifugal pendulum vibration absorbers (CPVAs). CPVAs are passive devices, consisting of movable masses suspended on a rotor, which act to reduce torsional vibrations in internal combustion engines and other rotating systems. When the system axis of rotation is not vertical, gravity acts directly on the absorbers, and can aect system behavior at low rotor speeds. The investigation is based on a mathematical model that is studied using perturbation methods and numerical simulations. The eects of gravity are captured by a parameter , and are examined for dierent absorber designs and operatingconditions, paying particular attention to cases relevant to internal combustion engines. It is found that the steady state system response can be divided into two cases, depending on the order n of the applied torque that leads to torsional vibrations. In the general case, n not equal 1 or 2, the absorber response to gravity and the applied torque are essentially uncoupled, and the system response can be systematically explored by the introduction of an equivalent system order tuning parameter. In the special cases, n = 1 or 2, nonlinear interactions from gravity can alter the order n system response in a nontrivial manner. Specically, we consider then = 2 case, in which a superharmonic response of the absorbers can occur, and the features of this response depend on the number of absorbers N and other system parameters. These predictive results will be of use in the design of CPVAs for automotive engines currently being developed for low speed idle conditions.
Read
