Dynamic Vibration Absorber

About: Dynamic Vibration Absorber is a research topic. Over the lifetime, 4764 publications have been published within this topic receiving 49429 citations.

Precision requirements for the bifilar hinge slots of a centrifugal pendulum vibration absorber

Abstract: Centrifugal pendulum vibration absorbers (CPVAs) are designed to respond to torsional excitation within a centrifugal field so that their dynamic reaction tends to reduce the torsional oscillation of the system in which they operate. A differentiating feature of a CPVA is that it is tuned not to a single frequency (as are traditional frequency tuned dampers), but rather to a multiple of average rotation speed, or order. Because rotating machinery tends to produce torsional oscillation at a rate that is a multiple of average rotation speed, when tuned properly, CPVAs can correct a specific order torsional vibration at all speeds. In order to function properly, CPVAs must be tuned precisely in relation to the excitation order they are to correct, which in turn implies that the machined pieces that define pendulum motion paths must be cut precisely. This article develops a novel technique for determining the cutting precision required to maintain a prescribed target tuning range for a CPVA. The investigation focuses on the precision required for the most common type of hinge used to create centrifugal pendulums, the bifilar hinge. Two types of machining errors are analyzed: coarse location error for hinge cut-outs, and radius of curvature errors within the cut-outs. Sensitivities for each type of error are derived. Results are applied to analyze CPVAs integrated into the design of an engine crankshaft for the purpose of improving automotive noise, vibration, and harshness (NVH).

Behavior of a New Type Dynamic Vibration Absorber Consisting of Three Permanent Magnets

Abstract: This paper presents some experimental and analytical studies on a new repulsive type dynamic vibration absorber consisting of three permanent magnets of thick disk type(1)∼(2). These magnets are so arranged in a non-magnetic conductive or non-conductive cylinder that one magnet can move freely between the two fixed ones. The result showed that: (1) Repulsive force(3) interacting between the two magnets may be assumed to be inversely proportional to the nth power of the center distance between the magnets. This assumption makes the analysis easier, and the results of the experiment show considerable coincidence with those of the analysis. (2) The new absorber may be able to control the resonant amplitude of the vibrating body which weighs several dozen times the free magnet. Further merits of the absorber are an eddy current damping generated in the conductive cylinder and arbitrary choice of the vibration direction as well as the frequency adjustability.

Optimum Preview Control of Vehicle Air Suspensions

Abstract: In this paper, the active vibration absorber controlling the pressure of the air spring is applied to a preview control system of a vehicle suspension. The front half-part of the vehicle functions as the sensor for the vibration absorption of the rear half-part. The design criterion for the optimum preview control absorber is the minimization of the rms value of the acceleration under the specified constraints on the relative displacement. The optimum preview system is realized by the feedforward and feedback compensation systems. Chang's optimum control theory is applied to the optimization. The experimental results show good coincidence with the analyses.