Study on an Oil Damper with Variable Damping Mechanism : 1st Report, Damping Characteristics of the Damper with a Piston Having Cylindrical Orifices

Abstract

The purpose of this work is how to design the variable oil damper whose damping is adjustable by varying the area of orifice in the piston. In this report, we deal with an oil camper having a few cylindrical orifices in order to study the fundamental characteristics of the variable oil damper. Two new method for analyze the damper are proposed. The first method of analysis is based on the assumption that the diameter of the piston is equal to the inner diameter of the cylinder but no friction occurs between the contact surfaces. However the assumption is far from being satisfactory in the actual oil damper. The second can be applied to the oil damper whose piston is smaller than the cylinder (in other words, the oil flows through the annular clearance and the cylindrical orifices). In these analyses, the flow through the channels is assumed to be incompressible, unsteady and laminar. Consequently, it is made clear that the magnitude of the damping in the latter type of oil damper is heavily subject to variation of the frequency of the oscillating piston.