• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.128-137
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• 2003

Continuously variable damper can yield diverse damping forces for a single damping velocity. It is widely used in the semi-active suspension system since, with right control logics, it can enhance ride comfort compared to the passive damper while not degrading driving safety. A key to the successful design of the continuously variable damper is the knowledge of its complex and nonlinear characteristics. In this paper, research has been done for analyzing characteristics of the continuously variable damper. Various damper components have been investigated and their effects upon the force-velocity characteristics of the damper have been examined. The effects of the damper characteristics change upon ride comfort and driving safety have also been investigated by numerical simulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.937-941
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• 2004

Since semi-active suspension systems of automobile, of which suspension damper are controlled actively, exhibit high performance with light system weight, low cost and low energy consumption. From this view point, semi-active suspension systems are greatly expected to be in the mainstream of future controlled suspension systems. In this Paper, mathematical modeling and dynamic characteristics analysis of a reverse continuously variable damper and valve used for semi-active suspension systems are investigated. The mathematical model of piston with valve are proposed by IMAGINE/AMESim in the paper. To verify the mathematical model developed, the dynamic characteristics are simulated by IMAGINE/AMESim and are compared with experimental results. It was confirmed that the developed models represent well the actual system and can be used for control system design.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.265-266
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• 2007

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.190-198
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• 1999

Continuously controlled semi-active suspension system may improve ride and handling properties. Here, as a mechanism to control the fluid flow solenoid valve mechanism is introduced and added to the basic passive damper to create damping forces of the shock absorbers. The system may produce continuously controlled damping forces in both solenoid valve only and combination with passive shock absorber including fluid flow is studied, and then the combined model is added to the full vehicle model to evaluate its ride and handling performance. Finally, the simulation results are compared to the vehicle models having similar suspension system.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.69-77
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• 1995

This paper presents performance investigation of a continuously variable ER(Electro-Rheological) damper for passenger vehicles. A dynamic model of the damper is formulated by incorporating electric field-dependent Bingham properties of the ER fluid. The Bingham properties are experimentally obtained through Couette type electroviscous measurement with respect to two different particle concentrations. The governing equation of the hydraulic model treating three components of fluid resistances;electrode duct flow, check valve flow and piston gap flow, is achieved via the bond graph method. A prototype ER damper is then designed and manufactured on the basis of parameter analysis. The damping forces of the system are experimentally evaluated by changing the intensity of the electric field, the particle concentration and the electrode gap.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.73-82
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• 2008

Recently MR CDC damper has been applied to semi-active suspension control system gradually. Compared to former hydraulic CDC damper, it has rapid time response performance as well as simple internal structure and wide range of damping force. In order to develop control logic algorithm which enables to take maximum advantage of unique characteristics of MR CDC damper, it is inevitable to perform a thorough investigation into its nonlinear performance. In many previous researches, MR fluid model was either simply assumed as Bingham Plastic, or a phenomenological model based on experiment was established instead to predict damping performance of MR CDC damper. These experimental flow model which is not based on flow analysis but intentionally built to fit damping characteristics, may lead to totally different results in case of different configuration or structure of MR CDC damper. In this study, a generalized flow formula from mathematical flow model of MR fluid for annular orifice is derived to analyze and predict damping characteristics when current is excited at piston valve.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.192-200
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• 2002

Semi-active suspension systems are greatly expected to be in the mainstream of future controlled suspensions for passenger cars. In this study, a continuous variable damper for a passenger car suspension is developed, which is controlled actively and exhibits high performance with light weight, low cost, and low energy consumption. To get fast response of the damper, reverse damping mechanism is adapted, and to get small pressure change rate after blow-off, a pilot controlled proportional valve is designed and analyzed. The reverse continuous variable damper is designed as a HS-SH damper that offers good body control with reduced transferred input force from tire, compared with any other type of suspension system. The damper structure is designed, so that rebound and compression damping force can be tuned independently, of which variable valve is placed externally. The rate of pressure change with respect to the flow rate after blow-off becomes smooth when the fixed orifice size increases, which means that the blow-off slope is controllable using the fixed orifice size. The damping force variance is wide and continuous, and is controlled by the spool opening, of which scheme is usually adapted in proportional valves. The reverse continuous variable damper developed in this study is expected to be utilized in the semi-active suspension systems in passenger cars after its performance and simplicity of the design is confirmed through real car test.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.2
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• pp.158-166
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• 2002

A mathematical model and dynamic characteristics ova continuously variable damper for semi-active suspen- sion systems are investigated. After analyzing the geometry of a typical continuously variable damper, mathematical models fur individual components including piston, orifices, spring, and valves are first derived and then the flow equations for extension and compression strokes are investigated. To verify the developed mathematical model, the dynamic response of the model are simulated using MATLAB/SIMULINK and are compared with experimental results. The proposed model can be used not only for mechanical components design but also for control system design.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.164-174
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• 1996

This paper presents control and response characteristics of a continuously variable ER(electrorheological) damper for small-sized vehicles. The ER damper is devised and its governing equation of motion is derived from the bond graph model. The field-dependent yield shear stresses are distilled from experimental investigation on the Bingham property of the ER fluid. The distilled data are incorporated into the governing system model and, on the basis of this model, an appropriate size of the ER damper is manufactured. After evaluating the field-dependent damping performance of the proposed ER damper, the skyhook control algorithm is formulated to achieve desired level of the damping force. The controller is then experimentally implemented and control characteristics of the ER damper are presented in order to demonstrate superior controllability of the damping force. In addition, response characteristics of the damping force with respect to the electric field with fast on-off frequency are provided to show the feasibility of practical application.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.4
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• pp.9-21
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• 2003

This paper describes the practical implementation of a semiactive hydropneumatic suspension system to provide the high off-road performance of military tracked vehicles. Real gas behavior of a spring system, frictional forces of joints, and the dynamics of a continuously variable damper are considered. The control system is consisted of two control loops, an outer loop calculates a target spool position which can deliver the required damping force and an inner loop tracks the required spool position. Dynamic tests of the one axis model show that the semiactive suspension system considerably reduces the acceleration as well as velocity and displacement of the sprung mass than the passive one.