• Transactions of the Korean Society of Automotive Engineers
• /
• v.25 no.1
• /
• pp.103-110
• /
• 2017

Most commercial vehicles have adopted the hydraulic power steering system. To reduce fuel consumption and to improve steering controllability, a hybrid electric power steering system is being developed for commercial vehicles. In this study, the HILS (Hardware In the Loop Simulation) system equipped with a commercial vehicle hybrid electric power steering system was developed and the vehicle dynamic performance of a truck with the steering system was evaluated. The hybrid electric power steering system is composed of the EHPS motor pump, column mounted EPS system, and ball nut steering gear box for heavy commercial vehicles. The accuracy of vehicle models equipped with the HILS system was verified with comparisons between the simulation results and field test results. The road reaction forces of the steering system were generated from the vehicle model and verified using field test results. Step steering tests using the verified HILS system were carried out and the performance of a newly developed commercial vehicle hybrid electric power steering system was evaluated.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.44 no.10
• /
• pp.911-920
• /
• 2016

For the pitch and yaw axis attitude control of launch vehicle, thrust vector control which changes the direction of thrust during the engine combustion is commonly used. Hydraulic actuation system has been used generally as a drive system for the thrust vector control of launch vehicles with the advantage of power-to-weight ratio. Nowadays, due to the developments of highly efficient electric motor and motor control techniques, it has done a lot of research to adopt electro-mechanical actuator for thrust vector control of small-sized launch vehicles. This paper describes system design and test results of the prototype of direct drive electro-mechanical actuation system which is being developed for the thrust vector control of $3^{rd}$ stage engine of KSVL-II.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.2
• /
• pp.153-160
• /
• 2019

Electro-mechanical actuator system for aircraft has advantages in compactness and its lightweight, compared to the hydraulic actuator system. Hinge line actuator has low air resistance and is suitable for special purpose such as stealth. This paper describes design contents of 10,000 lbf-in class dual redundant hinge line electro-mechanical actuator system for performance test. The control structure was designed to minimize impact of torque fighting. A mathematical model is proposed to analyze and validate the performances of actuator by comparison with experiment results.

• Journal of ILASS-Korea
• /
• v.19 no.1
• /
• pp.9-14
• /
• 2014

Performance of DI diesel engine with high-pressure fuel injection equipment is directly related to its emission characteristics and fuel consumption. So, the electro-hydraulic injector for the common-rail injection system should be designed to meet the precise high fuel delivery control capability. Currently, most high pressure injector in use has a needle driven by the solenoid coil energy or the piezo actuator controlled by charge-discharge of output pulse current. In this study, macroscopic spray approaching method was applied under constant volume chamber to research the performance of three different injectors : solenoid, indirect-acting piezo and direct-acting piezo type for CR direct-injection. LED back illumination for Mie scattering was applied on the liquid spray visible of direct-acting piezo injector, including hydraulic-servo type solenoid and piezo-driven injectors. As main results, we found that a direct-acting piezo injector had better a spray tip penetration than hydraulic-servo injectors in spray visualization.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.10
• /
• pp.1636-1647
• /
• 1997

As most of today's automatic transmissions in passenger car adopt a electro-hydraulic control system, the role of electronically controlled solenoid valves occupies an important position and it is essential to predict solenoid transient characteristics in order to design and evaluate the performance of the hydraulic control system. However, in general, both the magnetic and electrical parameters f the solenoid system are hardly known and it is not easy to model this section with moderate complexity although mechanical system could be developed using the classical second order system. This paper presents a dynamic modelling technique of a solenoid valve, that is controlled by pulse width modulation for an automatic transmission, in terms of system identification theory. In nonlinear computer simulation, it is shown that the identified systems which produce magnetic force to input duty cycle for various excitation signals predict the static and dynamic performance very well near the operating point and in experiment conducted to confirm the validity of identification theory for PWM solenoid valve, we find that there is a good agreement between the experimental data and simulation result. Hence, this model can be utilized in the development of pressure control system with PWM solenoid valve.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.3 no.6
• /
• pp.69-77
• /
• 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 Advanced Marine Engineering and Technology
• /
• v.39 no.5
• /
• pp.527-535
• /
• 2015

As a new technical approach, a hydraulic and magnetic clamp device was attempted to realize a magnetic clamp crane system that uses 8 simultaneously actuating individual hydraulic cylinders. Through this approach, a Sr type of ferritic permanent magnet ($SrO{\cdot}6Fe_2O_3$), not the previously employed electro-magnet, was utilized for the purpose of lifting and transporting the heavy weighted and oversized curved steel plates used for manufacturing the ships. This study is aimed at manufacturing and developing the hydraulic magnetic clamp prototype, which is composed of three main parts - the base frame, cylinder joint, and magnet joint - in order to safely transport such curved steel plates. Furthermore, this research was pursued to conduct a performance evaluation as to the prototype manufacture and acquire the planned quantity value and the development purpose items. The most significant item for a performance evaluation was estimated for the magnetic adhesive force (G) and in this process, a ferritic permanent magnet (Sr type) with 3700~4000 G of residual induction (Br) and 2640/2770 Oe of coercive force (Hc) was utilized. In addition, other relevant items such as hoist tension (kN), transportation time (sec), and the applied load (Kgf) exerted on the hydraulic cylinders were also evaluated in order to acquire the optimum quantity value. As a result of the evaluation, the relevant device turned out to be suitable for safely transporting the curved steel plates.

• Advances in nano research
• /
• v.9 no.3
• /
• pp.133-145
• /
• 2020

In this study, nonlinear vibrations and dynamic instabilities of a smart embedded micro shell conveying varied fluid flow and subjected to the combined electro-thermo-mechanical loadings are investigated. With the aim of designing new hydraulic sensors and actuators, the piezoelectric materials are employed for the body and the effects of applying electric field on the stability of the system as well as the induced voltage due to the dynamic behavior of the system are studied. The nonlocal piezoelasticity theory and the nonlinear cylindrical shell model in conjunction with the energy approach are utilized to mathematically modeling of the structure. The fluid flow is assumed to be isentropic, incompressible and fully develop, and for more generality of the problem both steady and time dependent flow regimes are considered. The mathematical modeling of fluid flow is also carried out based on a scalar potential function, time mean Navier-Stokes equations and the theory of slip boundary condition. Employing the modified Lagrange equations for open systems, the nonlinear coupled governing equations of motion are achieved and solved via the state space problem; forth order numerical integration and Bolotin's method. In the numerical results, a comprehensive discussion is made on the dynamical instabilities of the system (such as divergence, flutter and parametric resonance). We found that applying positive electric potential field will improve the stability of the system as an actuator or vibration amplitude controller in the micro electro mechanical systems.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.5B no.2
• /
• pp.111-117
• /
• 2005

Several of the conventional hydraulic systems in an automobile are now being replaced by more reliable and energy efficient electromechanical systems. Developments in the brushless permanent magnet machine and in the power and control electronics are the key factors responsible for this transformation. These applications brought out some performance challenges associated with the brushless machines. This paper will focus on these challenges to be able to use these machines in such applications. In terms of replacing hydraulic systems with electromechanical systems, steering system is leading the way in automobiles. Currently, steering systems using Electro-hydraulically assisted systems and Electrically assisted (Electromechanical) systems are in the market. Though the Electrically assisted power steering has several advantages over other systems, certain performance and cost challenges delayed the penetration of such systems in to the market.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.7
• /
• pp.138-147
• /
• 1995

The conventional PWM method, which was used in controlling the on-off valve, such as high-speed solenoid valve, was modulating the width of the pulse applied to the valve, by selecting arbitrary sampling time and modulating the duty-ratio in proportion to the error. However, in this method, a selection of long sampling time was inevitable and it was unable to get a high accuracy and a quick response. This study is for designing an appropriate controller for high-speed solenoid valve by proposing an improved duty-ratio modulation method using the Saw-toothed Carrier Wave which enables a short sampling time selection, high accuracy of control, and a quick response. Test which was carried out in the laboratory shows that transient and steady state response could be improved by PID controller.