• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.70-78
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• 2000

A balanced vane pump for the use of automotive power steering systems generates a flow ripple which is imposed upon the mean flow rate. The flow ripple interacts with the characteristics of the connected pipes, valves and steering gear in a complex manner to produce a pressure ripple, also known as fluid-borne noise. In order to reduce vibration level and produce quieter and more reliable power steering systems, it is important to measure the flow ripple produced by a pump with high accuracy and fast response. In this paper, the flow ripple generated by a vane pump in automotive power steering systems is measured by the remote instantaneous flow rate measurement method (RIFM) using hydraulic pipeline dynamics. In experiment, flow and pressure ripple wave forms are measured under various operating conditions. Also, the parameters affected upon the flow and pressure ripple are investigated by the frequency analysis.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.111-117
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• 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 Mechanical Science and Technology
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• v.17 no.9
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• pp.1261-1267
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• 2003

The Steering system is the most important system for a vehicle, in terms of safety and driving feel. But in many cases, experiments to improve the steering feel using a real vehicle are very difficult in the aspects of repeatability, safety and money. Repeatability in testing steering systems is very important because the steering feel for a driver varies according to the environmental conditions. In addition to that, steering tests using vehicle are so dangerous that the driver might not concentrate on the tests. In this paper, a new steering system simulator using the front part of a steering and suspension system is described. This simulator allows cheap, safe, and repeatable testing of the steering system compared with the real vehicle test.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.4
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• pp.38-45
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• 1996

Power steering systems play an important role for the vehicle handling characteristics and driver's steering center feeling during straightforward driving situation. In this paper, the rotary valve, the main component of power steering systems, is modeled and analyzed, and is combined with a 3-DOF(degree of freedom) lateral dynamics model of passenger cars to examine the effects of design parameters on the vehicle steering characteristics. The results can be applied to the development of advanced power steering systems for passenger cars such as electronically-con-trolled power steering system.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.186-193
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• 2000

EPS(Electric Power Steering) systems have many advantages over traditional hydraulic power steering systems in space efficiency engine efficiency and environmental compatibility. In this paper an EPS system control logic using a torque map is proposed. The main function of the EPS system is to reduce the steering torque exerted by a driver by assist of an electric motor. Vehcile speed steering torque and steering wheel angle are measured and fed back to the EPS control system where appropriate assist torque is generated to assist the operator's steering effort. Another capability of the EPS system for easy adaptation to different steering feels via simple tuning is demonstrated by the experiments. It will be also verified that the EPS system can also improve damping and return performance of the steering wheel by control of the assist motor.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.158-165
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• 2008

Hydraulic power steering system has been adopted in seniority passenger and commercial vehicle system for an easy maneuverability and a smoother ride. In this study, hydraulic power steering system analysis model which includes hydraulics and mechanical sub-systems was developed using commercial software, AMESim in order to predict characteristics for various steering components. Each component which constructs system was modeled and verified by experimentally obtained characteristics curves of each components. The agreement between simulation and experimental results shows the validity of the simulation model. The parameter sensitivity analysis such as valve opening area, torsional stiffness for system design are carried out by the analysis and experimental method.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.4
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• pp.401-407
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• 2016

For high fuel economy, many kinds of unit in vehicle have been developed. In steering system, as a result, HPS(Hydraulic Power Steering) system has been replaced as EHPS and EPS system. But the structures of these systems are totally different, and that causes the uncertainty of fuel economy evaluation. Therefore we undertake to research to find results and tendency of fuel economy and energy in steering system. For accurate evaluation, we modeled different types of steering systems on same vehicle model. The simulation came into action on various driving cycle. The driving condition is designed to show standby power of pump. Results show differences of fuel efficiency and energy consumption.

• International Journal of Automotive Technology
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• v.5 no.2
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• pp.69-76
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• 2004

This paper evaluates the effectiveness of four-wheel-steering system from the viewpoint of lane-keeping control theory. In this paper, the lane-keeping control system is designed on the basis of the four-wheel-steering automobiles whose desired steering response is realized with the application of model matching control. Two types of desired steering responses are presented in this paper. One is zero-sideslip response, the other one is steering response which realizes zero-phase-delay of lateral acceleration. Using simplified linear two degree-of-freedom bicycle model, simulation study and theoretical analysis are conducted to evaluate the lane-keeping control performance of active four-wheel-steering automobiles which have different desired steering responses. Finally, the evaluation is conducted on straight and curved roadway tracking maneuvers.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.101-109
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• 1994

Recently, four-wheel steering systems have been developed and studied as one of the latest automotive technologies for improving the handling characteristics of a vehicle. In much of the proposed four-wheel steering systems, the side slip angle at the vehicle's center of gravity is maintained at zero. This approach allows the greater maneuverability at low speed by means of counter-phase rear steering and the improved stability at high speed through same-phase rear steering. In this paper, the effects of several four-wheel steering systems are studied and discussed on the responsiveness and stability of the vehicle by using the linear analysis. Especially, the effects of the cornering stiffnesses of both front and rear wheels are investigated on the yaw velocity gain and critical speed of the vehicle.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.3
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• pp.66-78
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• 1995

In this paper, we address vehicle modeling and dynamic analysis of four wheel steering systems (4WS). 4WS is one of the devices used for the improvement of vehicle maneuverability and stability. All research done here is based on a production vehicle from a manufacturer. To study actual system response, a three dimensional, full vehicle model was created. In past research of this type, simple, two dimensional, bicycle vehicle models were typically used. First, we modelled and performed a dynamic analysis on a conventional two wheel steering(2WS) vehicle. The modeling and analysis for this model and subsequent 4WS vehicles were performed using ADAMS(Automatic Dynamic Analysis of Mechanical Systems) software. After the original vehicle model was verified with actual experiment results, the rear steering mechanism for the 4WS vehicle was modelled and the rear suspension was changed to McPherson-type forming a four wheel independent suspension system. Three different 4WS systems were analyzed. The first system applied a mechanical linkage between the front and rear steering mechanisms. The second and third systems used, simple control logic based on the speed and yaw rate of the vehicle. 4WS vehicle proved dynamic results through double lane change test.