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Technical Paper

Design, Testing and Analysis of a Novel Multiple-Disc Magnetorheological Braking Applied in Vehicles

This paper presents a new magnetorheological braking which can be used in vehicles. Magneto-rheological (MR) fluid is a novel material which can be used in different components of vehicle. Magneto-rheological fluids (MRF) are suspensions of micron size whose yield stress varies rapidly as the change of magnetic field. The use of MRF in vehicles has been gaining popular recently due to its strong rheological effect, fast response and low energy consumption. Besides, these performances give designers more choice in automotive designs. However, most of the related research of MRF brake is about the construction of small prototype to verify its rheological performance. As a result, research progress is limited to calculation and simulation which make the braking force of prototype can hardly meet the requirement of vehicle due to a lack of optimal design and the understanding of MRF in the situation of high sheer stress and magnetic field.
Technical Paper

DEHB (Distributed Electro-hydraulic Braking System) Having a Holding Function

Many types of brake by wire systems have been developed in past years, such as EMB (Electro-mechanical Brake) [1, 2], DEHB (Distributed Electro-hydraulic Braking System) [3] and EWB (Electric Wedge Brake) [4]. When the vehicle need braking in long period such as waiting for traffic light or downhill braking in those brake systems, the current will sustain very long time with very high level. This current will result in high temperature in motor, and will damage the power supplier. When a new DEHB is developing, a holding function is added in this DEHB. The holding function is self-energized when holding the brake, and automatic released after the brake. Advantageously, after activation of the holding function, the current delivered to the motor for braking is substantially decreased, especially, will be zero when the brake torque is not need to adjust.
Technical Paper

Tire Force Fast Estimation Method for Vehicle Dynamics Stability Real Time Control

A tire force estimation algorithm is proposed for vehicle dynamic stability control (DSC) system to protect the vehicle from deviation of the normal dynamics attitude and to realize the improved dynamics stability in limited driving conditions. The developed algorithm is based on the theoretical analysis of all the subsystems of the active brake control in DSC system and modulation in DSC, and the robustness is achieved by a compensation method using nonlinear filter in the real time control. The software-in-loop simulation using Matlab/AMEsim and the ground test in the real car show the validation of this method.
Technical Paper

Configuration Analysis and Performance Comparison of Drive Systems for Pure Electric Vehicle

Many kinds of drive systems can be adopted by a pure electric vehicle. In order to select the most suitable drive system, the configuration features of different drive systems were analyzed. After matching the drive systems in a pure electric vehicle, the dynamic performance comparison has been carried out; and on the basis of establishing the vehicle energy consumption model and taking the city driving cycle as an example, the economic comparison of these drive systems has been completed.
Technical Paper

Design and Testing of a Novel Multiple-Disc Magneto-Rheological Clutch Applied in Vehicles

In recent years, Magneto-rheological (MR) fluid has drawn a lot of attention for its applications in a variety of torque transmission devices, such as brakes, clutches and soft starters of mechanical equipment. Compared with the conventional clutch of vehicle, the novel MR clutch has the advantages of fast response with electronic signal, accuracy control and simple structure without mechanical wear in plates. Besides, MR clutch may be helpful to fast response of vehicle in some situation. Nowadays, most applications of MR fluids in the torque transmission field mainly are used in low-power situation. As far as we know, the proposed effective methods enhancing the output torque of MR devices will increase either the number of fluid gaps or the magnetic field in the MR fluid. This article presents a novel vehicle clutch utilizing magnetorheological fluid and multiple-disc structure.
Journal Article

Linear Control Performance Improvement of High Speed On-Off Valve Controlled by PWM

High speed on-off valve is applied widely in vehicle control systems. When high speed on-off valve is controlled by Pulse Width Modulation (PWM) of high frequency, the valve core can float at a certain position which is adjusted by changing the duty ratio within a certain effective range. Then the high speed on-off valve can control the flow and pressure linearly like proportional valve. Thus it is essential to extend the effective range of duty ratio to improve the linear control performance of high speed on-off valve. In this paper, the high speed on-off valve of the automotive Electronic Stability Program (ESP) is the focus, and its flow force is analyzed in detail to get the effects of hydraulic parameters on the valve performance. The mathematic model of the high speed on-off valve is derived. Then the valve structural parameters are optimized according to the Genetic Algorithm(GA), offering the theoretical references for extending the effective duty ratio of PWM.
Technical Paper

A New Type of Electro-Hydraulic Power Steering System for Heavy-Duty Commercial Vehicles

The earth's fossil energy is not limitless, and we should be taking advantage of the highly developed fields of science and technology to utilize it more efficiently and to create a fully environmentally friendly life. Considering the prodigious amount of vehicles in the world today, even a small improvement in their energy-saving performance could have a significant impact. In this paper, a new type of electro-hydraulic power steering (EHPS) system is described. It has two main advantages. First, it can significantly decrease the demand on the motor so that it can be used for a wider range of vehicles. Second, its pressure-flow characteristic can be programmed and is more flexible than hydraulic power steering (HPS) system. A prototype with a 500 W motor was applied to a truck with a front load of 2,700 kg, and static steer sweep tests were conducted to validate its feasibility.
Technical Paper

The Differential Braking Steering Control of Special Purpose Flat-Bed Electric Vehicle

Special purpose flat-bed vehicle is commonly utilized to move heavily items such as containers in warehouse, port and other freight handling scene, the hydraulic steering system have be gradually replaced by electric ones. However, the cost of electric steering system is high for commercial activities. Thus, for some corporates, the differential braking steering strategy becomes an ideal alternative. The purpose of this paper is to present a steering control method for flat-bed electric vehicle based on differential braking system. There are two main components of the control method, steering while moving forward and pivot steering, and each of them was composed by upper layer and executive layer. To evaluate the practicability of the control methods, a 7-DOF flat-bed vehicle model was established in Simulink.