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Technical Paper

Experiment Study and Design of Self-excited Eddy Current Retarder

2013-11-27
2013-01-2825
Good braking performance is an important guarantee for the vehicle driving. In the condition of frequent or prolonged braking, the overheating problem for the traditional mechanical braking device causes the recession of the braking performance, which is a prominent problem especially for the commercial vehicle perennial traveling in the mountains. Eddy current retarder can reduce the mechanical brake load as a kind of auxiliary braking device. Thus, the temperature of the mechanical braking device would not be too high, and the traveling safety of the vehicle can be ensured. But eddy current retarder would cause an enormous impact for automobile battery when it starts up and huge electricity energy would be consumed which means that more automotive batteries are needed. Considering above, a kind of self-excited eddy current retarder is developed in the paper.
Technical Paper

Design and Simulation Analysis for an Integrated Energy-Recuperation Retarder

2016-04-05
2016-01-0458
Vehicle auxiliary braking system is very significant to the brake safety. The eddy current retarder (ECR) has a good braking performance, but the braking torque would fade under high speed domain. In the contrary, the regenerative brake (RGB) could provide a satisfied braking performance in high speed domain. However, the braking torque in low speed domain is insufficient. This paper proposed a novel concept of the integrated energy-recuperation retarder (IEER), which would take advantage of the merits of both the ECR and the RGB to have a steady braking performance in all-speed domain. The IEER integrates the structures of rotary eddy current retarder (RECR) and the RGB, both of which share a stator. Braking torque of the IEER produced by stator core and armature-windings can stack together, and therefore the IEER can provide greater braking torque than the RECR. Besides, the IEER can recover electric energy from armature-windings.
Technical Paper

The Combined Braking Energy Management Strategy to Maximize Energy Recovery

2016-04-05
2016-01-0453
Eddy current retarder (ECR) shares a large market of auxiliary brakes in China, but shortcomings of the short continuous braking time and the high additional energy consumption are also obvious. The propose of combined braking partakes the braking torque of ECR. However, the existed serial-parallel braking strategy could hardly balance well the relationship between the braking stability and the energy recovery efficiency. This research puts forward an energy management strategy of combined braking system which aims to maximize energy recovery while ensure the brake stability. The motor speed, the braking request and the state of charge (SoC) of the storage module are analyzed synthetically to calculate the reasonable braking torque distribution proportion. And the recovered energy is priority for using in the braking unit to reduce the additional energy consumption in this strategy.
Technical Paper

Effect of Circumferential Magnetic Field on Braking Performance of a Direct Vane Magnetorheological Fluid Retarder

2019-04-02
2019-01-0342
The hydraulic retarder used in commercial vehicles can provide hydraulic damping to generate braking torque, reducing the pressure of the braking system on the slope section and increasing the safety. In this paper, the magnetorheological fluid with fast magnetic field reflection characteristics is used to increase the response speed of the hydraulic retarder, which can effectively reduce the response time of the hydraulic retarder. In this paper, the influence of the change of circumferential magnetic field on the braking torque of the magnetorheological fluid retarder is studied.
Technical Paper

Driving Fatigue Detection based on Blink Frequency and Eyes Movement

2017-03-28
2017-01-1443
The development of the vehicle quantity and the transportation system accompanies the rise of traffic accidents. Statistics shows that nearly 35-45% traffic accidents are due to drivers’ fatigue. If the driver’s fatigue status could be judged in advance and reminded accurately, the driving safety could be further improved. In this research, the blink frequency and eyes movement information are monitored and the statistical method was used to assess the status of the driving fatigue. The main tasks include locating the edge of the human eyes, obtaining the distance between the upper and lower eyelids for calculating the frequency of the driver's blink. The velocity and position of eyes movement are calculated by detecting the pupils’ movement. The normal eyes movement model is established and the corresponding database is updated constantly by monitoring the driver blink frequency and eyes movement during a certain period of time.
Technical Paper

Passenger Cabin’s Parking Cooling System Based on TEC and Air Conditioning Condensate Water

2019-04-02
2019-01-1066
In the passenger cabin of the parking under the summer sun, the air’s average temperature will reach about 60°C. Such temperature can cause discomfort to the person who has just entered the passenger cabin, also can damage components of the passenger cabin. The reason for this phenomenon is because it is not convective with the outside air. Some vehicles use the electric power to drive the blower in order to ventilate, but the air’s temperature of cabin is so high that the blower’s effect of ventilation is limited. The system proposes to use solar energy to drive the automobile blower and the thermoelectric cooler(TEC) in order to cool the cabin’s air, and use the air-conditioning condensate water collected during the driving process to cool the TEC’s hot end to improve the cooling efficiency.
Technical Paper

A Non-Contact Overload Identification Method Based on Vehicle Dynamics

2019-04-02
2019-01-0490
The vehicle overload seriously jeopardizes traffic safety and affects traffic efficiency. At present, the static weighing station and weigh-in-motion station are both relatively fixed, so the detection efficiency is not high and the traffic efficiency is affected; the on-board dynamic weighing equipment is difficult to be popularized because of the problem of being deliberately damaged or not accepted by the purchaser. This paper proposes an efficient, accurate, non-contact vehicle overload identification method which can keep the road unimpeded. The method can detect the vehicle overload by the relative distance (as the characteristic distance) between the dynamic vehicle's marking line and the road surface. First, the dynamics model of the vehicle suspension is set up. Then, the dynamic characteristic distance of the traffic vehicle is detected from the image acquired by the calibrated camera based on computer vision and image recognition technology.
Technical Paper

Temperature Control Characteristics of Automotive Power Battery Based on R-1233zd(E)’s Flowing Phase Change Heat Transfer

2018-04-03
2018-01-1191
Li-ion power battery is the core component of the electric vehicle power system, and the battery temperature will increase because of the electrochemical reaction of the Li-ion battery. The heat accumulates inside of the battery, which can degrade the working performance of the power battery and shorten the battery cycle life. At present, the wind cooling technology is relatively mature. However, it cannot achieve ideal heat dissipation effect under the working conditions of the high-power or high ambient temperature. In this research, the battery thermal management is carried out by the characteristics of the working fluid’s flowing phase change heat transfer. The phase change working fluid is R-1233zd(E) which is a kind of environmentally friendly liquid with nonconductive and nonflammable. It can achieve the purpose of controlling the battery’s temperature using the characteristics of isothermal heat absorption under different gas phase rate of phase change working fluid.
Technical Paper

The Study on Co-Simulation Based Tracked Vehicle Path Tracking Control

2015-04-14
2015-01-1114
The tracked vehicle with a fully hydraulic driving system, which has a strong traveling performance of passing and mobility ability in the complex terrain, is a typical system of mechanical-electrical-hydraulic integration. At the same time, for the good low-speed stability of the hydraulic system, this vehicle is widely applied in most engineering projects. However, for the complexity and unpredictability of the motion state in the complex environment and the power matching of the driving system, the driving path of the tracked vehicle with hydraulic driving is difficult to control. Moreover, for the complicated interaction between mechanics, the establishment of the mathematical model is much more complex, and the traditional mechanics-control and hydraulic-control co-simulation can not accurately simulate this physical phenomenon. The kinematic and dynamics characteristics of the tracked vehicle are studied firstly, and the dynamics model is built.
Technical Paper

The Experimental Study and Performance Analysis of Air-Friction Reduction System for Hydraulic Retarder

2015-04-14
2015-01-1127
The hydraulic retarder is an important auxiliary braking device for the heavy vehicle, which has some characteristics, such as the big brake torque and long duration braking, when the vehicle is traveling in braking state. However, the transmission power loss will be produced when the vehicle is traveling in non-braking state. This transmission power loss is called Air-friction. Firstly, the air flow distribution characteristics of retarder cavity are studied by computational fluid mechanics, and the Air-friction characteristic in different conditions is analyzed. Then, according to the Air-friction characteristics for the condition of different filling density, a set of vacuum air loss reduction system is designed. Meanwhile, the test bench for retarder Air-friction is set up, the test data of the revolution speed, pressure in cavity and air loss resistance is obtained according to the test bench for hydraulic retarder.
Technical Paper

Experimental Study of Hydraulic Retarder Waste Heat Recovery Based on the Organic Rankine Cycle

2016-09-27
2016-01-8079
The hydraulic retarder is an important auxiliary braking device. With merits such as its high braking torque, smooth braking, low noise, long service life and small size, it is widely used on modern commercial vehicles. Transmission fluid of traditional hydraulic retarder is cooled by engine cooling system, which exhausts the heat directly and need additional energy consumption for the thermal management component. On account of the working characteristics of hydraulic retarder, this study designs a set of waste heat recovery system based on the Organic Rankine Cycle (ORC). Under the premise of ensuring stable performance of hydraulic retarder, waste heat energy in transmission fluid is recycled to supplement energy requirements for cooling system. First of all, a principle model, which is scaled down according to D300 retarder`s thermal power generation ration of 1:100, is established. Then through theoretical calculations, components' structural parameters of the ORC are determined.
Technical Paper

Driving Path Planning System under Vehicular Active Safety Constraint

2016-09-27
2016-01-8105
Path planning system, which is one of driver assistance systems, can calculate the driving paths and estimate the driving time through the road information provided by information source. Traditional path planning systems calculate the driving paths through Dijsktra's algorithm or A* algorithm but only consider the road information from electronic maps. It is not safe enough for operating vehicles because of the insufficient information of vehicle performance as well as the driver's willingness. This study is based on the Dijsktra's algorithm, which comprehensively considered vehicular active safety constraints such as road information, vehicle performance and the driver's willingness to optimize the Dijsktra's algorithm. Then the path planning system can calculate the optimal driving paths that would satisfy the safety requirement of the vehicle. This study used LabVIEW as a visual host computer and MATLAB to calculate dynamic property of the vehicle.
Technical Paper

Color Variable Speed Limit Sign Visibility for the Freeway Exit Driving Safety

2017-03-28
2017-01-0085
Typical vehicle speed deceleration occurs at the freeway exit due to the driving direction change. Well conducting the driver to control the velocity could enhance the vehicle maneuverability and give drivers more response time when running into potential dangerous conditions. The freeway exit speed limit sign (ESLS) is an effect way to remind the driver to slow down the vehicle. The ESLS visibility is significant to guarantee the driving safety. This research focuses on the color variable ESLS system, which is placed at the same location with the traditional speed limit sign. With this system, the driver could receive the updated speed limit recommendation in advance and without distraction produced by eyes contract change over the dashboard and the front sight. First, the mathematical model of the drivetrain and the engine brake is built for typical motor vehicles. The vehicle braking characteristics with various initial speeds in the deceleration area are studied.
Technical Paper

Over-the-Horizon Safety Speed Warning System for Heavy-Duty Vehicle in Mountain Areas

2017-03-28
2017-01-0091
The mountainous roads are rugged and complex, so that the driver can not make accurate judgments on dangerous road conditions. In addition, most heavy vehicles have characteristics of large weight and high center of gravity. The two factors above have caused most of the car accidents in mountain areas. A research shows that 90% of car accidents can be avoided if drivers can respond within 2-3 seconds before the accidents happen. This paper proposes a speed warning scheme for heavy-duty vehicle over the horizon in mountainous area, which can give the drivers enough time to respond to the danger. In the early warning aspect, this system combines the front road information, the vehicle characteristics and real-time information obtained from the vehicle, calculates and forecasts the danger that may happen over the horizon ahead of time, and prompts the driver to control the vehicle speed.
Technical Paper

Safe Travelling Speed of Commercial Vehicles on Curves Based on Vehicle-Road Collaboration

2017-03-28
2017-01-0080
Mountain road winding and bumpy, traffic accidents caused by speeding frequently happened, mainly concentrated on curves. The present curve warning system research are based on Charge-coupled Device, but the existing obstacles, weather , driving at night and road conditions directly affect the accuracy and applicability. The research is of predictability to identify the curves based on the geographic information and can told the driver road information and safety speed ahead of the road according to the commercial vehicle characteristic of load, and the characteristics of the mass center to reduce the incidence of accidents. In this paper, the main research contents include: to estimate forward bend curvature through the node classification method based on the digital map.
Technical Paper

Co-simulation Based Hydraulic Retarder Braking Control System

2009-10-06
2009-01-2907
Hydraulic retarder has been widely applied on military vehicles and heavy commercial vehicles because of it could provide great brake torque and has lasting working time [1]. In order to reduce driver's frequent actions in braking process and prevent hydraulic retarder system from overheating, it is need to apply constant braking torque control, this control target has a strict requirement to hydraulic control system design. Many parameters often require repeated test to determine, which increases the R&D cost and extends the research cycle. This paper tries to find a time-efficient research method of hydraulic retarder control system through studying on a heavy military vehicle hydraulic retarder system. Hydraulic retarder model is set up through test data. The hydraulic control system is built based on AMESim. Controller model is set up based on PID control. The whole vehicle brake model is built based on MATLAB/Simulink.
Technical Paper

Research on Road Simulator with Iterative Learning Control

2009-10-06
2009-01-2908
Road simulation experiment in laboratory is a most important method to enhance the design quality of vehicle products. Presently, two main control techniques for road simulation—remote parameter control (RPC) and minimum variance adaptive control—are both defective: the former becomes an open-loop control after generating the drive signals, however the latter is essentially a kind of gradual control. To realize the closed-loop control and increase the control quality, this article brings forward a PID open-closed loop control method. Firstly taking the original road simulator as a group to identify, a nonlinear autoregressive moving average (NARMA) model was built with the dynamic neural network. Subsequently, this plant model was used to build the open-closed loop control system mentioned above. In the closed-loop a discrete PID controller was introduced to stabilize the system, while a P-type iterative learning control (ILC) was adopted to increase the control quality.
Journal Article

Boiling Coolant Vapor Fraction Analysis for Cooling the Hydraulic Retarder

2015-04-14
2015-01-1611
The hydraulic retarder is the most stabilized auxiliary braking system [1-2] of heavy-duty vehicles. When the hydraulic retarder is working during auxiliary braking, all of the braking energy is transferred into the thermal energy of the transmission medium of the working wheel. Theoretically, the residual heat-sinking capability of the engine could be used to cool down the transmission medium of the hydraulic retarder, in order to ensure the proper functioning of the hydraulic retarder. Never the less, the hydraulic retarder is always placed at the tailing head of the gearbox, far from the engine, long cooling circuits, which increases the risky leakage risk of the transmission medium. What's more, the development trend of heavy load and high speed vehicle directs the significant increase in the thermal load of the hydraulic retarder, which even higher than the engine power.
Technical Paper

Analysis of Passive Low Power Phase Change Heat Dissipation Method for Electric Vehicle Motor

2019-04-02
2019-01-1256
The electric vehicle motor is developing toward high power density, at the same time brings serious temperature rise problem, which affect the driving motor performance, efficiency, and useful life. Liquid cooling is usually used to solve the problem, but its energy consumption is large and the reliability is poor. In order to solve this problem, this paper proposes a heat dissipation method to improve the reliability and energy efficiency of the driving motor heat dissipation system. The method uses heat pipes heat transfer, and the heat pipes cold end are cooled by vehicle facing the wind. By establishing the motor temperature rise model, heat transfer model and vehicle dynamics model, this paper analyzes the maximum temperature region and reliability of the driving motor heat dissipation system, calculates and analyzes the efficiency of the driving motor under different driving conditions.
Technical Paper

Relationship between Braking Force and Pedal Force of a Pedal Controlled Parallelized Energy-Recuperation Retarder System

2014-04-01
2014-01-1783
Focusing the vehicle riding safety and global environmental problems, plenty of solutions on vehicle braking systems appeals during the recent period. Criteria and standards set up for commercial vehicles which should have equipped assisted braking systems were established by amounts of governments. Since eddy current retarders plays an important role in the area of assisted braking system, this article presents an energy-recuperation retarder, which is parallel connected with the driveline through a planet gear system. This paper offers a particular Energy-Recuperation Eddy Current Retarder (ERECR) system with a pedal control system and its characteristics is presented, either. Initially, the constitution of the energy-recuperation eddy current retarder system is established whereas the working principle of the energy-recuperation eddy current retarder is presented by modeling the system and simulation.
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