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Technical Paper

Real-time and accurate estimation of road slope for intelligent speed planning system of commercial vehicle

2020-04-14
2020-01-0115
In the intelligent speed planning system, real-time estimation of road slope is the key to calculate slope resistance and realize the vehicles’ active safety control. However,if the road slope is measured by the sensor while the commercial vehicle is driving, the vibration of the vehicle body will affect its measurement accuracy. Therefore, the relevant algorithm is used to estimate the real-time slope of the road when the commercial vehicle is driving. At present, many domestic and foreign scholars have analyzed and tested the estimation of road slope by the least square method or kalman filter algorithm. Although the two methods both can achieve the estimation, the real-time performance and accuracy still need to be improved. In this paper, for traditional fuel commercial vehicle, the kalman filter algorithm based on the kinematics and the extended kalman filter algorithm based on the longitudinal dynamics are respectively used to estimate the road slope.
Technical Paper

Research on Correction Algorithm of Head-up Display System in Vehicle Vibration

2020-04-14
2020-01-1368
The HUD(Head Up Display) system can superimpose the driving assistance information on the reality to assist the driver in driving. However, when the road conditions are quite bad, the driving assistance information could not coincide well with the reality. This paper presents a correction algorithm for a heads up display system. The algorithm calculates the offset between the driving assistance information and the reality according to the unevenness of the road and the inclination of the vehicle, and then adjusts the position of the driving assistance information. In this paper, according to the unevenness of the road, the algorithm could confirm the tilt state of the vehicle and calculate the tilt angle of the vehicle. The offset of the driving assistance information is calculated according to the inclination angle of the vehicle, and then the position of the driving assistance information is adjusted to coincide with the reality.
Technical Paper

Parameter Optimization of Anti-roll Bar Based on Stiffness

2020-04-14
2020-01-0921
Anti-rolling bar is an important structural part of the automobile, which can effectively prevent the automobile from rolling and improve the safety of the vehicle during bending. In the design of the current anti-rolling bar, the stiffness of anti-rolling is determined based on experience or oversimplified mathematic model. In this paper, an anti-rolling bar is determined by 7 parameters, and forces in different directions and perpendicular to the bar are applied at both ends. The mathematical model of stiffness of anti-rolling bar is established by combining the Deformation Energy Theorem and Castigliano Theorem. Nonlinear programming and genetic algorithm are used to acquire the optimal solution and corresponding values of parameters of the mathematical model. Then, by means of partial least-squares regression method, the correlation of different parameters to the stiffness of anti-rolling bar is analyzed.
Technical Paper

A Pre-warning Method for Cornering Speed of Concrete Mixer Truck

2020-04-14
2020-01-1003
The high gravity center of the concrete mixer truck reduces the truck’s stability while steering, and the rolling stirring tank makes the stability even worse than the regular engineering vehicle due to the dynamic variation of centroid position. Most of the researches on the rollover stability of concrete mixer trucks focus on the rollover model establishment and dynamics simulation module. The influence of concrete centroid changes is ignored when the safe cornering speed is calculated. This paper proposes a pre-warning method for cornering speed of concrete mixer truck based on centroid dynamic simulation. In the method, the mixing tank stirring model and the vehicle driving dynamics model are established on the Fluent and TruckSim simulation platforms, respectively.The theoretical speed threshold obtained by simulation is used as the evaluation index of warning of the speed for steering. First, the dynamic simulation of the stirring tank model is carried out by Fluent.
Technical Paper

Kalman Filter Slope Measurement Method Based on Improved Genetic Algorithm- Back Propagation

2020-04-14
2020-01-0897
How to improve the measurement accuracy of road grade is the key content of the research on the speed warning of commercial vehicles in mountainous roads. If there is a large measurement error, the obtained speed threshold will be biased, posing a safety hazard. Conventional measuring instruments such as accelerometers and gyroscopes generally have noise fluctuation interference or time accumulation error, resulting in large measurement errors. In response to this situation, the Kalman filter method is often used for filtering to reduce the interference of unwanted signals, thereby improving the accuracy of the slope measurement. However, the Kalman filtering method is limited by the estimation error of various parameters, and the filtering effect is difficult to meet the project research requirements.
Technical Paper

Optimal Management of Charge and Discharge of Electric Vehicles Based on CAN Bus Communication

2020-04-14
2020-01-1297
With the shortage of energy and the continuous development of automotive technology, electric vehicles are gradually gaining popularity. However, during the running of the electric vehicle, there is a risk of exhaustion of the electric power, and the position of the charging pile is fixed, which is likely to cause anxiety and worry of the owner. At present, there is a lack of an effective energy consumption prediction system, which is convenient for the driver to make reasonable driving planning guidance. As a standard serial communication protocol of ISO, CAN bus has a simple structure, short development cycle, stability and reliability. In this paper, the CAN bus is used to extract the dynamic parameter information of the speed, engine speed and throttle opening of the traveling vehicle in real time.
Technical Paper

Research on Solar Thermal Energy Warming Diesel Engine Based on Reverse Heat Transfer of Coolant

2020-04-14
2020-01-1343
In winter, the temperature of the coldest month is below -20℃.Low temperature makes it difficult to start a diesel engine, combust sufficiently, which increases fuel consumption and pollutes the environment. The use of electric power-driven auxiliary heating system increases the battery load and power consumption. Solar thermal energy has the advantages of easy access, clean and pollution-free. The coolant in the cylinder block of the diesel engine has a large contact area with the cylinder and is evenly distributed, which can be used as a heat transfer medium for warming up. A one-dimensional heat transfer model of the diesel engine block for the reverse heat transfer of the coolant is established, and the total heat required for the warming up is calculated by an iterative method in combination with the warming target.
Technical Paper

Parameter Optimization of Two-speed AMT Electric Vehicle Transmission System

2020-04-14
2020-01-0435
At present, small electric vehicles are often equipped with only a single-stage final drive. Although the single-stage speed ratio can meet the general driving requirements of electric vehicles, if the requirements of the maximum speed and the requirements for starting acceleration or climbing are met at the same time, the power demand of the drive motor is relatively large, and the efficient area of the drive motor may be far away from the operating area corresponding to daily driving. If the two-speed automatic transmission is adopted, the vehicle can meet the requirements of maximum speed, starting acceleration and climbing at the same time, reduce the power demand of the driving motor, and improve the economy under certain power performance. This is especially important for medium and large vehicles.
Technical Paper

Downhill Safety Assistant Driving System for Battery Electric Vehicles on Mountain Roads

2019-09-15
2019-01-2129
When driving in mountainous areas, vehicles often encounter downhill conditions. To ensure safe driving, it is necessary to control the speed of vehicles. For internal combustion engine vehicles, auxiliary brake such as engine brake can be used to alleviate the thermal load caused by the continuous braking of the friction brake. For battery electric vehicles (BEVs), regenerative braking can be used as auxiliary braking to improve brake safety. And through regenerative braking, energy can be partly converted into electrical energy and stored in accumulators (such as power batteries and supercapacitors), thus extending the mileage. However, the driver's line of sight in the mountains is limited, resulting in a certain degree of blindness in driving, so it is impossible to fully guarantee the safety and energy saving of downhill driving.
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

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

Energy Consumption Optimization for the Electric Vehicle Air Conditioning Using the Condensate Water

2019-04-02
2019-01-0148
In summer, the relatively low temperature water condenses in the evaporator when the vehicle air-conditioning (AC) is running. At present, the vehicle AC condensate water without well utilization is directly wasted. The condenser’s thermal transfer performance has a great influence on the AC performance, and to increase the convective heat transfer coefficient (CHTC) is the key to its design. In this paper, a method of using atomized condensate water (CW) to enhance the condenser’s thermal transfer performance is proposed, which can make the most of the CW's cold energy. It achieves the reuse of CW and increases the condenser’s CHTC. First, the CW flow calculation model in the evaporator and the calculation model of the condenser enhanced thermal transfer using atomized CW are both set up. The influence of the evaporation degree of atomized CW particles in the air on the enhancement effect is comprehensively considered.
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

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 Measures of Improving Power Generation Stability for Harvesting Automobile Exhaust Energy

2018-04-03
2018-01-1367
The automobile exhaust energy can be recovered by the thermoelectric module generator(TEG). Owing to the complex urban traffic, the exhaust gas’s temperature fluctuations are resulted, which means the unstable hot-end temperature of the TEG. By installing solid heat capacity material(SHCM) to the area between the outer wall of the exhaust pipe and the TEG, it is possible to appropriately reduce the temperature fluctuation, but there is still a fluctuation of the TEG’s power output. Then by adding voltage filter circuit (VFC) after the TEG, the power output stability can be improved. This research uses SHCM and VFC to improve the stability of the exhaust gas generation. Firstly, the three-dimensional heat transfer model of the exhaust pipe thermoelectric power generation system is established. The heat capacity materials with low thermal resistance and high heat capacity were selected as the research object based on previous research.
Technical Paper

Simulation Research of a Hydraulic Interconnected Suspension Based on a Hydraulic Energy Regenerative Shock Absorber

2018-04-03
2018-01-0582
The current paper proposes a hydraulic interconnected suspension system (HIS) based on a hydraulic energy-regenerative shock absorber (HESA) comparatively with the passive suspensions. The structure and working principles of the HIS system are introduced in order to investigate the damping performance and energy regeneration characteristics of the proposed system. Then, the dynamic characteristics of the HIS-HESA system have been investigated based on a 4-DOF longitudinal half vehicle model. In the simulation, two different road inputs were used in the dynamic characterization of the HIS-HESA; the warp sinusoidal excitation, and the random road signal. In addition, a comparative analysis was provided for the dynamic responses of the half vehicle model for both the HIS-HESA and the conventional suspension. Furthermore, a parametric analysis of the HIS-HESA has been carried out highlining the key parameters that have a remarkable effect on the HIS-HESA performance.
Technical Paper

Battery Thermal Management System Using Water as a Phase Change Material

2017-10-08
2017-01-2454
In these years, the advantages of using phase change material (PCM) in the thermal management of electric power battery has been wide spread. Because of the thermal conductivity of most phase change material (eg.wax) is low, many researchers choose to add high conductivity materials (such as black lead). However, the solid-liquid change material has large mass, poor flow-ability and corrosively. Therefore, it still stays on experiential stage. In this paper, the Thermal characteristics of power battery firstly be invested and the requirements of thermal management system also be discussed. Then a new PCM thermal management has been designed which uses pure water as liquid phase change material, adopts PCM with a reflux device for thermal management.
Technical Paper

The Research of the Heavy Truck’s Warming System

2017-10-08
2017-01-2221
It’s not easy to start the engine in winter, especially in frigid highlands, because the low temperature increases the fuel’s viscosity, decreasing the lubricating oil flow ability and the storage performance of battery. Current electrical heating method can improve the engine starting performance in low temperature condition, but this method adds an external power to the engine, leading to the engine cannot maintain an efficient energy utilization. A warming device using the solar energy is designed to conserve the energy during the daytime, and directly warm up the engine at the time when the engine turns off for a long time, especially during the night. A solar collector installed on the top of the vehicle is used to convert the solar energy to the thermal energy, which is then transferred to the heat accumulator that contain the phase-change medium which can increase the heat storage performance.
Technical Paper

Effect of Temperature on Braking Efficiency Stability of Magnetorheological Fluid Auxiliary Braking Devices

2017-09-17
2017-01-2510
Fluid auxiliary braking devices can provide braking torque through hydraulic damping, fluid auxiliary braking devices can also convert vehicular inertia energy into transmission fluid heat energy during the braking, which can effectively alleviate the work pressure of the main brake. Traditional hydraulic auxiliary braking devices use transmission fluids to transmit torque, however, there is a certain lag effect during the braking. The magnetorheological fluid (MR fluid) can also be used to transmit torque because it has the advantages of controlling braking torque linearly and responding fast to the magnetic field changed. The temperature of MR fluid will increase when the vehicle is engaged in continuous braking. MR fluid temperature changes will cause a bad influence on the efficiency stability of auxiliary braking.
Technical Paper

Brake Guidance System for Commercial Vehicles with Coordinated Friction and Engine Brakes

2017-09-17
2017-01-2508
Using friction brakes for long time can increase easily its temperature and lower vehicle brake performance in the downhill process. The drivers' hysteretic perception to future driving condition could mislead them to stop untimely the engine brake, and some other auxiliary braking devices are designed to increase the brake power for reduction of the friction brake torque. The decompression engine brake has complex structure and high cost, and the application of eddy current retarder or hydraulic retarder on the commercial vehicles is mainly limited to their cost and mass. In this paper, an innovative brake guidance system for commercial vehicles with coordinated friction brakes and engine brake is introduced to guide the drivers to minimize the use of the friction brakes on the downhill with consideration of future driving conditions, which is aimed at releasing the engine brake potential fully and controlling the friction brake temperature in safe range.
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