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Technical Paper

CATARC New Type Drivetrain NVH Test Facility

2019-04-02
2019-01-0788
A vehicle’s NVH performance has a significant impact on the user experience of the driver and passengers. About one-third of the vehicle complaints are related to NVH performance. As the core component of the vehicle, the drivetrain’s NVH characteristics have a significant impact on vehicle comfort. How to reliably and stably reproduce the specific condition of the whole vehicle through the test method, and obtain the highly consistent objective data for analyzing and improving the NVH characteristics of the drivetrain is of great significance in engineering. For this purpose, China Automotive Technology Research Center Co., Ltd. (CATARC) designed and built a new type drivetrain NVH test facility, which consists of five dynamometers, and can carry horizontal/vertical, front/rear drive or four-wheel drive structures including powertrain, transmission, and rear axle, or even a whole vehicle.
Technical Paper

Calculation and Analysis of Stiffness of Taper-Leaf Spring with Variable Stiffness

2014-04-01
2014-01-0929
Aiming at the difficulty of sovling the stiffness calculation of taper-leaf spring with variable stiffness, a combined method was proposed, which combine superposition method and finite difference method. Then the calculation results of different differential segments were compared with experimental results. The compared results show that the proposed method is effective and simple. So it has some practical significance in designing the taper-leaf spring. In addition, based on the stiffness test of the taper-leaf spring, the proper adjustments to the correction factor of the single parabolic leaf spring stiffness formula was recommended(ξ =0.92-0.96).
Technical Paper

Characteristics of Particulate Emissions Fueled with LPG and Gasoline in a Small SI Engine

2004-10-25
2004-01-2901
This paper presents experimental studies of particulate emissions in a small SI engine fueled with LPG and gasoline fuels. A single cylinder, four-stroke, water-cooled, 125cc EFI engine with gasoline fuel is used as the baseline engine. Characteristics of the particulate emissions of the two fuels are compared. Test results show that: there are great quantities of particulate emissions for both fuels, but the total numbers of particulate emissions for the two fuels are generally in the same level. The distribution of the particulate sizes is in bimodal type for the gasoline, but for the LPG its first peak is not markedly in some conditions. The particulate sizes of the second peak for the two fuels appear at about the same size. At middle loads and 3000r/min, the particulate emissions for both of the two fuels are the greatest.
Technical Paper

Chassis Tuning Study of a Commercial Vehicle

2015-03-10
2015-01-0016
This paper presents the study of chassis tuning of a commercial vehicle, which has a rear suspension with dual stage leaf spring assembly and a front suspension with double wishbone torsion bar. To balance the handling and ride performance of the vehicle, it is necessary to tune the key suspension parameters of the chassis including the dual stage stiffness of the leaf spring, the contact load of the leaf spring, the torsional rigidity of the torsion bar, the force curve of the front and rear dampers etc. The chassis tuning process of a physical commercial vehicle was first put forward. In the proposed flowchart, the kinematics and statics of front & rear suspensions were checked at the beginning of the tuning. Then the tire mechanical characteristics were tested by using a plate-type tire tester and the inertial parameters of the vehicle were indirectly measured. The K&C characteristics of front and rear suspensions were also tested and compared with the benchmark vehicle's.
Technical Paper

Co-Simulation Research of Integrated Electro-Hydraulic Braking System

2016-04-05
2016-01-1647
A program of integrated electro-hydraulic braking system is proposed, and its structural composition and working principle are analyzed. According to the structural and mechanical characteristics of all key components, through some reasonable assumptions and simplifications, a motor, a brake master cylinder, four brake wheel cylinders, solenoid valves and an ESP (Electronic Stability Program) algorithm model is set up and simulations of typical braking conditions are carried out based on the Matlab/Simulink. Finally, after the assembly of each sub-model is complete and combining a vehicle which is set up in CarSim software environment, simulation tests and comprehensive performance analysis of the active safety stability control for a vehicle in double lane change and single lane change situations are carried out respectively. According to the dynamic characteristic curves of system, the effects of different structural and control parameters on braking performance are analyzed.
Technical Paper

Combined Control Strategy for Engine Rotate Speed in the Shift Process of Automated Mechanical Transmission

2004-03-08
2004-01-0427
For the purpose of lessening fuel consumption, engine noise, shift jerk and clutch friction work in the shift process of Automatic Mechanical Transmission (AMT), a fuzzy-bang bang dual mode control strategy for engine rotate speed is put forward in this paper, which takes the advantages of time optimal control and fuzzy control. The combined control strategy is applied to the shift process control of AMT test minibus named SC6350 and proved to be successful by the experimental results.
Technical Paper

Combustion and Emissions Characteristics of a Small Spark-Ignited LPG Engine

2002-05-06
2002-01-1738
This paper presents an experimental study of the emission characteristics of a small Spark-Ignited, LPG engine. A single cylinder, four-stroke, water-cooled, 125cc SI engine for motorcycle is modified for using LPG fuel. The power output of LPG is above 95% power output of gasoline. The emission characteristics of LPG are compared with the gasoline. The test result shows that LPG for small SI engine will help to reduce the emission level of motorcycles. The HC and CO emission level can be reduced greatly, but NOx emissions are increased. The emission of motorcycle using LPG shows the potential to meet the more strict regulation.
Technical Paper

Combustion and Emissions of Ethanol Fuel (E100) in a Small SI Engine

2003-10-27
2003-01-3262
An air-cooled, four-stroke, 125 cc electronic gasoline fuel injection SI engine for motorcycles is altered to burn ethanol fuel. The effects of nozzle orifice size, fuel injection duration, spark timing and the excess air/ fuel ratio on engine power output, fuel and energy consumptions and engine exhaust emission levels are studied on an engine test bed. The results show that the maximum engine power output is increased by 5.4% and the maximum torque output is increased by 1.9% with the ethanol fuel in comparison with the baseline. At full load and 7000 r/min, HC emission is decreased by 38% and CO emission is decreased 46% on average over the whole engine speed range. However, NOx levels are increased to meet the maximum power output. The experiments of the spark timing show that the levels of HC and NOx emission are decreased markedly by the delay of spark timing.
Technical Paper

Commercial Vehicles Thrust Rod Static and Dynamic Characteristics Analysis

2016-10-17
2016-01-2345
In order to study the static and dynamic characteristics of the thrust rod. Based on the multi-body dynamics theory, the dynamic model of the thrust rod and the vehicle system is established by using ADAMS software. The limit braking condition is simulated, and the limit braking load of the thrust rod is obtained. Thrust rod finite element model is established, the load calculation value and rubber test data as a finite element analysis of input conditions, using ABAQUS software to carry on the stiffness and strength analysis, analysis results show that the strength meets the requirement, and the stiffness and strength calculation result is in good agreement with the sample test, accurately describes the finite element model. The analytical method used can be used to predict the stiffness of the thrust rod.
Technical Paper

Comparative Analysis of Truck Ride Comfort of 4 Degree of Freedom Rigid-Elastic Model with 2 Degree of Freedom Rigid Model

2015-04-14
2015-01-0615
In order to study the influence of body flexibility on the truck ride comfort, a 4 DOF half vibration model of truck based on the motion synthesis between rigid body and body flexibility is established using elastic beam theory of equal section with both free ends. At the same time, a corresponding 2 DOF rigid vibration model is also built. The frequency response functions of system and response variables of two models are derived based on front wheel. The power spectral densities and the root mean square values of body acceleration, dynamic deflections and relative dynamic loads are obtained. By comparing the simulation results of rigid-elastic model and rigid model, it shows that body flexibility has a great impact on truck ride comfort and it cannot be ignored.
Technical Paper

Computational Accuracy and Efficiency of the Element Types and Sizes for Car Acoustic Finite Element Model

2014-04-01
2014-01-0890
Automobile cabin acoustical comfort is one of the main features that may attract customers to purchase a new car. The acoustic cavity mode of the car has an effect on the acoustical comfort. To identify the factors affecting computing accuracy of the acoustic mode, three different element type and six different element size acoustic finite element models of an automobile passenger compartment are developed and experimentally assessed. The three different element type models are meshed in three different ways, tetrahedral elements, hexahedral elements and node coupling tetrahedral and hexahedral elements (tetra-hexahedral elements). The six different element size models are meshed with hexahedral element varies from 50mm to 75mm. Modal analysis test of the passenger car is conducted using loudspeaker excitation to identify the compartment cavity modes.
Technical Paper

Control Optimization of a Charge Sustaining Hybrid Powertrain for Motorsports

2018-04-03
2018-01-0416
The automotive industry is aggressively pursuing fuel efficiency improvements through hybridization of production vehicles, and there are an increasing number of racing series adopting similar architectures to maintain relevance with current passenger car trends. Hybrid powertrains offer both performance and fuel economy benefits in a motorsport setting, but they greatly increase control complexity and add additional degrees of freedom to the design optimization process. The increased complexity creates opportunity for performance gains, but simulation based tools are necessary since hybrid powertrain design and control strategies are closely coupled and their optimal interactions are not straightforward to predict. One optimization-related advantage that motorsports applications have over production vehicles is that the power demand of circuit racing has strong repeatability due to the nature of the track and the professional skill-level of the driver.
Technical Paper

Control Strategy of Hybrid Electric Vehicle with Double Planetary Gear Sets

2015-04-14
2015-01-1216
Hybrid Electric Vehicles with a power split system provide a variety of possibilities to promote the fuel economy of vehicles and better adapt to various driving conditions. In this paper, a new power split system of a hybrid electric bus which consists of double planetary gear sets and a clutch is introduced. The system is able to decouple both the torque and speed of the engine from the road load, which makes it possible for the engine to operate on its optimal operation line (OOL). Considering the features of the system configuration and bus driving cycle, the driving mode of the bus is divided into Electric Vehicle (EV) mode, Electric Variable Transmission (EVT) mode and Parallel mode. By controlling the engagement of the clutch at high vehicle speed (after the mechanical point), the system operates in the parallel mode rather than EVT mode. This avoids the problem that the system efficiency sharply declines in high speed region which EVT configurations are generally faced with.
Technical Paper

Control Synthesis for Distributed Vehicle Platoon Under Different Topological Communication Structures

2019-04-02
2019-01-0494
The wireless inter-vehicle communication provide a manner to achieve multi-vehicle cooperative driving, and the platoon of automotive vehicle can significantly improve traffic efficiency and ensure traffic safety. Previous researches mostly focus on the state of the proceeding vehicle, and transmit information from self to the succeeding vehicle. Nevertheless, this structure possesses high requirements for controller design and shows poor effect in system stability. In this paper, the state of vehicles is not only related to the information of neighbor vehicles, while V2V communication transmit information over a wide range of area. To begin with, the node dynamic model of vehicle is described by linear integrator with inertia delay and the space control strategy is proposed with different topological communication structures as BF, LBF, PBF, etc.
Journal Article

Cooperative Optimization of Vehicle Ride Comfort and Handling Stability by Integrated Control Strategy

2012-04-16
2012-01-0247
Vehicle needs suspension and steering systems with different features to fit different driving conditions. In normal straight driving condition, soft suspension and heavy steering systems are needed to achieve better ride comfort and straight line driving stability; in turning conditions, hard suspension and lightweight steering systems are needed to get better handing stability. The semi-active suspension system with Magneto-Rheological dampers can improve the ride comfort and handling performance of vehicle. Electrical power steering system is developed rapidly due to its portable and flexible operations as well as stable steering performance.
Technical Paper

Design and Control of Torque Feedback Device for Driving Simulator Based on MR Fluid and Coil Spring Structure

2018-04-03
2018-01-0689
Since steering wheel torque feedback is one of the crucial factors for drivers to gain road feel and ensure driving safety, it is especially important to simulate the steering torque feedback for a driving simulator. At present, steering wheel feedback torque is mainly simulated by an electric motor with gear transmission. The torque response is typically slow, which can result in drivers’ discomfort and poor driving maneuverability. This paper presents a novel torque feedback device with magnetorheological (MR) fluid and coil spring. A phase separation control method is also proposed to control its feedback torque, including spring and damping torques respectively. The spring torque is generated by coil spring, the angle of coil spring can be adjusted by controlling a brushless DC motor. The damping torque is generated by MR fluid, the damping coefficient of MR fluid can be adjusted by controlling the current of excitation coil.
Journal Article

Design and Position Control of a Novel Electric Brake Booster

2018-04-03
2018-01-0812
The electric vehicles and the intelligent vehicles put forward to new requirements for the brake system, such as the vacuum-independent braking, automatic or active braking, and regenerative braking, which are the key link for the vehicle’s safety and economy. However, the traditional vacuum brake booster is no longer able to meet these requirements. In this article, a novel integrated power-assisted actuator of brake system is proposed to satisfy the brake system requirements of the electric vehicles and intelligent vehicles. The electronic brake booster system is designed to achieve the function of boosting pedal force of driver, being independent on vacuum source, supplying autonomous or active braking. It is mainly composed of a permanent magnet synchronous motor (PMSM), a two-stage reduction transmission (gears and a ball screw), a servo body, and a reaction disk. The scheme design and power-assisted braking control are the key for the electronic actuator.
Journal Article

Design and Power-Assisted Braking Control of a Novel Electromechanical Brake Booster

2018-04-03
2018-01-0762
As a novel assist actuator of brake system, the electromechanical brake (EMB) booster has played a significant role in the battery electric vehicles and automatic driving vehicles. It has advantages of independent to vacuum source, active braking, and tuning pedal feeling compared with conventional vacuum brake booster. In this article, a novel EMB booster system is proposed, which is consisted of a permanent magnet synchronous motor (PMSM), a two-stage reduction by gears and ball screw, a servo body, and a reaction disk. Together with the hydraulic control unit, it has two working modes: active braking for automatic drive and passive braking for driver intervention. The structure and work principle of the electric brake booster system is first introduced. The precise control from pedal force to hydraulic pressure is the key for such a power-assisted brake actuator. We translate the control problem of force feedback control to position tracking control.
Journal Article

Design of Anti-lock Braking System Based on Regenerative Braking for Distributed Drive Electric Vehicle

2018-04-03
2018-01-0816
In this article, the regenerative braking system is designed, which can realize the torque allocation between electric braking and hydraulic braking, where the cost function designed in this article considers factors of braking torque following effect, energy regenerative power, and hydraulic braking consumed power. In addition, a complete anti-lock braking system (ABS) is designed, which is based on regenerative braking. With the optimal slip ratio as control target, target wheel speed, control wheel speed, braking torque control strategy, and enable/disenable control logic of ABS are determined. By MATLAB/Simulink-DYNA4 co-simulation and real vehicle test, the feasibility and applicability of ABS based on regenerative braking are verified, under the condition of small severity of braking.
Technical Paper

Design of Automatic Parallel Parking System Based on Multi-Point Preview Theory

2018-04-03
2018-01-0604
As one of advanced driver assistance systems (ADAS), automatic parking system has great market prospect and application value. In this paper, based on an intelligent vehicle platform, an automatic parking system is designed by using multi-point preview theory. The vehicle kinematics model was established, based on Ackermann steering principle. By analyzing working conditions of parallel parking, complex constraint condition of parking trajectory is established and reference trajectory based on sine wave is proposed. In addition, combined with multi-point preview theory, the design of trajectory following controller for automatic parking is completed. The cost function is designed, which consider the trajectory following effect and the degree of easy handling. The optimization of trajectory following control is completed by using the cost function.
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