Today, conventional CVT equipped vehicle controls engine torque and gear ratio by using engine torque map and shifting map. But this control process is difficult to optimize the fuel economy when the driving mode is changed arbitrary. In this study, I propose the real-time CVT control with considering the power loss of transmission system to improve vehicle fuel economy and drivability. The driving performance and fuel economy of the proposed control logic is analyzed by backward simulation and the validity of new control logic is verified.
The vibration of wheel is mainly affected by a fault on a wheel contacting with railway when average speed is over 60km/h. When the wheel vibration caused by wheel scratch increase more than a certain criterion, the wheel is shaved to reduce the vibration. This criterion of shaving is determined from the acceleration signal measured from the sensor mounted on the railway. In this study, vibration characteristics of the rolling wheels having a fault is analyzed with experimental approach to verify the acceleration criterion for shaving wheel.
For driver convenience, different types of transmission are being developed, such as AT(Automatic Transmission), AMT(Automated Manual Transmission), CVT(Continuously Variable Transmission) and DCT(Dual Clutch Transmission). To improve ride comfort and durability of the transmission, control system is important during launching and shifting process. For accurate control, vehicle mass and road gradient should be known. In this study, heavy duty vehicle’s mass and road gradient estimation method is developed. The method uses only signals from CAN(Controller Area Network) without applying extra sensors. Vehicle mass and gradient is estimated by LMS(Least Mean Square) method based on longitudinal vehicle dynamic model. To verify the estimation logic, test was conducted using a chassis dynamometer. The estimation results after test and test condition is compared. The error rate of vehicle mass estimation was 5 percent and gradient estimation result had 2 percent error.
To overcome recent emission regulation, various hybrid systems are being developed. In the E-4WD(electric four wheel drive) system, the engine and transmission drive the front wheel, electric motor and single reduction gear drive the rear wheel. As the gear ratio of the reduction gear set determines the electric motor's operating point, the gear ratio is important to enhancement efficiency of hybrid system. This study is to analyze motor reduction gear ratio's influence on E-4WD hybrid system for optimized efficiency and driving performance. Fuel economy, operating point of power source and hybrid mode are analyzed using simulation developed with dynamic programming method.
Because of environmental pollution and lack of resources, necessity of energy efficiency improvement and reduction of exhaust gas emission and CO2 have grown in importance. Therefore a lot of studies are conducted for HEV(hybrid electric vehicle) and PHEV(plug-in hybrid electric vehicle). In addition, automobile companies are researching and manufacturing HEV and PHEV. Due to cost and time problem, simulation is preferred than experimental test to find better component size for efficiency improvement. In this research, backward simulation program is developed base on Dynamic Programming. Using this simulation program, fuel economy sensitivities for each parameter are analyzed and compared. Fuel economy is measured for a combined cycle that is calculated from FTP-75 and HWFET cycle. The target parameters are front/rear power train efficiency, drag coefficient, vehicle mass, rolling resistance coefficient, tire radius, center of gravity. The most sensitive parameter is front power train efficiency and second is drag coefficient. Rear power train efficiency, vehicle mass, rolling resistance coefficient are third, forth and fifth. By comparing sensitivities, we can choose a better way to improve fuel economy of HEV.
The major complaint of hybrid vehicle driver is that real fuel economy is lower than the certified fuel economy. Therefore, it is important to analyze the cause of low fuel economy and to improve the fuel consumption at real driving condition. In this study, the various speed profile is measured by driving urban road with considering different traffic jam. By using backward simulation, the fuel economy characteristics of the acquired driving modes are analyzed. From the simulation results, the operating points of engine and motor analyzed and the cause of decrease of real fuel economy is examined.
A part of engine torque is used to overcome the interior friction and to accelerate engine inertia. To enhance the driveability at the clutch slip control of AMT(Automated Manual Transmission) or parallel type hybrid system, it is important to know the exact drving torque of clutch. In this study, engine friction and rotational inertia are estimated by using LMS(Least Mean Square) method with vehicle test result. To verify the validity of method, the performance of vehicle is simulated with adjusted parameters. The test result and simulation result show the similar trend.
Because industrial Vehicles drive and work under heavy load condition, the gear ratio of transmission and the stall torque ratio of torque converter is high. Recently, to reduce the cost of vehicle, many people have interest in applying multi-phase torque converter to vehicle and reducing the gear step. In this study, the target performance of vehicle is analyzed and the performance matching of multi-phase torque converter is studied to equip torque converter to heavy duty folk lift vehicle.
Engine power of industrial vehicle is used to control the driving load, steering load and operating load. In other words, one power source need to transmit part of power through several power transmission paths. To achieve this performance, we consider a gear box which have one input shaft and several output shaft. In this study, the performance of gear box is analyzed to find out the reliable test process in dynamometer. With test results, the validity of study is verified.
The conventional shifting map is developed to enhance the driving performance and fuel economy. According to the driver’s pedaling of accelerator, TCU controls gear ratio in view point of economy or driving performance. In this paper, various reverse engineering is applied to the driving test results of heavy duty AMT vehicle. With the test results, the performance of propulsion source is estimated and basic performance of vehicle is analized. Also the method to derive the shifting schedule according to power or fuel efficient, is developed and compared with the actual shifting map, and various shifting states is estimated. The developed numerical analysis model will be a stepping stone for the shift pattern development and various shift control research
The aim of this study was to assess the effectiveness of group therapeutic exercise programs on the cognitive function, Activities of Daily Living (ADL), and balance-performing ability in older adults. Fifteen community-dwelling subjects (mean age 73.7 yrs, standard deviation 2.4) participated in this study. An 8-week group therapeutic exercise program, including strengthening and balance training, breathing and gait exercise, and recreation, consisted of activities related to daily living. The Mini-Mental State Examination-Korean (MMSE-K), Modified Barthel Index (MBI), Berg Balance Scale (BBS), Functional Reaching Test (FRT), and Timed Up & Go (TUG) test were measured during pre-exercise and post-exercise points. The results of this study were as follows: 1. After eight weeks, the MMSE-K and MBI total score was more significantly increased for post-exercise tests than pre-exercise tests (respectively, p<.05, p<.01). 2. Of the MBI contents, personal hygiene, dressing, ambulation, and chair/bed transfers scores were significant increased for post-exercise tests. 3. Post exercise BBS, FRT, and TUG scores were higher than the pre-exercise scores. The difference was statistically significant (respectively, p<.05, p<.05, p<.01). These findings suggest that group therapeutic exercise can be used to improve the cognitive function, ADL, and balance-performing ability in elderly persons.