• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.4
• /
• pp.84-90
• /
• 2022

In this study, the acceleration performance improvement was analyzed for a 2-speed transmission applied EV. An EV simulator was developed to analyze the EV acceleration performance. The EV simulator includes a load transfer model between the front and rear. Thus, the EV simulator can analyze the acceleration performance difference between the front-and rear-wheel drive EVs. From the simulation results, it is deduced that the acceleration performance can be improved by 7.96% for the front-wheel drive EV and 16.10% for the rear-wheel drive EV. The 2-speed transmission can improve the acceleration performance without decreasing its maximum velocity. Moreover, the 2-speed transmission can improve the acceleration performance of the rear wheel drive more than that of the front-wheel drive EV.

• International Journal of Automotive Technology
• /
• v.4 no.3
• /
• pp.109-117
• /
• 2003

The analysis and evaluation of the transient performance by the transient response specifications under various acceleration speeds and types based on driver's typical acceleration habit are implemented by the experimental study to provide the appropriate direction for the transient control in a gasoline engine. The concept of the transient response specifications which consist of delay time, rising time, maximum overshoot and settling time, and the analysis method using them are introduced to evaluate the characteristics of the transient performance quantitatively. Furthermore four acceleration speeds and four acceleration types are set respectively to realize the various transient states which are similar to the real drive. Several performance parameters in terms of engine speed, manifold absolute pressure, fuel injection duration and air excess ratio are measured simultaneously during the various acceleration using a throttle actuator controlled by a PC. The transient response specifications characterized well the transient performance for the various acceleration speed and types quantitatively. Delay and rising time with increment of the acceleration speed became shorter, but settling time did longer. Intensified acceleration type appeared to be the most economical in view of fuel consumption, and linear acceleration type was found to have the least harmful emission concentration.

• Journal of Advanced Marine Engineering and Technology
• /
• v.24 no.1
• /
• pp.75-81
• /
• 2000

To provide the appropriate direction for development of transient control in a gasoline engine, transient performance analysis and evalution under four accelerating types based on typical driver's acceleration type were implemented by experimental study. In order to evaluate the characteristics of transient performance quanititatively, the concept and method by transient response specifications were introduced. Several performance parameters in terms of engine speed(RPM), manifold absolute pressure(MAP), fuel injection duration($\DeltatI_{nj}$) and air excess ratio($\lambda$) were emasured simultaneously during the four types of the throttle valve opening with the step motor controlled by PC. The result showed that transient response specifications in terms of delay time, rising time and settling time characterized the transient performance for four acceleration types quantitatively. Intensified acceleration type was most economical and linear acceleration type revealed the best emission performance.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.13 no.1
• /
• pp.794-803
• /
• 2021

The instantaneous acceleration affects the performance of the water-jet pump obviously. Here, based on the user-defined function, the method to simulate the inner flow in water-jet pumps under acceleration conditions was established. The effects of two different acceleration modes (linear acceleration and exponential acceleration) and three kinds of different acceleration time (0.5s, 1s and 2s) on the performance of the water-jet pump were analyzed. The results show that the thrust and the pressure pulsation under exponential acceleration are lower than that under linear acceleration at the same time; the vapor volume fraction in the impeller under linear acceleration is 27.3% higher than that under exponential acceleration. As the acceleration time increases, the thrust gradually increases and the pressure pulsation amplitude at the impeller inlet and outlet gradually decreases, while the law of pressure pulsation is the opposite at the diffuser outlet. The main frequency of pressure pulsation at the impeller outlet is different under different acceleration time. The research results can provide some reference for the optimal design of water-jet pumps.

• Journal of Advanced Marine Engineering and Technology
• /
• v.24 no.6
• /
• pp.110-119
• /
• 2000

In this paper, an experimental study is carried out under the operating conditions of low speed and rapid acceleration in order to investigate and improve the response characteristics of a turbocharged diesel engine with radial turbine driven by exhaust gas. A rapid acceleration for investigating the response performance is applied to the fuel-pump rack of the engine from 0-10% to 0-40% in steps of 10%, and accelerating time of 1, 2 and 3 seconds is applied to the engine. Further experiment for improving the low speed torque and acceleration performance is also performed by means of injecting air into the inlet manifold at compressor exit during the period of low speed and application of a rapid acceleration. The effects of air injection on the response performance are represented at subjected engine speed with the changes of response performance factors such as air injection pressure, air injection period, accelerating rate, accelerating time and load. From the experimental results obtained throughout this study, it is shown that air injection into the inlet manifold at compressor exit is closely related to the improvement of low speed and acceleration performance of a turbocharged diesel engine.

• Smart Structures and Systems
• /
• v.20 no.2
• /
• pp.197-205
• /
• 2017

The dynamic performance of railway bridges under high-speed trains draws the attention of bridge engineers. The vibration issue for long-span bridges under high-speed trains is still not well understood due to lack of validations through structural health monitoring (SHM) data. This paper investigates the correlation between bridge acceleration and train speed based on structural dynamics theory and SHM system from three foci. Firstly, the calculated formula of acceleration response under a series of moving load is deduced for the situation that train length is near the length of the bridge span, the correlation between train speed and acceleration amplitude is analyzed. Secondly, the correlation scatterplots of the speed-acceleration is presented and discussed based on the transverse and vertical acceleration response data of Dashengguan Yangtze River Bridge SHM system. Thirdly, the warning indexes of the bridge performance for correlation scatterplots of speed-acceleration are established. The main conclusions are: (1) The resonance between trains and the bridge is unlikely to happen for long-span bridge, but a multimodal correlation curve between train speed and acceleration amplitude exists after the resonance speed; (2) Based on SHM data, multimodal correlation scatterplots of speed-acceleration exist and they have similar trends with the calculated formula; (3) An envelope line of polylines can be used as early warning indicators of the changes of bridge performance due to the changes of slope of envelope line and peak speed of amplitude. This work also gives several suggestions which lay a foundation for the better design, maintenance and long-term monitoring of a long-span high-speed bridge.

• Smart Structures and Systems
• /
• v.23 no.1
• /
• pp.71-79
• /
• 2019

In general, it may be advantageous to measure the pressure pulsation near a valve to detect a valve defect in a linear compressor. However, the acceleration signals are more advantageous for rapid classification in a mass-production line. This paper deals with the performance improvement of fault classification using only the compressor-shell acceleration signal based on the relation between the refrigerant pressure pulsation and the shell acceleration of the compressor. A transfer function was estimated experimentally to take into account the signal noise ratio between the pressure pulsation of the refrigerant in the suction pipe and the shell acceleration. The shell acceleration signal of the compressor was modified using this transfer function to improve the defect classification performance. The defect classification of the modified signal was evaluated in the acceleration signal in the frequency domain using Fisher's discriminant ratio (FDR). The defect classification method was validated by experimental data. By using the method presented, the classification of valve defects can be performed rapidly and efficiently during mass production.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1853-1857
• /
• 2005

In most of motor-driven motion control systems, an encoder is used to measure a position of the motor and the velocity information is obtained by measuring the position increment over a sampling period. The quantization effect due to limited resolution of the encoder induces some measurement errors, and consequently causes deterioration of the motion performance especially in low velocity. In this paper, we propose a gain-scheduled acceleration estimator which works in wider velocity range than the original acceleration estimator. We investigate and analyze characteristics of the velocity measurement mechanism which takes into account the quantization effect of the encoder. Next, we introduce the acceleration estimator and propose a gain-scheduled acceleration estimator. The bandwidth of the gain-scheduled acceleration estimator is automatically adjusted by the velocity command. Finally, its performance is evaluated by simulation and experiment, and the results are compared with those of a conventional method and the original acceleration estimator.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.41 no.5
• /
• pp.562-572
• /
• 1992

In this paper, we propose software algorithms which provide acceleration/deceleration characteristics essential to high dynamic performance at the transient states where industrial robots or CNC machine tools start and stop. Software acceleration/deceleration methods are derived from the mathematical analyses of typical hardware systems controlling acceleration/deceleration. These methods make servo motors, which drive axes of motion, start and stop smoothly without vibration in the repeated tools. The path error, which is one of the most significant factors in the performance evaluation of industrial robots or CNC machine tools, is analyzed for linear, exponential, and parabolic acceleration/deceleration algorithms in case of circular interpolation. The analyses show that path error consists of the distance between the required path and generated one through acceleration/deceleration, and that between the generated one through acceleration/deceleration algorithm and the actual one of the end effector of the industrial robot or tool of the CNC equipment.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1860-1863
• /
• 1997

Transfer alignement is the process of initializing attitude of slave INS using the data of master INS. This paper presents the performance analysis of transfer alignment at sea using convariance analysis method. Velocity & angle matching and angular rate & acceleration matching are used for analysis, and the performance of two matching methods are compared. We propose a new method for angular rate & acceleration matching. Under the assumption of accurate modeling of ship flexure, the performance of transfer alignment time and accuray is improved very much for the new method.