Automotive Science and Engineering

Automotive Wheel Optimization to Enhance the Fatigue Life

Javad Marzbanrad

Nowadays, lightweight automotive component design, regarding fuel consumption, environmental pollutants and manufacturing costs, is one of the main issues in the automotive societies. In addition, considering safety reasons, the durability of the automotive components, as one of the most important design requirements should be guaranteed. In this paper, a two-step optimization process including topology and shape optimization of an automotive wheel, as one of the most significant chassis components, is studied. At first, topology optimization method with volume and fatigue life constraints is used to obtain the optimal initial lightweight design, followed by shape optimization technique to improve the fatigue life. The results show 31.841% weight and 33.047% compliance reduction by topology and also 652.33% average minimum fatigue life enhancement, by the shape optimization. Therefore, the proposed two-step optimization method is qualified in designing the lightweight automotive wheel. The method used in this study can be a reference for optimization of other mechanical components.

Improved Knock Detection Method Based on New Time-Frequency Analysis In Spark Ignition Turbocharged Engine

Majid Shalchian

Premature combustion that affects outputs, thermal efficiencies and lifetimes of internal combustion engine is called “knock effect”. However knock signal detection based on acoustic sensor is a challenging task due to existing of noise in the same frequency spectrum. Experimental results revealed that vibration signals, generated from knock, has certain frequencies related to vibration resonance modes of the combustion chamber. In this article, a new method for knock detection based on resonance frequency analysis of the knock sensor signal is introduced. More specifically at higher engine speed, where there is additional excitation of resonance frequencies, continuous wavelet transform has been proposed as an effective and applicative tool for knock detection and a formula for knock detection threshold based on this method is suggested. Measurement results demonstrate that this technique provide 15% higher accuracy in knock detection comparing to conventional method.

Antilock Regenerative Braking System Design for a Hybrid Electric Vehicle

Mohsen Esfahanian

Hybrid electric vehicles employ a hydraulic braking system and a regenerative braking system together to provide enhanced braking performance and energy regeneration. In this paper an integrated braking system is proposed for an electric hybrid vehicle that include a hydraulic braking system and a regenerative braking system which is functionally connected to an electric traction motor. In the proposed system, four independent anti-lock fuzzy controllers are developed to adjust the hydraulic braking torque in front and rear wheels. Also, an antiskid controller is applied to adjust the regenerative braking torque dynamically. A supervisory controller, is responsible for the management of this system. The proposed integrated braking system is simulated in different driving cycles. Fuzzy rules and membership functions are optimized considering the objective functions as SoC and slip coefficient in various road conditions. The simulation results show that the fuel consumption and the energy loss in the braking is reduced. In the other hand, this energy is regenerated and stored in the batteries, especially in the urban cycles with high start/stop frequency. The slip ratio remains close to the desired value and the slip will not occur in the whole driving cycle. Therefore, the proposed integrated braking system can be considered as a safe, anti-lock and regenerative braking system.

Improving the performance measurement using overall equipment effectiveness in an automotive industry

Abbas Rohani

Considering the present business competitive scenario, the automotive industry is under pressure to achieve higher productivity . A high level of performance and quality standard could be achieved through improving the Overall Equipment Effectiveness (OEE) of the equipment in an automotive industry. Thus, the aim of this study is to investigate the performance measurement through OEE theory in an Iranian automotive industry. Data and basic information collected from the Computerized Maintenance Management System (CMMS) of the production assembly lines . In this case study, two different assembly lines such Peugeot and Sports Utility Vehicle (SUV) were studied. The results indicated that the indices such availability rate, performance and quality for Peugeot assembly line obtained an OEE value of 0.99, 0.70 and 0.38, respectively, and, these indices for SUV assembly line obtained as 0.99, 0.39 and 0.53, respectively. Statistical analysis results of net operating time parameter for two assembly lines revealed that there is significant difference in the confidence level of 5% (P-value < 0.05). In addition, the OEE index for Peugeot and SUV assembly lines gained 0.27 and 0.21 over a period of one year. Consequently, to improve the OEE in the automotive assembly lines, managing the time losses by systematic planning of manufacturing and the implementation of Total Productive Maintenance (TPM) are suggested.

Optimal Idle Speed Control of a Natural Aspirated Gasoline Engine Using Bio-inspired Meta- heuristic Algorithms

Kamyar Nikzadfar

In order to lowering level of emissions of internal combustion engines (ICEs), they should be optimally controlled. However, ICEs operate under numerous operating conditions, which in turn makes it difficult to design controller for such nonlinear systems. In this article, a generalized unique controller for idle speed control under whole loading conditions is designed. In the current study, instead of tedious time-consuming trial-and-error based methods, soft computing techniques are employed to tune a proportional-integral-derivative (PID) controller which controls idle speed of engine. Since model based design technique is employed, a mean value model (MVM) is taken advantage due to its evidenced merits. Moreover, a brief introduction to the selected meta-heuristics is given followed by a flowchart to show how the engine model is linked to the optimization algorithms. A set point of 750 rpm is fed to the system, and the weighted sum of the three characteristics of mean squared error, control energy, and percent overshoot of the control system is set to the problem objective function to be minimized. It is evidenced that of all the examined meta-heuristics, Bees Algorithm (BA) converges to a better solution. Finally, to consider the effectiveness of the developed optimal controllers in disturbance rejection, they are implemented to the engine MVM model. The results of the research indicate, all the four optimally designed control systems, albeit the intermediate superiority, are of conspicuous success in compensating for the input disturbances of the load torque.

Improving the Cooling Process of Heavy-Duty Engines through Three Dimensional Simulation of Fluid Flow in its Coolant Centrifugal Pump

Sasan Asiaei

This paper investigates 3D simulation of fluid flow in a centrifugal pump from the Detroit Diesel company to extract possible engine cooling trends. The velocity and pressure profile of water, the coolant, is analyzed and the characteristic curves of the pump are derived. This provides a useful evaluation of the pump performance at all working conditions. For this aim, a computational fluid dynamic model is developed using ANSYS CFX for a wide span of flow rates and a number of shaft angular velocities. The variation of constituting parameters are examined using dimension-less descriptive parameters of flow, head and power coefficients, finally, the efficiency of the pump is examined. In this analysis, sst-k-w turbulent model is employed which is a combination of two different models for pumps and turbomachines. Numerical results show that prolonged cooling duty cycles of the vehicle should accompany a flow factor of 10%. In addition, the peak of the vehicle’s loading should match the maximum efficiency of the pump that can be increased to 62% by augmentation of flow rate and flow coefficient.