基于灵敏度分析的发动机悬置系统稳健优化设计

以发动机悬置系统能量解耦为目标,悬置刚度参数为设计变量,考虑目标函数和约束函数对于悬置刚度参数的灵敏度,构造了多目标优化数学模型.采用遗传优化算法对一款发动机悬置系统的悬置刚度参数进行了稳健优化设计,并用Monte Carlo方法进行了分析.结果表明,优化方法可以有效降低系统解耦度对悬置刚度参数的灵敏度,提高了悬置系统设计的实用性.     

Fuel economy comparison of conventional drive trains series and parallel hybrid electric step vans

A hybrid electric vehicle (HEV) is a vehicle that combines a conventional propulsion system with an on-board rechargeable energy storage system to achieve better fuel economy than a conventional vehicle HEVs do not have limited ranges like battery electric vehicles, which use batteries charged by an external source. The different propulsion power systems may have common subsystems or components. The objective of this study is to compare the fuel economies of a conventional step van, a series hybrid electric step van (HESV), and a parallel HESV by calculating the fuel consumption using the ADVISOR software by NREL. We also showed the results of the vehicles in different driving cycles including the Central Business District bus cycles, the New York City Cycle, and the US EPA City and Highway cycles.     

Analysis of a regenerative braking system for Hybrid Electric Vehicles using an Electro-Mechanical Brake

The regenerative braking system of the Hybrid Electric Vehicle (HEV) is a key technology that can improve fuel efficiency by 20∼50%, depending on motor size. In the regenerative braking system, the electronically controlled brake subsystem that directs the braking forces into four wheels independently is indispensable. This technology is currently found in the Electronic Stability Program (ESP) and in Vehicle Dynamic Control (VDC). As braking technologies progress toward brake-by-wire systems, the development of Electro-Mechanical Brake (EMB) systems will be very important in the improvement of both fuel consumption and vehicle safety. This paper investigates the modeling and simulation of EMB systems for HEVs. The HEV powertrain was modeled to include the internal combustion engine, electric motor, battery and transmission. The performance simulation for the regenerative braking system of the HEV was performed using MATLAB/Simulink. The control performance of the EMB system was evaluated via the simulation of the regenerative braking of the HEV during various driving conditions.     

城市道路交叉口合理角间距研究

由于缺乏城市道路交叉口合理角间距的标准,经常存在因角间距过小造成交通秩序混乱,导致交叉口通行能力严重降低。引用接入管理理论,在分析交叉口功能区长度的基础上,分别对不同类型的角间距进行计算,得到了不同条件下城市道路交叉口合理角间距的推荐值,为科学合理设置交叉口附近的接入道路提供了定量依据,有利于交叉口的畅通与安全。     

Model-based control system design in a urea-SCR aftertreatment system based on NH3 sensor feedback

This paper presents preliminary control system simulation results in a urea-selective catalytic reduction (SCR) aftertreatment system based on NH₃ sensor feedback. A four-state control-oriented lumped parameter model is used to analyze the controllability and observability properties of the urea-SCR plant. A model-based estimator is designed via simulation and a control system is developed with design based on a sliding mode control framework. The control system based on NH₃ sensor feedback is analyzed via simulation by comparing it to a control system developed based on NO_x sensor feedback. Simulation results show that the NH₃ sensor-based strategy performs very similarly in comparison to a NO_x sensor-based strategy. The control system performance metrics for NO_x index, urea index, urea usage, and NH₃ slip suggest that the NO_x sensor can be a potential alternative to a NO_x sensor for urea-SCR control applications.     

Belt routing and safety assessment through computer simulation

Most of the research on safety belt systems has involved crash simulation that only considered a dynamic human model. However, belt routing analysis, usually known as comfort level estimation, is also an important factor in safety belt design, considering that serious injuries of the abdominal region result from the infiltration of a belt into the neck or the chest. Thus, safety belt evaluations using kinematic human models are also needed. In this paper, a belt fit simulation method is suggested. Using the proposed process, both comfort and safety analyses can be performed under the same conditions continuously, and thus the safety belt design parameters, such as the location of anchor points, dummy posture and etc., can be evaluated. In conclusion, this computer process enables a belt system design to reduce injuries.     

A Study of the Response of a Double Bottom Vehicle to Steering and Braking

The paper describes the development, operation and some of the results obtained from a simulation of the steering behaviour of the double bottom articulated vehicle, in particular the effects that arise when certain axles are locked.     

Clamping performance of fastener in windshield wiper assembly using theoretical and experimental methods

Improper clamping of wiper arms can cause problems in the operation of the wiper. An excessive clamping force can cause damage to the wiper arm head. On the other hand, an insufficient clamping force can cause self-loosening of the nut. Given the lack of direct research on the clamping force of the fastener in wiper assembly, this study verifies the existing clamping performance of the fastener in windshield wiper assembly by theoretical and experimental methods. The theoretical calculation results show that all the clamping performance are satisfied under the general snow load condition. However, under the critical load condition, maximum assembly preload and safety margin against slipping are in disagreement with the standard values. This problem is solved by increasing the strength grade of the bolt. The experimental results show a reducing tendency of the clamping force during the snow durability test. However, this reducing clamping force during the 60,000 test cycles is acceptable. In the case of nut reusing more than two times possibly cause a problem of its loosening because of insufficient clamping force. Therefore, it is recommended that the nut should not be reused more than two times.     

Topological analysis of powertrains for refuse-collecting vehicles based on real routes–Part I: Hybrid hydraulic powertrain

In this two-part paper, a topological analysis of powertrains for refuse-collecting vehicles (RCVs) based on the simulation of different architectures (internal combustion engine, hybrid electric, and hybrid hydraulic) on real routes is proposed. In this first part, a characterization of a standard route is performed, analyzing the average power consumption and the most frequent working points of an internal combustion engine (ICE) in real routes. This information is used to define alternative powertrain architectures. A hybrid hydraulic powertrain architecture is proposed and modelled. The proposed powertrain model is executed using two different control algorithms, with and without predictive strategies, with data obtained from real routes. A calculation engine (an algorithm which runs the vehicle models on real routes), is presented and used for simulations. This calculation engine has been specifically designed to analyze if the different alternative powertrain delivers the same performance of the original ICE. Finally, the overall performance of the different architectures and control strategies are summarized into a fuel and energy consumption table, which will be used in the second part of this paper to compare with the different architectures based on hybrid electric powertrain. The overall performance of the different architectures indicates that the use of a hybrid hydraulic powertrain with simple control laws can reduce the fuel consumption up to a 14 %.