车辆经济性提升方向研究

本文从整车整备质量、整车滑行阻力、变速箱控制策略、发动机怠速油耗等影响整车经济性因素出发,对某车型A与对标车型B经济性差异进行分析.通过计算机仿真和实车试验验证在保证动力性基本不损失的情况下分析不同因素对油耗的影响,明确不同影响因素对整车经济性的影响程度.为整车研发阶段提升整车经济性,降低整车油耗提供参考及方向.     

整车参数对混合动力汽车NEDC工况油耗的影响

混合动力整车油耗不仅仅取决于混合动力系统的优劣,与整车参数也有很大的关系,但混合动力汽车与传统汽车相比,整车参数对油耗的影响是有一定差别的,本文研究了一些主要的整车参数对混合动力汽车的油耗影响。基于功率分流式混合动力车辆的Amesim仿真模型,选取整车质量、轮胎滚动半径、滑行阻力曲线三个因素并利用正交表的方法分析其对油耗的影响,从而指导利用该模型进行功率分流式混合动力车辆的油耗分析和优化。研究表明,混合动力汽车由于制动能量回收的影响,整备质量对油耗的影响小于传统汽车;由于功率分流的能量控制策略,轮胎滚动半径对油耗的影响很小;滑行阻力对油耗的影响和传统汽车接近。     

宇通：发动机升级延保不加价

C9完全可以凭借在油耗和可靠性上的卓越表现以及其自身清晰的发动机全生命周期成本（LCC），实现与ZK6122H整车的最佳应用匹配     

节能绿灯亮起来——宇通发布客车行业首款安节助驾系统

随着石油资源的日益减少,汽车燃油的经济性越来越受到关注,油耗已成为用户关注的主要性能之一。研究发现,影响汽车用户油耗的因素有两个方面,一方面是车辆本身的燃油经济性,一方面是用户的使用操作。调查显示,很多驾驶员的驾驶习惯并不合理,如驾驶过程中档位使用不合理、换挡时机不当等,尤其是发动机进入电控时代之后,由于驾驶员对电控发动机的特点不了解,导致使用过程中车辆油耗增高的现象时有发生。     

阻力加载对乘用车WLTC循环排放及油耗影响

基于一辆搭载1.4 L涡轮增压汽油机的乘用车汽车,通过WLTC循环工况测试,分别对比研究了不同阻力加载a和b对整车试验循环排放及油耗的影响。研究发现:阻力加载b在中低速阶段的阻力相对阻力加载a比较小,对排放和油耗均有一定程度的改善;但是第四阶段阻力加载b相对阻力加载a较大,排放和油耗均增加;但是整体综合排放和油耗均有改善。     

节油技术整车对比检测方法的应用

对汽车节油技术的检测主要分为发动机性能台架对比试验和整车性能道路对比试验两大类别,文章采用整车性能道路对比试验,使用流量计检测内燃机采用节油技术前后的燃油消耗量,来评定内燃机在运用了节油技术或产品后的节油效果,适用于车辆和柴油发电机组等内燃机的应用产品。     

Fuel-Cut策略对WLTC循环排放及油耗影响

基于一辆搭载1.4 L增压乘用车,通过WLTC循环工况测试,分别对比研究了Fuel-Cut策略,对整车试验循环排放及油耗的影响。研究发现,怠速起停技术(STT)、减速断油技术(DFCO)和换挡断油技术(CFCO)均能够改善油耗,使得油耗分别降低1.34%、1.67%和1.13%,但对CO、NOX、HC及NMHC排放都会产生一定恶化。     

柴油机大气修正试验分析

选择一台柴油发动机,在一年四季若干大气状态下进行发动机试验,求得发动机功率和油耗率,将该值与相同状态下的理论计算数值进行比较分析,研究发动机大气修正标准的应用情况,为发动机出厂试验提供依据。     

燃油添加剂对汽车排放性能影响分析研究

国内对于燃油添加剂效果的分析研究较少,文章为了探讨某型燃油添加剂对在用车排放和性能的影响,依据GB18285-2005《点燃式发动机汽车排气污染物排放限值及测量方法》,针对不同行驶里程的汽车,选用双怠速法检测汽车使用某型号燃油添加剂前后的排放变化,并对油耗和动力性进行简单测评。结果表明,使用燃油添加剂和选择合适标号燃油能有效降低汽车污染物排放及油耗,对车辆使用节能减排具有较为重要意义。     

底盘测功机阻力设定对重型商用车油耗的影响分析

文章研究了重型商用车辆分别采用推荐道路阻力与实测道路阻力对在底盘测功机上进行整车油耗试验的结果差异。结果表明,采用推荐道路阻力不能真实反应出车辆的油耗水平;底盘测功机的阻力设定直接影响车辆的油耗结果,阻力设定值越大,油耗越大,反之越小。     

Impact of control strategies on the emissions in a city bus equipped with power-split transmission

The continuously variable hydromechanical transmission is an interesting solution for high power vehicles subject to frequent changes of speed, in which the comfort is a significant requirement.Despite their low average efficiency with respect to the mechanical transmissions, the hydromechanical transmissions allow to release the engine speed by the vehicle speed, and to open the possibility for the optimal control of the engine. It follows that the performance and emissions of the powertrain is heavily affected by the logic control.The aim of the paper is to investigate the emission reductions that can be obtained using a Power-Split transmission.Therefore, a hydromechanical transmission has been sized and tested on a 12-ton-city bus by using a one-dimensional model developed in an AMESim environment. Four different control strategies of the powertrain were applied to the model. The CUEDC-ME standard cycle for the characterization of emissions in heavy vehicles was used as a reference mission.The simulation results showed that the hydromechanical transmission reduces consumption or the emission levels with respect to the traditional transmission when managed according to appropriate control strategies. By means of emission values normalized with respect to the standard limits, it is possible to identify a control strategy that allows the reduction of emissions in every usage condition of the vehicle at the expense of a slight increase of consumption.The suggested procedure could help the manufacturer to satisfy the emission standard requirements.     

Transportation — “Current on-board vehicle systems”

The paper reviews the current situation on-board microprocessor applications. It first describes the aspects of vehicle technology and performance that are the focus for on-board computing equipment, from engine management systems through to fully intergrated driver decision support. In the second section a wider perspective is taken by examining the interaction of the vehicle and its environment. The third and final section of the paper considers elements of communication which permit extensive transmission of vehicle and journey data for public and private use. The conclusion identifies factors which will influence the speed with which further applications will be adopted.     

Eco-driving: An economic or ecologic driving style?

In this work the trade-off between economic, therefore fuel saving, and ecologic, pollutant emission reducing, driving is discussed. The term eco-driving is often used to refer to a vehicle operation that minimizes energy consumption. However, for eco-driving to be environmentally friendly not only fuel consumption but also pollutant emissions should be considered. In contrast to previous studies, this paper will discuss the advantages of eco-driving with respect to improvements in fuel consumption as well as pollutant gas emissions. Simulating a conventional passenger vehicle and applying numerical trajectory optimization methods best vehicle operation for a given trip is identified. With hardware-in-the-loop testing on an engine test bench the fuel and emissions are measured. An approach to integrate pollutant emission and dynamically choose the ecologically optimal gear is proposed.     

Diesel-engined vehicle nitric oxide and soot emissions during the European light-duty driving cycle using a transient mapping approach

An engine mapping-based methodology is developed to gain a first approximation of a vehicle’s performance and emissions during a light-duty cycle. The procedure is based on a steady-state experimental investigation of the engine with an appropriate vehicle drivetrain model applied so that the cycle vehicle speed data can be transformed into engine speed and torque. Correction analysis is then applied based on transient experimentation to account for the transient discrepancies during real driving. The developed algorithm is applied for the case of a diesel-engined vehicle running on the European light-duty cycle. A comparative analysis is performed for each section of the cycle revealing its individual transient characteristics.     

Hardware-in-the-loop testbed for evaluating connected vehicle applications

Connected vehicle environment provides the groundwork of future road transportation. Researches in this area are gaining a lot of attention to improve not only traffic mobility and safety, but also vehicles’ fuel consumption and emissions. Energy optimization methods that combine traffic information are proposed, but actual testing in the field proves to be rather challenging largely due to safety and technical issues. In light of this, a Hardware-in-the-Loop-System (HiLS) testbed to evaluate the performance of connected vehicle applications is proposed. A laboratory powertrain research platform, which consists of a real engine, an engine-loading device (hydrostatic dynamometer) and a virtual powertrain model to represent a vehicle, is connected remotely to a microscopic traffic simulator (VISSIM). Vehicle dynamics and road conditions of a target vehicle in the VISSIM simulation are transmitted to the powertrain research platform through the internet, where the power demand can then be calculated. The engine then operates through an engine optimization procedure to minimize fuel consumption, while the dynamometer tracks the desired engine load based on the target vehicle information. Test results show fast data transfer at every 200 ms and good tracking of the optimized engine operating points and the desired vehicle speed. Actual fuel and emissions measurements, which otherwise could not be calculated precisely by fuel and emission maps in simulations, are achieved by the testbed. In addition, VISSIM simulation can be implemented remotely while connected to the powertrain research platform through the internet, allowing easy access to the laboratory setup.     

Developing link-based particle number emission models for diesel transit buses using engine and vehicle parameters

To better assess health impacts from diesel transportation sources, particle number emissions can be modeled on a road network using traffic operating parameters. In this work, real-time particle number emissions rates from two diesel transit buses were aggregated to the roadway link-level and modeled using engine parameters and then vehicle parameters. Modern statistical methods were used to identify appropriate predictor variables in the presence of multicollinearity, and controlled for correlated emission measurements made on the same day and testing route. Factor analysis helped to reduce the number of potential engine parameters to engine load, engine speed, and exhaust temperature. These parameters were incorporated in a linear mixed model that was shown to explain the variation attributable to link-characteristics. Vehicle specific power and speed were identified as two surrogate vehicle travel variables that can be used in the absence of engine parameters, although with a loss in predictive power compared to the engine parameter model. If vehicle speed is the only operating input available, including road grades in the model can significantly improve particle number emission estimates even for links with mild grade. Although the data used are specific to the buses tested, the approach can be applied to modeling emissions from other vehicle models with different engine types, exhaust systems, and engine retrofit technologies.     

Energy factors for flexible fuel engines and vehicles operating with gasoline-ethanol blends

This work investigates the energy factors for fuel conversion from the analysis of brake specific fuel consumption (BSFC) maps of a sample of 15 engines, representative of 75% of current models available in the Brazilian market. The method also employs the engine driving patterns of power output versus crankshaft speed obtained from bench dynamometer tests. The energy factors obtained from the engine analysis was validated against experiments carried out with two production vehicles in laboratory tests following the 1975 US Federal Test Procedure (FTP-75) procedure and road tests following 16 different urban and highway routes. The fuels used in the tests were hydrous ethanol (E100, 6 v/v % water) and a blend of 22 v/v % anhydrous ethanol and 78 v/v % gasoline (E22). The energy factors found from the 3D engine BSFC map analysis were higher than those obtained from the Willans line, currently adopted as a standard, by 52% for E22 and 57% for E100. The results from the 3D engine BFSC maps and the first vehicle following the FTP-75 cycle and 15 road routes were similar, also close to the results from the second vehicle, qualifying them to be representative of modern flexible fuel spark ignition engines and vehicles.     

Optimal vehicle speed trajectory on a signalized arterial with consideration of queue

Vehicle speed trajectory significantly impacts fuel consumption and greenhouse gas emissions, especially for trips on signalized arterials. Although a large amount of research has been conducted aiming at providing optimal speed advisory to drivers, impacts from queues at intersections are not considered. Ignoring the constraints induced by queues could result in suboptimal or infeasible solutions. In this study, a multi-stage optimal control formulation is proposed to obtain the optimal vehicle trajectory on signalized arterials, where both vehicle queue and traffic light status are considered. To facilitate the real-time update of the optimal speed trajectory, a constrained optimization model is proposed as an approximation approach, which can be solved much quicker. Numerical examples demonstrate the effectiveness of the proposed optimal control model and the solution efficiency of the proposed approach.     

基于最佳碳排放与油耗最优化的行驶车速区间研究

在碳排放实验的基础上,文章研究了CO2排放比例与行车速度之间的关系,并提出最佳碳排放行驶车速区间这一概念。文章结合前人提出的油耗与车速模型,建立了高速公路最优车速区间的计算模型,车辆在此区间上行驶时,油耗低并且燃油充分,即CO2排放比例高。利用面积法确定了最优行驶车速区间的计算方法,求得了这一车速区间,从而达到经济效益与社会环境效益的最大化,同时也能够为高速公路的运营管理提供理论支撑。