【正文】 ly utilize cooled exhaust gas recirculation (EGR) to reduce emissions. The addition of the EGR cooler to the conventional vehicle coolant system creates several challenges. Firstly, the engine cooling system flow and heat rejection requirements both increase as it is likely that some EGR will be required at the rated power condition. This adversely affects packaging and fuel economy. The system design is further plicated by the fact that the peak duty of the EGR cooler occurs at part load, low speed conditions, whereas the cooling system is traditionally designed to handle maximum heat duties at the rated power condition of the engine. To address the system design challenges, Ricardo have undertaken an analytical study to evaluate the performance of different cooling system strategies which incorporate EGR coolers. This was achieved by performing a cosimulation using mercially available 1dimensional codes.為了符合法規(guī)的排放水平，未來的柴油發(fā)動機將有可能采用冷卻時廢氣再循環(huán)(EGR)技術(shù)，以減少溫室氣體排放。增加的廢氣再循環(huán)(EGR)冷卻器給常規(guī)汽車冷卻系統(tǒng)也帶來一定挑戰(zhàn)。這對發(fā)動機的包裝和燃油經(jīng)濟性有非常不利的影響。為了解決系統(tǒng)設計的挑戰(zhàn)，里卡多進行了大量的分析研究，以評估不同性能的冷卻系統(tǒng)的策略，其中包括EGR冷卻器。INTRODUCTION引言The coolant system of current vehicles is already limited on performance due to package and styling constraints. Thus, any future incremental demands on the coolant system will need to be managed effectively so as to remain within these constraints. Further, the drive to increase fuel economy, particularly in the Class 7 amp。因此，未來在冷卻液系統(tǒng)上的任何增量式改進都需要被有效地管理，以便滿足這些限制和約束。由于車輛中的冷卻組件對迎風面積有重大影響，所以給與對散熱管理高度重視是很有必要的。這個冷卻系統(tǒng)的進一步改進需要進行適當?shù)墓芾?。這一點也體現(xiàn)了熱拒絕了發(fā)動機在低速和負荷相對比較小時的峰值水平。Figure 1. Typical Truck Engine Heat Rejection To CoolantFigure 2. Example Of Truck Engine EGR Strategy (EGR Rate) Needed To Meet US Fed Transient Test(EGR)的范例A typical strategy for EGR for truck diesel engines, over the operating range of the engine, is shown in Figure 2.在發(fā)動機額定工作范圍內(nèi)的一個典型的卡車柴油發(fā)動機的廢氣再循環(huán)策略，如圖2所示?？紤]到排氣氣體的總質(zhì)量流速和排氣溫度，所需的熱量抑制從廢氣再循環(huán)可以計算出來。Figure 3. Typical Truck Engine EGR Heat Rejection.As a result of the difference in cooling requirements between the engine and the EGR cooler, it is important that the coolant system is designed such that both needs are meet whilst maintaining a minimum fuel consumption. Hence the water pump will now need to deliver coolant at a correct temperature and flow rate to the EGR cooler at low engine speed, without producing excess coolant flow rates and pressure rises at rated engine speed and to avoid boiling in the EGR cooler. Also, engine and passenger partment warm up time is a concern for emissions and passenger fort needs. Thus, the incorporation of the EGR cooler needs to minimize any penalty in cooling system.由于在發(fā)動機和EGR冷卻器之間的不同冷卻需求的緣故，同時以滿足這兩個需求的冷卻系統(tǒng)的設計是非常重要的，同時還必須保證最小的燃油消耗。此外，發(fā)動機和乘客艙預熱時間是一個關系到發(fā)動機排放和乘客舒適度的需求。Obviously, more plex controlled coolant systems can be designed to cope with these demands relatively easily. However, to derive a design that best meets the needs for fuel economy, emissions, passenger fort and, also importantly, cost, a more detailed analysis of all the options available is necessary.很顯然，用更復雜的冷卻系統(tǒng)控制設計來應付這些需求相對比較容易。Traditionally, these systems have, somewhat, been designed in isolation. That is, the coolant system designer has little understanding of the impact of the coolant system on engine performance and vice versa. Also, the controls engineer will implement strategies based on discussion with the systems engineers but will have little direct experience on how his function influences the overall systems performance. Thus, there is a need to look at all the implications on the coolant system design of a large truck engine due to the incorporation of cooled EGR.傳統(tǒng)上，這些系統(tǒng)有時被孤立地設計。此外，控制工程師在實施控制策略時是基于系統(tǒng)工程師的討論結(jié)果的，但是很少有直接的經(jīng)驗了解該系統(tǒng)是如何影響整體系統(tǒng)性能的。In order to do this Ricardo have developed detailed models that could simulate the dynamic system interaction between engine, EGR and cooling system. This was achieved by performing a cosimulation using mercially available 1dimensional codes for engine and EGR system (WAVE), thermalfluid analysis (FLOWMASTER174。 Simulink174。這是通過執(zhí)行一個使用可用一維代碼的發(fā)動機和廢氣再循環(huán)系統(tǒng)(WAVE)聯(lián)合仿真，以及(FLOWMASTER)熱流體分析和(MATLAB SIMULINK)控制系統(tǒng)分析。This paper details the development of the vehicle model cosimulation, its use to evaluate different cooling system options, and some observations on potential fuel economy savings. The work includes an investigation of active ponents including solenoid coolant valves and an electric water pump.本文詳細介紹了汽車聯(lián)合仿真模型的發(fā)展，評估其使用不同的冷卻系統(tǒng)的效果，以及潛在的節(jié)省了燃油經(jīng)濟性上的一些建議。COSIMULATION BACKGROUND仿真背景The term cosimulation is often used to describe various types of analysis and thus it is worth providing some discussion as to how it is used here. The simplest method of analysis is to derive a model in a single code that simulates a system or multiple systems. This has limitations due to the level of plexity needed and the fact that there are dedicated codes designed to model specific systems that are more effective. Very often the next step is to build more plex models in individual codes. The data transfer between these codes is conducted offline (. the output data from the first simulation is manually input into another simulation to run). This is useful since each model runs separately and thus quickly and a reasonable level of plexity can be simulated. However, to gain true transient capability and to increase the level of interaction between systems it is necessary to link these models dynamically. Cosimulation has been investigated for other applications and the benefits of it discussed in other publications [1].協(xié)同仿真這個術(shù)語是經(jīng)常被用來描述不同類型的分析，因此把它用在這里需要值得討論。這有它的局限性，由于其復雜性的需要，事實上具體系統(tǒng)的專有代碼設計模型會更有效果。這兩者之間的代碼數(shù)據(jù)傳輸采用離線方式(即從第一模擬的輸出數(shù)據(jù)是手動輸入到另一個模擬運行)。然而，為獲得真正的瞬態(tài)性能和提高系統(tǒng)之間相互作用的水平，將這些模型的動態(tài)鏈接是非常有必要的。True cosimulation, as conducted in this study, involves writing code to link the various submodels, in different software codes, such that the submodels solve together in parallel and municate with each other at the required timesteps. In this study, three mercially available