车辆工程外文翻译.docx

1、车辆工程外文翻译（本文截取的是一篇国外学生的毕业论文中的一段 论文名字是“A Comprehensive Thermal Management System Model for Hybrid Electric Vehicles”）The automotive industry is facing unprecedented challenges due to energy and environmental issues. The emission regulation is becoming strict and the price of oil is increasing. Thus, t

2、he automotive industry requires high-efficiency powertrains for automobiles to reduce fuel consumption and emissions. Among high-efficiency powertrain vehicles, Hy-brid Electric Vehicles (HEVs) are under development and in production as one potential solution to these problems. Thus, one of the most

3、 critical objectives of the HEV development is improving fuel economy. There are many ways of maximizing the fuel econo-my of a vehicle such as brake power regeneration，efficient engine operation，parasitic loss minimization，reduction of vehicle aerodynamic drag, and engine idle stop. Figure 1 compar

4、es the balance of the energy of a conventional vehicle with a hybrid electric vehicle。As can be seen in Figure 1, the hybrid vehicle saves fuel by utilizing engine idle stop, brake power regeneration, and efficient engine operation. Figure 1 also shows that the fuel consumed by the accessories, whic

5、h include Vehicle Cooling System (VCS), Climate Control System (CCS), and electric accessories, is not negligible compared with the fuel consumed by the vehicle propulsion system. In addition, the portion of the energy consumption of the accessories in HEVs is bigger than that of conventional vehicl

6、es. This observation suggests that the efficient accessory system, particularly the VCS and CCS, is more important in high-efficiency vehicles because they have more effect on the fuel economy. The effect of the auxiliary load on the fuel economy of high-efficiency vehicles studied by Farrington et

7、al 2. They examined the effect of auxiliary load on vehicle fuel economy via a focus on climate control system. Figure 2 compares the impact of auxiliary load, i.e. the power consumed by accessory systems, on the fuel economy of the conventional and high fuel economy vehicle. As shown in the figure,

8、 a high fuel economy vehicle is much more affected by the auxiliary load than a conventional vehicle. Therefore, more efficient thermal management systems including VCS and CCS are essential for HEV. Figure 1. Energy flow for various vehicle configurations. (A) ICE, the conventional internal combust

9、ion, spark ignition engine; (B) HICE, a hybrid vehicle that includes an electric motor and parallel drive train which eliminates idling loss and captures some energy of braking 1.Figure 2. Comparison of fuel economy impacts of auxiliary loads between a conventional vehicle and a high fuel economy ve

10、hicle 2Achieving efficient VCS and CCS for HEVs requires meeting particular design challenges of the VCS and CCS. The design of the VCS and CCS for HEVs is different from those for conventional vehicles. VCS design for HEVs is much more complicated than that of conventional vehicles because the powe

11、rtrain of HEVs has additional powertrain components. Furthermore, the additional powertrain components are operated at different temperatures and they are operated independently of the engine operation. The design of CCS for HEVs is also different from that of conventional vehicles because the tempe

12、rature of the battery pack in HEVs is controlled by the CCS. Thus, the heat load for the CCS of HEVs is much higher than that for the CCS of conventional vehicles. Thus, this is another challenge for the design of the VTMS for HEVs.As noted above, these additional powertrain components such as a gen

13、erator, drive motors, a large battery pack, and a power bus require proper thermal management to prevent thermal run away of the power electronics used for the electric powertrain components. Thus, the thermal management of the power electronics and electric machines is one of the challenges for the

14、 HEV development and various studies have been conducted 3-7. Generally, dedicated VCS for the hybrid components are required as a result of the considerable heat rejections and different cooling requirements of the electric components. In the cooling system of HEVs, a cooling pump driven by an elec

15、tric motor, rather than a pump driven by the engine, is used for the cooling circuit of the electric powertrain components because they need cooling even when the engine is turned off. The benefits of a controllable electric pump over the mechanical pump were studied by Cho et al. 8 in the case of t

16、he cooling system for a medium duty diesel engine. They used numerical simulations to assess the fuel economy and cooling performance and it is found that the usage of an electric pump in place of the mechanical pump can reduce power consumption by the pump and permit downsizing of the radiator. In

17、addition to those benefits, the use of an electric pump makes the configuration of the cooing circuits in hybrid vehicles relatively flexible in terms of grouping components in different circuits. However, this flexibility raises an issue in optimizing cooling circuit architecture because of the com

18、plexity of the system and the parasitic power consumption of the cooling system. The performance and power consumption of the cooling system are also very sensitive to the powertrain operation. The powertrain operation is determined by the power management strategy, which changes in response to driv

19、ing conditions of HEVs. Therefore, the effects of driving conditions must be considered during the design process of the cooling system. Thus, in light of these additional components, design flexibility, and the effects by vehicle driving condition, it is clear that the design of the VCS for HEVs de

20、mands a strategic approach compared with the design of the VCS for conventional vehicles.Another challenge in designing the VTMS for HEVs is managing the cabin heat load generated as a result of the placement of the battery pack in the passenger compartment. In HEVs, the battery pack is located on b

21、oard because of its lower operating temperature compared with powertrain components. Therefore, battery thermal management system is a part of the Climate Control System (CCS) because the battery is cooled by using the CCS. Thus, the load on the CCS of HEVs is higher than that of conventional vehicl

22、es because the battery is the major heat source in the cabin. In addition, battery thermal management is important for the health and life of the battery. Although high temperature operation is better for the battery performance due to reduced battery loss and reduced battery thermal management powe

23、r, high temperature operation is limited due to the battery durability and safety. Figure 3 shows the temperature dependency of the cycle life of Liion battery. As can be seen in the figure, the battery life drops dramatically when the battery is operated at higher than 60C. The same happens at lowe

24、r temperature. In extreme cases, lithium ion battery can explode by a chain reaction. Generally, the battery operating temperature is limited lower than 60C for the lithium ion and lead acid battery 9-10. Accordingly, battery thermal management associated with climate control system is a critical pa

25、rt of vehicle thermal management system design of HEVs. Therefore, a comprehensive vehicle thermal management system analysis including VCS and CCS is needed for the HEV vehicle thermal management system design.Figure 3. Temperature dependency of the life cycle of Li-ion battery 11.Recognizing the n

26、eed for the efficient vehicle thermal management system (VTMS) design for HEVs, many researchers have tried to deal with the VTMS design for HEVs from various view-points. Because of the complexity and the necessity for the design flexibility of the thermal management system of HEVs, numerical model

27、ing can be an efficient way to assess various design concepts and architectures of the system during the early stage of system development compared with experiments relying on expensive prototype vehicles. Traci et al. 12 demonstrated that a numerical approach could be successfully used for thermal

28、management system design of HEVs. They simulated a cooling system of an all-electric combat vehicle that uses a diesel engine as a prime power source and stores the power in a central energy storage system. They conducted parametric studies on the effect of the ambient temperature on the fan power c

29、onsumption and the effect of the coolant temperature on the system size. Park and Jaura 13 used a commercial software package to analyze the under-hood thermal behavior of an HEV cooling system and studied the effect of the additional hardware on the performance of cooling system. They also investig

30、ated the effect of an electronic module cooler on the conventional cooling system. These previous studies, however, focused on parametric studies and did not deal with the architecture design of the vehicle thermal management system considering the power consumption of the system.There also have bee

31、n many efforts to analyze the impact of the CCS on the HEV. Bennion and Thornton 6 compared the thermal management of advanced powertrains using an integrated thermal management system model and studied on the peak heat load over a transient vehicle driving cycle to minimize the size of cooling syst

32、em. They also studied the cases involving efforts to minimize the cooling circuit by integrating low temperature circuits with high temperature circuits or A/C circuits. Kim and Pesaran 14 studied battery thermal management of HEV focused on the battery temperature distribution in the battery pack.

33、Pesaran 15-16 studied the battery thermal models and the various methods of battery cooling in HEVs. However, these previous studies did not deal with the battery thermal management integrated with the A/C system, which is a part of the vehicle thermal management system.As introduced above, although HEVs need more efficient VTMS than conventio