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While a Ni-MH battery has good performance properties, such as a high power density and no memory effect, it needs a powerful thermal management system to maintain within the required narrow thermal operating range for the 42V HEV applications. Inappropriate battery temperatures result in degradation of the battery performance and life. For the battery cooling system, air is blown into the battery pack. The exhaust is then vented outside due to potential safety issues with battery emissions. This cooling strategy can significantly impact fuel economy and cabin climate control. This is particularly true when the battery is experiencing frequent charge and discharge of high-depths in extreme hot or cold weather conditions. To optimize performance and life of HEV traction batteries, the battery cooling design must keep the battery operation temperature below a maximum value and uniform across the battery cells.

Increased cooling demands in Hybrid Electric Vehicles (HEVs), compactness of engine compartment, and the additional hardware under the hood make it challenging to provide an effective cooling system that has least impact on fuel economy, cabin comfort and cost. Typically HEVs tend to have a dedicated cooling system for the hybrid components due to the different coolant temperatures and coolant flow rates. The additional cooling system doubles the hardware, maintenance, cost, weight and affects vehicle fuel economy. In addition to the cooling hardware, there are several harnesses and electronics that need air cooling under the hood. This additional hardware causes airflow restriction affecting the convective heat transfer under the hood. It also affects the radiation heat transfer due to the proximity of hardware close to the major heat sources like the exhaust pipe.

Hybridization is one element in achieving better fuel economy in vehicles. Ford is pursuing a systems approach to achieve higher fuel economy. The goal is to synergistically use light weight materials, lower the rolling resistance, incorporate a low storage configuration Hybrid Electric Vehicle powertrain, with an efficient vehicle operating strategy, and reduce vehicle auxiliary losses (e.g., using high efficiency power steering and regenerative braking system) to maximize fuel economy without compromise in customer utility or cost. This paper presents an overview of this synergy being used in Ford's hybrid development.

Today, Hybrid Electric Vehicles (HEVs) are synonymous to vehicles that offer a greater fuel economy and lower emissions when compared to their conventional production platforms. The development of an affordable hybrid technology faces challenges on several forefronts. Challenges include, but are not limited to, their technical content and development, corporate challenges, government regulations, program challenges, selecting technology partners and producing a hybrid vehicle that customers find fun to drive. As technologists, our goal is to ensure that the consumer understands that HEVs go that extra mile and provide far more than better fuel economy and lower emissions. HEVs are attractive and fun to drive because they offer multiple attributes and features to that consumers want. Hybrids offer all-wheel drive capability, traction control, regenerative braking, zero emissions, active air conditioning at vehicle stops, silent re-starts.

In the 21st century automakers are continually being challenged to meet a myriad of new government regulations regarding Safety, Emissions, and Fuel Economy, but must balance key requirements such as Customer Satisfaction, Shareholder Value, and Profits. Customers desire high Fuel Economy (FE) in their vehicle selection, but they prefer it not to result in a loss to a vehicle's performance, roominess, and safety. Current advances in hybrid vehicle technology can significantly diminish these conflicting requirements. However, these come at a significantly higher cost to the customer. One solution to improving both vehicle performance and FE is weight reduction by the use of advanced materials. Reducing the mass of the vehicle will result in a lower rolling resistance that will allow the vehicle manufacturer to size the engine smaller for a particular vehicle. This will improve FE, acceleration, and handling performance.

Ford's H2RV is a Hydrogen engine propelled Hybrid Electric concept Vehicle that was unveiled and driven at Ford's Centennial Show in June 2003. This vehicle is an industry first by an OEM that demonstrates the concept and the marriage of a HEV powertrain with a supercharged Hydrogen ICE that propels the vehicle. Just as Model T was the car of the 20th century, Model U is the vehicle for the 21st century. The powertrain utilizes compressed gaseous hydrogen as fuel, a supercharged 2.3L internal combustion engine, a 25 kW traction motor drive, the electric converterless transmission, regenerative braking, an advanced lithium ion battery, electric power assist steering, electronic throttle and Vehicle System Controller (VSC). The vehicle could deliver a projected fuel economy of 45 mpg and near zero emissions without compromise to performance.

The idea of using a single electrical machine for both starting the engine and generating electrical power is not new. However, the real benefits, that justify the higher cost of a combined starter-alternator, become apparent when it is used as part of a hybrid powerplant. This powerplant allows a substantial improvement in fuel economy by a variety of methods (i.e. the engine shut-down during deceleration and idle, regenerative braking, etc.), as well as enhancements to engine performance, emissions, and vehicle driveability. This paper describes the analysis of the structure supporting the starter-alternator on the end of the engine crankshaft (Figure 1). It deals with the requirement to maintain a small radial gap between the rotor and stator, and it discusses how the rotor affects the loading on the crankshaft. In addition, thermal deformations of the rotor/clutch assembly are analyzed with three light-weight materials.

Hybrid Electric Vehicle (HEV) prototypes are based off production platforms. Several new systems are added to the vehicle, either to perform hybrid functions or to support them and enhance vehicle performance and fuel economy. All these systems are electrically connected in the vehicle with overlay wiring harnesses. Architecture of overlay wiring harness for the HEV requires identification of new systems and working out their electrical connectivity requirements. This dictates the level of changes required in the vehicle electrical system. Harnesses are built based on the circuit design and location of these systems in the vehicle. EMI requirements, routing and packaging challenges are resolved during the overlay process and testing of the prototype. This paper presents the process of harness design, its architecture and integration challenges in the vehicle.