Innovative Air Hybrid Engine Concepts for Next Generation Fuel Efficient Road Vehicles

众所周知，混合动力汽车能够显著提高燃油经济性，特别是在交通状况涉及大量停车和启动的城市和市区。在这种情况下，需要大量的燃料来加速车辆，其中大部分在减速过程中通过刹车摩擦转化为热量。因此，捕捉、储存和重复使用这些制动能量以提供额外的动力可以提高燃料效率，这可以通过利用车辆在滑行和减速期间的动量来为储能装置充电，然后在巡航和加速期间释放能量来推动车辆。本文的工作是通过系统建模和发动机试验，研究空气混合动力发动机的一些创新概念及其在提高燃油经济性和低排放方面的潜力。在拟议的空气混合动力发动机概念中，发动机本身被用作压缩机或膨胀机，通过发动机的活塞和曲轴传递动力，从而利用车辆现有的传动系统制动或推动车辆。气动能量在中等压力下存储在一个紧凑的压缩空气储能罐中，该储能罐可以集成到车辆副车架中。空气混合动力发动机将能够回收制动能量，并将其储存起来，供以后使用，以启动发动机并帮助车辆加速，从而显著提高燃油经济性，但不会增加电动混合动力的巨大重量和复杂性。这是一种温和的混合动力系统，发动机作为空气马达用于停止/启动操作，在车辆停止时关闭发动机，并在车辆启动时用压缩空气快速重新启动，从而在怠速期间不使用燃料。此外，储存的高压空气可根据需求随时用于其他用途，以改善驾驶性能和减少排放，例如短暂增强发动机以消除涡轮增压发动机的涡轮滞后，从而更好地响应和消除道路上柴油车辆加速产生的黑烟。储存的空气也可以用作二次空气的来源，以便在冷启动期间快速点燃排气催化剂。所有这些都是气动混合动力车独有的显著附加优势，这是其他混合动力车无法实现的。在拟议的研究中，将使用先进的建模和发动机实验来研究三个新的空气混合动力发动机概念。拟议研究的结果将用于开发一种新的前沿发动机，在性能、燃油经济性和尾气排放方面有跨越式改进。

The hybrid vehicles are known to be capable of dramatically improving the fuel economy, particularly in cities and urban areas where the traffic conditions involve a lot of stops and starts. In such conditions, a large amount of fuel is needed to accelerate the vehicle, and much of this is converted to heat in brake friction during deceleration. Capturing, storing and reusing this braking energy to give additional power can therefore improve fuel efficiency, and this can be achieved by using the momentum of the vehicle during coasting and deceleration to top up an energy storage device and later releasing the energy to propel the vehicle during cruising and acceleration. The proposed work is to study some innovative air hybrid engine concepts and their potentials in improved fuel economy and low emissions through systematic modelling and engine testing. In the proposed air hybrid engine concepts, the engine itself is used as the compressor or expander, transmitting power through the pistons and the crankshaft of the engine thus braking or propelling the vehicle using the existing drivetrain of the vehicle. Pneumatic energy is stored at moderate pressure in a compact compressed air energy storage tank which may be integrated into the vehicle sub-frame. The air hybrid engine will be able to recover the braking energy and stored it for later use to start the engine and help the vehicle to accelerate, allowing significant improvement in fuel economy but without adding the large weight and complexity of the electric hybrid. This is a mild hybrid system in which the engine is used as an air motor for stop/start operation, with the engine switched off when the vehicle stops and restarted quickly with compressed air when the vehicle is launched, thus not using fuel during the idle period. In addition, the stored high pressure air is available readily on demand for other uses to improve driveability and reduce emissions, such as briefly boosting the engine to eliminate turbo-lag in a turbo-charged engine resulting in better response and removal of the black smoke typically seen from accelerating diesel vehicles on the road. The stored air may also be used as a source of secondary air for rapid light-off of the exhaust catalyst during cold start. All these are significant additional benefits uniquely available with the pneumatic hybrid, which are not possible with the other hybrid types. In the proposed research, three new air hybrid engine concepts will be studied using both advanced modelling and engine experiments. The results from the proposed research will be used for the development of a new frontier engines with leapfrog improvements in performance, fuel economy, and exhaust emissions.