A Cost-Effective Regenerative Air Hybrid Powertrain for Low Carbon Buses and Delivery Vehicles

具有可再生能源回收的混合动力总成被公认为是中短期内低碳汽车最有效的手段之一。它可以显著提高燃油经济性，特别是在城市和城市地区的公交车和送货车辆，这些城市和城市地区的交通条件涉及大量的停靠和启动。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、储存和重新利用这些制动能量可以提高燃料效率，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。研究和开发最多的混合动力汽车是电动汽车。电动混合动力总成在客车和运输车辆上的应用受到了巨大附加成本的严重限制，这些附加成本与机电联合动力总成和传动系统的工程复杂性有关。目前，电动混合动力巴士得到了巨额补贴，不适合商业上可行的大批量生产。与电动和液压混合动力车不同，空气混合动力车在应用于往复式内燃机时，无需在车辆上添加额外的推进系统即可实现。在这种情况下，发动机本身可以在制动/减速期间用作压缩机，或用作启动/加速的膨胀机，通过活塞和发动机曲轴传递动力，从而利用车辆现有的传动系统制动或推动车辆。对于公共汽车和运输车辆，空气能量将在中等压力(低于15巴)下储存在这类车辆上已有的压缩空气储罐中。与电动混合动力车类似，空气混合动力车将能够回收制动能量，并将其储存起来，供以后启动发动机和帮助车辆加速，从而在不增加电动混合动力车的巨大重量和复杂性的情况下显著提高燃油经济性。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，例如短暂地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加速柴油车辆通常产生的黑烟。对于公共汽车和商用车辆，空气辅助制动和气动设备的操作(如开门和关门)需要压缩空气，目前由发动机驱动的压缩机产生。空气混合动力总成技术将通过提供来自再生式发动机制动的压缩空气来取代发动机驱动的压缩机，从而实现进一步和容易实现的燃油节约。这些都是令人兴奋的协同效应，以最低的成本增强了发动机的许多属性，并且可以立即获得，这是其他混合动力类型不可能实现的，而且只有空气混合动力才是独一无二的，因为可以随时获得空气供应。因此，利用这种协同效应将导致空气混合动力总成系统在燃油消耗、排放和性能方面有显著和同时的改善。本方案的目的是研究和开发一种用于城市公交车和商用车的新型空气混合动力总成系统，在燃油经济性、排放和性能方面比现有的内燃机发动机有显著和同时的改善。

The hybrid powertrain with regenerative energy recovery is recognised as one of the most effective means to low carbon vehicles in short to medium term. It can significantly improve the fuel economy, particularly for buses and delivery vehicles 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 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 most researched and developed hybrid vehicles are electric based. The application of electric hybrid powertrain to buses and delivery vehicles is severely limited by the huge additional cost associated with the engineering complexities of the combined electric and mechanical powertrain and transmission systems. Currently, the electric hybrid buses are heavily subsidised and will not be suitable for commercially viable large volume production. Unlike the electric and hydraulic hybrids, air hybrids can be implemented without adding an additional propulsion system to the vehicle when it is applied to a reciprocating internal combustion engine. In this case, the engine itself can be used as a compressor during braking/deceleration or an expander for starting/ acceleration, transmitting power through the pistons and the crankshaft of the engine thus braking or propelling the vehicle using the existing drivetrain of the vehicle. For buses and delivery vehicles, air energy will be stored at moderate pressure (less than 15 bar) in a compressed air storage tank already available on such vehicles. Similar to its electric cousins, the air hybrid will be able to recover the braking energy and store it for later use to start the engine and help the vehicle to accelerate, allowing significant improvement in fuel economy without adding the large weight and complexity of the electric hybrid. 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. For buses and commercial vehicles, compressed air is required for air assisted braking and the operation of pneumatic equipment (e.g. door opening and closing) and is currently produced by an engine driven compressor. Air hybrid powertrain technology will enable further and readily achievable fuel savings to be realized by providing the service compressed air from the regenerative engine braking in place of the engine driven compressor. These are exciting synergies enhancing many attributes of the engine at minimum cost and are immediately available, not possible with the other hybrid energy types and unique only with the air hybrid because of the readily available air supply. Therefore, the exploitation of such synergies will result in an air hybrid powertrain system with significant and concurrent improvements in fuel consumption, emission, and performance.The aim of this proposal is to carry out research and development of suh a novel air hybrid powertrain system for urban buses and commercial vehicles with significant and concurrent improvements in fuel economy, emissions, and performance over the current IC engines.