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

具有再生能量回收的混合动力系统被认为是中短期内实现低碳汽车的最有效手段之一。它可以显着提高燃油经济性，特别是对于城市和城市地区的公共汽车和运输车辆，其中交通条件涉及大量的停止和启动。在这种情况下，需要大量的燃料来加速车辆，并且其中大部分在减速期间在制动摩擦中转化为热量。因此，捕获、存储和再利用该制动能量可以提高燃料效率，并且这可以通过在滑行和减速期间使用车辆的动量来加满能量存储装置并且随后在巡航和加速期间释放能量以推进车辆来实现。大多数研究和开发的混合动力汽车是基于电动的。电动混合动力系统在公共汽车和运输车辆上的应用受到与组合的电动和机械动力系统和传动系统的工程复杂性相关的巨大额外成本的严重限制。目前，电动混合动力巴士的补贴很高，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，当空气混合动力车应用于往复式内燃机时，空气混合动力车可以在不向车辆添加额外的推进系统的情况下实施。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，或者用作用于起动/加速的膨胀器，通过发动机的活塞和曲轴传递动力，从而使用车辆的现有传动系制动或推进车辆。对于公共汽车和运输车辆，空气能将以中等压力（小于15巴）储存在此类车辆上已有的压缩空气储存罐中。与电动车类似，空气混合动力车将能够回收制动能量并将其储存起来，以供以后用于启动发动机并帮助车辆加速，从而在不增加电动混合动力车的重量和复杂性的情况下显着提高燃油经济性。此外，储存的高压空气可根据需要随时用于其他用途，以改善驾驶性能并减少排放，例如短暂地提升发动机以消除涡轮增压发动机中的涡轮滞后，从而导致更好的响应和通常从加速柴油车辆中看到的黑烟的去除。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（例如门打开和关闭）需要压缩空气，目前由发动机驱动的压缩机产生。空气混合动力传动系统技术将通过提供来自再生发动机制动的工作压缩空气代替发动机驱动的压缩机来实现进一步且容易实现的燃料节省。这些都是令人兴奋的协同作用，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，这对于其他混合能源类型是不可能的，并且由于容易获得的空气供应，只有空气混合动力才是唯一的。因此，这种协同效应的开发将导致空气混合动力系统的燃料消耗，排放和性能显着和并发的改善，本提案的目的是进行研究和开发这样一种新型的空气混合动力系统的城市公交车和商用车的燃料经济性，排放和性能显着和并发的改善，比目前的内燃机。

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.