车用发动机压缩空气制动循环特性

Performances of vehicle engine air compression braking

基于压缩空气储能回收车辆制动能量的思想,提出以单向阀作为能量回收阀的发动机压缩空气制动能量回收方法.通过热力学分析,建立发动机压缩空气制动模型,通过台架试验得到初步验证.通过对模型进行稳定工况仿真,得到发动机压缩空气制动在不同转速和不同气罐背压下的特性.通过车辆模拟制动仿真得到特定制动工况下气罐内气体累积过程及能量回收效率.结果表明:缸内最大压力与气罐背压之差是影响制动性能的内在关键因素,增大压缩比可以增加发动机制动转矩,提高能量回收效率;在稳定工况条件下,发动机压缩空气制动循环的最大制动转矩可达驱动时最大转矩的54%,最大能量回收率可达8.5%;在所选的模拟制动工况下,采用发动机压缩空气制动能够使车辆获得较稳定的减速度,整车能量回收率达到10.2%.

A novel engine regenerative braking method was presented which adopts a check valve for energy recovery based on the idea of braking energy recovery through compressed air. A single cylinder gasoline engine prototype was modeled and validated with preliminary test by using thermodynamics and gas dy- namics theory. Engine braking performances at steady state simulations were discussed, including engine braking torque and energy recovery efficiency with different engine speed and tank pressure. Transient simulations of vehicle deceleration were conducted to analyze tank pressure accumulating and energy recov- ery efficiency. Results show that the difference between maximum pressure in engine cylinder and tank pressure is the crucial factor influencing braking characteristics. The engine braking torque and efficiency can both increase with higher compression ratio. At steady state simulation cases, the braking torque rea- ches 54 % of the maximum driven torque of engine conventional mode and the maximum energy recovery ef- ficiency reaches 8.5 %. Vehicle braking simulation at certain conditions shows an effective deceleration and efficiency of 10.2%.