基于机械液压功率同步分流的液压变速器机理研究

A novel hydro-mechanical power split mechanism which can split engine power into mechanical and hydraulic power simultaneously in single unit has been proposed for series-parallel hydraulic hybrid system in this study. The series-parallel hydraulic hybrid system combines the advantages of both parallel and series hydraulic hybrid systems and has great potential in construction machinery since it can optimize engine operations by decoupling engine speed from vehicle speed while still has relatively high transmission efficiency. The power split device is the key component to split power in the series-parallel hydraulic hybrid system. The typically used power split device is the planetary gear set. It only splits the engine power into two mechanical power branches and the conversion from mechanical power to hydraulic power is still to be achieved by a hydraulic pump. To split the engine power into mechanical and hydraulic power simultaneously in single unit, a novel hydro-mechanical power split mechanism is developed. It originates from a double-acting balanced vane pump but with an additional output shaft and a floating ring. By coupling the floating ring to the output shaft, it essentially becomes a hydraulic transmission with a pressure control port. It splits the mechanical power on the input shaft into the mechanical power on the output shaft and the hydraulic power at the pressure control port simultaneously. The power split ratio can be adjusted by controlling the pressure at the pressure control port. The proposed hydro-mechanical power split mechanism provides a new approach to splitting power in series-parallel hydraulic hybrid systems.

针对混联式液压混合动力系统中机械和液压功率无法实现同步分流，提出了一种新的功率分流机理，在单个元件上实现机械和液压功率的同步分流。混联式液压混合动力集并联式和串联式混合动力的优势于一体，既能优化发动机工作点，又有较高传动效率，应用前景广泛。功率分流元件是混联式系统实现机械液压复合传动的重要元件，现有系统通常采用行星齿轮组进行功率分流，行星齿轮组只实现机械功率分流，机械功率转化成液压功率仍需液压泵来实现，无法实现机械和液压功率的同步分流。该研究提出的功率分流元件基于双作用式叶片泵，但区别是多一个输出轴并与浮动定子连接，本质上是一个带液压控制端的液压变速器，将输入轴机械功率转化成输出轴机械功率和液压控制端液压功率，在单个元件上实现机械和液压功率的同步分流，通过控制液压控制端压力实现功率分流比的调节。通过对液压变速器功率分流机理的研究，为混联式液压混合动力系统提供了一种新的功率分流方法。

针对混联式液压混合动力系统中机械和液压功率无法实现同步分流，提出了一种新的功率分流机理，在单个元件上实现机械和液压功率的同步分流。混联式液压混合动力集并联式和串联式混合动力的优势于一体，既能优化发动机工作点，又有较高传动效率，应用前景广泛。功率分流元件是混联式系统实现机械液压复合传动的重要元件，现有系统通常采用行星齿轮组进行功率分流，行星齿轮组只实现机械功率分流，机械功率转化成液压功率仍需液压泵来实现，无法实现机械和液压功率的同步分流。该研究提出的功率分流元件基于双作用式叶片泵，但区别是多一个输出轴并与浮动定子连接，本质上是一个带液压控制端的液压变速器，将输入轴机械功率转化成输出轴机械功率和液压控制端液压功率，在单个元件上实现机械和液压功率的同步分流，通过控制液压控制端压力实现功率分流比的调节。通过对液压变速器功率分流机理的研究，为混联式液压混合动力系统提供了一种新的功率分流方法。