Secondary unit, in term of application, is the combination of pump and motor, the valve plate specifically designed for pump or motor may not be suitable for a secondary unit. This paper mainly discusses design of valve plate of secondary unit applied in mobile crane, several critical points needed to be noticed during design have been discussed, furthermore, by adopting the proposed method to optimize a valve plate, which originates from closed-loop pump and now is used in opened-loop system, noise reduction was realized. Firstly, 1D simulation models, including pump condition and motor condition, were established in AMESim to obtain cylinder pressure, flow ripple and other critical parameters; secondly, by using Pumplinx, 3D numerical simulation was conducted to evaluate the cavitation risk; finally, a test bed was set up to validate the simulation result. Simulation result agreed well with the tested one. Both of them verified practicability of the proposed method. This research may provide a guidance for engineers and scholars who are interested in pump and motor.

二次机组，就应用而言，是泵和电机的组合，专为泵或电机设计的阀板可能不适用于二次机组。本文主要讨论了移动式起重机二次单元阀板的设计，讨论了设计中需要注意的几个关键点，并采用所提出的方法优化了源自闭环泵和泵的阀板。现在用于开环系统，实现了降噪。首先，在AMESim中建立泵工况、电机工况等一维仿真模型，获取气缸压力、流量脉动等关键参数；其次，利用Pumplinx，进行3D数值模拟，评估气蚀风险；最后，建立了一个试验台来验证模拟结果。仿真结果与测试结果吻合良好。他们都验证了所提出方法的实用性。本研究可为对泵和电机感兴趣的工程师和学者提供指导。