变转速泵控系统建压过程中流量死区特性分析

为揭示泵控系统中液压泵在控制过程中出现流量死区的机理,针对泵控系统在启动和换向过程中必需重新建压的特点,考虑压差流与剪切流导致的液压泵内泄漏以及油液可压缩性,建立包含流量死区的液压泵数学模型.通过分析得到:液压泵流量死区的宽度随液压泵的出口容腔、负载压力、油温和启动加速度的增大而增大,随液压泵排量的增大而减小.为此,以齿轮泵为例建立Simulink-Amesim联合仿真模型,进一步研究不同负载压力、油温和启动加速度对流量死区宽度的影响,并验证理论分析结果.结果表明:液压泵流量死区宽度与负载压力和启动加速度均呈线性关系,与油温接近指数关系.

Characteristic analysis of flow-dead-zone in pressure building of variable speed pump control system

In order to reveal dominant mechanism of the flow-dead-zone of a hydraulic pump in pump control system, a mathematical model of the hydraulic pump, including the flow-dead-zone, is established in this paper. The model takes into account the leakage in the hydraulic pump caused by differential pressure flow and shear flow as well as the compressibility of oil. Through analyses of the mathematical model, it is concluded that the width of the flow-dead-zone of the hydraulic pump increases with increase of the outlet cavity, load pressure, oil temperature and start-up acceleration of the hydraulic pump, and decreases with increase of displacement of the hydraulic pump. For this reason, taking a gear pump as an example, a Simulink-Amesim joint simulation model is established to study further effects of different load pressure, oil temperature and start-up acceleration on the dead zone width, and verify the results from theoretical analyses. The results show that the dead zone width of hydraulic pump flow has a linear relationship with load pressure and start-up acceleration, and is close to an exponential relationship with oil temperature.