【作者】 郭洪文；

【导师】 李幼德；

【作者基本信息】 吉林大学 ， 车辆工程， 2004， 硕士

【摘要】 车辆悬架系统在保证汽车具有良好的行驶平顺性和操纵性方面起着至关重要的作用。它能把路面作用于车轮上的垂直反力、纵向反力和侧向反力以及这些反力所造成的力矩都要传递到车架上，以保证汽车的正常行驶。 悬架系统分为：传统的被动悬架系统、半主动悬架系统以及主动悬架系统。然而，被动悬架系统由于其弹性元件和阻尼元件均不可控，所以实际上是一种同时满足行驶平顺性和操纵稳定性的折衷方案。另外，主动悬架虽然克服了被动悬架系统的缺陷，使悬架的参数能随路况、工况及速度的变化而变化，但主动悬架系统实现的造价很高，因此目前，实际应用较少。半主动悬架的性能虽然比不上主动悬架，但是其成本低，控制简单，使之更受到汽车生产厂商的重视，所以在一些车辆上得到了应用。悬架系统中的减震装置即减振器，是悬架中重要的部件，它能使弹性元件产生的振动迅速衰减，提高乘坐舒适性。我们所说的半主动悬架就是通过调节减振器的阻尼系数来改变悬架的参数，但是这种改变只是有级改变。 本文在前人理论研究的基础上，针对NJ2045越野车，着重探讨并试制了半主动悬架控制器，对其软、硬件进行了详细的介绍，并进行在线仿真调试，证明了它的可行性和实用性。 首先，本文建立了NJ2045越野车的七自由度车辆模型，根据运动微分方程建立了其状态方程表示式，然后，在频域下运用MATLAB软件编程，对直线行驶、加速制动及转向三种工况进行模拟仿真，得到了车身垂直加速度、俯仰角加速度、侧倾角加速度及悬架动行程、轮胎相对动载荷的均方根值随阻尼变化的曲线，并仿真分析了悬架阻尼系数对评价指标和各影响因素的影响趋势。基于模拟计算结果及经验参考，得到了两态可调减振器的软、硬阻尼值。 然后，根据弹性圆环薄板的大挠曲变形理论，推导减振器阻尼阀阀片的变形上的现成理论，并把它应用在NJ2045越野车的压缩阀阀片的变形计算上，再根据流体力学计算公式研究减振器阻尼特性。试验结果很好地验证了理论计算的可靠性及正确性，为减振器的设计提供了很好的理论指导。根据所确定的软硬阻尼值，推导出了两态可调减振器的结构参数。 再次，在借鉴前人经验的基础上，研制开发了半主动悬架的控制单元(ECU)。首先针对NJ2045越野车的实际情况，选择信号传感器，并设计输吉林大学硕士学位论文入硬件电路。根据控制要求及精度来选择控制计算单元即单片机，设计外围电路。在硬件开发的基础上，设计了半主动悬架控制软件。并针对NJ2045越野车设计了控制逻辑框图。 最后，自行研制了电磁阀控制的阻尼可调的液力减振器，并对所研制的可调减振器进行了台架试验，得到了软、硬阻尼速度特性曲线，很好地验证了理论计算的准确性。更多还原

【Abstract】 The semi -active suspension makes automobile possess good handling stability and ride comfort when it runs along straight line, speeds up, brakes and turns.My automotive control system control two modes of the variable dampers: soft and hard modes. In order to control the damping mode, the control signals from the ECU are applied to four damper actuators. Upon receiving the control signals from the ECU, the solenoid only operates to move an armature which opens and closes. When the damper control valve is open and the damper is operating under low damping force conditions, the associated vehicle experiences a relatively soft ride as a result. When the damper control valve is closed, the damper is operating under high damping force conditions and the associated vehicle experiences a relative firm ride as a result.Basing on the above considerations, firstly, in my paper, I set up a seven degree of freedom vehicle model to establish the state equation according to moving differential equation. With the state equation, in the time domain, I simulate four main working conditions: driving straight, speeding up, braking and steering to obtain their responses. Then considering the results of simulation and the experience, the two damping values of two-modes variable damper are obtained.Secondly, as for modeling for the damping valve, I use large deflection theory of thin elastic annular plate to analyze the deflection of the damping valve plate. Then I compute the velocity characteristic of variable damper by hydromechanic theory. That is to say to obtain the relation curve between damping force and piston velocity of variable damper.Thirdly, dampers of NJ2045 cross-country vehicle is my test coupon. Test result verify the reliability and accuracy of theoretical computation which gives the design of the damper an excellent guide, according to the two damping values obtained above structure parameters of the variable dampers are worked out.At last, I must develop the electrical control unit of semi-active suspension. The control system has a plurality of signal input sensors. The signals from thesignal input members are processed by an ECU in accordance with a preset program. After processing the signals, the ECU determines the desirable damping force for controlling the variable dampers which are fixed to the wheels of a vehicle. The above semi-active suspension thus provide comfortable ride to a driver and passengers and secure steering safety of the vehicle.更多还原