Dynamic instability will occur between the frictional plates in high speed wet clutch,which can lead to impact vibration and a sudden increase of power loss.A 3 degree of freedom fluid-solid coupled dynamic model was established,and an algorithm of finite element method to numerically solve the model and corresponding stability analyses were conducted.The model shows that the axial movement and angular wobble of the frictional plate are uncoupled,so they can be divided into two separate move-ments for analysis.Under two-phase flow condition,the frictional plate exhibits axial self-excited instability and wobble self-ex-cited instability.The stability of several grooves was analyzed.Increasing oil clearance helps to suppress axial self-excitation,but easily induces wobble instability of the frictional plate.Compared with the radial grooves,spiral grooves can realize higher wobble stability.Drag torque model considering impact vibration was proposed for high speed open wet clutch,the model indicates that the wobble in αand βdirections is coupled with each other.When the speed exceeds the threshold value,wobble instability will occur,in which the vibration amplitude and the vibration speed increase divergently.The wobble instability leads to an impact when the amplitude is greater than the oil thickness.Periodic vibration amplitude of the frictional plate remains unchanged due to constraints on both the stationary separated plates.The phase angle θof the impact point distributes circumferentially and varies between -180°-180°,which is called the nutation of rotating frictional plate.With the increase of the speed,impact velocity and impact force increase,so the drag torque increases linearly,which has been verified in physical experiments.The fluid-solid cou-pled dynamic model and the drag torque model considering impact vibration provide references for performance prediction and de-sign of the stability of high speed wet clutch.%湿式离合器高速工况会发生摩擦片之间的发生动力学不稳定,产生碰振,导致功率损失急剧增大.本研究建立了高速湿式离合器摩擦片的三自由度流固耦合动力学模型,并进行了有限元数值求解和稳定性分析.模型求解表明:摩擦片的轴向运动和角向摆动为解耦的,可分解成两个独立的运动进行分析.高速两相流工况下,摩擦片存在轴向自激振动和角向摆动自激振动.研究进行了几种槽型摩擦片的稳定性分析,增大油膜间隙有利于抑制轴向自振,但容易导致角向摆动自振,摩擦片的碰振通常表现为角向摆动自振.相比于径向槽,螺旋槽可获得更高的角向摆振稳定性.试验建立了考虑碰振的高速离合器带排转矩模型,模型分析表明,α、β方向的摆振为相互耦合的,当转速超过临界转速时,引起角向摆振的不稳定,振动幅值和振动速度均发散增大,当振幅大于油膜间隙时,产生碰撞,引起带排转矩的增加.碰撞发生后,由于两侧的固定位移约束,振幅维持不变,为周期碰撞,碰撞点的相位角θ为-180°~180°圆周方向分布,表现为旋转摩擦片的章动.随着转速的增加,碰撞速度和碰撞力增大,带排转矩呈线性增大,并进行了试验验证.流固耦合动力学模型和考虑碰振的带排转矩模型为高速离合器稳定性提供了性能预测和设计依据.
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