基于齿根弯曲疲劳强度的渐开线涡旋齿载荷模型

A Load Model for Involute Scroll Teeth Based on Tooth Root Bending-fatigue Strength

分析渐开线动涡旋齿的作用压力和应力特点,确定了涡旋齿根弯曲疲劳强度计算准则,得到基于齿根弯曲疲劳强度的载荷模型。研究表明,涡旋齿内外壁面的压力分布规律不同,涡旋齿上任意点的应力近似于脉动循环的弯曲应力,可用安全系数法计算涡旋齿根弯曲疲劳强度。涡旋齿工作中相当于受到展角间隔为π的π展角区域内压作用,内压载荷的大小等于涡旋齿内外壁面的压力差,内压作用载荷变化不连续;当曲柄转角为开始排气角时,不但载荷值最大,而且作用区域离涡旋齿中央区域最远,涡旋齿安全系数最小;选择合理的开始排气角是提高涡旋齿强度和稳定性的重要途径。

The specific features of acting pressure and stress of involute scroll teeth were analyzed and the criterion for calculating bending fatigue-strength of scroll tooth roots was determined with a load model based on tooth root bending-fatigue strength being obtained.The study shows that the pressure distribution law on the internal and external wall surface of the scroll tooth is different and the stress at any point on the scroll tooth approximates to the bending stress of a pulsation cycle.Thus,a safety factor method can be used to calculate the bending fatigue-strength of scroll tooth root.During operation the scroll teeth are subjected to the internal pressure in a π spreading angle area having a spread angle interval of π.The magnitude of the internal-pressure load is equal to the pressure difference of inner and outer wall surface of the scroll tooth.However,the load resulting from the inner pressure will change discontinuously.When the crank rotating angle assumes one featuring an exhaust-discharge initiation,the inner pressure not only reaches its maximum but also the acting area is farthest away from the central zone of the scroll tooth with its safety factor attaining a minimum value.The selection of a rational exhaust-discharge initiation angle constitutes a major approach for enhancing the scroll tooth strength and stability.