外啮合齿轮泵侧隙流量的精确计算

Accurate calculation of backlash flow in external gear pump

为计算出精确的侧隙流量以克服现有方法上的局限性,通过齿侧轮廓精确分析给出不同啮合位置和不同偏移量下的侧隙高度,然后由齿侧全间隙的等效齿廓和真实齿廓分多种方法计算出侧隙流量,并加以对比分析.结果表明,不同啮合位置处的侧隙流量变化很大,进入困油啮合时侧隙流量最小,退出啮合时侧隙流量最大;在困油压缩区域中,侧隙流量可采用等效齿廓法来计算,但不适用于膨胀区域;孔口流量理论不适宜于侧隙流量的计算,尤其在困油即将终止时以及侧隙值、压差较大时更不可取;任一位置处的齿侧全间隙长度基本保持不变,对于任一偏移量下的间隙值随位置变量的影响很小.同时,得出目前通行的等效齿廓法以及薄壁孔理论不适宜于侧隙流量的计算等重要结论.

To overcome the limitations of the available methods used for accurate calculation of backlash flow rate in external gear pumps,firstly by accurate analysis of tooth-profile near the minimum backlash position,together with meshing position variable and offset variable from theoretic meshing line,the formula to calculate length and height related to gap near the minimum backlash position was derived.And then,the corresponding backlash flow rates in a trapped-oil cycle were calculated by a variety of methods based on equivalent tooth-profile and actual tooth-profile.Under the same pressure difference,all results indicate that backlash flow rate is minimum in the beginning of trapped-oil section and is maximum in the end of trapped-oil section.The equivalent tooth-profile method can be used to calculate the backlash flow rate in the compression section of trapped-oil while cannot be used in the expansion section.The orifice flow theory is not suitable for calculation of backlash flow rate,especially at the termination of trapped-oil section,the bigger backlash value,or the higher pressure difference.The longest length of gap in backlash is readily unchanged at all meshing positions.Different meshing positions have little effects on gap value under a given offset.Finally,the important conclusion is that the popular equivalent tooth-profile method and the theory of thin-walled orifice are unsuitable for the backlash flow rate calculation.