| 摘要 |
PURPOSE:To improve the performance, efficiency, and reliability by keeping the minimum clearance over the whole range between the tooth forms in engagement by taking account of the thermal expansion in the actual operation, in the engagement between a female rotor and a male rotor. CONSTITUTION:The advance-surface flank 87 of a female rotor is formed with a smooth connection part from the secondary curves of a circular arc and a parabola, and a rtreat-surface flank is formed by the curve formed by the circular arc of the retreat-surface tooth top flanks 18 and 19 of a male rotor and the circular arc which is smaller than the circular arc at the leading tooth edge side of the advance-surface flank, and thus the service life of a tool is reduced, and the blow hole area is reduced, and the performance is improved. The rotor tooth form 48 which is changed by the thermal expansion during actual operation of rotors 1 and 2 is calculated by a definite element method etc., on the basis of the temperature distribution which is obtained through the measurement of temperature inside the rotor. The normal-temperature tooth form 50 of the female rotor 1 is obtained by restoring the rotor tooth form 49 of the female rotor 1 which is formed from the rotor tooth form 48, to the normal-temperature state through calculation. |
