| 摘要 |
<p>PURPOSE:To reduce pressure loss by setting the spiral pitch form of a blade groove so that a specific capacity ratio formula is met by the number of turns of the blade, the capacities of compression chambers, and capacities of groove bottom spaces. CONSTITUTION:The spiral pitch form of a blade groove 13 is set so that the capacity ratio formula (V1+Va)/(Vn-1+Vb)=3 thru 12 is met, where (n) is the number of turns of a blade 14, V1 is compression chamber capacity of the suction side first chamber, Va is the groove bottom space capacity of the first turn of blade in communication with the same compression chamber, Vn-1 is the compression chamber capacity of the discharge side final chamber, and Vb is the groove bottom space capacity of the prior-to-final turn in communication with the discharge side final chamber. Thereby the range of compression chamber capacity ratio to the number of turns of the blade, or the range of the pressure ratio, can be set appropriately, which allows preventing counterflow of the discharge gas with no risk of out of attainment of the pressure rise, reducing pressure loss, and enhancing the compressing performance.</p> |
