| 摘要 |
PURPOSE:To reduce the pressure gradient at the boundary and to prevent disturbed flow, noise or vibration by setting the clearance between the tip of gear and the innercircumferential face of casing at the boundary of high and low pressure areas such that the volume efficiency will be about 90%. CONSTITUTION:The clearance delta between the tip 2c, 3c of gears 2, 3 and the innercircumferential face 7a of the gear case 7 at the boundary of high pressure area H and low pressure area L is set such that the final volume efficiency will be about 92%. For example, the inner diameter A of the gear case 7 is set to 143.7phi, the outer diameter B of the gear 2, 3 is set to 143.3phi and delta is set to 200mu. Since delta is set to large level 200mu the pressure gradient between the low pressure area L and the high pressure area H will be slow. Consequently, the disturbed flow is prevented while erosion of the gear case 7 is prevented resulting in reduction of noise or vibration.
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