| 摘要 |
PURPOSE:To limit the vibration area of the downstream end part of a band piece and to prevent its fatigue destruction by providing swelling parts in the internal wall of a housing on both sides of the downstream-side fixation part of the band piece. CONSTITUTION:When fluid from an intake 1a is admitted to flow, the wavelength lambda2'' on the downstream side becomes shorter than the wavelength lambda1'' as shown by a curve 2'' and the part near the fixed shaft 2b of the band piece 2 is swept away to the downstream side; and its waveform tends to swell to the downstream side and it is further flowed to the downstream side beyond the fixed shaft 2b as shown by the curve 2'', and inflection is caused at wide angles to cause fatigue, so that destruction occurs finally. For this purpose, the swelling parts 4a and 4b are fixed to the internal wall of the housing 1. The height is 20-30% of the distance between parallel internal walls 1e and 1f and the upstream-side slanting surfaces are set at such positions and angles that the band piece 2 vibrates nearly in a sine waveform shape. Thus, the vibration range of the band piece near the fixed shaft 2b is limited and its waveform is held constant to prevent the fatigue destruction of the fixed part of the downstream-side band. |
