| 摘要 |
A butterfly valve (30) is described in which the plate member (32) is in facing relationship with a hollow shaft (34) and is moved by pistons (50, 52) disposed in the shaft. The pistons (50, 52) are mechanically coupled to the plate member (32) by cam followers (58, 60) which ride along cams (40, 42, 46, 48) formed in the shaft (34) and plate member. The plate member (32) is capable of both revolutionary and translation movement relative to the longitudinal axis of the shaft (34) toward the end of minimizing the externally supplied energy required to operate the valve (30). The pistons (50, 52) collectively have a center of mass that coincides with the center of the duct (68) toward the end of minimizing vibrational effects.
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