| 摘要 |
A fan impeller for axial flow having automatically variable-pitch blades attached to a rotatable hub for attaining maximum lift and inhibiting stall in a varying back pressure regime. The blades are attached for rotation about their axes to the hub, and are connected through a crank and link to a drive shaft. The hub is attached to the drive shaft to permit relative axial movement, but to preclude relative rotational movement. Varying back pressure moves the blades and the hub in variable blade rotation planes, causing changes in blade pitch. Springs and dash-pots, connecting the hub and shaft, act axially to give non-linear restoring forces and damping to the blade pitch changes.
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