Axial flow fan with variable pitch blades - has pitch adjusted by linkage from electric positioning motor

摘要

The fan has blades (3) on a shaft (2) which is driven by a belt (1). Each blade is turned on its own axis by a pinion (8) engaged by a rack (7). The rack is attached to a disc (6) which is fixed axially to a hub (5) and rotates round it. The hub slides axially over a sleeve (4) surrounding the shaft (2). The hub (5) is moved by a fork (10) which is rotated about its pivot by a lever (11) on the output gear (13) of an electric motor (12). The motor is supplied with current through a controller (14) from a dynamo (16) driven by the fan shaft. The mechanism can adjust the blades to vary the throughput and also turn them through 180 deg. when the direction of rotating is reversed.