초록 ▼

A low profile, externally controlled, variable pitch fan blade hub assembly is disclosed which is especially useful in high humidity environments such as are encountered in the fan induced, hot air discharge section of an industrial water cooling tower. The hub housing has central hub means includin

A low profile, externally controlled, variable pitch fan blade hub assembly is disclosed which is especially useful in high humidity environments such as are encountered in the fan induced, hot air discharge section of an industrial water cooling tower. The hub housing has central hub means including a member which is telescoped over the drive shaft therefor to limit the overall height of the assembly. The hub member is biased axially of the hub by a series of peripherally located springs contained within the housing. A fluid such as air may be introduced into the housing under pressure to shift the hub unit in a direction against the spring bias thereon. The housing has a plurality of radially extending bores each of which rotatably receives a respective fan blade axle provided with an elongated arm on the innermost end thereof within the housing positioned such that a cam follower on each arm is received in a cam track forming a part of the hub unit. As the hub unit shifts in the housing in response to introduction of pressurized fluid or release of fluid from the housing, concomitant swinging of the cam follower arm rotates the blade axles to simultaneously vary the pitch of the fan blades. Recessing of the hub unit springs in the housing and the use of a plurality of such springs around the circumference of the hub unit assures uniformity of spring bias on the hub unit without impairment of the moisture sealing integrity of the hub housing.

대표청구항 ▼

Variable pitch fan blade and hub assembly adapted to be mounted on a power driven shaft comprising: a rotatable housing having a central coupling configured to be secured to the driven shaft and provided with a length extending axially of the shaft when the assembly is mounted thereon, said housing

Variable pitch fan blade and hub assembly adapted to be mounted on a power driven shaft comprising: a rotatable housing having a central coupling configured to be secured to the driven shaft and provided with a length extending axially of the shaft when the assembly is mounted thereon, said housing further being provided with a plurality of radially-extending bores; a fan blade for each housing bore; an axle section connected to each blade and rotatably received in a corresponding housing bore; transmission means within the housing and operably coupled to said axle sections for imparting a rotational moment to each axle section such that the pitch of the blades is varied, said transmission means includes cam follower means extending from the inner end of each of said axle sections, said cam follower means being disposed eccentrically relative to said inner end of each of said axle sections; hub means including a hub member disposed coaxially within said housing, said hub member being complementally telescoped over said coupling and selectively movable longitudinally thereon relative to the rotational axis of said housing, said hub means being provided with circumferentially-extending cam track means, said cam track means cooperating with said cam follower means such that when said hub means moves longitudinally relative to the rotational axis of said housing, said cam follower means follows said cam track means so that a rotational moment is imparted to said axle section due to said eccentric disposition of said cam follower means relative to said inner end of said axle section for simultaneously varying the pitch of the blades; and a plurality of springs within said housing and engaging said hub means outboard of said hub member for biasing said hub means longitudinally relative to the axis of rotation of said housing, said springs being spaced circumferentially around said hub means and being positioned within the housing outboard of said cam track means.