US 4,662,819 AGranted

Centrifugal fan with variable blade pitch

AssigneeAmerican Standard Inc.

InventorsRodney Lakowske, James C. Tischer, David H. Eber

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Abstract

A centrifugal fan includes a fan wheel having airfoil blades mounted for pivotal movement about their center of gravity. A yoke mechanism exterior of the fan wheel, when moved axially of the fan wheel drive shaft axis, causes actuator rods to move through the sidewall of the fan wheel. The axial movement of the actuator rods is translated first into rotary movement of a quill hub relative to the fan wheel and finally to radial movement of blade pivoting levers interior of the fan wheel. The movement of the blade pivoting levers causes the pitch of the individual fan blades to be changed in accordance with the degree of movement of the yoke mechanism. The yoke mechanism, actuator rods, quill hub and blade pivoting levers operate independently of the fan wheel so that blade pitch can be varied over an operating range irrespective of whether the fan wheel is stopped or is rotating. The yoke mechanism is moved and fan modulation is accomplished in response to the demand for conditioned air by the variable air volume system in which the fan is employed.

Claims19

Dependent claims

A centrifugal fan comprising:

a fan housing having an inlet;
a centrifugal fan wheel mounted for rotation in said fan housing and having a first sidewall, a back plate and a plurality of fan blades, each of said fan blades being mounted for rotation about a pivot axis over a predetermined operating range of rotation, the degree of rotation of a fan blade about its pivot axis being determinative of the pitch of the blade in said fan wheel, said first sidewall defining an inlet cooperating with said fan housing inlet to provide a flow path for air into the interior of said fan wheel and said back plate defining a mounting surface;
a fan wheel driveshaft, said driveshaft penetrating and drivingly connected to said back plate so that driveshaft rotation causes the rotation of said fan wheel;
hub means, mounted on said back plate mounting surface, for rotation around said driveshaft irrespective of the rotational speed of said back plate or driveshaft, said hub means connected to said fan blades so that rotation of said hub means around said driveshaft causes the pitch of said fan blades to change;
a plurality of actuator rods penetrating and disposed for movement through said fan wheel back plate;
and
means for connecting said actuator rods to said hub means so that movement of said actuator rods through said back plate causes said hub means to rotate around said driveshaft.

4 more elements

Apparatus for varying the pitch of the blades of a centrifugal fan comprising:

a centrifugal fan wheel mounted for rotation on a driveshaft, said fan wheel having a back plate, a sidewall defining an inlet and a plurality of fan blades each mounted for rotation about a pivot axis;
hub means mounted on said back plate for rotational movement relative to said fan wheel back plate and around said driveshaft irrespective of whether said fan wheel and driveshaft are at rest or are rotating;
means for causing said fan blades to rotate in response to the rotational movement of said hub means relative to said fan wheel back plate;
a plurality of actuator rods spaced around and parallel to said driveshaft, said actuator rods carried by and slidably penetrating said back plate for movement therethrough;
ring means penetrated by and spaced from said driveshaft, said ring means being fixedly connected to the ends of said actuator rods on one side of said back plate;
means for connecting said ring means to said hub means so that movement of said ring means axially of said driveshaft, in response to movement of said actuator rods through said back plate, causes said hub means to rotate;
and
yoke means having a rotatable portion attached to the ends of said actuator rods opposite the ends attached to said ring means, said rotatable portion of said yoke means being penetrated by and spaced from said driveshaft, whereby said fan wheel, said hub means, said means for causing said blades to rotate, said actuator rods, said ring means, said means for connecting and said rotatable portion of said yoke means are all driven at the rotational speed of said driveshaft and whereby movement of said yoke means axially of said driveshaft causes said hub means to rotate around said driveshaft, independent of the rotational speed of said driveshaft, thereby causing the rotation of said fan blades about their pivot axes to a degree which is predetermined and independent of fan wheel speed.

5 more elements

Dependencies are inferred from the claim text.