Pumps – Motor driven – Pump and motor interconnected by endless flexible...
Reexamination Certificate
1999-09-28
2001-02-20
Walberg, Teresa (Department: 3742)
Pumps
Motor driven
Pump and motor interconnected by endless flexible...
Reexamination Certificate
active
06190140
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
This invention relates generally to high capacity, industrial and agricultural ventilation fans. More particularly, my invention relates to an improved, motor-mounting system for belt-driven fans that continuously maintains and regulates belt tension.
II. Description of the Prior Art
High volume fans provide ventilation and cooling for many agricultural facilities, especially in the poultry and dairy industries. Such fans are designed to properly control the direction, velocity, and volume of air being moved. I have previously proposed a fan adept at controlling air over long ranges. One of my previous fan inventions, issued as U.S. Pat. No. 5,480,282, on Jan. 2, 1996, and its teachings are hereby incorporated by reference. It was classified in U.S. Class 415, subclass 125. As can be seen from that patent and the prior art therein, the known prior art comprises many different types and designs of fans adapted to satisfy various criteria.
High volume ventilation fans include a rigid housing that protectively encloses the fan blade and motor. Protective guards shroud the housing. So-called “box fans” have a tubular housing that is “square,” i.e., in the general form of a cube or parallelepiped. A tubular, cylindrical housing, in the form of a cylinder, is used by so-called “barrel fans,” Depending upon the design and configuration, a number of different accessory items such as screen guards, shutters, electrical controls, discharge cones, and venturis may be deployed. Typical high capacity fans may be mounted on the ground, or secured in an elevated position upon an adequate support. The two principal fan-drive designs employed with modern high capacity fans are direct drive and belt-drive systems. Both arrangements have advantages and disadvantages.
Such fans are often deployed in rugged, industrial environments, where they may be used for long hours without periodic maintenance. As dust and dirt accumulate, vibrations develop, causing various parts to loosen. Obviously moving parts such as motors, belts, and rotors will wear with time. Periodic maintenance, while desirable, will be lacking in many industrial or agricultural applications. When maintenance is performed, the servicing technician faces a number of problems. The design features and differences between various fans used in a given application make it difficult to inventory proper parts, tools, and service diagrams. The servicing technician must possess knowledge of several different types and designs of fans. Another problem involves the protective safety guards installed on most fans. These must be removed to expose the fan's innards for service. Over time, the guards can vibrate loose, and in response to vibration and rough handling, they may become deformed and difficult to remove or adjust.
In general, the more a fan is used, the “looser” the guard and fan housing becomes. Often the housing is warped or damaged over time, and as a result, the guards simply do not “fit” as tightly as they did when the fan was newer.
Typically belt-driven ventilation fans have drive assemblies that are mounted on spaced-apart bearing/shaft assemblies. A drive motor is typically mounted such that its axis of rotation is parallel to and spaced apart from the fan shaft. The motor and fan shafts are connected by a suitable “V” belt entrained over pulleys that establish an adequate gear drive ratio. Many structural variations for mounting the fan, the motor, and the linkage components have been proposed. A major problem with belt-driven fans is the lack of a simple belt tensioning method.
As high capacity ventilation fans age, accumulating wear on the belts, motors and associated pulleys can loosen critical parts. When belt wear becomes appreciable, belt tension varies unpredictably, degrading performance. To maintain peak operating efficiency, belts in common designs must be inspected, and the apparatus must be adjusted relatively frequently. Unfortunately, this type of routine maintenance requires considerable time and effort. Tension adjustments to belt-driven fans generally require the removal of at least one guard. Consequently, structure that maintains belt integrity and reduces service requirements is desirable. A reliable system for automatically maintaining belt tension in a belt-driven fan would increase reliability, and optimize efficiency.
SUMMARY OF THE INVENTION
My new motor mounting system for belt-driven fans provides a system that inherently maintains proper belt tension. Fan longevity and reliability are increased, while service requirements are reduced. The disclosed mounting concept minimizes problems associated with mounting orientation and friction, and combines fan and motor mounting into a simple structure with a reduced number of parts. During operation the torsional reaction of the motor produces a tendency to increase the belt tension under heavy load conditions, like that encountered during starting. The pulling side of the belt is near the pivot of the motor mount, so the resultant torque stresses the motor toward the pulling side. As a result, slipping, is eliminated.
The preferred fan comprises a rigid, outer housing of a predetermined shape. The invention may be incorporated in “box fans” having a cubicle shape like a parallelepiped, or it can be employed with “barrel fans” having round or cylindrical housings. In either case at least pair of rigid, spaced-apart rails extend through the enclosure, preferably vertically. The rails also serve as a wire duct for the switch cord and the power cord, resulting in a smooth, aesthetically pleasing appearance. The “C-shaped” cross section of the preferred rails reduces turbulence as air rushes through the fan housing.
A single-piece, mounting unit with a generally “X-shaped” cross section is suspended between the frame rails and supports both the motor and the propeller assembly. The unit's arms, which form an “X-shaped” profile, enable the mounting unit to be rigidly secured between and to the rails. The arms diverge outwardly away from a rigid, tubular mandrel at the center of the mounting unit. The mandrel coaxially receives and rotatably mounts the fan axle. Thus the fan is centered for rotation coaxially with the mounting unit mandrel, between the rails.
Importantly, the motor is secured upon a deflectable wing that is pivoted with a rigid hinge to the body of the mounting unit. This mounting automatically compensates for dimensional changes and stresses. The hinge axis is parallel with the axis of rotation of the fan (i.e., the mandrel) and the motor. The motor and fan are mechanically coupled with a conventional V-belt entrained between suitable pulleys. A coiled, heavy-duty spring normally biases the wing to tension the belt. Since the wing hinge pivot axis is parallel to the axis of rotation of the fan and the drive motor, the motor drive pulley will remain coplanar with the fan pulley notwithstanding wing deflections.
In effect the wing is activated by the heavy-duty spring that yieldably biases it outwardly from the mount, with a force much greater than the weight of the motor and the unitary mounting assembly. Variations in motor position are rendered possible by the hinged wing, which will deflect as torque increases. In this manner, suitable belt tension is maintained and regulated.
The fan may be mounted vertically or horizontally over the motor, or upon either side. In other words, the motor may be oriented above or below the fan. Since both the fan and the motor are mounted within the fan by a single part, complexity is reduced while reliability is enhanced. In operation, no adjustment is required after assembly for the life of the fan. The unitary mounting system increases fan life and reliability significantly over more-complex, prior art, fixed-mounted fans. Preferably, there is in fact no adjustment—except when originally installing the “V” belt. The only specification is the center distance between the pulleys. The simplicity of the design eliminates damage from poor maintenanc
Carver Stephen D.
Fastovsky Leonid
Triangle Engineering of Arkansas Inc.
Walberg Teresa
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