The invention pertains to drive clutches for oscillating air fans wherein the degree of fan oscillation may be adjusted.
Oscillating fans have long been available wherein the fan moves in an oscillating manner to distribute the airstream over a large area, and thus more effectively ventilate an area than a stationary fan. Oscillating fans are made in all sizes and are commonly available with small household fans, as well as with large commercial units.
Fan oscillation is driven by the fan motor rotating the blade. A clutch is usually interposed between the oscillation drive and the oscillating lever which has one end stationarily mounted upon the fan frame, and the other end upon a crank pin driven by the fan motor. It is common that the clutch incorporate adjusting means so that the crank pin distance from the drive shaft may be varied in order to adjust the degree of fan oscillation. By adjusting the “throw” of the oscillating pin the area covered by the fan moving airstream can be readily designed for the particular space in which the fan is used.
Unfortunately, oscillating fans are sometimes located adjacent stationary objects, or in locations wherein fan clearance is restricted, and the degree of oscillation for which the oscillation drive clutch is adjusted is greater than the degree of movement that the fan is capable of, or perhaps, an object has been moved into an interference position with respect to the path of the oscillating fan. In such instances, the encounter of the moving fan structure during oscillation with the stationary object will cause the oscillation to cease stalling out the oscillation drive structure and the fan motor, rendering the fan inoperable.
Such unintended engagement of the oscillating fan with a stationary object as to stall the fan motor may result in the fan motor overheating and burning out, or becoming a fire hazard. It is for this reason that oscillating fans carry warning labels cautioning users not to place the fan, or adjust it, in such a manner as to cause interference with the oscillating movement. Such warnings are sometimes ignored.
It is an object of the invention to provide an oscillating drive for an oscillating fan wherein the drive may be easily adjusted to vary the degree of fan oscillation without the requirement of tools or special skills.
A further object of the invention is to provide an oscillating fan with an oscillating drive which is capable of self-adjustment if the fan movement is restrained against its adjusted degree of movement and the drive clutch automatically adjusts to a lesser degree of oscillation, even to 0°, to prevent oscillation completely.
A further object of the invention is to provide an oscillating fan clutch capable of easy adjustment for various degrees of oscillation, and automatically adjustable to a degree of oscillation movement as to prevent fan motor stalling and reduce the likelihood of damage to the fan or surrounding environment.
The oscillating fan clutch in accord with the invention uses a bell crank which is mounted upon a drive shaft operatively connected to the fan motor so that the bell crank will rotate when the fan motor is energized. An oscillating pin support is mounted upon the bell crank for relative rotation thereto about an axis which is offset with respect to the fan motor drive shaft axis.
A oscillating pin mounted upon the pin support cooperates with an oscillating lever wherein one end of the lever is mounted upon the pin, and the other lever end is mounted upon a fixed point on the fan structure offset with respect to the fan oscillating pivot. This structure is common to most oscillating fan clutch constructions.
The degree of oscillation is adjusted by varying the distance of the oscillating pin from the drive shaft axis. The greater this distance, the greater the degree of fan oscillation. If the axis of the pin coincides with the axis of the drive shaft no oscillation occurs.
The adjustment of the oscillating pin to the fan motor drive shaft is accomplished by the relative rotational location of the bell crank to the pin support which are interconnected by a connecting pin having a spring associated therewith whereby the bell crank and pin support are biased toward each other. Both the bell crank and the pin support include planar opposed surfaces spaced from such other and detents are interposed between the surfaces. A pair of recesses formed in the bell crank surface are diametrically on opposite sides of the connecting pin, while three sets of recesses are formed in the flat surface of the pin support. As recesses defined on both the bell crank and pin support are equally spaced from the connector pin spherical ball detents received within the recesses will be selectively engaged in order to maintain the relative rotation of position of the bell crank and pin support.
The recesses formed within the bell crank and pin support are semi-spherical to match the configuration of the ball detents, and the detents spherical configuration surface forms a cam with respect to the recess in which it is received as only about a third of the circumference of a detent ball is received within a recess. Accordingly, relative rotation of the ball crank and pin support varies the distance between the axis of the drive shaft and the oscillating lever pin varying the degree of fan oscillation.
The degree of fan oscillation is readily adjusted by manually rotating the pin support relative to the bell crank. The spring surrounding the connecting pin biasing the bell crank and pin support toward each other is compressed as the balls ride out of their associated recess for engagement of the ball detents with other recesses during the relative rotation which changes the distance between the axes of the drive shaft and the oscillating pin.
In the event that, during oscillation, the fan structure, motor housing, or fan guard, engages a fixed object, or relatively fixed object, a torque is immediately applied to the pin support by the oscillating lever. This torque, which will prevent further rotation of the pin support, causes the detent balls to ride out of their associated recesses and automatically adjust the rotation between the bell crank and pin support to reduce the degree of oscillation. If the adjustment of the ball detents in a new set of grooves does not sufficiently reduce the “throw” of the oscillating mechanism as to avoid the restraining force, the relative rotation between the bell crank and pin support continues until the axis of the oscillating pin coaxially aligns with the drive shaft axis reducing the fan oscillation to 0. Accordingly, this automatic adjustment of the degree of oscillation will prevent stalling of the fan motor and prevent overheating or motor burnout.
As will be appreciated, the structure of the oscillating fan clutch as described above is relatively simple so as to permit manual adjustment by those not mechanically skilled, and the objects of the invention are met.
The aforementioned objects and advantages of the invention will be appreciated from the following description and accompanying drawings wherein:
In
The rear end of the fan motor 14 includes an oscillation drive generally indicated at 16 which includes a plurality of reduction gears and a downwardly extending drive shaft 18. The oscillating clutch of the invention is illustrated at 20 and is mounted upon the lower end of the fan motor drive shaft 18.
The clutch 20 includes an oscillating pin 22 which is connected at one end to the oscillating lever 24 whose other end is connected to a point on the stationary base 11, and the fan motor 14 and blade oscillate about the fan vertical pivot axis 26 as caused by the torque imposed on the oscillating fan structure by the lever 24.
The clutch 20 includes a bell crank element 28,
The drive pin support 38 for the oscillating pin 22 is also in the form of a circular plate,
In the illustrated embodiment six recesses 44, 44′ and 44″ are mounted in the third side 40 equally spaced from each other and the central hole 46 defined in the pin support. If desired additional sets of recesses 44 could be formed in the third side 40 if more than three adjustments of angular oscillation of the fan are desired.
A connecting pin best shown in
The biasing force of the spring 58 frictionally locates the ball detents 60 within the recesses 36 and 44+ so that, under normal conditions, the bell crank 28 and the pin support 38 rotate together and no relative location occurs therebetween. However, when it is desired to adjust the degree of oscillation the operator manually rotates the pin support 38, or merely rotates the fan upper structure, so that the spherical surface of the ball detents 60 will ride out of their associated recesses permitting relative rotation between the bell crank 28 and pin support 38. Preferably, the recesses 36 are slightly “deeper” than the recesses 44+ so the ball detents 60 remain in the recesses 36 and ride out of the recesses 44+ during relative rotation of the bell crank 28 and the pin support 38.
The greatest degree of fan oscillation, 90°, occurs when the distance separating the axes of the drive shaft 18 and the oscillating pin 22 are the greatest as determined when the ball detents are located in recesses 44″,
It is appreciated that various modifications to the inventive concepts may be apparent to those skilled in the art, and it is intended that the invention only be limited by the scope of the following claims:
Number | Name | Date | Kind |
---|---|---|---|
1337644 | Dilg | Apr 1920 | A |
2209155 | Fagg | Jul 1940 | A |
2341220 | Jordan | Feb 1944 | A |
2732746 | Livermont | Jan 1956 | A |
2838956 | Schneider | Jun 1958 | A |
2900127 | Smith | Aug 1959 | A |
3147639 | Braskamp | Sep 1964 | A |
6468036 | Song et al. | Oct 2002 | B1 |