Patent Application
20130039766
The subject matter disclosed herein relates to a dual direction axial fan and, more particularly, to a dual direction axial fan having a switching mechanism.
Industrial environments often employ totally enclosed, fan cooled (TEFC) motors. These motors are only slightly more expensive than open motors yet offer protection against common hazards. They are constructed with a small fan on the rear shaft of the motor, which is usually covered by a housing. This fan draws air over the motor fins and removes excess heat to cool the motor. The motor is dust tight and has a moderate water seal as well.
In many rotating machines, it is necessary to use radial fans even though axial fans would be the ideal choice. The reason for this is that the motors are designed to rotate in both directions and, normally, single axial fans do not work in both directions. Thus, the use of radial fans represents a compromise on performance.
According to one aspect of the invention, a dual direction axial fan is provided and includes a body having a retention assembly and being rotatable in first or second directions, a blade being retained by the retention assembly such that the airfoil section extends from the body with the blade assuming first, second or third orientations and a switching mechanism coupled to the retention assembly to urge the blade to assume the second or the third orientation when the body rotates in the first or the second direction, respectively.
According to another aspect of the invention, a dual direction axial fan is provided and includes a body having a blade retention assembly and being rotatable about a centerline thereof in first or second directions, a blade having an airfoil section and a shank, the shank being retained in the body by the blade retention assembly such that the airfoil section extends from the body with the blade assuming first, second or third orientations and a switching mechanism coupled to the blade retention assembly to urge the blade to assume the second or the third orientation when the body rotates in the first or the second direction, respectively.
According to yet another aspect of the invention, a dual direction axial fan is provided and includes a hub, which is rotatable about a centerline thereof, having an annular sidewall and an endplate at a first end of the annular sidewall through which a u-shape hole is defined, a cover, through which a radial holes defined, and which is fittable to a second end of the sidewall such that the cover occupies and moves between first, second or third positions, a blade having a shank to extend through a radial hole defined in the sidewall, the blade being configured to assume first, second or third orientations, a sleeve, which is tightly fittable about the shank of the blade, a first elastic element anchored on the hub and engageable with the sleeve, a pin and nut combination to extend through a corresponding pair of the u-shaped hole and the radial hole and a second elastic element to bias the pin and nut combination toward a position whereby the cover is constrained in the second or the third position when the hub rotates in the first or the second direction, respectively.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
In accordance with an aspect of the invention, an axial fan is provided that can be operated in first and second rotational directions. For the purposes of the detailed description below, an axial fan is a fan that blows fluid in axial directions. Normally, axial fans have blades with a given orientation that are rotated in one directed such that fluid is blown in only one direction. In the present invention, however, the blade orientation can be switched and the axial fan can be rotated in first and second directions to blow air in first and second axial directions. The axial fan can be used in many applications it would be otherwise necessary to employ inefficient radial fans. In order to achieve this, the axial fan includes a switching mechanism that adjusts the blades in both the directions of rotation. The switching mechanism is a combination of a rack and pinion mechanism and a centrifugal switch mechanism.
With reference to
With reference to
Although described above as being plural in number and arrayed about the body 20, the blade retention assembly 21, the blade 30 and the switching mechanism 40 will be hereinafter described as single features for the purpose of clarity and brevity. This is to be understood as being merely exemplary and not a limiting embodiment of the invention.
With reference back to
As shown in
As shown in
The centrifugal switch mechanism 42 includes an array of pin and nut combinations 220 and a second elastic element 230. Each pin and nut combination 220 includes an elongate pin 221, which extends through a corresponding pair of a pin hole 205 and a radial pin hole 212, and a nut 222 that locks the cover 210 onto the hub 201 in the axial direction. The second elastic element 230 may be a spring with a hook at each end to be respectively anchored to the hub 201 and the pin 221. The second elastic element 230 biases each pin and nut combination 220 toward a position whereby the cover 210 is constrained in the first, second or third position when the body 20 is not rotating or when the body 20 rotates in the first or the second direction, respectively.
With reference back to
The rack and pinion mechanism 41 includes a gear 240 to which the shank 32 of the blade 30 is coupled and a rack 241 of the cover 210 to rotatably engage with the gear 240. The gear 240 includes a ring portion 242, which is tightly connected to the shank 32 of the blade 30 and teeth 243 extending from the ring portion 242 to rotatably engage with the rack 241 of the cover 210. Since the gear 240 moves with the hub 201, the relative rotational movement in the first and second directions between the hub 201 and the cover 210 causes the gear 240 to rotate about a longitudinal axis of the shank 32 of the blade 30. Thus, when the cover 210 is rotated toward and constrained in the second or the third position, the gear 240 rotates in respectively opposite directions as well. Since the ring portion 242 is tightly connected to the shank 32, the rotation of the gear 240 causes corresponding rotation of the blade 30 into the second or the third orientations, respectively, in accordance with a rotational direction of the body 20.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
