US2909229A

US2909229A - Reversible pitch fan

Info

Publication number: US2909229A
Application number: US602843A
Authority: US
Inventors: Cross Harrel; James A Midgley
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-08-08
Filing date: 1956-08-08
Publication date: 1959-10-20
Anticipated expiration: 1976-10-20

Description

Oct. 20, 1959 H. CROSS ET REVERSIBLE PITCH'F'AN Filed Aug. 8, 1956 INVENTORS JAMES A. MIDGLEY HARRE L GROSS ATTORNEY 2,909,229 REVERSIBLE PITCH FAN Harrel Cross, Fort Myers, and James A. Midgley,

' Fort Myers Beach, Fla.

Application August 8, 1956, Serial No. 602,843

1 Claim. (Cl. 170-16024) This invention relates to fans, and it particularly relates to fans having blades the pitch of which can be adjusted.

There are many dilferent situations where the pitch of the blades of a fan must be reversed. One such instance is in the case of earth moving equipment such as United States Patent bulldozers, draglines, and the like. It has been common "1 practice to carry two cooling fans of opposite pitch in such equipment so that when the radiator becomes fouled by sand, dust, leaves and dirt sucked up by the fan, the fan is removed from the shaft and the fan of opposite pitch is attached. When this opposite pitch fan is then actuated, the accumulated fouling matter is blown out.

Among the great disadvantages of this prior system, consisting of the use of two opposite pitch fans, is the fact that it generally takes at least an hour or more of arduous labor to remove one fan and replace it with the other. As a result, there is a tendency to omit changing the fans as often as necessary, especially when the equipment is hot from heavy use. This often leads to damage of the engine since the fan is, when fouled, not capable of providing a suflicient cooling effect.

It is one object of the present invention to overcome the above disadvantages by providing a fan construction, the pitch of which can be easily adjusted or reversed without the necessity of any bodily replacement.

Another object of the present invention is to provide a fan of reversible pitch wherein the pitch can be reversed in seconds without any necessity for using tools or other handling equipment and without any undue labor.

Another object of the present invention is to provide a reversible pitch fan wherein the pitch can be reversed simply, easily and almost instantaneously.

Other objects of the present invention are to provide an improved fan, of the character described, that is easily and economically produced, which is sturdy in construction, and which is highly eflicient in operation.

With the above and related objects in view, this invention consists in the details of construction and combination of parts, as will be more fully understood from the following description, when read in conjunction with the accompanying drawing in which:

Fig. 1 is a front elevational view of a fan device embodying the present invention.

Fig. 2 is a top plan view of the device of Fig. 1.

Fig. 3 is a fragmentary top plan view showing the device at the time when the pitch is being reversed.

Fig. 4 is a fragmentary top plan view showing the device after the pitch has been reversed.

Fig. 5 is a front elevational view of one of the blades when removed from the fan device.

Fig. 6 is a front elevational view of one of the pivot rods used in conjunction with the blades.

Referring now in greater detail to the drawing wherein similar reference characters refer to similar parts, there is shown a fan device, generally designated 10, compris- 2,909,229 Patented Oct. 20, 1959 ing a pair of coaxially-spaced

rings

12 and 14. Each of the rings is provided with a plurality of sockets, here shown as six in number, such sockets being indicated at 16 on

ring

12 and 18 on ring 14. The sockets on each ring are circumferentially spaced from each other by equal arcuate distances. At the same time, in their normal positions, the sockets 16 are also circumferentially ofiset from the sockets 18. 3

These

rings

12 and 14 surround a hub 20 having a central opening 22 adapted to receive a shaft, not shown. The hub 20 is also provided with a plurality of sockets 24, equal in number to the sockets on each ring, these sockets 24 being provided on the external periphery of the hub.

Positioned between the two

rings

12 and 14, on the one hand, and the hub 20, on the other hand, are a plurality of radially-extending, circumferentially-spaced blades 26. Each of these blades may be provided with a relatively wide, arcuate outer edge 28 and a relatively narrow inner edge 30. The side edges 32 of each blade may taper inwardly from the outer to the inner edge. The blades are constructed of sheet metal which may have substantial flexibility while the rings are rigid; or, vice versa, the blades may be substantially rigid, and the rings may be of substantial flexibility.

Connected to the outer edge of each blade 26 are a pair of rods or pins 34 and 36, the pins 34 being closer to one edge 32 and the pins 36 being closer to the other edge 32 of each of the blades. These pins 34 and 36 are connected to the blades by any convenient means such as the rivets indicated at 38. The pins, themselves, are preferably provided with recesses 40 which interengage with recesses 42 in the arcuate edges of the blades. The bodies of the pins extend down below these recesses and are provided with holes 44, adapted to mate with holes 46 in the blades, to receive the rivets 38. The opposite ends of each of the pins 34 are received in a corresponding socket 16 in the ring 12 while the opposite ends of each of the pins 36 are received in corresponding sockets 18 in the ring 14.

The inner edges of the blades are connected to the hub 20 by means of rods or pins 48 attached, at one end, to the blades by means of interengaging groo ves similar to grooves 40 on pins 34 which engage with recesses 50 on .the inner edges of the blades, and rivets 52 or the like, which extend through holes in pins 48, similar to those of pins 34, and through holes 54 in the blades. The opposite ends of the pins 48 are received in sockets 24 in the hub.

Since the leading edge portion of each blade is connected to one ring while the trailing edge portion is connected to the other ring by means of their respective pivot pins 34 and 36, when the rings are rotated in opposite directions,'all the blades turn in unison and force the rings axially away from each other until they reach the extreme position indicated in Fig. 3. Thereafter, as the rings are continued to be rotated contra to each other, the blades turn into the reverse angle or pitch and the rings come closer together again. The pitch of the blades is now reversed.

The pitch of the blades can also be reversed by simply turning one blade. The movement of the one blade will act simultaneously on all the others through the

rings

12 and 14, and the same movement as described above will take place.

As the blades are rotated from one pitch to the opposite pitch, the angle between the pivot pins 34 and 36 on blades 26 and the sockets 16 on ring 12 and sockets 18 on ring 14 must necessarily change from a stress free condition when in either pitch to an increasingly stressed condition as the blades are rotated outwardly to the center point, and then the stressed condition assists in rotating the blades beyond the center point back to the stress free condition to thus retain the blades blocked in fan operating position.

The pins being fairly tight in their sockets, either the blades must yield or bend slightly between the pins on each blade, or the rings must bend or yield slightly in an outward direction from each other, with their outer peripheries moving further away from their inner peripheries from each other, or both may bend or yield slightly, depending on the relative strength of the material of the rings and the blades. This bending or yielding is slight and within the elastic limits of the material, hence it resists the movement until the center point is passed, then it assists the movement until normal pitch is reached and thus tends to hold or lock the blades in either normal pitch.

Although this invention has been described in considerable detail, such description is intended as being illustrative rather than limiting, since the invention maybe variously embodied, and the scope of the invention is to be determined as claimed.

Having thus set forth and disclosed the nature of this invention, what is claimed is:

In a rotatable fan construction, a hub having an outer 4 rim and a plurality of equidistantly spaced peripheral sockets in said outer rim, a pin rotatably mounted in each socket, a substantially sector shaped flexible blade secured to each pin at its smaller end, a pair of pins fixed to the outer end of each blade in spaced relation, a pair of flexible rings, each having an inner rim coaxial with said hub extending about the outer ends of said blades, the inner rim of each ring having a plurality of sockets therein, the sockets of each ring rotatably engaging one of each of said pairs of pins on the outer ends of said blades, said blades being of width at their outer ends of slightly less than the length thereof, said pair of pins on the outer end of each blade being located on radii extended from the axis of rotation of said fan a suflicient distance on opposite sides of the radius of the pin on the smaller end of the blade whereby the resiliency of said blades and rings serves to retain the pin on the smaller end of the blades in a preset position of angular adjustment.

Longauer Nov. 19, 1895 Artibee Jan. 5, 1915