US2785009A - Propeller fan - Google Patents

Description

March 12, 1957 G. E. sTocKlNG 2,785,009

PROPELLER F'AN INVENTOR.

GEORGE E. STOCKING HIS ATTORNEY March 12, 1957 G. E. sTocKlNG 2,785,009

PROPELLER FAN Filed March 7, 1955 2 Sheets-Sheet 2 FIG. 2

INVENTOR. GeoRef-1 E. sToKlN@ HIS ATTORNEY United States Patent O PROPELLER FAN George E. Stocking, Erie, Pa., assignor to General Electric Company, a corporation of New York Application March 7, 1955, Serial No. 492,709 1 Claim. (Cl. 299-63) My invention relates to propeller fans and more particularly to propeller fans for use in self-contained air conditioning apparatus such as room air conditioners.

Axial flow propeller fans are normally used in room air conditioners for setting up a flow of outdoor air over the condenser. Heretofore metal fans have been used due to the heavy duty requirements to which the condenser fans are subjected. No molded plastic fan has been available which will stand up under this type of use. When it has been attempted to use molded plastic fans, deformation of their blades has occurred after short use with the result that not enough air is blown over the condenser for satisfactory operation of the conditioner. It would be advantageous however if a molded plastic fan could be employed as a condenser fan without these undesirable results occurring. Molded plastic fans are easier to manufacture and are much less expensive than metal fans so that an appreciable saving could be effected through their use. Also, plastic material will withstand the corrosive wet atmosphere to which condenser fans are subjected better than metal does.

Accordingly, it is a primary object of my invention to provide a new and improved one-piece molded plastic propeller fan particularly adapted for heavy duty use in self-contained air conditioning apparatus.

It is another object of my invention to provide a onepiece molded plastic propeller fan having novel stilfening means for preventing deformation of the blades during use.

A further object of my invention is to provide a onepiece molded plastic propeller fan having novel means for reducing radial air flow across the leading faces of the blades, which means thereby both increase axial air flow and cause a reduction in the air noise at the tips of the blades.

My invention also has as its object the provision of a one-piece molded plastic propeller fan having a centrifugal slinger molded integrally therewith, which slinger is so -arranged that it acts as a blade stilfening means as well as a slinger.

In carrying out my invention, I provide a one-piece molded plastic propeller fan having a center hub and a plurality of blades attached to the hub. On the rear surfaces of the blades there are formed reinforcing and stiffening means comprising at least one rib extending outwardly from the hub toward the periphery of each blade. Further included in the fan is an annular sec `tion concentric with the hub, which extends around and is attached to the periphery of the blades. This annular section stiffens the'blades even more, and also, through its concentric arrangement, is adapted for use as a centrifugal slinger. The fan may also include a generally concentric rib on the front face of each blade. These concentric ribs protrude upwardly from lthe front faces and extend completely across the blades from the leading edges to the trailing edges thereof. The concentric ribs thereby hinder radial air flow across the frontfaces as well as further strengthening the blades; and this inter- ICC ference with the radial ow both increases the axial air flow from the fan and reduces noise at the tips of the blades.

The novel features which I believe to be characteristic of my invention are pointed out with particularity in the appended claims. My invention itself, however, may be best understood by reference to the following description taken in conjunction with the accompanying drawings in which:

Fig. 1 is a plan view of the chassis of a room air conditioner including a preferred embodiment of my Anew and improved molded plastic propeller fan as the condenser fan thereof;

Fig. 2 is a vertical elevational view of the molded plastic fan of Fig. 1, looking at the intake side thereof; and

Fig. 3 is a side elevational view of the fan.

Referring now to Fig. l, I have shown therein the chassis of a room air conditioner 1 which utilizes one preferred form of my molded plastic propeller fan as the condenser fan thereof. It will be understood, however, that this air conditioner is intended only to be illustrative of the various air conditioners in which the fan may be used. Its use is in no way restricted to this particular air conditioner. The air conditioner l includes a refrigerant compressor 2, a refrigerant evaporator 3, and a refrigerant condenser 4 connected to form a closed refrigerating system. The evaporator 3 is connected to the intake of the compressor 4 by a suction line 5 and the condenser 4 is connected to the discharge of the compressor by a discharge conduit 5. The evaporator and the condenser are themselves connected together by means of a capillary expansion tube 7, which completes the closed system. The system operates in the well known manner of refrigerating systems so that the evaporator 3 acts as an air cooling means.

During the operation of the air conditioner l, air from the conditioned enclosure is blown over the evaporator 3 and thereby cooled. rIhis flow of room air is set up by a suitable air moving means, such as a centrifugal blower (not shown) mounted within the scroll 8. The centrifugal blower is driven by an electric motor 9, and also driven by the motor 9 is an axial ilow propeller fan 10 which sets up a ow of outdoor air over the condenser 4. In flowing over the condenser 4 the outdoor air carries away the heat which was absorbed from the conditioned air by the evaporator 3. The flows of indoor and outdoor air are separated from each other by suitable baffle means, such as the battle 11, which divide the conditioner l into an outdoor side and an indoor side. The illustrated chassis of the conditioner is of course enclosed within a cover or housing during use, and openings are provided in the cover whereby the indoor and outdoor air streams are introduced into and discharged from their respective sides of the conditioner.

According to my invention the propeller fan l0 comprises a new and improved one-piece molded. plastic member. It may be molded from any suitable plastic material such as for example Bakelites-BMCll or RMD 4001, other polystyrene compounds, or nylon.

The novel features of the fan which enable it to be satisfactory used as the condenser fan of a room air conditioner may bc more clearly seen by reference to Figs. 2 and 3. .As there shown the one-piece fan includes an inner hub l2 and an outer hub 13 which are joined together by suitable spokes ld. shaft of its driving motor by means of the hub l2, any suitable manner of attachment being used, and the outer hub 13 serves as the means for mounting the blades of the fan.

The fan 10 includes three identical blades 15 which are attached to or, more accurately, are formed integrally The fan is mounted on thel with the vhub 13. in order `to set up the proper air flow, the sizes and pitch of these bla-des is such that they include portions at both their leading and trailing edges which extend outwardly beyond their region of attachment to the hub 13. Specifically, each blade includes a center portion lo which is attached throughout the entire length of its inner edges 17 to the hub lil, and portions 18 and i? which extend outwardly from the portion 16 and which are not supported directly from the hub along their inner edges Ztl and 2l respectively. rIhe fan is adapted to rotate in the counterclocirwise` direction as viewed in Fig. 2 so that the portion l@ comprises the leading portion of each blade lli and the portion i9 comprises the trailing portion. With this direction of rotation and the illustrated shape of the blades 15 the direction of air ow through the fan is as indicated by the arrows in Fig. 3. That is, the flow is from left to right as viewed in Fig. 3, or, in other words, is from the side of the fan seen in Fig. 2 to the other side thereof.

By my invention, the blades ld are so stiffened and reinforced that they do not deform during use. More specifically, they are so reinforced that the outwardly extending, leading and trailing portions 18 and 19 retain their original. shape shown in the diagrams. For this purpose the blades 15 each include a plurality of stiffening ribs 'ZZ and 123 formed on the rear faces 24. of the blades. The faces 24 are the faces seen when the fan is viewed from its intake side, i. e. the side seen in Fig. 2, but since the opposite faces 25 are the ones which actually scoop or pull the air through the fan, the faces 24 are best referred to as being the rear faces of the blades. The stiffening ribs Z2 and 235, it will be noted, extend outwardly from the hub i3 at the extreme ends of the region or line of attachment EW between the hub and the blades. l have found that disposed in this manner, they add the most strength to the blades. it will also be noted that the one stiffening rib 23 extends outwardly to the periphery of the blade whereas the other rib 22 does not extend all the way to the periphery. With the preferred blade illustrated this has been found to be the best arrangement, but it will be understood that with different shaped blades it may be advantageous to extend the second stilfening rib also all the way to the periphery of the blades. One additional relationship which may be noted of the ribs 22 and 23 of my preferred embodiment is that they extend outwardly from the hub 13 in parallel planes7 which planes are parallel to a radius of the hub. Such a relationship between the ribs provides for ease of molding while supplying the needed strength to the blades.

In addition to the stiffening ribs 22 and 23, my new and improved fan includes a further stiffening means in the form of a dual function annular section 2o which serves both as `a blade stitfener and as centrifugal condensate slinger. The annular section 26 is concentric with the hub 13, and extends around and is attached to the peripheries of the blades 15. Specifically, the annular section 26 is integrally attached to the peripheries of the blades adiacent their trailing ends by means of the connecting tabs Tf?. The annular section, which preferably is generally channel shaped in cross section, thereby aids materially in preventing `deformtfltion of the trailing portions of the blades. it pro-vides an additional stiifening eiect beyond. the regions of `attachment l? between the blades and. the hub particularly valuable to prevent depitching of the blades.

Besides acting as a blade stiifening means, t e section 26 also serres as centrifugal slinger for throwing or spraying condensate water onto the condenser d of the air conditioner'. During the operation of the air conditioner, ino' ure is condensed out of the conditioned air by means of ther evaporator 3, and this condensate is fed to .a sump 2d beneath the fan lll by suitable conduit deans. rlfhe sump 23 in its sirnpliest form merely comprises a depression in the bottom plate of the air conditioner chassis. The fan 10 is so mounted that the annular section 26 dips into this sump at its lower end. During its rotation the annular section 26 therefore picks up any condensate which accumulates in this sump7 and through centrifugal action slings it outwardly into the air stream leaving the fan. The air stream then deposits the moisture onto the condenser where it aids in the cooling of the hot refrigerant flowing through the condenser.

By my invention, the fan 1G in its preferred form includes still another means which strengthens the blades 15 against deformation. This additional means also reduces radial air ow across the leading or front faces 25 of the blades, thereby reducing air noise at the tip of the blades and -increasing axial air flow through the fan. This additional means specifically comprises a generally concentric rib 29 which is formed on the leading or front face 25 of each of the blades. The ribs 29 are curved in an arc around the hub 13 and in my preferred embodiment they are truly concentric with the hub. However these arcuate ribs 29 are not necessarily truly concentric with the hub in all embodiments of my invention and l, therefore, prefer to describe them as being generally concentric. The generally concentric ribs 29 protrude upwardly from the front faces 25 and extend completely across the blades from their leading edges 30 to their trailing edges 31. The ribs 29 thereby not only additionally strengthen the blades but also hinder and reduce radial air llow across the front faces 25 of the blades. in other words, they act as somewhat of a barrier to prevent air from slipping radially across the front faces 25. As a result the axial air flow from the fan is increased over what it is without such generally concentric ribs, and further the air noise at the tips of the blades is reduced. Since it is at the tips that the most noise is produced, the ribs 29 thereby result in an appreciable decrease in the overall noise produced by the fan.

Due to the above described features incorporated therein, my new and improved one-piece molded plastic propeller fan is able to stand up when used as the condenser fan of a room air conditioner. Besides being far easier to produce and much less expensive than metal fans, the plastic fan has better corrosion resistant properties and `therefore longer life. It also has the additional ad vantage over metal fans that it is much quieter in operation. The aforesaid ribs 29 result in lsome lowering of the noise, and further the fact that the fan is formed of plastic rather than metal also results in a decrease in noise. There appears to be less resonant effect set up in the plastic fan during rotation than in a metal fan and thereby the noise level is materially decreased.

While in accordance with the Patent Statutes I have described what at present is considered to be the preferred embodiment of my invention, it will be understood .by those skilled in the art that various changes and modifications may be made therein without departing from my invention and I, therefore, aim in the appended claim to cover all such changes and modifications as fall Within thetrue spirit and scope of my invention.

l claim:

In combination with a condensate collection sump, a one-piece molded plastic propeller fan comprising a center hub, a plurality of thin blades attached to said hub, said blades extending axially beyond said hub whereby said blades are attached to said hub only along a portion of their inner edges, a plurality of reinforcing and stilening ribs formedon the rear face of each of said blades and extending parallel to a radius of said hub, said ribs on each blade extending outwardly from said hub at the opposite ends of the region of attachment of said blade to said hub and at least one of said ribs extending outwardly to the periphery of said blade, an annular channel shaped section dipping into said sump and extending around and attached to the peripheries of said blades, said annular channel shaped section being concentric with said hub and being displaced axially therefrom in akplane parallel to said stifening ribs thereby to stien a portion of said blade not attached -to said hub at its inner end, said annular channel shaped section being` shaped for use as a centrifugal slinger, and at least one concentric rib formed on the front face of each of said blades, said concentric rib protruding upwardly from said front face on each blade and extending completely across said 'blade from the leading edge to the trailing edge thereof, whereby in addition to strengthening said blade said concentric rib lli References Cited in the le of this patent hinders radial air flow across said front face .foo reduce air 1() 2,613,514

noise and increase axial air flow.

UNITED STATES PATENTS Oakes Apr. 16, 1912 Sparks Sept. 2, 1913 Ogrissek Aug. 1, 1922 Hueglin Mar. 31, 1936 Cohen Mar. 8, 1938 Swinburne et al. Oct. 29, 1940 Borgerd et al. Oct. 14, 1952

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