US2908335A

US2908335A - Fan blade coupling

Info

Publication number: US2908335A
Application number: US592349A
Authority: US
Inventors: Petty Macon
Original assignee: Hudson Engineering Corp
Current assignee: Hudson Engineering Corp
Priority date: 1956-06-19
Filing date: 1956-06-19
Publication date: 1959-10-13
Anticipated expiration: 1976-10-13

Description

Oct. 13, 1959 Filed June 19, 1956 M. PETTY 2,908,335

FAN BLADE COUPLING 2 Sheets-Sheet 1 Macon Pe z z 5/ INVENTOR.

wg I 63% M. PETTY FAN BLADE COUPLING Oct. 13, 1959 2 Sheets-Sheet 2 Filed June 19, 1956 M0 0 0/7 Fe 2 (5 INVENTOR United States Patent Ofiiice 2,908,335 Patented Oct. 13, 1959 2,908,335 FAN BLADE COUPLING Macon Petty, Houston, Tex., assignor to Hudson Engn i ering Corporation, Houston, Tex., a corporation cxas Application June 19, 1956, Serial No. 592,349

7 Claims. (Cl. 170-173) This invention relates to apparatus for coupling fan blades to hubs. In one of its aspects, this invention relates to apparatus of this type which is an improvement over that disclosed and claimed in my earlier copending application, Serial No. 464,963, filed October 27, 1954, and entitled F an Blade Coupling.

As in my earlier application, it is an object of the present invention to provide apparatus which permits the blade to be adjusted to a desired pitch and then securely coupled to the hub while maintaining such pitch.

-It is a further object, however, to provide a fan blade coupling having a housing for receiving the blade shank which is of less expensive construction than the housing of my earlier invention in that it requires no machining of tapers.

Another object is to provide apparatus including a coupling which enables the blade to be inserted within and removed from the housing thereof without dismantling either the housing or the fan ring which conventionally closely surrounds the tip of the blade.

Other and further objects of this invention will appear as the description proceeds.

In the accompanying drawings forming a part of the instant specification and wherein like reference numerals are used in the various views to indicate like parts:

Fig. 1 is an elevational view of a pair of fan blades coupled to a rotatable hub, in accordance with the present invention, and closely surrounded at their outer tip ends by a fan ring, with the leftmost blade in the process of either being inserted within or removed from the housing of its coupling;

Fig. 2 is an enlarged sectional view of part of the fan of Fig. 1, showing in more detail the novel coupling apparatus thereof;

Fig. 3 is a cross-sectional view of the coupling apparatus, taken substantially along broken line 3-3 of Fig. 2;

Fig. 4 is a sectional view, taken similarly to Fig. 2, of a slightly modified form of the novel coupling apparatus of the present invention;

Fig. 5 is a cross-sectional view of the form of coupling apparatus of Fig. 4, taken substantially along broken line 55 of Fig. 4; and

Fig. 6 is a partial sectional view of a still further modified form of the invention.

Referring now particularly to Fig. 1 of the drawings, there is shown in Fig. 1 a hub 10 rotatable with a shaft 11 disposed centrally within an annular fan ring 12. A pair of fan blades 13 are coupled to the hub by means of one form of the apparatus of the present invention, which includes a shank 13a on the inner end of each blade received within a clamp 14 attached to the hub. The outer tip ends of the blades are closely surrounded by the ring 12 so that they canot be moved radially of the hub or axially of the clamp a distance suflicient to permit their shanks to be inserted within or removed from the clamps without dismantling either or both of the clamp and the fan ring. As will be apparent from the description to follow, however, the coupling apparatus of the present invention is so constructed as to permit the fan blade 13 to be tilted with respect to the axis of the clamp '14, as shown by the leftmost blade in Figs. 1 and 2, so that its shank 1311 may be inserted within or removed from the clamp without such dismantling.

As shown in Fig. 2, the hub 10 comprises a cup-shaped member 1 5 open at one end and provided at its opposite end with an inwardly disposed boss 16 having a socket 17 fixedly secured therein for receiving the shaft 1'1 (removed from Fig. 2). An annular space 18 between the inner periphery of the cup 15 and the boss 16 permits I access to the means of attaching each clamp 14 to the hub.

Each clamp 14 comprises a housing 19 having rear wall 20 and an opening 21 therein opposite the rear wall for receiving the shank 13a of the blade. Each housing is attached to the hub 10 with the axis of its opening 21 extending radially thereof by means of a bolt 22 received through aligned openings 23 and 24 in the rear wall 20 of the housing and the cup 15 of the hub, respectively. More particularly, each housing is spaced from the cup 15 by a spacer 25 disposed therebetween and having an opening' 26 therethrough receiving an intermediate length of bolt 22. As shown in Fig. 2, the head of each bolt bears against a washer 27 held against the inside of the rear wall 20 of the housing, and a nut 28 is received over the threaded end of the bolt for hearing against a similar washer 27 held against the inner periphery of the cup within annular space '18. Each of the washers and spacer may be slotted to receive a lock pin 29 for the nut and bolt. I

The opening 21 in the housing is cylindrical and of such diameter as to permit the blade shank 13a to be inserted therein and removed therefrom, in a manner to be described hereinafter. The opening 21 is also provided with a groove 30 about its inner periphery within which a retainer element is adapted to be disposed in position for engagement by a shoulder 31 about the blade shank in a manner to maintain the blade against rotation within the housing. More particularly, the shoulder 31 faces away from the rear wall 20 of the housing and the groove 30 is adapted to receive separate curved portions 32 of the retainer element having parts which project radially inwardly of the periphery of the opening when so received, so that the shank of the blade may be moved, by force transmitting means to be described hereinafter, in a direction axially of the opening and away from the rear wall and into abutment about its shoulder 31 with the inwardly projecting parts. On the other hand, the means for so moving the blade shank may be relieved or retracted in such a manner that the shoulder on the blade shank is sufficiently free from the retainer element so that the blade can be rotated to a desired pitch or, if desired, the afore-mentioned parts of the retainer element may be removed from inwardly projecting relation within the housing opening to permit removal of the blade shank therefrom, in a manner to be described.

It will be noted from the foregoing that, in accordance with a novel aspect of the present invention, the cylindrical opening in the housing obviates the necessity of machining a taper therein, as was the case in my earlier invention. Furthermore, in providing an arrangement which permits insertion and removal of the fan blade without dismantling of the housing, the novel coupling apparatus of the present invention enables such housing to be fabricated as an integral part.

As previously mentioned, the retainer element parts are removable from inwardly projecting relation within housing opening $20. In a preferred form, such removal is accomplishedby removal of the portions 32 from the 3 housing, as illustrated in Fig. 2 and in a manner to be described hereinafter.

As can be seen from Fig. 2, that portion 33 of the blade shank 13a between shoulder 31 and the end thereof is tapered or, more specifically, conically shaped convergently way from the shoulder. Thus, with the force transmitting means retracted and the retainer element parts removed, the blade may be tilted with respect to the axis of housing opening 21 to such a position as to permit it to be moved inwardly or outwardly past the fan ring 12 without dismantling same. That is, as illustrated by the leftmost blade 13 of Figs. 1 and 2, the blade may be tilted to such a position that its outer tip end will be clear of the open end of the fan ring, while, at the same time, its shank is free to be inserted within or removed from the housing 19. The length of the tapered portion 33 of the blade shank is shorter than the length of opening 21 between the rear wall 20 and the groove 32 to permit the shank to be cocked in the manner illustrated in Fig. 2, as well as to permit the shoulder 31 of the blade shank to be moved into and out of fixed engagement with respect to the retainer element portions 32.

The portion of the blade shank 13a on the side of shoulder 31 opposite from the end of the shank is substantially cylindrical for a suflicient length to permit the portions 32 to be moved through the end of the opening within an annular space between this cylindrical portion of the blade shank and the opening 21 in the housing 19. The retainer element portions 32 are spaced circumferentially apart, as best shown in Fig. 5, so that with the blade shank shoulder 3'1 free of the portions, they may be individually removed, as by prying with a suitable tool (not shown), from a position within groove 30 to a position removed from the housing. Obviously, the portions may be forced into place by a reversal of such procedure. Also, as illustrated in Fig. 2, tilting of the blade may facilitate removal or insertion of the portion (in this case, the lowermost portion). In this preferred form of the invention, the portions are tubular or circular in cross section and the groove 30 is arcuate or curved to accommodate the outer periphery thereof when the portions are disposed within the grooves.

In the modified form of coupling apparatus shown in Fig. 6, the retainer element portions 34 are tapered along their inner surfaces 35 convergently toward the open end of the housing for wedging engagement with a similarly tapered shoulder 35a on the blade shank 13a. As in the case of the tubular retainer element portions 32, the tapered portions 34 are circumferentially spaced apart and removably disposable within grooves 36 of any suitable cross-section. It will be understood that the tapered surfaces 35 on the portions 34 provide a large bearing surface for resisting the centrifugal force of the blades during rotation.

Along this same line, it can be seen from the modified form of coupling apparatus shown in Fig. 4 that the shoulder 37 on the blade shank 13a may be provided with a recessed portion 37a curved to substantially the radius of the retainer portions 32. In this manner, the shoulder and rings are abuttable along mating portions of their curved surfaces, instead of along what is at least initially a line contact in the case of shoulder 31 of the form of the apparatus shown in Fig. 1.

The blade shank 13a is, in each form of the coupling apparatus of this invention, movable axially of the opening .21 in the housing and in a direction away from the rear wall thereof by a means which acts to transmit force between the housing and the blade shank concentrically ,of the axis of the opening. In this manner, as in my earlier copending application, the blade may be rotated within the opening of the housing to a predetermined pitch and then moved into abutment with the retainer element without disturbing the predetermined pitch. For this purpose, there are provided a plurality of jack screws 38 which are carried by and extended through the rear wall 4 20 of the housing for engagement at their inner ends with the end of the blade shank and for manipulation at their outer ends exteriorly of the'housing within the space between the housing and hub provided by spacer 25. It will be understood that when arranged concentrically of the axis of the opening 21 in the housing and the means for attaching the housing to the hub 10, the jack screws may be rotated to transmit force between the housing and the blade shank in a direction concentrically of the opening, so that there is no tendency for the predetermined pitch of the blade to be disturbed. This arrangement of the jack screws 38 also permits one or more of them to be tightened to a greater extent than one or more of the others so that the blade may be adjusted to bring its center of gravity into or toward axial alignment with the housing opening, it such adjustment is required.

It is contemplated that with the blade 13 molded into the hollow shape indicated in the drawings, the centrally disposed means for attaching the clamp to the hub may project within the open end of the blade shank. Also, when fabricated of a relatively soft material, such as plastic, the ends of the blade shanks may include a bearing part in the form of an annular metallic plate 39 so positioned on the end of the plastic portion of the blade shank as to be engaged by the inner ends of the jack screws 38. As indicated in Figs. 2 and 3, the annular plate 39 may be provided with suitable projections 40 receivable in complementary recesses of the plastic portion of the blade shanks 13a for aligning the plate 39 with respect thereto. Obviously, a suitable adhesive material may be used for cementing the plate to the plastic portion of the blade shank. I

The form of the coupling apparatus of this invention shown in Fig. 4 illustrates another means by which the housing of the clamp may be connected to a hub. In this case, a rod 41 extending radially outwardly from the hub (not shown) may be threaded at its outer end for connection with a threaded opening 42 through the rear wall 43 of the housing and locked with respect there to by a nut 44 bearing upon a washer against the inside of the rear wall 43. In this form, as in the form of Fig. 6, the open end of the plastic portion of the blade shank may be closed by a plug 45 of any suitable material which provides a balance for the blade and is recessed at 46 to accommodate a projecting portion of the means of attaching the housing to the hub. Also, in these forms of the coupling apparatus, the inner ends of jack screws 38 bear upon an annular metallic plate 47 secured to the ends of the plastic portion of the blade and the plug.

Further, as shown in each of the forms of Figs. 4 and 6, the jack screws 38 include a lock nut 48 received about the threaded length thereof and adapted to be made up against the outside of the rear wall of the housing for fixedly locating the jack screws and preventing the screws from being accidentally backed 01f or retracted from engagement with the end of the blade shank.

Although the manner of using the coupling apparatus of the present invention is believed apparent from the foregoing description, it will be assumed, for purposes of summary, that a fan blade 13 is to be coupled to the hub 10. In such a case, the jack screws 38 are backed off and the retainer element portions 32 are removed from within the housing so that the fan blade may be lifted into a tilted position and moved clear of the fan ring 12 to insert the shank 13a into the housing opening. With the blade so disposed, a first of the retainer element portions may be moved through the annular space between the housing opening and the blade shank and forced into the groove 30 by means of a suitable tool. It may be found necessary to hold the blade in a slightly tilted position away from the portion of the groove for receiving the retainer element. At any rate, the second or succeeding retainer element portions are then moved through the annular space and forced into the groove 30, wherein they are disposed in circumferentially spaced apart relation with respect to one another.

At this time, or for that matter during insertion of the blade shank into the housing opening, the blade may be rotated to the desired pitch. The jack screws 38 are then manipulated from a position exteriorly of the housing so as to move the shoulder on the blade shank tightly into abutment with the retainer element. Although the jack screws may require individual and successive tightening, their concentric arrangement maintains the predetermined pitch of the blade as the shank shoulder is moved into abutment with the retainer element.

If it is desired to adjust the pitch of the blade, the jack screws 38 need only be backed otf an amount sufficient to free the shoulder from its tight engagement with the retainer element, and the blade rotated to the new pitch. As described above, the blade shank may then be moved back into a position in which it is held against rotation, Without disturbing the predetermined pitch to which it has just been rotated.

The fan blade 13 may be uncoupled from the hub 16 by a reversal of the above procedure. That is, the jack screws 38 may be backed off and the retainer element portions 32 removed from within the housing. This permits the blade to be tilted to such a position that its tip end is free of the fan ring 12, and wherein its tapered shank portion permits it to be moved outwardly of the housing opening.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, What is claimed is:

1. Apparatus coupling a fan blade to a hub, comprising a housing having a rear wall and a cylindrical opening therein opposite the rear wall, a shank on the blade received within the opening and having a shou1der thereabout facing away from the rear wall of the housing, a

groove about the periphery of the opening, a retainer element within the groove and having parts projecting radially inwardly of the housing opening, and force transmitting means operable between said wall and blade shank to move said shoulder into fixed engagement with said retainer element parts and the end of the shank being spaced from the wall to permit its retraction out of fixed engagement therewith, the shank and opening providing an annular space therebetween when said shoulder is retracted to permit said retainer element to be inserted within and removed from said groove through the end of said opening when said shoulder is retracted.

2. Apparatus of the character defined in claim 1 where in a portion of the blade shank intermediate the shoulder and end thereof is tapered convergently toward said end to permit the shank to be tilted with respect to the axis or the housing opening during insertion or removal thereot.

3. Apparatus of the character defined in claim 1, wherein said force transmitting means comprises jack screw means carried by and extending through the rear wall of the housing for engagement with the blade shank and manipulation from the exterior of the housing.

4. Apparatus of the character defined in claim 3, where in the rear wall of the housing has a part disposed axially of the opening therein for attachment to the hub, and said jack screw means comprises a plurality of jack screws arranged concentrically of said attaching part.

5. Apparatus of the character defined in claim 1, wherein said retainer element comprises separate portions curved about an axis concentric with the housing opening disposable within the groove in circumferentially spaced apart relation.

6. Apparatus of the character defined in claim 5, wherein the retainer element portions are circular in cross section and the groove is arcuate.

7. Apparatus of the character defined in claim 5, wherein the retainer element portions are tapered convergently toward the end of the housing opening for abutment with a similarly tapered surface on the blade shank shoulder.

References Cited in the file of this patent UNITED STATES PATENTS