US3733147A

US3733147A - Radial and axial airflow fan

Info

Publication number: US3733147A
Application number: US00095768A
Authority: US
Inventors: S Felker
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-12-07
Filing date: 1970-12-07
Publication date: 1973-05-15
Anticipated expiration: 1990-05-15

Abstract

The open forward unobstructed root portions of radially extending fan blades are secured to the arms of front and rear portions spaced apart axially. A large aperture in the central portion of the front spider enables air to flow axially into a chamber between the front and rear spiders which opens radially outwardly between the root portions of the blades. Trailing edge margins of the blades are connected to the rear spider by angles riveted to such blade portions and to the rear spider and leading edge margins of the blades are riveted to arms of the front spider.

Description

United States Patent @191 Felker May 15, 1973 541 RADIAL AND AXIAL AIRFLOW FAN 2,347,839 5 1944 Norris ..416/185 [76] Inventor: Samuel A. Felker, 10233 Green FOREIGN PATENTS OR APPLICATIONS Lane S.W., Tacoma, Wash. 98499 621,326 4/1949 Great Britain ..416/214 [22 Filed: Dec. 7, 1970 [21] APPL No: 95,768 Primary ExaminerEverette A. Powell, Jr.

Attorney Robert W. Beach [52] U.S. Cl ..416/214, 416/186 [57] ABSTRACT [51] Int. Cl ..F04d 29/34 [58] Field of Search.....-. ..416/214, 243, 185, f fi 6/186 179 182 132A 183 a y extending fan a es are secure to the arms 0 front and rear portions spaced apart axially. A large aperture in the central portion of the front spider ena- [56] References C'ted bles air to flow axially into a chamber between the UNITED STATES PATENTS front and rear spiderswhich opens radially outwardly I between the root portions of the blades. Trailing edge 2,032,224 2/1936 Paton 4l6/132 margins of the blades are connected to the rear spider 3,323,711 6/1967 y? l UX by angles riveted to such blade portions and to the 1,01 et al X rear pider and leading edge margins of the blades are 2,262,695 l1/l941 Mueller ..416/93 riveted to arms of the from Spider. 2,347,838 5/l944 Norris ..416/185 8 Claims, 12 Drawing Figures PATENTED MAY 1 51973 SHEET 2 OF 2 3 AMJH. A FHA 6 RADIAL AND AXIAL AIRFLOW FAN In the fan of the present invention a principal object is to provide a central air chamber opening both radially outwardly between root portions of the blades and forwardly to enable air to flow axially into such air chamber and then generally radially outwardly, in addition to the axial flow of air produced by the radially outer portions of the blades.

A further object is to provide strong and rugged blade-mounting structure which is of open center and unobstructed root character, to enable air forward of the hub portion of the fan to flow through the blademounting structure with minimum turbulence.

Another object is to provide mounting structure for the fan blades which is simple in character, yet which will support the fan blades securely under high blade loading with no substantial forward bending.

Another object is to provide a fan having unusually large air-moving ability for its size.

Additional objects are quietness and elimination of air surges caused by high turbulence.

FIG. 1 is a rear elevation of a fan according to the present invention, and FIG. 2 is an edge elevation of such fan. FIG. 3 is a front elevation of the fan having parts broken away. FIG. 4 is an enlarged detail section of a portion of the fan taken on line 4--4 of FIG. 1. FIG. 5 is a diametral transverse section through the fan on line 5 5 of FIG. 3.

FIG. 6 is a rear elevation of a modified type of fan, and FIG. 7 is an edge elevation of such fan. FIG. 8 is an enlarged detail section of a portion of the fan taken on line 8-8 of FIG. 6.

FIG. 9 is a front elevation of a further modified fan according to the present invention. FIG. 10 is a transverse diametral section through such fan on line 10-10 of FIG. 9. FIGS. 11 and 12 are enlarged detail sections taken on line llll of FIG. 9, showing parts indifferent positions.

The fan of the present invention is intended to be used primarily for automotive purposes, specifically for drawing or forcing air through an engine-cooling radiator, although the fan can be used in a variety of installations for producing a current of air. Such air current moves predominantly axially of the fan, but locally, at its central portion, the air moves first axially, then radially and then axially again, generally smoothly, instead of turbulent conditions predominating in front of the central portion of the fan.

The number of fan blades is not critical; from two to twelve or more blades can be used. The representative fans shown in the drawings have size blades. Each blade is cambered, preferably being of circular arcuate cross sections from root to tip. The transverse arc of each blade preferably is less than 90. Also preferably the blade is tapered outwardly as shown and has a rounded tip. It should be understood, however, that the particular profile and camber of the blade is not critical for the present invention and can be selected according to the.

type of installation for which the fan is designed and its desired operating characteristics.

In the construction shown the fan blades are mounted to have a high angle of attack, such as approximately 45. Consequently, the blades are supported so that their leading edges are located a substantial distance ahead of their tralling edges. To mount the blades in such fashion their inner end portions are secured to two axially-spaced central plates, preferably in the form of spiders, without a solid hub. The front spider 2 includes a ring portion and arms 3 projecting outward from circumferentially spaced portions of such ring portion to form throats 3' between adjacent arms. One edge of each spider arm extends substantially tangentially of an inscribed circle passing through the throats between the arms and the other edge of each arm extends generally radially of the spider. Each spider arm projects radially beyond the inscribed circle through the throats for a radial distance greater than half of the radius of such circle, as shown in FIG. 3. The inner end portions of the blades project inward beyond the throats of the front spider into overlapping relationship with the spider ring portion. Such arms are secured to the inner end portions of the leading edge margins of the blades by a plurality of spaced rivets 4 arranged in a radial row.

The rear spider 5 is connected to the front spider 2 by connecting pins 6, such as bolts, extending through the front spider arms 3 and the corresponding rear spider arms 7. Such corresponding front and rear spiders arms are disposed generally in registry axially of the fan and are mutually supported and held indefinitely spaced parallel relationship by spacer sleeves 8 interposed between such spiders, through which the pins 6 connecting these spiders extend.

Because of the transverse curvature of the blades, their trailing edge margins are disposed at a substantial angle to the plane of the rear spider 5. Consequently, the trailing edge margin of the blade is connected to the rear spider by an angle connector. In the fan shown in FIGS. 1 to 5, inclusive, the

spiders

2 and 5 are spaced apart a distance less than the axial extent of the inner ends of the blades 1, and consequently the flange 9 of the angle connector parallel to the rear spider 5 is secured by rivets 10 to the back of the rear spider. The other flange 11 of each angle connector projects generally rearwardly and is secured to the trailing edge margin of a blade by rivets 12. As shown in FIG. 1, such flange extends along the major portion of the length of the blade trailing edge to which it is connected.

For many installations, and particularly for automotive cooling air fans, the space in which the fan must be accommodated is limited. Disposition of the

spiders

2 and 5 closer together than the axial extent of the blades, as indicated in FIG. 4 and 5 in particular, is therefore necessary. The end of the drive shaft for the fan or a drive shaft boss can project forward into an aperture 13 in the center of the rear spider. Holes 14 arranged in a circle around the hole 13 receive bolts for anchoring the hub portion of the fan to the drive mechanism.

A large aperture 15 in the central portion of the front spider 2 opens into the central chamber between the front spider 2 and the rear spider 5 which is in communication with the inner ends 16 of the fan blades that are secured to the spiders. The width of such aperture should be greater than half of the minimum diameter of an inscribed circle defined by throats 3' of the front spider. Such central chamber opens radially outward at a plurality of locations between the inner end portions of adjacent blades.

Rotation of the fan blades about the rotative axis of the fan causes the outer portions of the fan blades to produce an axial flow of air rearward. The entire body of air forward of the fan tends to move rearwardly as a unit, but in conventional fans closed fan hub portions block rearward flow of air directly forward of such a hub portion, so that the air cannot flow smoothly rearward but becomes turbulent and consequently interferes with the axial rearward flow of air past the outer portions of these blades, which decreases the efficiently of the fan operation.

In the fan of the present invention the aperture through the central portion of the front spider 2 enables air directly ahead of the fan center to flow into the central chamber of the fan between the

spiders

2 and 5. The circumferential propulsive effect of the inner end portions of the blades and the aspirating action of the air current flowing axially through the radially outer portion of the fan induces air to flow radially outwardly from the central hub chamber to join the axial flow through the radially outward portion of the fan. Consequently, the axial flow of air through the front spider aperture 15 into the central chamber and flow of air radially outward from such chamber between the blade inner ends provides a definite flow pattern which minimizes turbulence both ahead of and behind the central portion of the fan and increases both the capacity and efficiency of operation of the fan.

The blades 1 of the fan shown in FIGS. 6, 7 and 8 are essentially the same as the blades of the fan shown in FIGS. 1 to 5, inclusive. In this instance again the front spider 17 has arms 18 to which the leading margins of the blades are secured by rivets 19. The arms 21 of the rear spider 20 are connected to the arms 18 of the front spider 17 by pins 21 in a definitely spaced relationship established by the spacer sleeves 22 between the spiders through which the pins 21 extend.

The spacing of the

spiders

17 and 20 of the fan shown in FIGS. 6, 7 and 8 is greater than the spacing of the front and rear spiders of the fan shown in FIGS. 1 to 5, and is substantially equal to the axial extent of the blade inner ends as shown in FIG. 8. The margins of the trailing edges of the inner blade ends are connected to the rear spider 20 by angle connectors having flanges 23 secured to the arms of the rear spider 20 by rivets 24. The forwardly projecting flanges 25 of the angle connectors are secured to the trailing edge margins of the blade inner edge by rivets 26.

As described in connection with the fan shown in FIGS. 1 to 5, the rear spider 20 has a central aperture 27 arranged to receive the forward end of a fansupporting shaft or shaft boss. Fan-securing bolts can extend through the holes 28 arranged in a circular row around the central aperture 27 to secure the fan to the driving mechanism. The front spider 17 has a large central aperture 29 communicating with the chamber between the front spider 17 and the rear spider 20 through which bolts in holes 28 are accessible.

Because the chamber between the front spider 17 and the rear spider 20 of the fan shown in FIGS. 6 to 8 is deeper axially than the chamber between the front spider 2 and the rear spider 5 of the fan shown in FIGS. 1 to 5, the flow of a given quantity of air through the hollow central chamber of FIGS. 6 to 8 will be slower, and it will not be necessary for the airflow entering the opening 29 to change direction so abruptly for flow outward through the openings between the inner ends of the blades. Consequently, the airflow ahead of the rear spider mounting portion of the fan shown in FIGS. 6 to 8 will be much greater and the turbulence resulting from meeting of the radially outward flow and the axially rearward flow beyond the discharge openings from 4 the hollow central chamber will be less than in the fan of FIGS. 1 to 5.

The fan construction of FIGS. 9 to 12 is quite similar to that of the fan shown in FIGS. 6 to 8, including the rear spider 20 and its connection to the margins of the trailing edges of the blades by an

angle connector

23,25 and rivets 24,26. In this instance, however, the front spider 30 is not directly connected to the rear spider 20 by bolts as in the fan construction described above.

In the fan of FIGS. 9 to 12, inclusive, the front spider 30 has arms connected to the margins of the inner end portions of the blade leading edges by rivets 32 arranged in radial rows, as shown in FIG. 9. Such arms 31 form throats 31 between them. The central portion of the spider 30 has in it an aperture 33 communicating with the central chamber between the front spider 30 and the rear spider 20.

In this type of fan the blades 1 in relaxed condition will be cupped to establish the minimum spacing between the front spider 30 and the rear spider 20, as illustrated in FIG. 11. As the rotative speed of the fan increases the blade 1 will flex toward flattened contour,

as shown in FIG. 12, so that the front spider will move away from the rear spider to some extent to increase the axial depth of the central chamber between the front and rear spiders.

The operation of the fan shown in FIGS. 9 to 12, inclusive, is generally similar to the operation of the fans shown in FIGS. 1 to 5 and 6 to 8. In this instance, however, as the rotative speed of the fan increases to produce a greater quantity and velocity of airflow, the front and rear spiders will move apart to increase the axial depth of the central chamber and blade projected width at the same time that the flow through such central chamber is increasing. Consequently, the tendency for turbulence to be produced in the central region of the fan will be reduced while airflow will be increased by such automatic enlargement of the central chamber into which the air flows axially through the aperture 33, and from which it flows radially between the inner end portions of the fan blades.

I claim:

1. A fan comprising a front plate, a rear plate spaced axially from said front plate, a plurality of radial fan blades bridging between said front plate and said rear plate, each of said blades being curved transversely to form an are between its leading edge and its trailing edge substantially less than degrees and to dispose the trailing portion of each blade at a substantial angle to said rear plate, means connecting the leading portion of each blade to said front plate, and means connecting said blade trailing portion to said rear plate, the central portions of said front plate and of said rear plate being spaced apart axially for providing a central chamber between said plates, said front plate having a central aperture therethrough enabling air to flow in an axial direction inwardly into said central chamber and said central chamber opening generally radially outwardly between the inner end portions of said blades for discharge of air therefrom.

2. The fan defined in claim 1, in which the front plate is a spider including a ring portion and circumferentially spaced arms radiating from said ring portion, having throats therebetween and connected, respectively, so the leading edge margins of the blades, the inner end portions of the blades projecting inward beyond said throats into overlapping relationship with said spider ring portion.

3. The fan defined in claim 1, and angle connectors each having a first flange connected to the rear plate and a second flange projecting generally axially of the fan from said first flange and connected to the blade trailing portion.

4. The fan defined in claim 3, in which the second flange of each angle connector projects rearwardly from the first flange of such connector.

5. The fan defined in claim 3, in which the second flange of each angle connector projects forwardly from the first flange of such connector.

6. The fan defined in claim 1, in which the front plate and the rear plate are spiders including corresponding circumferentially spaced arms projecting generally radially from the central portions of said spiders, said arms of the front plate spider and corresponding arms of the rear plate spider being disposed generally in registry axially of the fan, and spacer means independent of the blades connecting the corresponding registering arms of said front plate spider and said rear plate spider, respectively, in definitely spaced relationship.

7. The fan defined in claim 3, in which the second flange of each angle connector extends along a major portion of the length of the blade trailing edge portion to which it is connected.

8. The fan defined in claim 6, and angle connectors each having a first flange connected to a rear plate spider arm and a second flange projecting generally axially of the fan from said first flange and connected to a blade trailing portion, the outer end portion of each angle connector projecting generally radially outwardly to a location a substantial distance beyond the outer end of the radiating arm of the front plate spider corre sponding to the rear plate spider to which such angle connector is connected.

Claims

1. A fan comprising a front plate, a rear plate spaced axially from said front plate, a plurality of radial fan blades bridging between said front plate and said rear plate, each of said blades being curved transversely to form an arc between its leading edge and its trailing edge substantially less than 180 degrees and to dispose the trailing portion of each blade at a substantial angle to said rear plate, means connecting the leading portion of each blade to said front plate, and means connecting said blade trailing portion to said rear plate, the central portions of said front plate and of said rear plate being spaced apart axially for providing a central chamber between said plates, said front plate having a central aperture therethrough enabling air to flow in an axial direction inwardly into said central chamber and said central chamber opening generally radially outwardly between the inner end portions of said blades for discharge of air therefrom.

8. The fan defined in claim 6, and angle connectors each having a first flange connected to a rear plate spider arm and a second flange projecting generally axially of the fan from said first flange and connected to a blade trailing portion, the outer end portion of each angle connector projecting generally radially outwardly to a location a substantial distance beyond the outer end of the radiating arm of the front plate spider corresponding to the rear plate spider to which such angle connector is connected.