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US3901625A - Self-adjusting fan vane - Google Patents

Self-adjusting fan vane Download PDF

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Publication number
US3901625A
US3901625A US392085A US39208573A US3901625A US 3901625 A US3901625 A US 3901625A US 392085 A US392085 A US 392085A US 39208573 A US39208573 A US 39208573A US 3901625 A US3901625 A US 3901625A
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Prior art keywords
webs
fan
insert
vane
edge portion
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Expired - Lifetime
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US392085A
Inventor
Karlheinz Witzel
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Walker Manufacturing Co
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Walker Manufacturing Co
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Priority to US392085A priority Critical patent/US3901625A/en
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Publication of US3901625A publication Critical patent/US3901625A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/26—Rotors specially for elastic fluids
    • F04D29/32—Rotors specially for elastic fluids for axial flow pumps
    • F04D29/38—Blades
    • F04D29/382—Flexible blades

Definitions

  • a 1atticed insert is embedded in the vane, the insert having a first set of webs extending rectilinearly along a concave surface of the vane in a direction tangential to the periphery of the hub and a second set of webs ex tending in a direction radial to the hub, the webs of the second set being corrugated.
  • Fans of this type are known wherein a plurality of vanes are attached to the periphery of a hub mounted for rotation about its axis.
  • a narrow. thickened. inflexible vane portion at the leading edge of the vane is attached to the periphery of the hub and an elastically flexible vane flap is attached to the inflexible vane portion and is freely movable in respect thereto.
  • the above and other objects are accomplished in accordance with the invention by embedding a Iatticcd insert in a vane ofsynthctic resin.
  • the insert has a first set of webs extending rcctilinearly along a concave sur face of the vane in a direction generally tangential to the periphery of the hub. and a second set of webs ex tending in a direction generally radial to the hub.
  • thc webs of the second set being corrugated.
  • the corrugations of the webs of the second set extend in the dircction of the other surface of the vane opposite to the concave surface thereof.
  • the insert may be of metal. for instance perforated sheet metal. a wire grid or an expanded metal sheet. It may also consist of glass fibre reinforced synthetic resin.
  • a narrow beaded portion forms the trailing edge of the ⁇ anc. and weights are embedded in thc beaded portion.
  • FIG. I is a partial front view of a fan according to this invention.
  • FIG. 2 is a fragmentary side view of the fan of FIG. 1'.
  • FIG. 3 is a section along line III-III of FIG. 1;
  • FIG. 4 is a section along lines line IV
  • FIGS. 5 and 6 are enlarged illustrations of the details shown at V and VI, respectively. of FIGS. 3 and 4;
  • FIG. 7 is similar to FIG. 6, showing a modification of the corrugated insert web
  • FIG. 8 illustrates an embodiment of an insert. in top view
  • FIG. 9 is a section along lines IXIX of FIG. 8.
  • FIG. I0 is an end view of the insert of FIG. 8.
  • the illustrated fan comprises hub I mounted for rotation about its axis 10.
  • a plurality of self-adjusting vanes 2 of synthetic resin are distributed about the periphery of the hub. either regularly or. if found desirable. irregularly spaced from each other.
  • the fan rotates clockwise in the direction of arrow 4 so as to present a leading edge 5 and a trailing edge 9 to the incident air.
  • a concave vane surface 17 and another surface 20 axially offset from the surface 17, extend between the leading and trailing edges of each vane.
  • the leading edge of the vane extends about perpendicularly to rotary axis I0 of the fan and about parallel to a radius of the hub.
  • the outer vane edge 7 extends about perpendicularly to the radius and is slightly curved. as shown. to connect with trailing edge 9 by way of a rounded corner 8.
  • the trailing edge is about parallel to the leading edge 5.
  • the vanes are so mounted on the hub that the angle of incidence of the air decreases outwardly in a radial direction.
  • a narrow. thickendcd. inflexible vane portion 11 attachcs each vane to the periphery of the hub at the leading edge of the vane.
  • the vane portion II is tapered in a radial direction. being narrower at the outer end than at the root.
  • the wedge-shaped vane portion 11 has the flap 14 of the vane attached thereto along a line I2 which is inclined in respect of the radius. which assures good use of the centrifugal forces.
  • Flap 14 is elastically flexible and freely movable in respect of inflexible portion 11. Under the influence of air flow and centrifugal forces at increased rotary speeds of the fan. the flap 14 is flexed. thus changing the angle of incidence and the radius of curvature of the fan vane. The effect of the centrifugal forces is increased by providing a narrow beaded portion 15 at the trailing edge 9 of the vane. and by loading the beaded portion with weight means. such as balls or a weight 21.
  • the vanes 2 may consist of any suitable synthetic resin. such as polypropylene. As best shown in FIGS. 3 and 4, a latticeshapcd insert 3 is embedded in each vane. The coefficient of thermal expansion of the insert material is lower than that of the synthetic resin forming the vane.
  • a useful insert material is metal but a synthctic resin reinforced with glass fibres may also be used.
  • the insert has a first set of webs I6 extending along concave surface 17 of the vane in parallel planes generally tangential to the periphery of huh I. As shown in FIG. I, the webs 16 extend across substantially the entire width of the vane 2. A second set of webs 18 con nect the webs l6 and extend in a direction generally radial to the hub. Sections of webs 18 between adjacent webs 16 are corrugated, the corrugations 19 thereof extending from webs 16 towards vane surface and having axes of curvature extending in the common direction of elongation of webs 16.
  • the corrugations I9 are about semi-cylindrical about axes of curvature parallel to the direction of elongation of webs I6 while the corrugations 19' in the modification of FIG. 7 are flattened and form a pinched neck portion.
  • the latter modification provides a more secure connection of the insert with the vane since the corru gations I9 will more or less hook the webs 18 into the synthetic resin material of the vane when the insert is embedded therein.
  • FIGS. 8 to 10 A useful embodiment of an insert is illustrated in the various views of FIGS. 8 to 10.
  • the specifically described and claimed web structure of the insert produces increased curving of vane 2 about the longitudinal axes of webs 16 with an increase in the ambient temperature since the thermal expansion coefficient of the synthetic resin material of the vane considerably exceeds that of webs 16.
  • the synthetic resin material of the vane can expand independently of the lower thermal expansion coefficient of webs 19 in the direction thereof. Therefore, the vane will not be curved in this direction and will assume form 2' (FIG. 2). At lower temperatures and under the influence of the centrifugal forces, the vane will be flexed outwardly, as shown at 2" in FIG. 2.
  • the insert 3 may be placed in an injection mold, with the webs I6 flush against the mold wall, and the syn thetic resin is then injection molded about the insert to form the vane.
  • the vanes of the present invention will operate at optimal efficiency since such power-determining factors as the angle of incidence and the curvature of the vane will change as a direct function of temperature changes as well as air flow and centrifugal forces. Furthermore, the manufacture of the vanes is very simple and a very good connection is provided between the insert and the vane.
  • a hub having an axis of rotation and a periphery
  • each vane including a leading edge portion attached to said hub and substantially inflexible, and a flap attached to said leading edge portion and more flexible than said edge portion, said flap including a trailing edge portion remote from said leading edge portion and having two axially offset surfaces connecting said edge portions, one of said surfaces being concavely arcuate about an axis of curvature approximately radial relative to said axis of rotation,
  • said flap essentially consisting of synthetic resin composition and a lattice-shaped insert embedded in said composition, the insert being of a material having a coefficient of thermal expansion smaller than the coefficient of thermal expansion of said composition
  • said insert including two sets of webs, the webs of each set being elongated in a common direction, being transversely spaced from each other, and transversely intersecting the webs of the other set,
  • the insert consisting of perforated sheet metal.
  • the insert consisting of a wire grid.
  • the insert consisting of an expanded sheet metal.
  • the insert consisting of glass fibre reinforced synthetic resin.
  • the webs of said one set having each a plurality of sections interposed between respective pairs of adjacent webs of the other set, said sections being corrugated.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

A self-adjusting fan vane of synthetic resin has a narrow, thickened, inflexible portion at the leading edge attached to the periphery of the fan hub and an elastically flexible vane flap attached to the inflexible vane portion and freely movable in respect thereto. A latticed insert is embedded in the vane, the insert having a first set of webs extending rectilinearly along a concave surface of the vane in a direction tangential to the periphery of the hub and a second set of webs extending in a direction radial to the hub, the webs of the second set being corrugated.

Description

[4 1 Aug. 26, 1975 1 1 SELF-ADJUSTING FAN VANE [75] Inventor: Karlheinz Witzel, Heidelberg,
Germany [73] Assignee: Walker Manufacturing Company,
Mannheim, Germany [22] Filed: Aug. 27, 1973 [21] App]. No.: 392,085
[52] US. Cl. 416/132; 416/224; 416/240; 416/241 [51] Int. Cl. F04c 29/38 [58] Field of Search 416/132, 132 A, 240, 241 A, 416/139, 224
3,594,098 7/1971 Pratinidhi 416/240 X 3,637,325 1/1972 Morley 416/230 3,751,181 8/1973 Hayashi 416/132 3,758,231 9/1973 Barnstead 416/132 FORElGN PATENTS OR APPLICATIONS 2,013,481 10/1970 Germany 416/132 Primary ExaminerEverette A. Powell, Jr. Attorney, Agent, or FirmKurt Kelman 5 7 ABSTRACT A self-adjusting fan vane of synthetic resin has a narrow, thickened, inflexible portion at the leading edge attached to the periphery of the fan hub and an elastically flexible vane flap attached to the inflexible vane portion and freely movable in respect thereto. A 1atticed insert is embedded in the vane, the insert having a first set of webs extending rectilinearly along a concave surface of the vane in a direction tangential to the periphery of the hub and a second set of webs ex tending in a direction radial to the hub, the webs of the second set being corrugated.
10 Claims, 10 Drawing Figures PATENTEU AUBZ 6 I975 SHEET 1 OF PA {ENTED AUG 2 61875 sum 3 o PATENTEDAUBZBIQYS 3,901,625 SHEET 8 [If SELF-ADJUSTING FAN VANE The present invention relates to improvements in fans for internal combustion engines. j
Fans of this type are known wherein a plurality of vanes are attached to the periphery of a hub mounted for rotation about its axis. A narrow. thickened. inflexible vane portion at the leading edge of the vane is attached to the periphery of the hub and an elastically flexible vane flap is attached to the inflexible vane portion and is freely movable in respect thereto.
In the design of such fans. care must be taken that there is sufficient cooling of the engine at low rotary speed of the fan and at low engine speed. Such fans produce excessive and unneeded cooling at high and engine speeds. This unwanted cooling effect causes a considerable increase in the power requirements of the fan which must be met by the engine.
It has been attempted to avoid this disadvantage by designing the fan vane so that such power-determining properties of the vane as the angle ofincidence and the radius of curvature of the vane change at higher rotary speeds under the influence of the air flow and centrifu gal forces. While this influences the efficiency in de pendence on the rotary speed. it does not influence it in dependence on the ambient temperature.
It has also been proposed to provide a laminated fan vane with layers of different coefficients of thermal expansion to cause changes in the angle ofincidence and the curvature of the vane in dependence on the ambicnt temperature. This type of fan vane has the consid crablc disadvantage that the thermal expansion extends in all directions. causing unfavorable effects of the efficicncy and increased fan noise. Also. the two layers. one of metal and the other of synthetic resin. are bonded together by an adhesive providing insufficient cohesion between the layers and eventually causing the vane layers to separate under the influence of the constant form changes. A further disadvantage of this type of vane is its high manufacturing cost because of the labor involved.
It is the primary object of this invention to overcome the above disadvantages of conventional fan vanes and to provide a vane which is selfadjusting by changing its form in dependence on the ambient temperature as well as the air flow and centrifugal forces to which the vanes are subjected during rotation of the fan.
The above and other objects are accomplished in accordance with the invention by embedding a Iatticcd insert in a vane ofsynthctic resin. The insert has a first set of webs extending rcctilinearly along a concave sur face of the vane in a direction generally tangential to the periphery of the hub. and a second set of webs ex tending in a direction generally radial to the hub. thc webs of the second set being corrugated. The corrugations of the webs of the second set extend in the dircction of the other surface of the vane opposite to the concave surface thereof.
The insert may be of metal. for instance perforated sheet metal. a wire grid or an expanded metal sheet. It may also consist of glass fibre reinforced synthetic resin.
According to one preferred feature. a narrow beaded portion forms the trailing edge of the \anc. and weights are embedded in thc beaded portion.
The abovc and other objects. advantages and features ofthe present invention will become more apparent from the following detailed description of a now preferred embodiment thereof. taken in conjunction with the accompanying drawing wherein FIG. I is a partial front view ofa fan according to this invention;
FIG. 2 is a fragmentary side view of the fan of FIG. 1'.
FIG. 3 is a section along line III-III of FIG. 1;
FIG. 4 is a section along lines line IV|V of FIG. 1;
FIGS. 5 and 6 are enlarged illustrations of the details shown at V and VI, respectively. of FIGS. 3 and 4;
FIG. 7 is similar to FIG. 6, showing a modification of the corrugated insert web;
FIG. 8 illustrates an embodiment of an insert. in top view;
FIG. 9 is a section along lines IXIX of FIG. 8; and
FIG. I0 is an end view of the insert of FIG. 8.
Referring now to the drawing and first to FIGS. 1 to 4, the illustrated fan comprises hub I mounted for rotation about its axis 10. A plurality of self-adjusting vanes 2 of synthetic resin are distributed about the periphery of the hub. either regularly or. if found desirable. irregularly spaced from each other. In operation. the fan rotates clockwise in the direction of arrow 4 so as to present a leading edge 5 and a trailing edge 9 to the incident air. A concave vane surface 17 and another surface 20 axially offset from the surface 17, extend between the leading and trailing edges of each vane.
The leading edge of the vane extends about perpendicularly to rotary axis I0 of the fan and about parallel to a radius of the hub. The outer vane edge 7 extends about perpendicularly to the radius and is slightly curved. as shown. to connect with trailing edge 9 by way of a rounded corner 8. The trailing edge is about parallel to the leading edge 5. In a conventional manner. the vanes are so mounted on the hub that the angle of incidence of the air decreases outwardly in a radial direction.
A narrow. thickendcd. inflexible vane portion 11 attachcs each vane to the periphery of the hub at the leading edge of the vane. The vane portion II is tapered in a radial direction. being narrower at the outer end than at the root. Thus. the wedge-shaped vane portion 11 has the flap 14 of the vane attached thereto along a line I2 which is inclined in respect of the radius. which assures good use of the centrifugal forces. Flap 14 is elastically flexible and freely movable in respect of inflexible portion 11. Under the influence of air flow and centrifugal forces at increased rotary speeds of the fan. the flap 14 is flexed. thus changing the angle of incidence and the radius of curvature of the fan vane. The effect of the centrifugal forces is increased by providing a narrow beaded portion 15 at the trailing edge 9 of the vane. and by loading the beaded portion with weight means. such as balls or a weight 21.
The vanes 2 may consist of any suitable synthetic resin. such as polypropylene. As best shown in FIGS. 3 and 4, a latticeshapcd insert 3 is embedded in each vane. The coefficient of thermal expansion of the insert material is lower than that of the synthetic resin forming the vane. A useful insert material is metal but a synthctic resin reinforced with glass fibres may also be used.
The insert has a first set of webs I6 extending along concave surface 17 of the vane in parallel planes generally tangential to the periphery of huh I. As shown in FIG. I, the webs 16 extend across substantially the entire width of the vane 2. A second set of webs 18 con nect the webs l6 and extend in a direction generally radial to the hub. Sections of webs 18 between adjacent webs 16 are corrugated, the corrugations 19 thereof extending from webs 16 towards vane surface and having axes of curvature extending in the common direction of elongation of webs 16.
In the embodiment shown in FIGS. 4 and 6, the corrugations I9 are about semi-cylindrical about axes of curvature parallel to the direction of elongation of webs I6 while the corrugations 19' in the modification of FIG. 7 are flattened and form a pinched neck portion. The latter modification provides a more secure connection of the insert with the vane since the corru gations I9 will more or less hook the webs 18 into the synthetic resin material of the vane when the insert is embedded therein.
A useful embodiment of an insert is illustrated in the various views of FIGS. 8 to 10. The specifically described and claimed web structure of the insert produces increased curving of vane 2 about the longitudinal axes of webs 16 with an increase in the ambient temperature since the thermal expansion coefficient of the synthetic resin material of the vane considerably exceeds that of webs 16. On the other hand, the synthetic resin material of the vane can expand independently of the lower thermal expansion coefficient of webs 19 in the direction thereof. Therefore, the vane will not be curved in this direction and will assume form 2' (FIG. 2). At lower temperatures and under the influence of the centrifugal forces, the vane will be flexed outwardly, as shown at 2" in FIG. 2.
Manufacture of the described vane is very simple. The insert 3 may be placed in an injection mold, with the webs I6 flush against the mold wall, and the syn thetic resin is then injection molded about the insert to form the vane.
Since the insert webs 16 are flush with the surface of the vane, good heat conductivity is assured so that the vanes will adapt very quickly to temperature changes. Thus, the vanes of the present invention will operate at optimal efficiency since such power-determining factors as the angle of incidence and the curvature of the vane will change as a direct function of temperature changes as well as air flow and centrifugal forces. Furthermore, the manufacture of the vanes is very simple and a very good connection is provided between the insert and the vane.
What is claimed is:
I. In a fan for an internal combustion engine, in combination:
a. a hub having an axis of rotation and a periphery, and
b. a plurality of vanes extending radially from said periphery in spaced relationship, each vane including a leading edge portion attached to said hub and substantially inflexible, and a flap attached to said leading edge portion and more flexible than said edge portion, said flap including a trailing edge portion remote from said leading edge portion and having two axially offset surfaces connecting said edge portions, one of said surfaces being concavely arcuate about an axis of curvature approximately radial relative to said axis of rotation,
(i) said flap essentially consisting of synthetic resin composition and a lattice-shaped insert embedded in said composition, the insert being of a material having a coefficient of thermal expansion smaller than the coefficient of thermal expansion of said composition,
(2) said insert including two sets of webs, the webs of each set being elongated in a common direction, being transversely spaced from each other, and transversely intersecting the webs of the other set,
(3) the webs of one set being corrugated about axes of curvature extending in the direction of elongation of the webs of the other set, the webs of said other set being elongated in a direction from one of said edges toward the other edge.
2. In the fan of claim 1, the webs of the insert being of metal.
3. In the fan of claim 2, the insert consisting of perforated sheet metal.
4. In the fan of claim 2, the insert consisting of a wire grid.
5. In the fan of claim 2, the insert consisting of an expanded sheet metal.
6. In the fan of claim I, the insert consisting of glass fibre reinforced synthetic resin.
7. In the fan of claim I said trailing edge portion being beaded, and weight means embedded in the beaded portion.
8. In the fan of claim I, the webs of said one set having each a plurality of sections interposed between respective pairs of adjacent webs of the other set, said sections being corrugated.
9. In the fan of claim 8, said webs of said other set being substantially flush with said one surface, said c0rrugations projecting from the webs of said other set toward the other one of said two surfaces of said flap.
10. In the fan of claim I, said sets being fixedly fastened to each other.

Claims (10)

1. In a fan for an internal combustion engine, in combination: a. a hub having an axis of rotation and a periphery, and b. a plurality of vanes extending radially from said periphery in spaced relationship, each vane including a leading edge portion attached to said hub and substantially inflexible, and a flap attached to said leading edge portion and more flexible than said edge portion, said flap including a trailing edge portion remote from said leading edge portion and having two axially offset surfaces connecting said edge portions, one of said surfaces being concavely arcuate about an axis of curvature approximately radial relative to said axis of rotation, (1) said flap essentially consisting of synthetic resin composition and a lattice-shaped insert embedded in said composition, the insert being of a material having a coefficient of thermal expansion smaller than the coefficient of thermal expansion of said composition, (2) said insert including two sets of webs, the webs of each set being elongated in a common direction, being transversely spaced from each other, and transversely intersecting the webs of the other set, (3) the webs of one set being corrugated about axes of curvature extending in the direction of elongation of the webs of the other set, the webs of said other set being elongated in a direcTion from one of said edges toward the other edge.
2. In the fan of claim 1, the webs of the insert being of metal.
3. In the fan of claim 2, the insert consisting of perforated sheet metal.
4. In the fan of claim 2, the insert consisting of a wire grid.
5. In the fan of claim 2, the insert consisting of an expanded sheet metal.
6. In the fan of claim 1, the insert consisting of glass fibre reinforced synthetic resin.
7. In the fan of claim 1 said trailing edge portion being beaded, and weight means embedded in the beaded portion.
8. In the fan of claim 1, the webs of said one set having each a plurality of sections interposed between respective pairs of adjacent webs of the other set, said sections being corrugated.
9. In the fan of claim 8, said webs of said other set being substantially flush with said one surface, said corrugations projecting from the webs of said other set toward the other one of said two surfaces of said flap.
10. In the fan of claim 1, said sets being fixedly fastened to each other.
US392085A 1973-08-27 1973-08-27 Self-adjusting fan vane Expired - Lifetime US3901625A (en)

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4242046A (en) * 1978-06-15 1980-12-30 Wallace Murray Corporation Fan spider with rake angle
US4251189A (en) * 1978-05-13 1981-02-17 Heidolph & Zinsser Gmbh Fan
US5163814A (en) * 1989-06-09 1992-11-17 Caframo Limited Portable electric fan assembly
US5558499A (en) * 1993-10-06 1996-09-24 Kobayashi; Takao Centrifugal blower wheel with backward curved blades
US20060174595A1 (en) * 2003-04-25 2006-08-10 Aerosynthesis Llc, A Massachusetts Corporation Inducing air
US20060225696A1 (en) * 2003-04-25 2006-10-12 Moktader Mohammed S Inducing air
US20060254228A1 (en) * 2005-05-16 2006-11-16 Mohammad Moktader Inducing air
US20110255987A1 (en) * 2010-04-14 2011-10-20 Ocean Rich Electricity Product Company Compound balde of a fan
US9410438B2 (en) 2013-03-08 2016-08-09 Pratt & Whitney Canada Corp. Dual rotor blades having a metal leading airfoil and a trailing airfoil of a composite material for gas turbine engines

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2251887A (en) * 1938-06-13 1941-08-05 Master Electric Co Flexible fan unit
US2498348A (en) * 1947-05-29 1950-02-21 Jr Frank E Thompson Marine propeller
US3275082A (en) * 1965-08-19 1966-09-27 Robert E Stark Propellers for water craft
US3318388A (en) * 1966-01-21 1967-05-09 Otto L Bihlmire Marine propeller
US3452843A (en) * 1967-08-18 1969-07-01 Berwick Forge & Fabricating Co Rotary impeller and reinforcing means therefor
US3584969A (en) * 1968-05-25 1971-06-15 Aisin Seiki Flexible blade fan
US3594098A (en) * 1969-02-28 1971-07-20 Fram Corp Fan with weighted flexible blades
US3637325A (en) * 1968-11-19 1972-01-25 Secr Defence Blade structure
US3751181A (en) * 1970-01-31 1973-08-07 Aisin Seiki Fan for cooling automotive vehicle engine
US3758231A (en) * 1971-07-15 1973-09-11 Vernco Corp Flexible fan

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2251887A (en) * 1938-06-13 1941-08-05 Master Electric Co Flexible fan unit
US2498348A (en) * 1947-05-29 1950-02-21 Jr Frank E Thompson Marine propeller
US3275082A (en) * 1965-08-19 1966-09-27 Robert E Stark Propellers for water craft
US3318388A (en) * 1966-01-21 1967-05-09 Otto L Bihlmire Marine propeller
US3452843A (en) * 1967-08-18 1969-07-01 Berwick Forge & Fabricating Co Rotary impeller and reinforcing means therefor
US3584969A (en) * 1968-05-25 1971-06-15 Aisin Seiki Flexible blade fan
US3637325A (en) * 1968-11-19 1972-01-25 Secr Defence Blade structure
US3594098A (en) * 1969-02-28 1971-07-20 Fram Corp Fan with weighted flexible blades
US3751181A (en) * 1970-01-31 1973-08-07 Aisin Seiki Fan for cooling automotive vehicle engine
US3758231A (en) * 1971-07-15 1973-09-11 Vernco Corp Flexible fan

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4251189A (en) * 1978-05-13 1981-02-17 Heidolph & Zinsser Gmbh Fan
US4242046A (en) * 1978-06-15 1980-12-30 Wallace Murray Corporation Fan spider with rake angle
US5163814A (en) * 1989-06-09 1992-11-17 Caframo Limited Portable electric fan assembly
US5558499A (en) * 1993-10-06 1996-09-24 Kobayashi; Takao Centrifugal blower wheel with backward curved blades
US20060243135A1 (en) * 2003-04-25 2006-11-02 Aerosynthesis Llc, A Massachusetts Corporation Inducing air
US20060225696A1 (en) * 2003-04-25 2006-10-12 Moktader Mohammed S Inducing air
US20060174595A1 (en) * 2003-04-25 2006-08-10 Aerosynthesis Llc, A Massachusetts Corporation Inducing air
US7393374B2 (en) * 2003-04-25 2008-07-01 Aerosynthesis Llc Inducing air
US20090038474A1 (en) * 2003-04-25 2009-02-12 Moktader Mohammed S Inducing air
US7691179B2 (en) 2003-04-25 2010-04-06 Aerosynthesis Llc Inducing air
US20060254228A1 (en) * 2005-05-16 2006-11-16 Mohammad Moktader Inducing air
US7553348B2 (en) 2005-05-16 2009-06-30 Aerosynthesis Llc Inducing air
US20110255987A1 (en) * 2010-04-14 2011-10-20 Ocean Rich Electricity Product Company Compound balde of a fan
US9410438B2 (en) 2013-03-08 2016-08-09 Pratt & Whitney Canada Corp. Dual rotor blades having a metal leading airfoil and a trailing airfoil of a composite material for gas turbine engines

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