US3799697A

US3799697A - Flexible bladed fan with tab connected reinforcing member

Info

Publication number: US3799697A
Application number: US00310596A
Authority: US
Inventors: Jong A De
Original assignee: Fram Corp
Current assignee: Siemens Bendix Automotive Electronics Ltd; Bendix Engine Components Ltd; Fram Corp
Priority date: 1972-11-29
Filing date: 1972-11-29
Publication date: 1974-03-26
Anticipated expiration: 1991-03-26
Also published as: CA1004196A; JPS4983905A

Abstract

An automotive cooling fan having a flexible blade connected to a reinforcing member along the blade leading edge by lance tabs integral with the reinforcing member.

Description

United States Patent 11 1 De Jong Mar. 26, 1974 FLEXIBLE BLADED FAN WITH TAB [56] References Cited CONNECTED REINFORCING MEMBER UNITED STATES PATENTS [75] Inventor: Allan W. De Jong, Chatham, 3,289,924 12/1966 Weir 416/240 X o tari .canada 3,594,098 7/1971 Pratinidhi 416/132 3,711,219 1/1973 Strick 416/132 173] Asslgnee: Fram Corporation, East Providence,

1 Primary Examiner-Everette A. Powell, Jr. [221 Filed: Nov. 29, 1972 121 1 App]. No; 310,596 [57] ABSTRACT An automotive cooling fan having a flexible blade connected to a reinforcing member along the blade [52] US. Cl. 416/132, 416/240 leading edge by lance tabs integral with the reinforc [51] Int. Cl. F04d 29/36 b mg mem er.

Field of Search 416/132, 240, 241 A, 210

7 Claims, 3 Drawing Figures FIELD OF THE INVENTION This invention relates to automotive cooling fans and more particularly to such fans having flexible, resilient blades connected to reinforcing members against which they decamber rotational speed increases.

SUMMARY OF THE INVENTION It is a principal object of this inventionto connectthe blade to the reinforcing member, adjacent the blade tip, along the blade leadingedge and to reduce stress concentrations in the'blade. Further it is an object of this inventionto reduce fan weight and to simplify assembly.

In general the invention features, in a fan having a'reinforcing member extending radially along and forwardly of the leading edge of the fanblade, fastening means adjacent the blade connecting the blade and reinforcing member, the fastening means comprising a tab integral with the reinforcing member, extending from the blade leading edge toward the trailing edge and bent around the leading edge and against the side of the blade opposite the reinforcing member. In preferred embodiments the tab is connected to the reinforcing member parallelto the blade leading edge and the tab contacts the blade at acentral depression in the tab.

The resulting structure positively restrains the blade leading edge preventing any tendency of the leading edge to separate from the reinforcing member adjacent the outer tip during operation. Stress concentrations in theblade are reducedby eliminating rivet holes therein adjacent the outer tip. The elimination of tip rivets reduces fan weight. Finally, the use of tabs eliminates rivet hole alignment problems during assembly.

Other objects, features and advantages of this invention will be apparent to those skilled in the art from the following detailed description of a preferred embodiment thereof taken together with the accompanying drawing in which:

BRIEF DESCRIPTION OF TH DRAWING FlGsl is a fragmentary plan view of a fan embodying the invention; I

FIG. 2 is an enlarged, fragmentary view taken along the line 22 of FIG. 1 and FIG. 3 is a fragmentary, sectional view taken along the line 3--3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIGS. 1 and 2, the fan comprises a hub 12 having a centrally located pilot hole 14 centered on the axis of rotation A and mounting holes 16. Hub 12 lies in a plane normal to the axis of rotation A.

A plurality of arms-18, integral with hub 12, extend generally radially outward from hub 12. Each arm 18 is twisted at its root 20, adjacent hub 12, to extend outwardly therefrom at an acute angle, 25 in the preferred embodiment, relative to the plane of fan rotation, the arm leading edge 22, defined by the direction of rotation, lying upstream, defined by the direction of airflow, relative to the arm trailing edge 24. The outer portion of arm 18 lies in a plane, extending transversely between the leading and

trailing edges

22, 24

thereof to define a flat blade mounting surface 26 on the upstream side thereof.

A blade 28 is positionedon the upstream side of each arm 18 and extends from adjacent root 20 radially to a position outwardly of arm 18. Blade 28 comprises a flat leading portion 30 positioned against mounting surface26 and extending transversely from blade leading edge 32 adjacent arm leading edge 22 to a position trailing arm 18. Blade 28 also comprises a trailing portion 34, integral with leading portion 30 and extending transversely therefrom to trailing edge 36 including a folded weighting portion 38 as disclosed in US. Pat. No. 3,594,098. Trailing portion 34 is cambered about an axis of curvature C downstream, the convex side of blade 28facing upstream and the concave side facing downstream.

Overlying leading portion 30 of blade 28, against the upstream side thereof opposite arm 18, is a reinforcing member 40 radially, substantially coextensive with blade 28 and extending transversely from adjacent blade leading edge 32 to a position adjacent arm trailing edge 24 intermediate the blade leading and

trailing edges

32, 36. Member 40 comprises a support surface 42 on the downstream side thereof adjacent blade 28 having a flat leading portion 44 against blade leading portion 30 and a trailing portion 46 curved upstream and progressively more remote from blade 28 toward the blade trailingportion 34, the trailing portion 46 separating from blade 28 on a line of separation B. Reinforcing member 40 extends forwardly of arm 18 to provide an extended air foil structure, in accordance with the disclosure in US. Pat. No. 3,639,078 and includes a radially extending strengthening rib 48. In accordance with US. Pat. No. 3,639,079 the inner edge 49 of member 40 is turned upwardly to strengthen member 40. 1

A plurality of fasteners, rivets 50, 50, 52, 52, extend through arm 18 and the leading

portions

30, 44 of blade 28 and reinforcing member 40 securing them together.

Rivets

50, 50 are spaced apart along a radial line R and

rivets

52, 52 are spaced apart in staggered relation to

rivets

50, 50.

As best shown in FIG. 1, the line B, on which the trailing portion 46 of reinforcing member 40 separates from blade 28, lies at an acute angle to radial line R, intersecting line R outwardly of blade tip 29. In the illustrated embodiment the acute angle between lines B and R is 8. The trailing edge 36 of blade 28 extends a greater distance behind the line B adjacent blade tip 29 than at the root 31 of blade 28. The trailing edge 36 may and preferably is, however, also disposed at an acute angle to radial line R, a line D extending therefrom intersecting (not shown) line R outwardly of blade tip 29, the angle between line R and the line D being less than the angle between lines B and R, 5 in the illustrated embodiment. The axis of curvature C of blade 28 is parallel to the blade trailing edge 36.

As best shown in FIGS. 2 and 3, fastening means in the form of

lance tabs

54, 56, 58, cut from reinforcing member 40, are provided in reinforcing member radially outwardly of arm 18 securing the blade leading edge 32 to reinforcing member 40. Each

tab

54, 56, 58 is connected to member 40 along a line parallel to blade leading edge 32 and extends therefrom toward the blade trailing edge 36. Each

tab

54, 56, 58 is bent from reinforcing member 40 downstream and thence toward the blade trailing edge 36 against the side of blade 28 opposite reinforcing member 40. Each tab 54,

56, 58 includes a central depression 60 extending toward and contacting blade 28 to prevent stress risers in blade 28 which would be created by contact with the edges of

tabs

54, 56, 58.

In operation, as the fan rotates the trailing portion 34 of blade 28 decambers in an upstream direction. The progressively longer moment arm from root 31 to tip 29 of the blade 28, provided by the angled separating line B, results in greater deflection toward the tip of the blade, improving blade profile in operation and thereby resulting in a significant reduction of fan noise. As blade 28 is decambered and stressed,

tabs

54, 56, 58 retain the leading edge 32 of blade 28 in flush contact with reinforcing member 40 outwardly of arm 18, lowering stress concentrations in the blade adjacent the outer leading portion 30 thereof.

Other embodiments of this invention will be apparent to those skilled in the art which are within the scope of the following claims.

What is claimed is:

1. In an automotive cooling fan comprising a hub, a plurality of arms projecting radially outwardly from said hub, a blade positioned against one side of each of said arms said blade extending transversely from a leading edge, defined by the direction of fan rotation, adjacent said arm to a trailing edge behind said arm, a reinforcing member positioned against each said blade on the side thereof opposite the arm against which the blade is positioned and extending forwardly of said leading edge, each said blade thereby positioned between an overlying reinforcing member and an arm, said blade and said reinforcing member extending together radially beyond said arm, fasteners adjacent said arm securing said blade, reinforcing member and arm together, and fastening means radially beyond said arm securing said blade and said reinforcing member together, that improvement in which each said fastening means comprises a lance tab integrally connected to said reinforcing member parallel to and adjacent said blade leading edge, the remainder of said tab cut from said reinforcing member, said tab extending from adjacent said blade leading edge toward said trailing edge, and said tab bent from said reinforcing member around said blade leading edge and against the side of said blade opposite said reinforcing member.

2. The improvement claimed in claim 1 in which said blade lies on the upstream side of said arm and said reinforcing member lies on the upstream side of said blade.

3. The improvement claimed in claim 1 in which said fastening means comprises a plurality of said tabs.

4. The improvement claimed in claim 1 in which said tab includes a central depression, said depression contacting and lying against said blade on said side thereof opposite said reinforcing member.

5. The improvement claimed in claim 4 in which said tab is integrally connected to said reinforcing member parallel to and adjacent said blade leading edge and the remainder of said tab is cut from said reinforcing member.

6. The improvement claimed in claim 5 in which said blade lies on the upstream side of said arm and said reinforcing member lies on the upstream side of said blade.

7. The improvement claimed in claim 6 in which said fastening means comprises a plurality of said tabsv

Claims

1. In an automotive cooling fan comprising a hub, a plurality of arms projecting radially outwardly from said hub, a blade positioned against one side of each of said arms, said blade extending transversely from a leading edge, defined by the direction of fan rotation, adjacent said arm to a trailing edge behind said arm, a reinforcing member positioned against each said blade on the side thereof opposite the arm against which the blade is positioned and extending forwardly of said leading edge, each said blade thereby positioned between an overlying reinforcing member and an arm, said blade and said reinforcing member extending together radially beyond said arm, fasteners adjacent said arm securing said blade, reinforcing member and arm together, and fastening means radially beyond said arm securing said blade and said reinforcing member together, that improvement in which each said fastening means comprises a lance tab integrally connected to said reinforcing member parallel to and adjacent said blade leading edge, the remainder of said tab cut from said reinforcing member, said tab extending from adjacent said blade leading edge toward said trailing edge, and said tab bent from said reinforcing member around said blade leading edge and against the side of said blade opposite said reinforcing member.

7. The improvement claimed in claim 6 in which said fastening means comprises a plurality of said tabs.