Patent US1491924A successfully refreshed from Google Patents.
Patent US5297931A successfully refreshed from Google Patents.
US5297931A
Expired / Lapsed
US
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Forward skew fan with rake and chordwise camber corrections
Assignee: Bosch Automotive Motor Systems Corp
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Filing: 1993-04-28
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Granted: 1994-03-29
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Expires: 2013-04-28
Abstract
Abstract An improvement to forwardly skewed axial fans whereby blade camber and rake are coordinated with skew. The blades are characterized in that a line defined by the points of maximum chordwise camber (f max ) as a function of changing radial position (r) is on the leading edge side of the mid-chord line (M CL ) at values of r toward the root of the blade, and is less forwardly skewed than the leading edge (LE), the mid-chord line (M CL ), and the trailing edge (TE) of said blade; the blade is raked forwardly so that the trailing edge of the blade tip is axially forward of the trailing edge at the blade root; rake (k) increases monotonically as radial position r increases from 0.75R to 1.0R, R being the fan radius; the blade has a relatively large pitch ratio (P/D); and rake is corrected to reflect the chordwise position of maximum camber. As a result, the fan produces a flow that is generally in radial equilibrium having a reduced component of flow normal to the2 desired axial flow and normal to the tangential flow. The coordinated fan can be (but need not be) combined with a housing/band configuration for controlling airflow that recirculates (i.e., counter to the desired axial airflow) in a channel formed between the band and housing.
Inventors
- 👤 Martin G. Yapp
- 👤 Robert Van Houten
- 👤 Robert I. Hickey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 21:51
CPC Classifications
F; F04; F04D; F04D29/00; F04D29/08; F04D29/16; F04D29/161; F04D29/164; F01; F01D; F01D5/00; F01D5/12; F01D5/14; F01D5/141; F04D29/26; F04D29/32; F04D29/325; F04D29/326; F04D29/38; F04D29/384; F04D29/386; Y; Y02; Y02T; Y02T50/00; Y02T50/60
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
260 words
An axial flow fan comprising a hub rotatable on an axis and blades extending in a generally radial direction from said hub to a circular band connecting tips of said blades, each of said blades terminating at a leading edge which is forwardly swept at least in the region defined by r/R>0.90 where r=radial position and R=fan radius, and each of the blades having a trailing edge which is forwardly swept in that region, and each of the blades being characterized in that: a) in an axial projection of the blade, a line defined by the points of maximum camber (f max ) as a function of changing radial position (r) is on the leading edge side of the mid-chord line M CL at the root of the blade, said f max radial function being less forwardly skewed than the leading edge, the mid-chord line, and the trailing edge of said blade; b) the blade is raked forwardly so that the trailing edge of the tip of the blade is axially forward of the trailing edge at the root; the absolute value of said rake (k) increases monotonically as r increases from 0.75R to 1.0R, where R is the fan radius; c) the blade has a pitch (ratio (P/D)) of at least 0.6 (where P=pitch and D=fan diameter) generally throughout the extent of the blade; and d) the rake (k) where r/R>0.75 is a linear function of the midchord axial displacement (AD MC ) at radius r expressed in degrees is corrected to reflect the chordwise position of maximum camber.
Claim 2
Dependent Claim
260 words
An axial flow fan comprising a hub rotatable on an axis and blades extending in a generally radial direction from said hub to a circular band connecting tips of said blades, each of said blades terminating at a leading edge which is forwardly swept at least in the region defined by r/R>0.90 where r=radial position and R=fan radius, and each of the blades having a trailing edge which is forwardly swept in that region, and each of the blades being characterized in that: a) in an axial projection of the blade, a line defined by the points of maximum camber (f max ) as a function of changing radial position (r) is on the leading edge side of the mid-chord line M CL at the root of the blade, said f max radial function being less forwardly skewed than the leading edge, the mid-chord line, and the trailing edge of said blade; b) the blade is raked forwardly so that the trailing edge of the tip of the blade is axially forward of the trailing edge at the root; the absolute value of said rake (k) increases monotonically as r increases from 0.75R to 1.0R, where R is the fan radius; c) the blade has a pitch (ratio (P/D)) of at least 0.6 (where P=pitch and D=fan diameter) generally throughout the extent of the blade; and d) the rake (k) where r/R>0.75 is a linear function of the midchord axial displacement (AD MC ) at radius r expressed in degrees is corrected to reflect the chordwise position of maximum camber.
Claim 3
Dependent Claim
30 words
The fan of claim 1 further characterized in that the chord length C of each blade increases monotonically with respect to increasing radius as r increases from 0.75R to 1.0R.
Claim 4
Dependent Claim
33 words
The fan of claim 2 further characterized in that the first derivative of chord length with respect to increasing radius (dC(r)/dr) increases monotonically with increasing radius as r increases from 0.75R to 1.0R.
Claim 5
Dependent Claim
39 words
The fan of claim 1 further characterized in that the absolute value of the angular displacement of the mid-chord of each blade (AD MC ) increases monotonically with respect to increasing radius as r increases from 0.75R to 1.0R.
Claim 6
Dependent Claim
38 words
The fan of claim 4 further characterized in that the first derivative of the absolute value of the mid-chord angular displacement with respect to r (AD MC (r)/dr) increases monotonically with as r increases from 0.75R to 1.0R.
Claim 7
Dependent Claim
37 words
The fan of claim 1 further characterized in that absolute value of the overall (from root-to-tip) mid-chord angular displacement (AD MC ) of each said blade is at least 0.25·the blade spacing (360°/N, where N=number of blades).
Claim 8
Dependent Claim
32 words
The fan of claim 1 further characterized in that the absolute value of the leading edge sweep angle (S LE ) is at least 50° at a point between r=0.9R and r=R.
Claim 9
Dependent Claim
19 words
The fan of claim 1 further characterized in that the maximum blade camber to chord ratio (f max /C).
Claim 10
Dependent Claim
43 words
The fan of claim 1 further characterized in that absolute value of the rake k is substantially a linear function of midchord skew S corrected for the chordwise position of the maximum chamber (X fmax ) according to the function k(r n )=A+B-E.
Claim 11
Dependent Claim
30 words
The fan of claim 9 further characterized in that first derivative of the absolute value of rake with respect to r(dk(r)/dr) increases mononically as r increases from 0.75R to 1.0R.
Claim 12
Dependent Claim
22 words
The fan of claim 1 further characterized in that the pitch ratio (P/D) decreases monotonically as r increases from 0.75R to 1.0R.
Claim 13
Dependent Claim
15 words
The fan of claim 1 wherein the pitch ratio (P/D)>0.8 at all values of R.
References Cited (Backward Citations)
US2981461A
Cited
US3189260A
Cited
US3307776A
Cited
US3285501A
Cited
US3447741A
Cited
DE1905269A1
Cited
US3627440A
Cited
DE2462465A1
Cited
US3972646A
Cited
US4357914A
Cited
USRE32462E
Cited
US4432694A
Cited
SU918559A1
Cited
US4358245A
Cited
GB2124303A
Cited
EP0168594A1
Cited
US4569631A
Cited
WO1986001263A1
Cited
US4791520A
Cited
JPS62282198A
Cited
US4871298A
Cited
US4900229A
Cited
US4981461A
Cited
US5000660A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-03-28 | 1997-09-27 | 1998-03-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-03-28 | 2001-09-27 | 2002-03-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-03-28 | 2005-09-27 | 2006-03-29 | $7700.00 | Window Closed / Lapsed |