US5297931A
Expired / Lapsed
US
⏱️ 0.0 years remaining
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 17:22
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.
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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 |