EP0469302A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Mixing impellers and impeller systems for mixing and blending liquids and liquid suspensions having a wide range of viscosities
Assignee: SPX Technologies Inc
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Filing: 1991-06-27
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Granted: —
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Expires: 2011-06-27
Abstract
Abstract The impellers have a plurality of fluidfoil blades (12,14,16) and have camber and twist. The geometric pitch or blade angle increases from the tip (24) of the blade towards their axis of rotation in a manner to provide an over pitched condition so that the pitch ratio of the blades at 40% of the blade radius from the axis is greater than the pitch ratio at the tip. The blades are preferably smoothly tapered and increased in width from the tip towards the axis. The impeller blades are mounted on a hub (18) connected to a drive shaft. The blades may decrease in width where they connect to the hub. The pitch angle at the tip is in the range of 18° to 30° (preferably about 20°). The angle at the tip of two diametrically disposed blades of a four blade impeller may have a different blade angle at the tip than the other pair of blades. A pair of impellers may be used. These impellers may be of different diameter and disposed in close proximity so that they are in dependent relationship (preferably spaced apart by less than the diameter of the larger impeller).
Inventors
- 👤 Ronald J. Weetman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 16:07
CPC Classifications
F; F04; F04D; F04D29/00; F04D29/26; F04D29/32; F04D29/38; B; B01; B01F; B01F27/00; B01F27/05; B01F27/11; B01F27/113; B33; B33Y; B33Y80/00; Y; Y10; Y10S; Y10S416/00; Y10S416/02
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
163 words
An impeller which produces flow ranging from turbulent to laminar flow in bodies of liquid and liquid suspensions and which is effective in mixing and blending such bodies, said impeller having a plurality of blades rotatable about an axis, said blades having tips which define the radius (R) of said impeller, said blades extending from said tips radially toward said axis, characterized in that said blades have twist defined by inclinations thereof with respect to a plane perpendicular to said axis at angles which increase smoothly along said blades toward said axis to provide an over pitched condition, where the pitch ratio (PR) of the blades at a section thereof spaced 0.4R from said axis is greater than PR at said tips, where PR is defined by the following equation: where r is the radius from the axis of rotation to the section where PR is computed in accordance with said equation, and is the angle of inclination at said section in degrees.
Claim 2
Dependent Claim
163 words
An impeller which produces flow ranging from turbulent to laminar flow in bodies of liquid and liquid suspensions and which is effective in mixing and blending such bodies, said impeller having a plurality of blades rotatable about an axis, said blades having tips which define the radius (R) of said impeller, said blades extending from said tips radially toward said axis, characterized in that said blades have twist defined by inclinations thereof with respect to a plane perpendicular to said axis at angles which increase smoothly along said blades toward said axis to provide an over pitched condition, where the pitch ratio (PR) of the blades at a section thereof spaced 0.4R from said axis is greater than PR at said tips, where PR is defined by the following equation: where r is the radius from the axis of rotation to the section where PR is computed in accordance with said equation, and is the angle of inclination at said section in degrees.
Claim 3
Dependent Claim
43 words
Am impeller according to claim 1, characterized in that the twist (Δβ) is defined by where PR' is the pitch ratio at a radial distance of about 0.4R and PR is the pitch ratio at the tip and PR' is greater than PR.
Claim 4
Dependent Claim
21 words
An impeller according to claim 1 or claim 2, characterized in that A is in the range of 30 to 45°.
Claim 5
Dependent Claim
27 words
An impeller according to any of claims 1 to 3, characterized in that the inclination of the blades at their tips is in the range of 18°-30°.
Claim 6
Dependent Claim
34 words
An impeller according to any of claims 1 to 4, characterized in that the inclination of said blades is invariant for approximately 10% of the radial distance from their said tips to said axis.
Claim 7
Dependent Claim
50 words
An impeller according to any of claims 1 to 5, characterized in that said blades are fluidfoils having camber as well as said twist, and in that said pitch blade angles are measured between chords of said blades at a point at said tips and at a point at 0.4R.
Claim 8
Dependent Claim
57 words
An impeller according to claim 6, characterized in that said chords at said tip extend between points at intersections of radial lines of length R from said axis and said leading and trailing edges, and said chords at 0.4R, and between intersections of radial lines of length 0.4R from said axis and said leading and trailing edges.
Claim 9
Dependent Claim
53 words
An impeller according to claim 6 or claim 7, characterized in that the width of said blades in terms of the ratio of the length of said chord (W) to the diameter (D) of said impeller (W/D) at their said tips is about 0.25 at the tips, and at 0.4R is about 0.33.
Claim 10
Dependent Claim
46 words
An impeller according to claim 8, characterized in that the ratio of said thickness to the length of said chord at said tip is about 0.1, and the ratio of said thickness, to the length of said chord at 0.4R is from about 0.14 to 0.22.
Claim 11
Dependent Claim
38 words
An impeller according to any of claims 1 to 9, characterized in that said blades have opposite surfaces which respectively produce relatively high and relatively low pressure in said bodies, and projections defining flow guides on said surfaces.
Claim 12
Dependent Claim
38 words
An impeller according to any of claims 1-10, characterized in that said blades have opposite surfaces which develop relatively low and relatively high pressures in said bodies, and means for generation, turbulence disposed on said low pressure surfaces.
Claim 13
Dependent Claim
37 words
An impeller according to any of claims 1-11, characterized by a second impeller, said second impeller having a plurality of blades rotatably disposed coaxially with said first named plurality of blades and spaced in dependent relationship therewith.
Claim 14
Dependent Claim
64 words
An impeller according to claim 12, characterized in that said first named plurality of blades and the blades of said second impeller have opposite surfaces, which develop relatively low and relatively high pressures in said bodies, said impellers being disposed with the relatively low pressure surfaces of said blades of said second impeller adjacent said relatively high pressure surface, of said first named blades.
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