Centrifugal Fan Assembly For Road Sweeping Machines

• US 20170016453A1
• Filed: 03/18/2015
• Published: 01/19/2017
• Est. Priority Date: 03/20/2014
• Status: Active Grant

• Current Assignee: Bucher Municipal Pty Ltd. (Bucher Industries AG)
• Original Assignee: Johnston Sweepers Limited (Bucher Industries AG)
• Inventors: Knopp, Gareth, Sandford, Michael, Catchpole, Stephen
• Granted Patent: US 10,502,225 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: E01H 1/0809 Loosening or dislodging by blowing combined with suction E01H1/0863; with steam E01H1/10; removing snow by blowing E01H5/106; cleaning rails by blowing E01H8/105, E01H8/125; removing fog by blowing E01H13/00; cleaning joints in road construction by blowing E01C23/0906; Drying by means of gas streams by heat only E01H1/08; combined with snow or ice melting E01H5/10, E01H5/106, E01H5/108
• CPC Class Codes: E01H 1/0818 in apparatus with mechanical loosening or feeding instruments, e.g. brushes, scrapers brushing devices per se E01H1/02, other loosening devices per se E01H1/105
• CPC Class Codes: E01H 1/0845 with mechanical loosening or feeding instruments for the dirt to be sucked- up, e.g. brushes, scrapers brushing installations per se E01H1/02; other loosening devices per se E01H1/105
• CPC Class Codes: F04D 29/281 for fans or blowers
• CPC Class Codes: F04D 29/422 Discharge tongues F04D17/04 takes precedence
• CPC Class Codes: F04D 29/4226 Fan casings
• CPC Class Codes: F04D 29/4246 comprising more than one outlet
• CPC Class Codes: F04D 29/441 especially adapted for elastic fluid pumps
• CPC Class Codes: F04D 29/665 by means of resonance chambers or interference
• CPC Class Codes: F04D 29/666 by means of rotor construction or layout, e.g. unequal distribution of blades or vanes

Abstract

The present invention is directed to a centrifugal fan assembly (19) for the debris collection arrangement (100) of a road cleaning machine (10). The assembly (19) comprises a casing (101), a rotatable impeller (103) and a wall (107). The casing (101) comprises a volute potion (30) connected to an outlet passageway (31), a corner (106) being formed therebetween. The impeller (103) comprises a plurality of blades (25) and is located in the volute portion (30) proximate the corner (106). The wall (107) separates the outlet passageway (31) into a first and second passageway (36, 37) and extends to an inner end (102) proximate the impeller (103). The inner end (102) is positioned, and the impeller (103) is arranged, such that when a blade (25) passes the inner end (102) a second pressure wave is formed that destructively interferes with a first pressure wave formed by a blade (25) passing the corner (106). The distance W between the inner end (102) and impeller (103) is greater than the distance Z between the corner (106) and impeller (103).

Claims

1. A centrifugal fan assembly for the debris collection arrangement of a road cleaning machine, the assembly comprising:

a casing comprising a volute portion connected to an outlet passageway and an air inlet, a corner being formed in the casing between the volute portion and the outlet passageway;

a rotatable impeller comprising a plurality of blades, the impeller being located in the volute portion proximate the corner and arranged to draw in air from the air inlet and direct the air to the outlet passageway; and

a wall separating the outlet passageway into a first and second passageway, the wall extending to an inner end proximate the impeller,

wherein the inner end is positioned, and the impeller is arranged, such that when a blade passes the inner end a second pressure wave is formed that destructively interferes with a first pressure wave formed by a blade passing the corner; and

wherein the distance W between the inner end and impeller is greater than the distance Z between the corner and impeller.

2. A centrifugal fan assembly as claimed in claim 1 wherein W is in the range of from 1.1Z to and including 1.5Z.

3. A centrifugal fan assembly as claimed in any one of the preceding claims wherein the angle about the centre of rotation of the impeller between the inner end and corner is the sum of:

the angle between at least two of the plurality of blades; and

an angle, which is less than the angle between two adjacent blades, resulting in the second pressure wave being out of phase by approximately 180°

to the first pressure wave.

4. A centrifugal fan assembly as claimed in claim 3 wherein the angle about the centre of rotation of the impeller between the inner end and corner is the sum of:

the angle between three of the plurality of blades; and

an angle, which is less than the angle between two adjacent blades, resulting in the second pressure wave being out of phase by approximately 180°

to the first pressure wave.

5. A centrifugal fan assembly as claimed in any one of the preceding claims wherein the number of blades is a multiple of three.

6. A centrifugal fan assembly as claimed in any one of the preceding claims wherein the angle about the centre of rotation of the impeller between the inner end and corner is 132.5°

.

7. A centrifugal fan assembly as claimed in any one of the preceding claims wherein the throat size of the outlet passageway increases towards the exit of the outlet passageway.

8. A centrifugal fan assembly as claimed in any one of the preceding claims wherein the wall is positioned such that a substantially similar amount of air is directed through each of the first and second passageways when the impeller is rotating.

9. A centrifugal fan assembly as claimed in any one of the preceding claims wherein the inner end is positioned midway between the outer periphery of the impeller and casing in the volute portion.

10. A centrifugal fan assembly as claimed in any one of the preceding claims wherein the exit of the outlet passageway is connected to a rear outlet arrangement, the rear outlet arrangement comprising an internal rear duct enclosed by a cover leading to an air exit from the centrifugal fan assembly.

11. A centrifugal fan assembly as claimed in claim 9 wherein the internal rear duct is split into first and second passageways by a wall.

12. A centrifugal fan assembly as claimed in claim 10 or claim 11 wherein the throat size of the internal rear duct increases towards the air exit.

13. A centrifugal fan assembly as claimed in any one of the preceding claims wherein the impeller comprises first and second plates mounted around a hub, the plurality of blades being mounted between the first and second plates and spaced around the hub, wherein each blade has a first adjacent blade located on one side thereof and a second adjacent blade located on an opposing side thereof, and the spacing between each blade and the first adjacent blade is different to the spacing between each blade and the second adjacent blade.

14. A centrifugal fan assembly as claimed in claim 13 wherein the plurality of blades are formed of one or more set(s) of a leading blade, a primary blade and a lagging blade, wherein:

the leading blade is separated from the primary blade by a first angle;

the lagging blade being separated from the leading blade by a second angle;

the primary blade being separated from an adjacent leading blade by a third angle; and

the third blade angle is greater than the first blade angle and the second blade angle is greater than the third blade angle.

15. A centrifugal fan assembly as claimed in claim 14 wherein the first blade angle is X°

, the second blade angle is X°

+2Y° and

the third black angle is X°

+Y°

.

16. A centrifugal fan assembly as claimed in any one of claims 13 to 15 wherein the blades are rearwardly curved.

17. A centrifugal fan assembly as claimed in any one of claims 13 to 16 wherein the offset angle between the inner end and corner is calculated using the equation:

18. A debris collection arrangement comprising the centrifugal fan assembly of any one of claims 1 to 17.

19. A road cleaning vehicle comprising the aforementioned centrifugal fan assembly or debris collection arrangement of any one of claims 1 to 18.

20. A road cleaning vehicle as hereinbefore described and in reference to the attached drawings.

21. A centrifugal fan assembly as hereinbefore described and in reference to the attached drawings.

22. A debris collection arrangement as hereinbefore described and in reference to the attached drawings.