Engine-cooling fan assembly with overlapping fans

• US 6,817,831 B2
• Filed: 03/17/2003
• Issued: 11/16/2004
• Est. Priority Date: 03/15/2002
• Status: Expired due to Term

• Current Assignee: Robert Bosch Corporation (Robert Bosch GmbH)
• Original Assignee: Robert Bosch Corporation (Robert Bosch GmbH)
• Inventors: Coté, F. Raymond, Stevens, William M.
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): McAleenan, James M.
• Application Number:
  US10/390,218
• Publication Number:
  US 20040020449A1
• Time in Patent Office: 610 Days
• Field of Search: 415/61, 415/65, 415/228, 416/120, 416/198.R, 416/189
• US Class Current: 415/61
• CPC Class Codes: F01P 2005/025 using two or more air pumps
• CPC Class Codes: F04D 25/166 using fans
• CPC Class Codes: F04D 29/386 Skewed blades
• CPC Class Codes: F04D 29/582 specially adapted for elastic fluid pumps

Abstract

An automotive engine-cooling fan assembly uses pairs of overlapping fans to improve flow uniformity through the heat exchanger cores and to maximize the amount of fan power that can be achieved with limited motor sizes. One fan of each pair has upstream supports and the other has downstream supports, and these supports are so configured to minimize the axial dimension of the assembly. The use of banded fans maximizes fan performance, and blade skew minimizes fan noise.

Claims

1. An automotive engine-cooling fan assembly comprising

a) a first fan driven by a first motor, said first motor being supported by a first motor mount, said first motor mount being supported by a first set of arms, said first set of arms extending to and being supported by a shroud, and

b) a second fan, driven by a second motor, said second motor being supported by a second motor mount, said second motor mount being supported by a second set of arms, said second set of arms extending to and being supported by said shroud, and

c) a heat exchanger, and

where said shroud guides the flow of air at least a portion of the distance between said fans and the core of a heat exchanger, and

where said first fan and said second fan are each characterized by a diameter, and

where said first fan and said second fan each comprise a hub and a plurality of elongated blades, each of said blades having a root, a tip, a leading edge, and a trailing edge,

further characterized in that said first and second fans overlap each other when viewed axially from the upstream or downstream direction, and

further characterized in that said first set of arms is located upstream of said first fan and said second set of arms is located downstream of said second fan.

2. The automotive engine-cooling fan assembly of claim 1 in which a small clearance gap is maintained between said shroud and each of said fans along the portion of the fan'"'"'s circumference outside the overlap region.

3. An automotive engine-cooling fan assembly according to claim 1 further characterized in that the axial position of said first fan is substantially the same as the axial position of said second set of arms and the axial position of said second fan is substantially the same as the axial position of said first set of arms.

4. An automotive engine-cooling fan assembly according to claim 1 further characterized in that when said first and second sets of arms are projected onto a plane perpendicular to the axis of one or both of said fans, and said first and second fans are projected onto said plane, the projected area of said second set of arms falls outside a first circular disk centered on the projection of the axis of said first fan, the diameter of said first disk being equal to the diameter of said first fan, and the projected area of said first set of arms falls outside a second circular disk centered on the projection of the axis of said second fan, the diameter of said second disk being equal to the diameter of said second fan.

5. An automotive engine-cooling fan assembly according to claim 1 further characterized in that the distance between said heat exchanger core and the farthest point on said first motor is between 0.8 and 1.25 times the distance between said core and the farthest point on said second motor.

6. The automotive engine-cooling fan assembly of any one of claims 1-4 further comprising no additional fans.

7. The automotive engine-cooling fan assembly of any one of claims 1-4 further comprising at least one fan in addition to said first fan and said second fan.

8. The automotive engine-cooling fan assembly of claim 6 in which said fans move air through an approximately rectangular area of said heat-exchanger core, and the larger dimension of said rectangular area is between 1.25 and 1.8 times the smaller dimension of said rectangular area.

9. The automotive engine-cooling fan assembly of claim 6 in which the diameters of the two fans are equal, or, if unequal, the diameter of the smallest of said fans is greater than 0.85 times the diameter of the largest of said fans.

10. The automotive engine-cooling fan assembly of claim 8 in which the diameter of at least one of said fans is greater than 0.75 times said smaller dimension of said rectangular area.

11. The automotive engine-cooling fan assembly of any one of claims 1-4 in which the extent of overlap, when measured in a plane which contains the rotation axis of at least one of said fans and at least one point on the axis of the other fan, is greater than 10 percent of the diameter of the smaller of said fans, and less than the blade span of the smaller of said fans.

12. The automotive engine-cooling fan assembly of any one of claims 1-4 in which the motors are electric motors.

13. The automotive engine-cooling fan assembly of any one of claims 1-4 comprising a plenum between said fans and said heat-exchanger core, in which the depth of said plenum adjacent to the fan farther from the core is greater than the depth adjacent to the fan closer to the core.

14. The automotive engine-cooling fan assembly of any one of claims 1-4 in which the clearance gap between said shroud and each of said fans is less than 2 percent of the fan diameter along a substantial fraction of the non-overlapping portion of the fan'"'"'s circumference.

15. The automotive engine-cooling fan assembly of any one of claims 1-4 in which at least one of the fans is banded.

16. The automotive engine-cooling fan assembly of any one of claims 1-4 in which, viewed axially from the downstream direction, one of said fans rotates in the clockwise direction and the other of said fans rotates in the counter-clockwise direction.

17. The automotive engine-cooling fan assembly of any one of claims 1-4 in which, viewed axially from the downstream direction, both of said fans rotate in the same direction.

18. The automotive engine-cooling fan assembly of any one of claims 1-4 in which said first fan has a first number of blades and said second fan has a second number of blades, and the first number of blades is unequal to the second number of blades.

19. The automotive engine-cooling fan assembly of any one of claims 1-4, in which at least one of said plurality of blades has unevenly spaced blade tips.

20. The automotive engine-cooling fan assembly of any one of claims 1-4 in which both of said fans have forward-swept leading edges at the tip.

21. The automotive engine-cooling fan assembly of claim 16 in which the downstream fan has tip leading-edge sweep which is opposite the upstream fan tip trailing-edge sweep.

22. The automotive engine-cooling fan assembly of claim 17 in which the downstream fan has tip leading-edge sweep which is of the same sign as the upstream fan tip trailing-edge sweep.

23. The automotive engine-cooling fan assembly of claim 21 in which the upstream fan has root trailing-edge sweep in a direction opposite the tip trailing-edge sweep.

24. The automotive engine-cooling fan assembly of claim 22 in which the upstream fan has root trailing-edge sweep in a direction opposite the tip trailing-edge sweep.

25. The automotive engine-cooling fan assembly of any one of claims 1-4 in which said fans are made of injection-molded plastic.

26. The automotive engine-cooling fan assembly of any one of claims 1-4 in which said first motor mount, said first set of arms, said second motor mount, said second set of arms, and at least a portion of said shroud are made of injection-molded plastic.

27. The automotive engine-cooling fan assembly of claim 26 in which a single injection molded part comprises said first motor mount, said first set of arms, said second motor mount, said second set of arms, and at least a portion of said shroud.

28. The automotive engine-cooling fan assembly of claim 1 in which a projection of the shroud opening in a plane perpendicular to at least one fan axis is two generally circular elements that overlap in the region of fan overlap.

29. The automotive engine-cooling fan assembly of any one of claims 1-4 in which the shroud comprises a barrel surrounding said first fan, and said barrel extends into the region axially downstream of said second fan, and contributes to the support of said second motor mount.

30. The automotive engine-cooling fan assembly of any one of claims 1-4 in which the shroud comprises a barrel surrounding said second fan, and said barrel extends into the region axially upstream of said first fan, and contributes to the support of said first motor mount.