Cooling fan, in particular a radiator fan for motor vehicles

Information

  • Patent Grant
  • 6364004
  • Patent Number
    6,364,004
  • Date Filed
    Friday, September 29, 2000
    24 years ago
  • Date Issued
    Tuesday, April 2, 2002
    22 years ago
Abstract
A cooling fan, in particular a radiator fan for a motor vehicle, includes an electronically commutated electric motor and an electronics casing (21) with an electronic control for controlling the electric motor. The outer surface of the electronics casing (21) has cooling fins (25), the free ends of which project into the cold air flow produced by the impeller (9) of the fan. The free ends (27) of the cooling fins (25) projecting into the cold air flow have air diverting elements through which a part of the predominantly axial cold air flow produced by the impeller (9) is diverted in a radial direction relative to the impeller (9) and then in the longitudinal direction of other ends (29) of the cooling fins (25) arranged on the surface of the electronics casing (21). This provides effective cooling of the electronics casing.
Description




FIELD OF THE INVENTION




The present invention relates to a cooling fan, in particular to a radiator fan for motor vehicles with an electronically commutated electric motor.




BACKGROUND INFORMATION




Because of the aerodynamic optimization (C-values), fan wheels with specific diameters are required for cooling internal combustion engines. This restriction also applies to condenser fans which are arranged in front of the actual radiator and condenser of the air-conditioning unit. There is therefore a demand for compact electric fans with a short length, for which a speed adjustment is also desirable for reasons of noise and performance. For this, a conventional electric motor with brushes and an electronic combinational circuit module is particularly suitable or even a brushless motor with corresponding power electronics.




To minimize interference, the electronics must be located as close as possible to the motor because the short cables radiate less interference energy. But, on the other hand, direct heat transfer from the motor to the electronics must be avoided. For this purpose, according to U.S. Pat. No. 4,668,898 the electronics are arranged in their own control casing which is connected to the motor casing by struts. This electronically commutated motor is not suitable for a compact fan for cooling internal combustion engines.




Furthermore, an electric motor with an external rotor and a fan wheel connected to it is known from German Patent Laying-Open Document 38 20 857, in which the electric motor is designed as a direct-current motor with electronic commutation. In this case, the electronic components are arranged on a printed circuit board, which is attached to a fan casing which has cooling fins. This electronically controlled direct-current motor cannot be used for cooling condensers and/or radiators in motor vehicles.




An electronically controlled electric motor with a fan wheel for sucking in cold air is also known from German Patent Laying-Open Document 44 18 000 A1, in which the drive electronics are axially continued in a control casing which has cooling fins arranged at least on its external peripheral surface in the direction of flow of the cold air flow produced by the fan wheel. This motor certainly has a compact design, but its axial extension prevents easy mounting because of the very limited space available between the radiator and the engine in a motor vehicle.




Finally, a radiator fan for motor vehicles with an electronically commutated electric motor is known from German Patent Laying-Open Document 196 12 679 A1, in which the drive electronics are arranged in a control casing which is connected to the radiator casing. This control casing is attached to the radiator casing outside the outer ring of the fan wheel and has cooling fins which project as far as the center of the cold air flow.




SUMMARY OF THE INVENTION




The object of the invention is to further develop a cooling fan, in particular a radiator fan for motor vehicles, in such a manner that an even better cooling of the electronics in the electronics casing is achieved.




The above object has been achieved according to the invention in a cooling fan, in particular a radiator fan for motor vehicles, arranged in a radiator casing with an electronically commutated electric motor, a fan wheel or impeller driven by its rotor, and electronics influencing the speed and/or output of the electric motor, which are arranged in an electronics casing attached to the radiator casing radially outside the impeller. The outer surface of the electronics casing has cooling fins, the free ends of which project into the cold air flow produced by the impeller. According to the invention, the free ends of the cooling fins projecting into the cold air flow have air diverting elements, through which a part of the predominantly axial cold air flow produced by the impeller is diverted in a radial direction relative to the impeller and then in a longitudinal direction of and toward the other ends of the cooling fins arranged on the surface of the electronics casing.




The cooling fan according to the invention is characterized by an improved cooling effect of the electronics casing, for which only simple additional tools and/or slight constructional changes are required in comparison to the known fans.




In an advantageous embodiment of the invention, the air diverting elements comprise an air-guiding sheet-metal plate that covers the free ends and the back edges of the cooling fins so as to close the back of hollow spaces between adjacent ones of the cooling fins. This achieves a simple diversion of a part of the axial cold air flow by means of a simple baffle plate. This in turn ensures that the cold air sweeps over the whole length of the cooling fins.




According to a further embodiment of the invention, the free ends of the cooling fins projecting into the cold air flow are shaped to extend counter to the rotational direction of the impeller in such a manner that the tangential air flow produced by the impeller is diverted radially outward. This guarantees a sure diversion of part of the cold air flow produced in the rotational direction of the fan wheel by means of the special shape of the free ends of the cooling fins.











BRIEF DESCRIPTION OF THE DRAWINGS




The invention will be described in the following, in connection with several example embodiments, with reference to the drawings, wherein:





FIG. 1

shows a cross-section of a radiator fan according to the invention;





FIG. 2

schematically shows a cross-section of the electronics casing in a first embodiment of the inventive fan arrangement, as an enlarged detail view of a portion of

FIG. 1

;





FIG. 3

is a perspective view of the arrangement of

FIG. 1

;





FIG. 4

is a schematic cross-sectional view of a second embodiment of the electronics casing;





FIG. 5

is a schematic axial view of a first embodiment of the free ends of the cooling fins; and





FIG. 6

is a schematic axial view of a second embodiment of the cooling fins.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS





FIGS. 1 and 2

show a cross-section through a radiator fan


1


for motor vehicles designed as a cooling fan with an electronically commutated electric motor, which consists, in particular, of a brushless direct-current motor


3


designed as an external rotor motor. By means of this fan


1


, cooling air is sucked through an air conditioning system condenser


2


and an engine cooling system radiator


4


of the motor vehicle. A pot-shaped hub


7


of a fan wheel or impeller


9


is placed over the casing


5


of this direct-current motor


3


, whereby the hub


7


is connected with no rotational freedom of movement to the drive shaft


11


of the direct-current motor


3


. The fan wheel


9


has an outer ring


13


which is rigidly connected to the outer ends of the fan vanes or blades


15


and which is surrounded by an air-guide ring


17


of a frame, i.e. fan shroud or housing


19


shaped concentrically to this outer ring


13


.




An electronics casing


21


is attached to the frame


19


and/or the radiator casing, which is not shown in the figures, at a location radially outside the outer ring


13


of the fan wheel


9


relative to the center rotation axis A of the fan wheel


9


. In order to better dissipate the heat produced by the electronic components in the electronics casing


21


, cooling fins


25


are provided on the electronics casing


21


. Free ends


27


of the cooling fins


25


point and extend longitudinally toward the center of the cooling air flow F produced by the fan wheel


9


.




Effective dissipation of the heat from the electronics casing


21


is achieved by means of the free ends


27


of the cooling fins


25


projecting into the air flow F, whereby the free ends


27


have air diverting elements, e.g.


31


, through which a part of the predominantly axial cooling air flow F produced by the fan wheel or impeller


9


is diverted into a radial outward direction relative to the axis A of the impeller


9


, and then in the longitudinal direction toward the other ends


29


of the cooling fins


25


arranged on the surface of the electronics casing


21


. This ensures that the cold air sweeps longitudinally along the whole length of the cooling fins


25


, thereby ensuring that the heat can be dissipated.




According to

FIGS. 1

,


2


and


3


, the air diverting elements consist of an air-guiding sheet-metal plate


31


which provides an air-tight cover of the hollow spaces


33


respectively between the adjacent free ends


27


of the cooling fins


25


. Thereby the plate


31


is arranged on the radially inner end edges


35


and on the rear edges


37


of the cooling fins


25


facing away from the impeller


9


. This covering runs from the radially inner ends


35


of the fins


25


up to the area of the radially inner surface


34


of the electronics casing


21


, whereby this radially inner surface


34


is arranged to face the air-guide ring


17


with an air gap therebetween. This ensures that the electronics casing


21


, which consists of a cast aluminum part together with the integrally arranged cooling fins


25


, can be removed easily from the mold used for forming it.




The free ends


27


of the cooling fins


25


are advantageously curved or rounded toward the electronics casing


21


, from the radially inner corners


38


facing the impeller


9


to the rear edge


37


facing away from the impeller


9


. The air-guiding sheet-metal plate


31


has an appropriate curvature


36


for diverting the substantially axial air flow F radially outward.




An effective dissipation of the heat from the electronics casing


21


is achieved according to

FIG. 4

by means of an air-guiding sheet-metal plate


39


(instead of curved plate


31


), which is linearly slopingly shaped within the hollow spaces


41


respectively between the cooling fins


25


. The plates


39


respectively extend linearly from the free ends


43


of the fins


25


facing the impeller


9


obliquely relative to the direction


45


of the axial air flow F of the impeller


9


, radially outward into the area of the frame


19


surrounding the impeller


9


. In this case, the cooling fins


25


run above and below the obliquely arranged air-guiding sheet-metal plate


39


, in which the parts


47


of the cooling fins


25


arranged above the air-guiding sheet-metal plate


39


each have a curvature


51


at their free ends


49


which runs from the radially inner corners


53


of the free ends


49


of the cooling fins


25


outward to the rear edges


55


of the fins


25


. The plates


39


divert a part of the cooling air flow F from the substantially axial flow direction


45


to a substantially radial or outward flow direction


46


longitudinally along the cooling fins


25


.





FIGS. 5 and 6

show further embodiments for diverting the cooling air flow, in which the free ends


57


,


67


of the cooling fins


59


,


69


projecting into the cooling air flow are shaped to face contrary to or against the rotational direction


61


,


71


of the impeller


9


. According to

FIG. 5

, the free ends


57


of the cooling fins


59


are curved to face contrary to or against the rotational direction


61


of the impeller


9


, so that the cooling air flow, and particularly the tangential component of the air flow in the rotational direction


61


, can be guided without turbulence losses to the other ends


63


of the cooling fins


59


on the electronics casing


65


. In particular, these other ends


63


of the cooling fins


59


run linearly in a radial direction relative to the impeller


9


.




According to

FIG. 6

, the free ends


67


of the cooling fins


69


projecting into the cooling air flow run tilted or angled toward being tangential to the rotational direction


71


of the impeller


9


and have a linear shape. These cooling fins


69


run linearly on the surface


73


of the electronics casing


75


.



Claims
  • 1. A cooling fan arrangement comprising:an electronically commutated electric motor including a motor rotor; a fan impeller connected to said motor rotor to be rotationally driven about a rotation axis so as to produce an air flow that flows predominantly axially parallel to said rotation axis; a housing in which said fan impeller is arranged, with said housing extending radially outwardly relative to said fan impeller; electronics that are electrically connected to said electric motor and are adapted to influence at least one of a rotation speed and an output of said electric motor; an electronics casing in which said electronics are arranged, and which is attached to said housing radially outwardly relative to said fan impeller, and which has an outer casing surface; cooling fins which respectively include fixed ends that are arranged on and extend in a longitudinal direction along said outer casing surface of said electronics casing, and free ends that project from said electronics casing so as to overlap a radially outermost extent of said fan impeller and so as to be adapted to reach into said air flow; and at least one air diverting element that is provided on said free ends of said cooling fins adapted to reach into said air flow, and that is configured, arranged and adapted to divert a part of said air flow radially outwardly relative to said rotation axis into said longitudinal direction toward and along said fixed ends of said cooling fins.
  • 2. The cooling fan arrangement according to claim 1, wherein said cooling fan arrangement is a radiator fan for a motor vehicle, and said housing is a radiator housing, and further comprising a radiator connected to said radiator housing on a side of said fan impeller opposite from said electronics housing and said cooling fins.
  • 3. The cooling fan arrangement according to claim 1, wherein said cooling fins are respectively bounded along rear edges opposite said outer casing surface and free end edges at which said free ends terminate projecting away from said electronics casing, wherein said cooling fins are spaced apart from one another with respective hollow spaces therebetween, and wherein said at least one air diverting element comprises an air-guiding sheet-metal plate that is arranged on said free end edges and said rear edges of said cooling fins so as to air-tightly cover said hollow spaces along said free end edges and said rear edges at least in an area extending from said free end edges along said rear edges at least outwardly beyond said radially outermost extent of said fan impeller.
  • 4. The cooling fan arrangement according to claim 3, wherein said free end edges have a curved contour transitioning into said rear edges, and wherein said air-guiding sheet-metal plate has a curvature matching said curved contour and adapted to divert said part of said air flow radially outwardly.
  • 5. The cooling fan arrangement according to claim 4, wherein said curved contour is a rounded contour.
  • 6. The cooling fan arrangement according to claim 1, wherein said cooling fins are spaced apart from one another with respective hollow spaces therebetween, wherein said at least one air diverting element comprises respective sheet-metal plates that are arranged in said hollow spaces between said free ends of said cooling fins, wherein each one of said sheet-metal plates has first and second ends and extends obliquely relative to said rotation axis from said first end, which is relatively closer to said rotation axis and to a fan plane on which said fan impeller lies perpendicular to said rotation axis, to said second end, which is relatively farther from said rotation axis and from said fan plane, and wherein said second end of each one of said sheet-metal plates is located radially outwardly beyond said radially outermost extent of said fan impeller.
  • 7. The cooling fan arrangement according to claim 6, wherein said cooling fins are respectively bounded along rear edges opposite said outer casing surface and front edges that extend along a plane of said outer casing surface, and wherein said sheet-metal plates are respectively confined between said rear edges and said front edges of said cooling fins.
  • 8. The cooling fan arrangement according to claim 1, wherein said fan impeller is adapted to be rotationally driven in a rotation direction about said rotation axis so as to produce said air flow, wherein said air flow includes a tangential air flow component that flows tangentially in said rotation direction, and wherein said free ends of said cooling fins are shaped to protrude from said electronics casing against said rotation direction so as to be adapted to divert said tangential air flow component radially outward.
  • 9. The cooling fan arrangement according to claim 8, wherein said free ends of said cooling fins are curved to protrude from said electronics casing against said rotation direction.
  • 10. The cooling fan arrangement according to claim 9, wherein said free ends of said cooling fins taper linearly on said outer casing surface of said electronics casing in a direction radial relative to said rotation axis.
  • 11. The cooling fan arrangement according to claim 8, wherein said free ends of said cooling fins extend and protrude linearly from said electronics casing in a direction tilted toward being tangential to said rotation direction, and wherein said fixed ends of said cooling fins extend linearly on said outer casing surface of said electronics casing respectively linearly aligned with said free ends.
Priority Claims (1)
Number Date Country Kind
199 49 321 Oct 1999 DE
US Referenced Citations (6)
Number Name Date Kind
4668898 Harms et al. May 1987 A
4699208 Wolf et al. Oct 1987 A
4709560 Voorhis et al. Dec 1987 A
5242013 Couetoux et al. Sep 1993 A
5947189 Takeuchi et al. Sep 1999 A
6203293 Yamamoto Mar 2001 B1
Foreign Referenced Citations (4)
Number Date Country
3517149 Nov 1986 DE
3820857 Dec 1989 DE
4418000 Nov 1995 DE
19612679 Oct 1997 DE