Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Vane or deflector
Reexamination Certificate
1998-12-07
2001-03-27
Lopez, F. Daniel (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Vane or deflector
C415S210100, C415S193000, C415S211200
Reexamination Certificate
active
06206635
ABSTRACT:
SUMMARY OF THE INVENTION
The present invention relates to axial flow fans and in particular to a stator device for altering the air flow from the fan.
BACKGROUND OF THE INVENTION
Axial flow fans are commonly used in cooling systems for engines of vehicles. Such fans consist of a hub with a number of blades extending substantially radially from said hub to a tip region. The shape of the blades is such that as the fan itself is rotated, air is caused to move axially according to the direction of the rotation of the fan. It would be understood by those skilled in the art that axial flow fans impart rotational components to the air which they move, and this creates turbulence effects which can both reduce efficiency and increase the noise from the u se of the fan.
It is known to use so-called “stator devices” in association with such axial flow fans, which stator devices are intended to straighten the air flow resulting from the fan. Such stator devices are static arrangements of blades or other members which “break up” the rotational components of air movement and which deflect the air towards a more axial flow path.
Axial flow fans in engine cooling systems are disposed within a so-called shroud which guides the air from or to a vehicle heat exchanger such as a radiator and which may also guide the air to or from a condenser of a vehicle air conditioning system.
Motion of the vehicle causes air to be passed through the radiator and/or air conditioning condenser but under certain circumstances is necessary to provide further air movement and this is effected by the movement of the fan. It is desirable to use a high efficiency fan due to the need to reduce fuel consumption as far as possible and also due to the fact that inefficiencies of the fan tend to give rise to higher ambient noise which is undesirable in modern vehicles.
Modern engine fans are driven by electric motors, and the motors themselves are supported within an opening of the shroud by a number, commonly three, of arms which depend from the peripheral wall of the shroud to a support ring which serves to support the motor. Such supports are supplemented in known stator arrangements by a number of additional radially-extending members which are curved in cross-section, or otherwise shaped in the axial direction so as to generally straighten the motion of the air from the fan. A number of problems has been found to exist in the prior art. Specifically, due to the axially packaging constraints, the axial chord of the stator members is too small to provide efficient straightening of the air flow. Furthermore early flow separation may occur on the stators which substantially increases the drag and thus reduces the aerodynamic efficiency of the stator assembly itself.
It would be possible to overcome these limitations by increasing the camber of the stator profile, but this would limit the working range of the fan system to an undesirable extent.
OBJECTS OF THE INVENTION
It is a primary object of the present invention to at least partially mitigate the disadvantages of the prior art.
It is a further object of the present invention to increase the overall efficiency of a fan system by virtue of an enhanced stator stage, thus allowing for use of a smaller motor to provide the same amount of cooling effort from the fan system.
It is a further object of the present invention to reduce the weight of the fan assembly.
SUMMARY OF THE INVENTION
According to the present invention there is provided a stator device for an axial flow fan comprising plural stator members depending from a peripheral wall defining an opening for air flow from the fan, said members extending radially inwardly to a fan motor support member, wherein the stator device has an axially rearward extremity and an axially forward extremity, the rearward extremity, in use, being disposed more remote from the fan, and the forward extremity being disposed closer to the fan, plural stator members comprise a plurality of first stator elements and a corresponding plurality of second stator elements, the first stator elements being disposed axially rearwardly of the second stator elements whereby a forward edge region of the first stator element and a rearward edge of the second stator elements defines a slot therebetween.
Preferably the first and second stator elements are curved in cross section.
Advantageously the first and second stator elements have a greater thickness in their respective forward regions to their rearward regions.
According to a second aspect of the present invention there is provided an axial flow fan device comprising an axial flow fan disposed in a fan shroud in spaced relationship to a vehicle heat exchanger, the vehicle shroud having an internal peripheral wall defining an opening for air flow from the fan and the fan motor being secured to a fan support portion, the system further comprising a stator device depending from said wall and extending to said support portion, the stator device comprising a plurality of first stator elements and a corresponding plurality of second stator elements, the first stator elements being disposed axially rearwardly of the second stator elements whereby a forward edge region of the first stator element and a rearward edge of the second stator elements defines a slot therebetween.
Preferably the first and second stator elements are curved in cross section.
Advantageously the first and second stator elements have a greater thickness in their respective forward regions to their rearward regions.
According to a third aspect of the present invention there is provided a stator device for an axial flow fan, having an axially rearward and an axially forward extremity, the rearward extremity, in use, being disposed more remote from the fan and the forward extremity being disposed closer to the fan, the stator device comprising a plurality of first stator elements, a plurality of second stator elements, and a plurality of third stator elements, wherein the first stator elements are disposed axially rearwardly of the second stator elements and the third stator elements are disposed axially forwardly of the second stator elements whereby slots are provided between each of the first and second, and the second and third stator elements.
REFERENCES:
patent: 2313413 (1943-03-01), Weske
patent: 3173604 (1965-03-01), Sheets et al.
patent: 4946348 (1990-08-01), Yapp
patent: 5342167 (1994-08-01), Rosseau
Golm Norman
Moreau Stephane
Lopez F. Daniel
Morgan & Finnegan , LLP
Valeo Inc.
Woo Richard
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