Patent Application
20240301814
The invention relates to a fan shroud which has a central impeller receptacle for receiving a fan impeller, an outer shroud ring and a plurality of struts which are fastened at a strut base to the impeller receptacle at a strut tip to the shroud ring. The invention also relates to a radiator fan having such a fan shroud.
Radiator fans of this type are used in motor vehicles for cooling further components, for example an internal combustion engine. In addition, they can also be used for exchanging heat with further components. For example, such a radiator fan can also be used in the case of an air heat exchanger, for example a heat pump system of a motor vehicle, or else for cooling electrical high-performance components, for example an electric traction motor or an electric traction battery in the case of electric vehicles. As a rule, a heat exchanger through which a heat transfer medium flows is connected upstream of the radiator fan. The heat transfer medium is frequently a cooling liquid.
The actual fan impeller which rotates about a rotational axis during operation and with which an air flow is conveyed from an inflow side to a pressure side is held rotatably on the fan shroud. Typically, for this purpose, a hub part of the fan impeller is held in the central impeller receptacle of the fan shroud. The fan impeller is driven, for example, by a belt drive and preferably by an electric motor which sits in the central impeller receptacle of the fan shroud. For the mechanical securing of the central impeller receptacle, a plurality of struts extend distributed over the circumference between the impeller receptacle and the shroud ring. These struts therefore form a flow obstacle for the air conveyed by the fan impeller during operation.
In order to keep the flow resistance as low as possible, special designs of the struts are provided. Published, non-prosecuted German patent application DE 10 2016 221 642 A1, corresponding to U.S. Pat. No. 11,078,924, discloses a fan shroud in which the struts are oriented with respect to a fan plane, which is oriented perpendicular to the rotational axis of the fan impeller, at a strut angle which increases from the inside to the outside in the direction of the fan shroud.
Taking this as the starting point, the invention is based on the object of permitting a flow-optimized fan shroud.
The object is achieved according to the invention by a fan shroud for a radiator fan of a motor vehicle and by a radiator fan having such a fan shroud according to the features of the independent claims. The fan shroud has a central impeller receptacle for receiving a fan impeller and defines a rotational axis for the fan impeller, the rotational axis being oriented in an axial direction. The axial direction extends from an inflow side to a pressure side of the fan shroud, i.e. the flow passes through the fan shroud from the inflow side to the pressure side during operation. The fan shroud furthermore has an outer shroud ring. The shroud ring and the impeller receptacle define a fan plane which is oriented perpendicular to the axial direction and therefore perpendicular to the rotational axis.
The fan shroud has a plurality of struts which extend, on the one hand, in a radial direction from the impeller receptacle as far as the shroud ring and which also extend, on the other hand, from the inflow side in the direction of the pressure side. Radial direction is understood here as meaning the direction of extent of the respective strut from the impeller receptacle in the direction of the shroud ring. This radial direction typically deviates from a mathematical radial which is oriented perpendicular to the rotational axis.
The struts are fastened at a strut base to the impeller receptacle and at a strut tip to the shroud ring. The struts are formed overall in the manner of a strut blade or shovel blade. As viewed in cross section, they are therefore typically overall of approximately elongate design and have a rectangular cross-sectional area typically with rounded end faces. In principle, other cross-sectional profiles and therefore strut profiles with, for example, curved surfaces are also possible. The struts are inclined with respect to the fan plane, and therefore a flow-guiding function is obtained by the inclined strut. The struts are oriented with respect to the fan plane at a strut angle, which is also referred to as angle of attack. They are conventionally positioned at an acute angle with respect to the pressure side, i.e. the struts form an acute angle with the pressure-side fan plane. In order to achieve a fan shroud which is as flow-optimized as possible, it is provided according to the invention that the strut angle changes differently in a radially inner region in comparison to a radially outer region. The radially inner region adjoins the impeller receptacle and extends as far as an intermediate position. The radially outer region extends—preferably starting from the intermediate position—as far as the strut tip.
Preferably, the strut is divided overall merely into the inner and the outer region which therefore adjoin each other.
Alternatively, there is also the possibility that the strut is divided into more than two regions and therefore has a plurality of intermediate positions. For example, the strut is divided in particular into three regions with two intermediate positions or else into four regions. In this case, at least two of the regions have different changes in the strut angle. Alternatively, all of the regions have strut angle changes differing from one another.
The starting point below, without limiting the generality, is merely one inner region and one outer region. However, the refinements described can also be logically transferred to variants with more regions, in particular with three regions.
The inclination of the struts with respect to the fan plane is initially based in general on the consideration that an intensely swirl-affected flow specifically in the flow direction is generated by the fan impeller during operation, and that it is advantageous to position the struts with respect to the swirl-affected air flow in such a manner that a flow resistance is reduced and therefore the efficiency of the fan impeller is improved.
The invention is now based on the finding that the portion of an axial component and of a circumferential component of the flow and thus what is referred to as a velocity triangle of the flow velocity significantly change from the impeller receptacle in the direction of the shroud ring. Specifically, it has been found that the circumferential component of the flow significantly increases in the outer region.
According to the invention, it is therefore provided that the strut angle overall is adapted as optimally as possible to the flow conditions varying in the radial direction and that, for this purpose, a greater change and variation of the strut angle is also set in the outer region, in which the flow field changes particularly intensely.
Where a change in the strut angle is mentioned here, this is understood as meaning a relative change per length unit of the strut in the radial direction. If the strut angle is plotted in relation to the radial direction and thus in relation to a length of the strut, the change in the strut angle corresponds to a pitch. This pitch therefore differs in the outer region in comparison to the inner region. The pitch in a respective region is preferably constant. Alternatively, however, it may also vary within a region. In this case, the condition applies that the pitch (change per length unit) of the two regions differs, for a mean pitch (mean change per length unit) of the respective region.
According to a preferred refinement, the relative change and thus the pitch in the outer region is greater in terms of value than in the inner region, i.e., in the outer region, the absolute change in the strut angle is greater than in the inner region, per length unit. As good an adaptation as possible to the actual flow conditions is therefore achieved.
Investigations have furthermore shown that it is of particular advantage if the strut angle initially increases in the inner region and subsequently decreases in the outer region. Such a configuration is correspondingly also provided in a preferred embodiment.
Preferably, the inner region extends over 60% to 90% of the overall length of the respective strut and in particular over 70% to 85% of the overall length. For the preferred configuration that the strut angle decreases in the outer region, this means that the strut angle initially increases and then decreases again over the indicated length.
Preferably, it is furthermore provided that the change in the strut angle at least in one of the regions and preferably in all of the (two) regions is constant and therefore has a continuous and linear profile. This is understood as meaning that the previously defined pitch in the respective region is constant.
In a preferred configuration, the strut angle is greater at the strut base than at the strut tip. Specifically, the strut angle increases starting from the strut base from an initial value up to a maximum value at the intermediate position and decreases from there in the outer region up to a minimum value. The absolute change in the strut angle in the inner region is therefore smaller than the absolute change in the outer region.
In a preferred variant, it is therefore provided overall that the inner region extends over 60% to 90% of the overall length of the strut, that it is adjoined by the further region as the outer region, the further region extending as far as the strut tip, and that the strut angle increases continuously, in particular at a constant pitch, starting from the strut base in the inner region up to a maximum value and subsequently decreases in turn, preferably at a constant pitch, in the outer region as far as the strut tip to a minimum value which is smaller than the strut angle at the strut base.
In general, the strut angle at the strut base lies in the range between 35° and 55° and in particular in the range of 40° to 50°.
Furthermore preferably, the maximum strut angle lies in a range between 55° and 80° and in particular in the range of 65° to 75°.
Furthermore preferably, the strut angle at the strut tip has a value in the range between 25° and 45° and in particular in the range of 30° to 40°.
Particularly good flow properties are achieved with these values.
Specifically, it is provided that the strut angle changes in the inner region by 10° to 30° and in particular by 15° to 25° and/or that the strut angle changes in the outer region by 20° to 50° and in particular by 30° to 40°.
In conjunction with a fan impeller, such a fan shroud forms a radiator fan according to the invention. The fan impeller sits with a hub in the impeller receptacle of the fan shroud. The impeller receptacle is in particular a receptacle for an electric motor which is provided for driving the fan impeller. The impeller receptacle to this extent therefore forms a motor mount.
The fan shroud described here is distinguished in that it has improved efficiency in comparison to a configuration according to the prior art, which is reflected, inter alia, in a reduced rotational speed level of the fan impeller and in reduced electrical power consumption of the electric motor for driving the fan impeller. Furthermore, lower noise emissions are therefore also achieved.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a fan shroud and radiator fan for a motor vehicle, and a radiator fan having the fan shroud, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
In the figures, identically acting parts are provided with the same reference signs.
Referring now to the figures of the drawings in detail and first, particularly to
The individual struts 8 each extend in a radial direction 24 which at the same time defines a longitudinal direction of the respective strut 8. Each strut 8 to this extent has a dedicated longitudinal direction and therefore radial direction which is inclined with respect to a mathematical radial to the rotational axis and therefore to the axial direction 20, as can be seen with reference to
A respective strut 8 is overall approximately leaf-shaped in the manner of a shovel blade and preferably has an approximately rectangular cross-sectional area, as can be gathered in particular with reference to the illustration according to
A respective strut 8 generally extends from a strut base 26, at which the strut is fastened to the impeller receptacle 4, as far as a strut tip 28, at which the strut is fastened to the shroud ring 6.
A respective strut 8, i.e. the respective blade surface of the strut 8, is inclined obliquely at a strut angle α in relation to a fan plane L. Specifically, a respective strut 8 is arranged at an acute angle with respect to the pressure side 18. The strut angle α is measured here between the fan plane L and the orientation of the blade surface along a transverse direction 30 (cf.
The length region of the strut 8 as far as an intermediate position 31, which is formed by the intersecting position 3B-3B in the exemplary embodiment, defines an inner region 32 of the strut 8, which is adjoined in the radial direction 24 by an outer region 34, which extends as far as the shroud ring 6.
The course of the strut angle α over the length R of the strut 8 in the radial direction 24 is illustrated by way of example in
The strut angle is indicated on the x axis and the ratio of the radial length R to the overall length Ra of the strut 8 is indicated in percent on the Y axis. The intersecting positions illustrated in
At the strut base 26, the strut angle has a value of 45° which increases continuously and constantly to a maximum value at the intermediate position (intersecting line 3B-3B), at which the strut angle assumes a value of approximately 69°. In the outer region 34, the strut angle α subsequently in turn decreases, in particular constantly, to a minimum value of 35°. In the two regions 32, 34, the strut angle α therefore shows a constant pitch, and thus has a linear course.
The outer region 34 is generally preferably significantly shorter than the inner region 32. The inner region 32 has, for example, a length in the range between 60 and 85% of the overall length Ra.
A radiator fan 36 as a combination of the fan shroud 2 with the fan impeller 12 fastened thereto can be gathered from the partial sectional illustration in
As can be seen specifically with reference to
By means of the specific configuration described here of the struts 8 with the strut angle α, which changes differently in the inner region 32 and in the outer region 34, with it specifically increasing linearly in the inner region 32 and subsequently decreasing linearly in the outer region 34, the result, in comparison to the known design according to the prior art, is improved efficiency of the radiator fan, a lower rotational speed level and lower noise emission.
The invention is not restricted to the exemplary embodiment described above. On the contrary, other variants of the invention can also be derived therefrom by a person skilled in the art without departing from the subject matter of the invention. In particular, furthermore, all of the individual features described in conjunction with the exemplary embodiment are also combinable with one another in a different way without departing from the subject matter of the invention.
The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 213 044.5 | Nov 2021 | DE | national |
This application is a continuation, under 35 U.S.C. § 120, of copending International Patent Application PCT/EP2022/081911, filed Nov. 15, 2022, which designated the United States; this application also claims the priority, under 35 U.S.C. § 119, of German Patent Application DE 10 2021 213 044.5, filed Nov. 19, 2021; the prior applications are herewith incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2022/081911 | Nov 2022 | WO |
| Child | 18668468 | US |
