Patent Description:
The driving force of a vehicle is generated from its engine or driving motor. An engine or a battery that supplies power to the driving motor generates a lot of heat. Thus, cooling of the engine or battery is one of the important factors to increase output efficiency, which may be implemented by a coolant and a radiator.

The cooling fan assembly serves to lower the temperature of the coolant by introducing outside air into the radiator for cooling an engine or a battery. The cooling fan assembly includes a cooling motor, a fan and a shroud. The fan is coupled to the cooling motor and rotates to form a cooling airflow. The shroud protects the cooling motor and the fan and serves as a connecting member that allows the cooling motor and fan to be coupled to the vehicle.

Vibration and noise occurring when the cooling fan assembly is driven are one of the challenges to be solved. The vibration and noise of the cooling fan assembly are mainly caused by the rotations of the fan and the cooling motor. In particular, when resonance occurs in the shroud due to cogging torque generated by the interaction between the rotor and the stator of the cooling motor, vibration and noise peaks increase.

As one of the approaches for reducing vibration and noise of the cooling fan assembly, a shroud design change may be considered. For this purpose, for example, noise generation has been conventionally suppressed by adding or reinforcing members, for example, by increasing the thickness of the shroud.

However, this method had the following problems: the weight of products was increased; the manufacturing cost of products was increased; and the stiffness of the cooling fan assembly was also increased through this method more than necessary.

Furthermore, reference is made to <CIT> which discloses a shroud according to the preamble of appended claim <NUM>.

The object is to reduce vibration and noise of a cooling fan assembly without adding or reinforcing members in the shroud to solve the previous problems as explained above.

According to the present invention, there is provided a shroud according to appended claim <NUM>. Further aspects of such a shroud are defined in the appended claims <NUM>-<NUM> and a cooling fan assembly comprising such a shroud is defined in appended claim <NUM>.

According to the present invention, it is possible to decrease noise and vibration occurring in the shroud and to maintain the stiffness of the shroud sufficiently despite the slots.

<FIG>, <FIG> and <FIG> are, respectively, a front perspective view, a dissembled perspective view and a front view of a cooling fan assembly <NUM> related to the present invention.

Cooling fan assembly <NUM> comprises a cooling motor <NUM>, a fan <NUM> and a shroud <NUM>, and shroud <NUM> comprises a plenum <NUM>, an opening <NUM>, stators <NUM>, a barrel <NUM> and ribs <NUM>.

Plenum <NUM> constitutes a frame of shroud <NUM> and is configured to be large enough to cover fan <NUM>. Plenum <NUM> may be provided in a plate shape, and particularly the front surface may include a flat area.

Opening <NUM> is formed in a circular shape.

A bracket <NUM> for coupling cooling motor <NUM> and fan <NUM> to shroud <NUM> is provided in the center of shroud <NUM>. Cooling motor <NUM> and fan <NUM> may be coupled through screws <NUM>, and the combination of cooling motor <NUM> and fan <NUM> may also be fixed to bracket <NUM> through screws <NUM>. Stators <NUM> allow bracket <NUM> to be fixed on shroud <NUM> while securing the area of opening <NUM>. Barrel <NUM> forms a wall along circumference <NUM> of the opening on shroud <NUM>. Barrel <NUM> as the wall provides an area in which stators <NUM> can be coupled, protects the side of fan <NUM> by wrapping it, and guides the airflow formed by fan <NUM>.

Shroud <NUM> has preferably a light weight, but should have sufficient stiffness. The thin plate-shaped plenum <NUM> contributes to achieving a light weight of shroud <NUM>, but, on the contrary, is disadvantageous in terms of stiffness. Ribs <NUM> increase the stiffness of this shroud <NUM>. Ribs <NUM> may be walls protruding on plenum <NUM> in a vertical direction. In particular, ribs <NUM> may be configured to connect plenum <NUM> and barrel <NUM>. One end of rib <NUM> may be connected to one end of stator <NUM> or provided on the same line such that rib <NUM> and stator <NUM> may serve as one frame.

As the number of ribs <NUM> increases, the stiffness of shroud <NUM> increases. The plurality of ribs <NUM> has the advantage of reducing vibration and noise occurring on shroud <NUM>. However it is not necessary to increase stiffness beyond a certain range, and further too many ribs <NUM> increase the weight of shroud <NUM>. Thus, it is preferable to have an appropriate number of ribs.

A plurality of ribs <NUM> may meet at one point to provide an area in which a fastening portion <NUM> is provided. Fastening portion <NUM> allows shroud <NUM> to be coupled to the radiator. Fastening portion <NUM> may be in the form of a hole for screw coupling, or may be in the form of a hook for snap-fit coupling.

Since the vibration and noise take the form of a wavelength, the vibration and noise generated from cooling motor <NUM> and fan <NUM> are transmitted to barrel <NUM> and plenum <NUM> through bracket <NUM> and stators <NUM>. That is, vibration and noise will radiate outwardly from the center of shroud <NUM>. In particular, since plenum <NUM> is a thin plate-shaped member, it has low stiffness and is more vulnerable to vibration and noise generation.

The present invention reduces vibration and noise through slots <NUM> formed in plenum <NUM>. Slots <NUM> formed in plenum <NUM> weaken a transmission of the vibration and noise which are caused by fan <NUM> and cooling motor <NUM>, especially by the cogging torque of cooling motor <NUM>, to the outside through bracket <NUM> and stators <NUM>. In other words, the vibration of plenum <NUM> is reduced by dispersing the cogging torque transmitted from cooling motor <NUM>.

Slots <NUM> may be provided anywhere in plenum <NUM>. According to the present invention, a slot is provided along an opening's circumference <NUM>. Slots <NUM> which are provided along circumference <NUM> of the opening more effectively minimize the transmission of vibration and noise from the center of shroud <NUM> to plenum <NUM>. That is, plenum <NUM> is a thin plate-shaped member, and noise and vibration radiate outward from the center of shroud <NUM>, so this may be blocked by slots <NUM> from the beginning.

According to the present invention, a slot <NUM> is formed along a part of opening's circumference <NUM>, and may be provided in a plurality of segmented shapes at an appropriate position and length.

<FIG> illustrates an enlarged view of area A of <FIG>.

In particular, slots <NUM> may be provided between two adjacent ribs <NUM> or adjacent to the outside of two adjacent ribs <NUM>. Since the area of shroud <NUM> in which ribs <NUM> are provided has relatively high stiffness, even if slots <NUM> slightly decrease the stiffness, the area of shroud <NUM> having ribs <NUM> and slots <NUM> may maintain appropriate stiffness.

Plenum <NUM> may be made of plastic, and in this case, plenum <NUM> may be injection molded by a mold. When plenum <NUM> is injection molded by a mold, slots <NUM> may also be formed together by the mold. Since the protrusions corresponding to slots <NUM> are included in the mold for forming plenum <NUM>, slots <NUM> may be formed without a separate slot forming process. It is preferable for slots <NUM> to have a thinner width, but when slots <NUM> are molded through a mold process, the width is preferably <NUM> or more in order to secure the shape reliability of slots <NUM>. Preferably, the width of slots <NUM> may be <NUM> to <NUM>, and in particular <NUM>.

Slot <NUM> is formed along opening's circumference <NUM> and is defined as an arc slot <NUM>.

Also according to the present invention, slot <NUM> is formed along rib <NUM> and is thus defined as a rib slot <NUM>.

Slots <NUM> are preferably formed to be about <NUM> apart from opening <NUM> (more specifically, from barrel <NUM> from a design point of view) or ribs <NUM>. That is, since barrel <NUM> forms the boundary of opening <NUM>, slots <NUM> formed along opening's circumference <NUM> may be treated as being formed along circumference <NUM> of the barrel, and it may be understood that keeping a certain distance from circumference <NUM> of the opening is to keep a certain distance from circumference <NUM> of the barrel.

One slot <NUM> may be configured to have arc slot <NUM> only, or rib slot <NUM> only. According to the present invention, a slot <NUM> is configured to have arc slot <NUM> and rib slot <NUM> together.

According to the invention, for a slot <NUM> including both arc slot <NUM> and rib slot <NUM>, one end of arc slot <NUM> and one end of rib slot <NUM> are connected to each other, and the other end of arc slot <NUM> is thus not connected to rib slot <NUM>. This is to prevent the stiffness of shroud <NUM> from being excessively deteriorated by slots <NUM> being excessively provided in adjacent areas.

Rib slot <NUM> provided between adjacent two ribs <NUM> may be provided on a side having a larger angle among two sides made by intersection of rib <NUM> and opening's circumference <NUM>. This is because the effect of reinforcing stiffness by ribs <NUM> is less in the side having a larger angle than in the other side having a smaller angle, and thus, vibration and noise are more likely to occur in the side of a larger angle. That is, arc slot <NUM> and rib slot <NUM> provided between two adjacent ribs <NUM> may form an obtuse angle. In addition, arc slot 151a and rib slot 152a provided adjacent to the outside of two adjacent ribs <NUM> may also form an obtuse angle. On the other hand, like rib group <NUM> located at the lower right of <FIG>, when the difference between the two angles created by one rib <NUM> and opening's circumference <NUM> is small, arc slot <NUM> and rib slot <NUM> may be connected at a right angle or an acute angle close to a right angle.

<FIG> illustrates a partial view of a shroud <NUM> according to an embodiment of the slots which is not according to the present invention.

The in <FIG> illustrated arc slot <NUM> and rib slot <NUM> are provided as separate slots <NUM> rather than in one slot <NUM> between two adjacent ribs <NUM> or adjacent to the outside of the two adjacent ribs <NUM>. This means that arc slot <NUM> and rib slot <NUM> are provided to be spaced apart. The feature that arc slot <NUM> and rib slot <NUM> are spaced apart from each other has advantage for the stiffness of plenum <NUM>.

Other features and effects regarding arc slot <NUM> and rib slot <NUM> provided as separate slots <NUM> are the same as those of one slot <NUM> including both arc slot <NUM> and rib slot <NUM>.

<FIG> illustrates an enlarged view of area B of <FIG>.

In one slot <NUM> provided between two adjacent ribs <NUM>, wherein one end of arc slot <NUM> and one end of rib slot <NUM> are connected to each other, a margin area <NUM> may be formed such that the other end of arc slot <NUM> does not extend to another adjacent rib <NUM> and may maintain an appropriate distance with adjacent rib <NUM> to keep an appropriate stiffness of shroud <NUM>. For example, margin area <NUM> may be formed in the vicinity of at least some of arc slots <NUM> of the plurality of slots <NUM> provided between two adjacent ribs <NUM>, wherein one end of arc slot <NUM> and one end of rib slot <NUM> are connected to each other.

Referring to <FIG>, a plurality of ribs <NUM> may be gathered to form a rib group <NUM>. Rib group <NUM> consists of at least two ribs <NUM> configured to be adjacent to each other, and in particular, may consist of three ribs <NUM>. In one rib group <NUM>, ribs <NUM> may be gathered at one point where fastening portion <NUM> may be positioned.

For example, rib group <NUM> may be located in four areas of upper left, lower left, upper right, and lower right of shroud <NUM> as shown in <FIG>.

The total length of the plurality of slots <NUM> corresponding to each rib group <NUM> may be longer as the size of rib group <NUM> is larger. The size means the area on plenum <NUM> occupied by rib group <NUM>. That is, between two rib groups <NUM>, if a size of a first rib group <NUM> is bigger than a size of a second rib group <NUM>, a total length of slots <NUM> formed corresponding to first rib group <NUM> is longer than a total length of slots <NUM> formed corresponding to second rib group <NUM>. The larger rib group <NUM> may mean that the area of plenum <NUM> corresponding to rib group <NUM> is larger. The larger area of plenum <NUM> has a greater need to reduce vibration and noise through more or longer slots <NUM>.

Motor electrical connector <NUM> may be attached to or around at least one of the plurality of rib groups <NUM>. In this case, the stiffness of the relevant area may be reinforced by the attachment of motor connector <NUM>, and therefore, vibration and noise reducing effects may be achieved without slots <NUM>. Accordingly, slots <NUM> corresponding to rib group <NUM> on the side where motor connector <NUM> is provided may be omitted.

Such omission of slots <NUM> may be equally applied even when any structure, other than motor connector <NUM>, is attached to increase the stiffness according to embodiments.

Rib group <NUM> of the area where the structure such as motor connector <NUM> is attached but slots <NUM> are not provided may be partly supplemented by slots <NUM> of another adjacent rib group <NUM>. For example, as shown in <FIG>, motor connector <NUM> is provided on the upper right, and thus four slots <NUM> may be provided to rib group <NUM> on the lower right while three slots <NUM> may be provided to each rib group <NUM> on the upper left and lower left.

<FIG> illustrates frequency (Hz) - noise (dB) graphs according to a certain number of revolutions of the cooling fan assembly related to the present invention.

The left graph is a test result of the cooling fan assembly without slots, and the right graph is a test result of the cooling fan assembly with the slots. Duty corresponds to the speed of rotation of the fan. For example, Duty <NUM>% may correspond to about <NUM> rpm, and Duty <NUM>% to about <NUM> rpm. The graphs of <FIG> show the results of the case where the mean Duty is <NUM>% corresponding to approximately <NUM> rpm.

Referring to the graphs, there is at least one point where the noise level is relatively high compared to surrounding noise levels. The frequency corresponding to the at least one point is defined as the resonance frequency band of the cooling fan assembly. With respect to a plurality of resonance frequency bands in graphs of <FIG>, the noise of the right graph for the case where slots are provided is reduced compared to that of the left graph for the case where slots are not provided. In particular, referring to Point A and Point B where the noise level is much higher than the surroundings, it can be found that the noise is significantly reduced.

<FIG> has graphs showing the results of the case where the mean Duty is <NUM>%. It was confirmed that the technical effect of a similar trend was obtained in the cases of having different Duty values, which can be also found in <FIG>.

<FIG> is a duty (%) - noise (dBA) graph of the cooling fan assembly related to the present invention.

<FIG> is a test result of measuring noise while maintaining the number of revolutions of the cooling fan assembly for a predetermined time, for example, <NUM> seconds. '600W Base' indicates a case where there is no slot, and '600W Slot' indicates a case where there is a slot.

The noise is reduced when the slot is provided, and in particular, the noise is reduced by 5dBA or more at <NUM>% Duty.

Claim 1:
A shroud (<NUM>) comprising a plenum (<NUM>) and an opening (<NUM>) to secure an area for airflow by rotation of an axial fan (<NUM>), wherein the plenum (<NUM>) constitutes a frame of the shroud (<NUM>) and is configured to be large enough to cover the fan (<NUM>), wherein that said shroud (<NUM>) further comprises a slot (<NUM>) formed on said plenum (<NUM>) and wherein said opening (<NUM>) is provided in a circular shape and said slot (<NUM>) comprises an arc slot (<NUM>) formed along a part of a circumference (<NUM>) of said opening (<NUM>) and wherein said shroud (<NUM>) further comprises a rib (<NUM>) formed on said plenum (<NUM>), and said slot (<NUM>) further comprises a rib slot (<NUM>) formed along said rib (<NUM>), characterized in that said slot (<NUM>) comprises said arc slot (<NUM>) and said rib slot (<NUM>) such that one end of said arc slot (<NUM>) is connected to one end of said rib slot (<NUM>).