EP-4314569-B1 - AXIAL FAN WITH SERRATED BLADE LEADING EDGES

Inventors

• PIETRAS, Piotr

Dates

Publication Date

20260513

Application Date

20220324

Claims (2)

1. A low-speed axial fan for mounting in a horizontal or vertical position, in particular in computer enclosures, comprising a frame, a motor and a plurality of blades extending from the rotor towards the frame, the frame comprising a support part and slats connected to the support part and fixing the motor and the plurality of fan blades mounted on the motor rotor, wherein each of the plurality of blades (2) has a uniformly terminated trailing edge (3) and a substantially serrated leading edge (4) provided with serrations (5) such that the serrated leading edge has a shape approximating a sine wave, wherein the spacing between the individual serrations (5) is 1/10 to 1/5 of the length of the leading edge (4) of the blade (2); characterised in that the rotor is fitted with a fluid dynamic bearing (FDB) and in that the shape of the serrated leading edge approximates a sine wave that is vanishing in a direction towards the tip of the blade.
2. Fan according to claim 1, characterised in that the spacing between the individual serrations (5) is 1/7 of the length of the leading edge (4) of the blade (2).

Description

The subj ect-matter of the invention is a low-speed axial fan suitable for mounting in a horizontal or vertical position, in particular in computer enclosures, CPU air coolers, CPU liquid coolers and other computer components, like computer PSUs. Many modifications of fan blades are known in the state of the art. For example, a blower fan is known from the European application description EP3343045 A1, in which a part of the ridge of each blade is equipped with symmetrical serrations. European Application Description EP3591238 A1 relates to an engine cooling system comprising an axial fan including a hub having an axis of rotation; a plurality of blades extending radially from the hub; and a fan cowl. Wherein each blade has a front edge and a rear edge, and wherein each blade has at least one flow element to reduce the airflow turbulence, selected from the group consisting of: a plurality of ridges positioned at the front edge, a plurality of serts positioned at the rear edge, and ribs extending transversely across each blade. The fan cowl, on the other hand, includes a guard with a wire extending between the first and second opening. Whereby the guard has a tapering section configured to restrict the flow of air moving from the first opening to the second opening. In contrast, European Application Description EP3034886 A1 discloses a blade for a fan rotor having an end region facing the hub, a first blade side and a second blade side, wherein the blade has at least one rib in the end region facing the hub. The rib has an outer contour that simulates a flow profile and at least one rib having, at the rib start point, a rib base in the end region facing the hub and a rib base at the opposite rib end point, the rib base being positioned higher in the axial direction than the rib base at the rib end point; the rib has an end geometry in the area of the outer contour, the end geometry forms a sawtooth profile, the end geometry of the rib forms an alpha angle between -45° and + 45° to the tangent to the contour of the surface of the other side of the blade, characterized in that: on the approach to the hub, the rib has a beta angle to the radial direction, with the beta angle ranging between -80° and + 80°. Furthermore, the document CN 207 920 966 U discloses a fan according to the preamble of claim 1. The purpose of the invention was to provide a new structure of a low-speed axial fan with improved acoustic properties. The invention is a fan according to claim 1. Preferably, the spacing between the serts is 1/7 of the length of the serrated leading edge of the blade. The invention in question provides the following advantages: Improved psychoacoustic properties, i.e. reduction of the perceived noise;Thanks to the serrated leading edge of the fan blades according to the invention, the solution ensures the elimination of prominent tonal sounds in the bands of about 315 Hz and about 3150 HZ;Elimination of tonal sounds of about 4350 Hz of prominent intensity;Relatively low production cost;The serrated shaping of the leading edge of the fan blades according to the invention can be produced by means generally known in the state of the art without increasing the cost of production. The subject-matter of the invention is depicted in the embodiments shown in the drawing, wherein: fig. 1 shows a fan according to the invention in front view; fig. 2 shows the fan according to the invention in a frameless view; fig. 3 shows the tonal noise intensity of known low-speed axial fans; fig. 4 shows a diagram of the fans compared in example 4, where A) shows the test fan and B) shows the control fan; fig. 5 shows a comparison of the sound intensity emitted by the fan according to the invention and the control fan in accordance with PN-EN 61260-1:2015-01; fig. 6 shows a comparison of the sound spectrum emitted by the fan according to the invention and by the control fan, obtained by the Fourier analysis of the signal recorded at the output of an amplifier with the Z frequency characteristics. Embodiment 1. The axial fan according to the invention is designed to be mounted in a horizontal or vertical position in various cooling systems, e.g. it can be mounted in a computer enclosure. Whereby, in the field of computer cooling, the fan according to the invention may be used, for example, in air cooling of the CPU, liquid cooling of the CPU and other computer components like computer PSUs. In this non-limiting embodiment, the axial fan according to the invention is mounted horizontally in the computer enclosure and is used for liquid cooling of the computer processor (i.e. the CPU). As shown in fig. 1 and fig. 2, an axial fan according to the invention comprises a frame 1, a motor and a plurality of blades 2 extending from the rotor towards the frame 1. Whereby, said frame 1 comprises a support part 1a and slats 1b connected to the support part 1a and fixing the motor and a plurality of fan blades 2 mounted on the motor rotor equipped