FAN BLADE STRUCTURE

FIELD OF THE INVENTION

[0001]The present invention relates to a fan blade structure, and more particularly, to a fan blade structure that enables upgraded fan efficiency.

BACKGROUND OF THE INVENTION

[0002]Following the prosperous development of the electronic industry, electronic elements in the electronic products produces more and more heat when they operates, and the produced heat could not be thoroughly removed through natural convection. A cooling fan is a good way for removing the large amount of waste heat from the electronic product. Therefore, the cooling fan has become an indispensable role in the current electronic products, such as servers, communication systems, and computers.

[0003]In response to the increasingly strict requirement for the heat dissipation of electronic products, the currently commonly used cooling fans, such as axial fans, must have a highly upgraded rotational speed. Meanwhile, the issue of energy saving gets more and more attention from users. Please refer to FIGS. 5A and 5B. A conventional fan impeller 31 for a cooling fan includes a hub 311 and a plurality of blades 312 circumferentially spaced on an outer side of the hub 311. Each of the blades 312 has an upwind side 313 and a downwind side 314, which are smooth or linearly smooth surfaces. When the blades 312 of the fan impeller 31 rotate and produce airflows, the smooth upwind side of the blade 312 fails to force or push all the airflows toward the axial air outlet of the cooling fan, and a part of the airflows stays on the upwind side 313 to produce fluid resistance. The stayed airflows slide over the upwind side 313 of the blade 312 and are finally dispersed and lost to cause lowered fan efficiency. In addition, when the fluid resistance increases, it would inevitably result in maximized energy (power) consumption and accordingly, increased fan electrical consumption. In other words, for the conventional fan to maintain a constant rotational speed, it is necessary to increase the input power of the motor, which would lead to large power consumption when the fan rotates and accordingly, the problem of failing to save energy.

[0004]It is therefore tried by the inventor to develop an improved fan blade structure to overcome the problems of high power consumption and low fan efficiency in the fan with a conventional fan blade structure.

SUMMARY OF THE INVENTION

[0005]To effectively solve the above problems, a primary object of the present invention is to provide a fan blade structure that can decrease flow resistance to reduce the fan power consumption and effectively upgrade the fan efficiency.

[0006]To achieve the above and other objects, the fan blade structure according to the present invention includes a hub and a plurality of blades. The hub has a top wall and a sidewall outward extended from a periphery of the top wall. The blades are circumferentially and radially spaced on the sidewall of the hub. Each of the blades has an upper and a lower surface, which are a downwind and an upwind side, respectively; a front and a rear edge, which are sequentially arranged in a rotation direction of the blade; and a root portion connected to the sidewall of the hub and a tip portion located opposite to the root portion. Areas on the blade between the tip portion and the root portion are divided into at least one first and one second section. The first section is located between the tip portion and the second section, and the second section is located between the first section and the root portion. The second section of the blade has a thickness that may be larger or smaller than that of the first section, such that a stepped configuration is formed on the upwind side of the blade to provide a height difference thereon.

[0007]With the height difference provided by the stepped configuration on the upwind side of the blade, it is able to change the direction of the airflow passing through the upwind side of the blade and accordingly, reduce the airflow resistance, lower the fan power consumption, and upgrade the fan efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein

[0009]FIG. 1 shows a perspective view of a fan blade structure according to a preferred embodiment of the present invention and a partially enlarged view thereof;

[0010]FIG. 2 is a fragmentary sectional view of a blade of the fan blade structure according to the preferred embodiment of the present invention;

[0011]FIG. 3 is an assembled sectional view of the fan blade structure according to the preferred embodiment of the present invention;

[0012]FIG. 4A is a comparison graph showing measured curves of the fan blade structure of the present invention and a conventional fan blade structure;

[0013]FIG. 4B is a graph comparing measured airflow and static efficiency of the fan blade structure of the present invention and a conventional fan blade structure;

[0014]FIG. 5A is a perspective view of a conventional fan blade structure; and

[0015]FIG. 5B is a fragmentary sectional view of a blade of the conventional fan blade structure of FIG. 5A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016]The present invention will now be described with some preferred embodiments thereof.

[0017]The present invention provides a fan blade structure 1. Please refer to FIGS. 1, 2 and 3. The fan blade structure 1 is applied to a fan structure 2, such as an axial fan, a frameless fan, or a serial fan. In the illustrated preferred embodiment of the present invention, the fan blade structure 1 is mounted in a frame 21 of the fan structure 2, such as an axial fan. As shown in FIG. 3, the frame 21 defines an air inlet 24 and an opposite air outlet 25. The fan blade structure 1 of the present invention includes a hub 11 and a plurality of blades 12. The hub 11 has a top wall 111 and a sidewall 112 extended outward from a periphery of the top wall 111, such that a receiving space 113 is defined between the top wall 111 and the sidewall 112. The hub 111 is internally provided with a shaft 14 and a magnetic element 15, such as a magnet. The shaft 14 is centered in the receiving space 113 with an end fixed to the hub 11 and another end pivotally connected to a shaft seat 22 provided in the frame 21. The magnetic element 15 is mounted on around an inner wall surface of the hub 11 to face a stator 23 provided on the shaft seat 22 to achieve the purpose of induction and excitation.

[0018]The blades 12 are circumferentially spaced on the sidewall 112 of the hub 11. Each of the blades 12 has an upper and a lower surface, which are a downwind side 121 and an upwind side 122, respectively. The downwind side 121 (i.e. a suction side) is located at the upper surface of the blade 12 corresponding to the air inlet 24 of the frame 21, while the upwind side 122 (i.e. a pressure side or push side) is located at the lower surface of the blade 12 corresponding to the air outlet 25 of the frame 21. Each of the blades 12 has a front edge 123 and a rear edge 124, which are sequentially arranged in a rotation direction of the fan structure 2, and a root portion 125 and a tip portion 126. The root portion 125 is connected to the sidewall 112 of the hub 11 and is located opposite to the tip portion 126.

[0019]Please refer to FIGS. 1, 2 and 3. An area on each of the blades 12 between the tip portion 126 and the root portion 125 is divided into at least one first section 129 and one second section 130. The first and the second section 129, 130 of the blade 12 have a thickness h1, h2, respectively, which are the thickness of the blade 12 between the downwind side 121 and the upwind side 122. The first section 129 of the blade 12 is located between the second section 130 and the tip portion 126 of the blade 12, and the second portion of the blade 12 is located between the first section 129 and the root portion 125 of the blade 12. Further, the thickness h2 of the second section 130 of the blade 12 may be larger or smaller than the thickness h1 of the first section 129. In the illustrated embodiment, the thickness h1 of the first section 129 is smaller than the thickness h2 of the second section 130, i.e. thickness h1<thickness h2. The upwind sides 122 on the first section 129 and the second side 130 of the blade 12 are facing toward the same direction but there is a height difference between the upwind side 122 at the first section 129 and the upwind side 122 at the second section 130, so that the upwind side 122 of each blade 12 has a stepped configuration. The stepped configuration may include only one step or a plurality of steps and is located adjacent to the first section 129 for guiding and pushing airflow on the upwind side 122 toward the air outlet 25 of the frame 21 of the fan structure 2.

[0020]The stepped configuration of each of the blades 12 includes at least one stepped surface 127, which can be an inclined surface, as shown in FIG. 2, or a vertical surface (not shown). The stepped surfaces 127 on the blades 12 can change the flow direction of the air on the upwind side 122, so as to reduce or decrease flow resistance. Further, the stepped surfaces 127 on the blades 12 may have a profile the same as or different from that of the tip portions 126 of the blades 12.

[0021]Please refer to FIG. 4A that is a comparison graph showing measured curves of the fan blade structure 1 of the present invention for the fan structure 2 and the conventional fan blade structure for a fan. In the drawing, the x-axis indicates airflow in cubic per minute CFM), and the y-axis indicates air pressure (or static pressure) in mmAq. Further, the solid line in FIG. 4A is the measured curve of the fan blade structure 1 of the present invention, while the phantom line is the measured curve of the conventional fan blade structure. According to experiments conducted on the fan blade structure 1 of the present invention and the conventional fan blade structure that are the same in size and mounted in a similar frame 21, the experimental results indicate that the fan blade structure 1 shows higher air pressure than the conventional fan blade structure when the fan blade structure 1 of the present invention and the conventional fan blade structure producing the same airflow; and that the fan blade structure 1 produces more airflow than the conventional fan blade structure when the fan blade structure 1 and the conventional fan blade structure show the same air pressure. From the experimental data, it is clear the fan structure 2 using the fan blade structure 1 of the present invention produces increased airflow and shows higher static pressure. Please refer to FIG. 4B that is a graph comparing measured airflow and static efficiency of the fan blade structure 1 of the present invention and the conventional fan blade structure. In FIG. 4B, the x-axis indicates airflow in CFM, and the y-axis indicates static efficiency in %. Further, the solid line in FIG. 4B is the measured curve of the fan blade structure 1 of the present invention, while the phantom line is the measured curve of the conventional fan blade structure. According to the results from the experiments conducted on the fan blade structure 1 and the conventional fan blade structure, the fan structure 2 using the fan blade structure 1 of the present invention has better efficiency than the fan with the conventional fan blade structure, and the fan structure 2 using the fan blade structure 1 of the present invention has static efficiency increased by 0.7%. In conclusion, the present invention not only indeed effectively upgrades the efficiency of the fan structure 2, but also saves the power consumption of the fan structure 2.

[0022]In the illustrated embodiment, the stepped configuration formed between the tip portion 126 and the root portion 125 of the blade 12 includes one single step, which is located in the first section 129; and the upwind side 122 of the blade 12 is a non-smooth or non-flat surface. However, it is understood the present invention is not particularly limited thereto. In another embodiment of the present invention, the stepped configuration formed between the tip portion 126 and the root portion 125 of the blade 12 includes two or more steps, which are located in the first section 129. In a further embodiment, the blade 12 includes a plurality of first sections 129 in various thicknesses or heights, which are sequentially increased from the tip portion 126 toward the root portion 125 of the blade 12 to form three steps. That is, a first step located closer to the tip portion 126 has a thickness or height smaller than that of a second step located immediately behind the first step. With these arrangements, the stepped configuration including multiple steps can effectively reduce the airflow resistance and accordingly, upgrade the efficiency of the fan structure 2.

[0023]In an alternative embodiment of the present invention, the stepped configuration formed between the tip portion 126 and the root portion 125 of the blade 12 may include one step or a plurality of steps, which are located in the second section 130 of the blade 12. The blade 12 may include a plurality of second sections 130 in various thicknesses or heights, which are sequentially decreased from the tip portion 126 toward the root portion 125 to form one or more steps to reduce the airflow resistance and achieve upgraded efficiency of the fan structure 2. In the above described embodiments, the steps in the stepped configuration of the upwind side 122 of the blade 12 may have different widths, heights and lengths without being limited to those shown in the drawings. Different steps may have the same or different width, height and length, which are designed depending on the actually required fan efficiency.

[0024]With the stepped configuration, height differences are existed on the upwind side 122 of each blade 12 to form one or more steps, which can control the direction of airflow passing through the upwind sides of the blades. In this way, it is able to avoid the loss of airflow that sweeps across the upwind sides of the blades 12 and to allow more airflow to be pushed toward the air outlet 25 of the fan structure 2 directly. As a result, the airflow resistance on the upwind sides 122 of the blades 12 can be reduced to effectively reduce the power consumption of the fan structure 2 and effectively upgrade the fan efficiency.

[0025]The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.