Fan and manufacturing method thereof

Abstract

A fan includes a motor base, a bearing, an impeller, a stator and a magnetic element. The motor base has a bearing stand in a center portion thereof. The bearing is accommodated within the bearing stand. The impeller includes a metallic case, a hub, plural blades and a rotating shaft. The metallic case has a top wall and a sidewall. The hub is sheathed around the metallic case. The blades are disposed around an outer periphery of the hub. The rotating shaft is inserted into a central opening of the top wall and penetrated through the bearing stand, wherein no raised ring structure is formed in the top wall of the metallic case, and the rotating shaft and the metallic case are jointed together by a laser welding process. The magnetic element is disposed on an inner wall of the metallic case and aligned with the stator.

Claims

1. A fan, comprising: a motor base having a bearing stand in a center portion thereof; a bearing accommodated within said bearing stand; an impeller comprising: a metallic case having a top wall and a sidewall extended axially from an outer periphery of said top wall, wherein said top wall has a central opening, a bottom surface, and a top surface, said top surface continuous with a curved surface that defines part of said central opening, and a depth of said central opening from said top surface to said bottom surface is equal to a thickness of said top wall; a hub sheathed around said metallic case; plural blades disposed around an outer periphery of said hub for driving axial airflow or radial airflow; and a rotating shaft inserted into said central opening and penetrated through said bearing stand, said rotating shaft is combined within said central opening by a laser welding process; a stator disposed around an outer periphery of said bearing stand; and a magnetic element disposed on said metallic case and aligned with said stator, wherein said metallic case further comprises a sub-top wall at a horizontal level lower than said top wall and the bottom surface extends from said central opening to said sub-top wall.

2. The fan according to claim 1 wherein said thickness of said top wall of said metallic case is ranged from 0.1-2.0 mm.

3. The fan according to claim 1 wherein said rotating shaft is made of metal.

4. The fan according to claim 1 wherein no embossed recess is formed in said rotating shaft.

5. The fan according to claim 1 wherein said plural blades are integrally formed with said hub.

6. The fan according to claim 1 wherein said sub-top wall of said metallic case is sheltered by said hub.

7. The fan according to claim 1 wherein said fan further comprises a fan frame, which is arranged at an outer portion of said fan.

8. The fan according to claim 1 wherein an overall thickness of said fan is smaller than 10 mm.

9. A fan, comprising: a motor base having a bearing stand in a center portion thereof; a bearing accommodated within said bearing stand; an impeller comprising: a metallic case having a top wall and a sidewall extended axially from an outer periphery of said top wall, wherein said top wall has a central opening, and a depth of said central opening is equal to a thickness of said top wall; a hub sheathed around said metallic case; plural blades disposed around an outer periphery of said hub for driving axial airflow or radial airflow; and a rotating shaft inserted into said central opening and penetrated through said bearing stand, said rotating shaft is combined within said central opening by a laser welding process; a stator disposed around an outer periphery of said bearing stand; a magnetic element disposed on said metallic case and aligned with said stator; and a fan frame, which is arranged at an outer portion of said fan, wherein a top surface of the rotating shaft, a top surface of the top wall of the metallic case, a top surface of the hub, and a top surface of the fan frame are coplanar.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1A is a schematic perspective view illustrating an impeller of a conventional fan;

(2) FIG. 1B is a schematic exploded view illustrating the impeller of FIG. 1A;

(3) FIG. 1C is a schematic cross-sectional view illustrating the impeller of FIG. 1A;

(4) FIG. 2A is a schematic perspective view illustrating an impeller of a fan according to an embodiment of the present invention;

(5) FIG. 2B is a schematic exploded view illustrating the impeller of FIG. 2A;

(6) FIG. 2C is a schematic cross-sectional view illustrating the impeller of FIG. 2A;

(7) FIG. 2D is a partial enlargement schematic view of FIG. 2C;

(8) FIG. 3 is a schematic cross-sectional view illustrating a fan according to an embodiment of the present invention; and

(9) FIG. 4 is a schematic cross-sectional view illustrating a fan according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(10) The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed.

(11) FIG. 2A is a schematic perspective view illustrating an impeller of a fan according to an embodiment of the present invention. FIG. 2B is a schematic exploded view illustrating the impeller of FIG. 2A. FIG. 2C is a schematic cross-sectional view illustrating the impeller of FIG. 2A. FIG. 2D is a partial enlargement schematic view of FIG. 2C. Please refer to FIGS. 2A, 2B, 2C and 2D. The impeller 2 comprises a hub 20, plural blades 21, a metallic case 22 and a rotating shaft 23. The metallic case 22 is sheathed by the hub 20. The blades 21 are disposed around the outer periphery of the hub 20 for driving axial airflow or radial airflow. In addition, the blades 21 and the hub 20 are integrally formed by a plastic injection molding process.

(12) The metallic case 22 has a top wall 221 and a sidewall 222. The sidewall 222 is axially or downwardly extended from the outer periphery of the top wall 221. As shown in FIG. 2C and FIG. 2D, the top wall 221 has a central opening 221a in its central portion, and the depth h1 of the central opening 221a is equal to or less than the thickness h2 of the top wall 221. The rotating shaft 23 is made of metallic material, and protruded from a center portion of the top wall 221. After the rotating shaft 23 is inserted into the central opening 221a of the top wall 221, the rotating shaft 23 is combined within the central opening 221a of the top wall 221 by a laser welding process, and a top surface 230 of the rotating shaft 23 and a top surface 2210 of the top wall 221 of the metallic case 22 are coplanar. In FIG. 2C, the welding region S is circled by a dashed line. During the laser welding process is performed, high power laser beams are projected on the metallic surface to melt the metallic surface. After the molten metal is cooled, the rotating shaft 23 and the metallic case 22 are jointed together. Since the laser welding process has small welding joints 221b, high precision and centralized energy, the laser welding process is able to form a secure welded structure through thin-walled parts. Since the laser welding process may create a strong adhesion between the rotating shaft 23 and the metallic case 22, the raised ring structure of the hub and the embossed recess of the rotating shaft that are used in the conventional impeller may be omitted. Moreover, since the thickness of the top wall 221 of the metallic case 22 is too small (e.g. 0.1-2.0 mm), it is advantageous to design a slim-type fan by using the impeller 2. As the thickness of the metallic case 22 is decreased, the space under the metallic case 22 for accommodating the stator of the fan will be increased. In this situation, the coil turn may be increased in order to enhance the operating performance of the fan.

(13) For manufacturing the impeller 2, the rotating shaft 23 and the metallic case 22 are firstly jointed together by the laser welding process, then the combination of the rotating shaft 23 and the metallic case 22 is placed within a plastic injection mold (not shown), and finally the hub 20 and the blades 21 of the impeller 2 are produced by the plastic injection molding process. In accordance with the present invention, no raised ring structure is formed in the top wall 221 of the metallic case 22, and no embossed recess is formed in the rotating shaft 23. In addition, the thickness of the top wall 221 of the metallic case 22 is ranged from 0.1 to 2.0 mm.

(14) Since the rotating shaft 23 and the metallic case 22 are firstly jointed together by the laser welding process and then the hub 20 and the blades 21 of the impeller 2 are produced by the plastic injection molding process, the mold for the impeller 2 of the present invention is simpler than the mold used in the conventional impeller. In addition, the adhesion between the rotating shaft and the hub is not necessarily taken into consideration, the possibility of abrading the rotating is minimized, the thicknesses of the hub and the metallic case are not needed to be greater than the minimum thickness, and the hub and the metallic case are not shrunk or deformed after the plastic injection molding process is done. Moreover, since no embossed recess is formed in the rotating shaft, the process of producing the rotating shaft is vey simple. Since the welding points for performing the laser welding process are symmetrically arranged or arranged in a ring-shaped profile, the range of the torsion force of the rotating shaft will be widened.

(15) The laser welding process may be performed to weld various metals. That is, the metallic case 22 and the rotating shaft 23 of the impeller 2 may be made of any metallic material or alloy, for example gold, silver, copper, iron, titanium, nickel, tin, aluminum, chromium, or the alloy thereof. In addition, the metallic case 22 and the rotating shaft 23 may be made of identical material or different materials.

(16) Please refer to FIG. 2C. The outer surface of the metallic case 22 may has a level difference. That is, the metallic case 22 further comprises a sub-top wall 223, whose horizontal level is slightly lower than the top wall 221. When the metallic case 22 is sheathed by the hub 20, the sub-top wall 223 of the metallic case 22 is sheltered by the hub 20, but the top wall 221 of the metallic case 22 and the hub 20 are substantially at the same level. As a consequence, the overall height of the fan is not considerably increased.

(17) FIG. 3 is a schematic cross-sectional view illustrating a fan having the impeller of FIGS. 2A-2C according to an embodiment of the present invention. As shown in FIG. 3, the fan 3 comprises a hub 30, plural blades 31, a metallic case 32, a rotating shaft 33, a motor base 34, a bearing 35, a stator 36, a magnetic element 37 and a fan frame 38. The metallic case 32 is sheathed by the hub 30. The blades 31 are disposed around the outer periphery of the hub 30 for driving axial airflow or radial airflow. In addition, the blades 31 and the hub 30 are integrally formed by a plastic injection molding process. The metallic case 32 is an integral part, and comprises a top wall 321 and a sidewall 322. The sidewall 322 is axially or downwardly extended from the outer periphery of the top wall 321. The top wall 321 has a central opening 321a in its central portion. The rotating shaft 33 is made of metallic material, and protruded from the center portion of the top wall 321. The rotating shaft 33 is inserted into the central opening 321a of the top wall 321, and the rotating shaft 33 is combined within the central opening 321a of the top wall 321 by a laser welding process. A top surface 330 of the rotating shaft 33 and a top surface 3210 of the top wall 321 of the metallic case 32 are coplanar.

(18) A bearing stand 341 is formed in a center portion of the motor base 34. The bearing 35 is accommodated within the bearing stand 341. The rotating shaft 33 is penetrated through the bearing 35. The stator 36 is disposed around the outer periphery of the bearing stand 341. The magnetic element 37 is disposed on the inner wall of the metallic case 32 and aligned with the stator 36. The fan frame 38 is disposed at the outer portion of the fan 3 and surrounds the hub 30, the blades 31, the metallic case 32, the rotating shaft 33, the motor base 34, the bearing 35, the stator 36 and the magnetic element 37. Since the rotating shaft 33 and the metallic case 32 are jointed together by the laser welding process, the thicknesses of the metallic case 32 is not needed to be greater than the minimum thickness. In this situation, the overall thickness H of the fan 3 may be smaller than 10 mm. Preferably, the overall thickness H of the fan 3 is smaller than 7 mm. Consequently, this slim-type fan 3 is achievable and may be used in an ultra-thin notebook computer or other slim-type electronic device.

(19) The present invention further provides a method of manufacturing a fan. Firstly, the rotating shaft 33 and the metallic case 32 are firstly jointed together by a laser welding process. Then, the combination of the rotating shaft 33 and the metallic case 32 is placed within a plastic injection mold (not shown). Afterward, the hub 30 and the blades 31 of an impeller are produced by the plastic injection molding process. In accordance with the present invention, no raised ring structure is formed in the top wall 321 of the metallic case 32, and no embossed recess is formed in the rotating shaft 33. In addition, the thickness of the top wall 321 of the metallic case 32 is ranged from 0.1 to 2.0 mm. Then, a motor base 34 is provided, wherein the motor base 34 has a bearing stand 341 in a center portion thereof. Afterward, a bearing 35 is accommodated within the bearing stand 341, and a stator 36 is disposed around the outer periphery of the bearing stand 341. Then, a magnetic element 37 is disposed on the inner wall of the metallic case 32. Thereafter, the rotating shaft 33 is penetrated through the bearing 35 such that the magnetic element 37 is aligned with the stator 36. Then, a fan frame 38 is disposed at the outer portion of the above resulting structure. Meanwhile, the fan 3 is assembled.

(20) FIG. 4 is a schematic cross-sectional view illustrating a fan according to another embodiment of the present invention. As shown in FIG. 4, the fan 4 comprises plural blades 41, a metallic case 42, a rotating shaft 43, a motor base 44, a bearing stand 441, a bearing 45, a stator 46, a magnetic element 47 and a fan frame 48. In this embodiment, the blades 41 are made of metallic material rather than plastic material. As a consequence, the blades 41 are integrally formed with the metallic case 42, and blades 41 are disposed around the outer periphery of the metallic case 42. In addition, no hub is included in the fan 4. The configurations of the other components of the fan 4 are similar to those of the fan 3 as shown in FIG. 3, and are not redundantly described herein. Since the rotating shaft 43 and the metallic case 42 are jointed together by the laser welding process, the thicknesses of the metallic case 42 is not needed to be greater than the minimum thickness. In this situation, the overall thickness H of the fan 4 may be smaller than 10 mm. Preferably, the overall thickness H of the fan 4 is smaller than 7 mm. Consequently, this slim-type fan 4 is achievable and may be used in an ultra-thin notebook computer or other slim-type electronic device.

(21) From the above description, the fan impeller of the present invention comprises a hub, plural blades, a metallic case and a rotating shaft. The rotating shaft is inserted into the central opening of the top wall of the metallic case. The rotating shaft and the metallic case are directly jointed together by a laser welding process. In addition, no raised ring structure is formed in the top wall of the metallic case. In accordance with the present invention, the top wall of the metallic case has a thickness of 0.1-2.0 mm. The problem of abrading the rotating shaft will be eliminated. In addition, the mold for the impeller is simplified. Since no embossed recess is formed in the rotating shaft, the range of the torsion force of the rotating shaft will be widened. Moreover, since the overall thickness of the fan may be smaller than 10 mm, the slim-type fan of the present invention may be used in an ultra-thin notebook computer or other slim-type electronic device.

(22) While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.