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Cooling fanRelated Patent Categories: Pumps, Motor Driven, Electric Or Magnetic Motor, Rotary Motor And Rotary Nonexpansible Chamber Pump, Having Bearing, With LubricatorCooling fan description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060292020, Cooling fan. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention relates generally to a cooling fan, and more particularly to a design of an air inlet of a centrifugal cooling fan (blower) in order to improve performance thereof. DESCRIPTION OF RELATED ART [0002] With continuing development of the electronic technology, electronic packages such as CPUs are generating more and more heat that is required to be dissipated immediately. Conventional cooling fans are commonly used for cooling the CPUs and other heat-generating electronic components. [0003] A conventional cooling fan typically can be classified into two types: axial fan and centrifugal fan (blower). The blower is more suitably used in a laptop computer since it has a flat configuration and a large air flow rate. A blower comprises a motor and a housing receiving the motor therein. The housing defines at least an air inlet and an air outlet. The inlet and outlet are oriented to be perpendicular to each other. An airflow generated by the motor flows into the housing via the air inlet and out of the housing through the air outlet. The motor comprises a stator and a rotor being rotatable with respect to the stator. The rotor includes a plurality of fan blades extending radially from an outer-periphery of the rotor and a shaft extending downwardly thereof. The stator includes a bearing ratatably receiving the shaft therein. The most direct and effective way to improve cooling and heat dissipation efficiency of the cooling fan (blower) is to increase the air flow rate thereof. Increasing the air flow rate can be achieved by different measures, for example, by increasing the revolution speed (i.e. rpm (revolutions per minute)) of the fan or by increasing the size of the fan. [0004] Increasing the revolution speed of the fan increases the air flow rate of the fan; therefore, the cooling and heat dissipation effectiveness is relatively improved. However, increasing the revolution speed of the fan causes a bearing of the fan to wear quickly. Furthermore, heat produced by friction between a shaft and the bearing of the fan causes the bearing to be damaged quickly, resulting in short service life of the cooling fan. On the other hand, to increase the size of the fan is not practical since the computer industry has required the computer components to be smaller and smaller. [0005] Furthermore, keeping the fan blades in balance is another important factor to be taken into account when wishing to increase the air flow rate by increasing the revolving speed of the fan. If the fan blades are not arranged in precise balance, the blades will vibrate when operating the cooling fan at a high speed, which affects the operation quality of the cooling fan and its service life. Nevertheless, a precise balance of the fan blades means a high manufacturing cost. Therefore, it is not a good idea to increase the air flow rate of the cooling fan simply by increasing the revolving speed of the fan blades. Further, increasing the revolving speed of the fan blades also results in consuming more power and increasing more heat. [0006] Therefore, it is desired to design a blower which can increase the amount of airflow without either increasing the revolving speed of the fan or increasing the size of the blower. SUMMARY OF INVENTION [0007] According to a preferred embodiment of the present invention, a cooling fan comprises a motor for generating an airflow, and a housing defining a space for receiving the motor therein. The housing defines an air inlet for enabling the airflow to enter the housing. The air inlet is circular and has a center. The center of the air inlet is laterally offset from a center of the motor. By such design, the airflow can be more smoothly drawn into the housing through the air inlet. Accordingly, air flow rate of the cooling fan is increased, whereby the cooling and heat dissipation efficiency of the cooling fan is improved. [0008] Other advantages and novel features of the present invention will be drawn from the following detailed description of a preferred embodiment of the present invention with attached drawings, in which: BRIEF DESCRIPTION OF DRAWINGS [0009] FIG. 1 is an isometric, assembled view of a cooling fan in accordance with a preferred embodiment of the present invention. [0010] FIG. 2 is an isometric, explored view of the cooling fan of FIG. 1; [0011] FIG. 3 is similar to FIG. 1, but showing a second embodiment of the cooling fan; [0012] FIG. 4 shows a third embodiment of the cooling fan; and [0013] FIG. 5 shows a forth embodiment of the cooling fan. DETAILED DESCRIPTION [0014] Referring to FIGS. 1-2, a cooling fan according to a preferred embodiment of the present invention includes a housing 10 and a motor 30 received in the housing 10. The cooling fan is a centrifugal fan which is also called as a blower. [0015] The housing 10 includes a base 20 and a cover 50 mounted on the base 20. Together the base 20 and cover 50 defines a space 40 for receiving the motor 30 therein. The base 20 is approximately planar and has a circular rear side. Four mounting portions 28 extend outwardly from the base 20 for securing the base 20 with the cover 50. The mounting portions 28 are arranged along a circumferential periphery of the base 20. Each mounting portion 28 defines a mounting hole 29 therein for extension of a fixing element (not labeled), such as a rivet. A protrusion 21 extends outwardly from a front edge of the base 20. A plurality of fins 22 is arranged on the protrusion 21. A flow channel 23 is defined between each two adjacent fins 22. [0016] A central tube 24 extends upwardly from a central portion of the base 20 for supporting the motor 30 thereon. An opening 25 is defined in the base 20 around the central tube 24. The opening 25 is circular and has a center at A. The center A is laterally offset from a center of a curvature of the circular rear side of the base 20. Three ribs 27 connect the base 20 and the central tube 24, and separate the opening 25 into three portions. [0017] The cover 50 includes a top wall 51 and a sidewall 53 extending downwardly from an outer-periphery of the top wall 51. The top wall 51 has a shape and size similar to the base 20. A circular shaped air inlet 57 is defined in the top wall 51 and communicates with the space 40 of the housing 10. The air inlet 57 has a center at B. The center B of the air inlet 57 is laterally offset from the center A of the opening 25 of the base 20. An ear 58 extends outwardly from the outer-periphery of the sidewall 53 for connection with a corresponding mounting portion 28 of the base 20. The ear 58 defines a through hole 59 for being aligned with the mounting hole 29 of the corresponding mounting portion 28. A flange 55 extends outwardly from a front edge of the cover 50 corresponding to the protrusion 21 of the base 20. Together the flange 55 and protrusion 21 define an air outlet 56 receiving the fins 22 therein. The air outlet 56 communicates with the air inlet 57 via the space 40 of the housing 10, and is perpendicular to the air inlet 57. [0018] The motor 30 is received in the housing 10 and supported by the central tube 24. The motor 30 is located under the air inlet 57. The motor 30 is circular and defines a center at C. A plurality of fan blades 31 extends radially and outwardly from an outer-periphery of the motor 30. An outer edge of the fan blades 31 defines a circle V. A center of the circle V is coincidental with the center C of the motor 30 and the center A of the opening 25 of the base 20, but is laterally offset from the center B of the air inlet 57 of the cover 50. [0019] During assembly, the cover 50 fixedly secures with the base 20 and together defines the space 40 therein. The fixing elements extend through the through holes 59 of the cover 50 and the mounting holes 29 of the base 20 to secure the cover 50 with the base 20. The motor 30 is received in the housing 10 and supported by the central tube 24. The center C of the motor 30 is laterally offset from the center B of the air inlet 57; thus, a distance between the circumference of the air inlet 57 and the center C of the motor 30 is various. Since the center of the circle V is coincidental with the center A of the opening 25, and the center A is laterally offset from the center of the curvature of the circular rear side of the base 20; thus, the center of the circle V is laterally offset from the center of the curvature of the circular rear side base 20. In this embodiment, the center of the circle V is located close to a left lateral side of the base 20 as viewed from FIGS. 1 and 2. Thus, a wedge-shaped interspace is defined between the inner surface of the sidewall 53 and the circle V. The distance between the inner surface of the sidewall 53 of the housing 10 and the circle V increases along the rotation direction of the motor 30. In this embodiment, the motor 30 rotates clockwise as viewed from FIG. 1. Continue reading about Cooling fan... Full patent description for Cooling fan Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Cooling fan patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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