Abstract:
A blower having a plurality of impellers is described. The blower has two driving devices and two impellers respectively mounted on the two driving devices. The blades of the two impellers, which are radially or axially disposed, are overlapped so as to enhance the heat-dissipating efficiency of the blower.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of Invention  
           [0002]    The present invention relates to a blower. More particularly, the present invention relates to a blower with a plurality of impellers.  
           [0003]    2. Description of Related Art  
           [0004]    The blower is one of the high-performance dissipation devices on the market. Basically, the blower is suitable for installation in a high impedance system.  
           [0005]    Blower size and volume need to be reduced even if blower performance is high. The reduced size is essential if the blower is to fit in smaller mobile electronic devices such as notebook computers and tablet PCs.  
           [0006]    Further, the blower must not fail during system operation. In fact, in order to protect the system, power automatically turns off if the blower malfunctions. Therefore, a backup blower is added to the system to avoid failure. Adding extra blower must occupy more space, and this is undesirable.  
         SUMMARY OF THE INVENTION  
         [0007]    It is therefore an objective of the present invention to provide a blower with a plurality of impellers in order to improve heat dissipation efficiency.  
           [0008]    In accordance with the foregoing and other objectives of the present invention, a blower having a plurality of impellers is disclosed. The blower has two driving devices and two impellers respectively mounted on the two driving devices. The blades of the two impellers, which are radially or axially disposed, are overlapped so as to enhance heat-dissipating efficiency of the blower.  
           [0009]    In one preferred embodiment of the present invention, two impellers and two driving means are disposed in one case, in which the blades of the two impellers are overlapped axially. The diameters of two impellers are the same.  
           [0010]    In another preferred embodiment of the present invention, two impellers and two driving means are disposed in one case, in which the blades of two impellers are overlapped radially. The diameters of the two impellers are different.  
           [0011]    In a further preferred embodiment of the present invention, two impellers and two driving means are disposed in one case, in which the blades of two impellers are overlapped obliquely. The diameters of the two impellers may be different or identical.  
           [0012]    In light of the preferred embodiments of the present invention, at least two driving means are employed to drive the impellers avoid system failure in the event that one of the at least two driving means malfunctions and causes system failure. In addition, the present invention provides flexible design patterns, such as rotating directions and air inlet options. Two blowers disposed radially not only shrink the volume of the blower but also increase the flow rate of passing air.  
           [0013]    It is to be understood that both the foregoing general description and the following detailed description examples only, and are intended to provide further explanation of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings,  
         [0015]    [0015]FIG. 1A illustrates a cross-sectional sideview of a blower cross-sectional according to one preferred embodiment of this invention;  
         [0016]    [0016] 
         [0017]    [0017]FIG. 1B illustrates cross-sectional top view of FIG. 1A;  
         [0018]    [0018]FIG. 2A illustrates a cross-sectional sideview of a blower according to another preferred embodiment of this invention;  
         [0019]    [0019]FIG. 2B illustrates cross-sectional top view of FIG. 2A;  
         [0020]    [0020]FIGS. 3A, 3B illustrate the blade design and rotating directions according to one preferred embodiment of this invention; and  
         [0021]    FIGS.  4 A- 4 D illustrate patterns of overlap according to one preferred embodiment of this invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]    Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.  
         [0023]    The easiest way to reduce the volume of the blower is to shrink the impeller structure, driving means (such as motor), and outer case of the blower. The method of present invention is to assemble multiple driving means and impellers in one case, thus reducing the volume of the blower and avoiding the risk of only one driving means.  
         [0024]    In one preferred embodiment of the present invention, multiple driving means and impellers are disposed in one case and the blades of the impellers are overlapped to reduce the volume. Thus, the present invention focuses on how to overlap the blades of the impellers.  
         [0025]    [0025]FIG. 1A illustrates a cross-sectional sideview of a blower according to one preferred embodiment of the present invention. FIG. 1B illustrates a top view of FIG. 1A. In one preferred embodiment of the present invention, the blades  20  of two blowers are disposed axially. A gap separating the impellers  30  is desirable to avoid contact between the same. FIG. 1A is divided into two illustrations. In the upper illustration, inlets are located in both sides of the blower, while in the lower illustration one inlet is located in either side of the blower. With regard to the rotational direction, the two blowers can rotate in either identical or opposite directions (as shown in FIGS. 3A and 3B). In particular, the blades should be designed as illustrated in FIG. 3A if rotational directions of two blowers are identical. The blades should be designed as in FIG. 3B if rotational directions of two blowers are opposite.  
         [0026]    [0026]FIG. 4A illustrates enlarged details of the blades in FIG. 1A. The blade design can have different types of patterns. For example, the blades of two impellers overlap obliquely in FIG. 4B. The diameters of the two impellers are the same both in FIG. 4A and FIG. 4B. Alternatively, the blades of two impellers overlap radially (FIG. 4D). The blades of the two impellers also overlap obliquely in FIG. 4C, but the diameters of the two impellers there illustrated are different.  
         [0027]    [0027]FIG. 2A illustrates a cross-sectional view of a blower according to another preferred embodiment of this invention. FIG. 2B illustrates a top view of FIG. 2A. In another preferred embodiment of the present invention, the blades  20  of two blowers are disposed radially. A gap separating the two impellers  30  is desirable to avoid contact between the same. Radial disposition of the two blowers not only shrink the volume of the blower but also increase the flow rate of passing air. FIG. 2A is divided into two illustrations. In the upper illustration, inlets are located in both sides of the blower, while in the lower illustration one inlet is located in either side of the blower. Rotational direction of two blowers can be identical or opposite (as shown in FIGS. 3A and 3B). In particular, the blades should be designed as in FIG. 3A if rotational directions of two blowers are identical. The blades should be designed as in FIG. 3B if rotational directions of two blowers are opposite.  
         [0028]    Although the present invention has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. For example, in the preferred embodiments, two blowers are disposed axially and radially to shrink the volume of the blower, but more blowers (at least three blowers) can be disposed axially and radially to achieve the same purpose. Therefore, their spirit and scope of the appended claims should no be limited to the description of the preferred embodiments contained herein.  
         [0029]    In light of the preferred embodiments of the present invention, at least two driving means are employed to drive the impellers and avoid system failure cause by malfunction of one of the at least two driving means. In addition, the present invention provides flexible design patterns, such as rotating directions and air inlet options. Two blowers disposed radially not only shrink the volume of the blower but also increase the flow rate of passing air.  
         [0030]    It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.