Abstract:
A motor assembly includes: a suction motor; at least one inner casing adapted to enclose at least a part of the suction motor; and at least one outer casing configured to enclose at least a part of the at least one inner casing, wherein a diffusion passage is formed between the at least one inner casing and the at least one outer casing and has an average cross-section that gradually increases to allow air to diffuse therein.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of priority under 35 U.S.C. § 119 from Korean Patent Application No. 2005-40917, filed May 16, 2005, the entire contents of which are incorporated herein by reference. This application may also be related to commonly assigned U.S. patent application Ser. No. 10/851,243, filed May 24, 2004, U.S. patent application Ser. No. 11/206,905, filed Aug. 19, 2005, as well as to attorney docket no. 116511-00204, entitled “MOTOR ASSEMBLY AND VACUUM CLEANER HAVING THE SAME.” The contents of each of these three applications are incorporated herewith. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a vacuum cleaner, and more particularly, to a motor assembly adapted to reduce a noise generated in a suction motor and a vacuum cleaner having the same.  
         [0004]     2. Description of the Related Art  
         [0005]     A vacuum cleaner draws in dust using a suction force that is generated as a suction motor is driven. The dust is then collected in a dust-collecting chamber. Generally, a cleaner includes a high output motor having a high number of RPMs. However, such a high output motor causes a high level of noise when being driven.  
         [0006]     Korean Patent Publication No. 1997-32650 describes a motor casing including a noise absorbing member and a noise blocking member, which encloses the noise absorbing member and has perforations formed on a surface thereof. Japanese Patent Publication No. H01-268524 describes a motor casing including a first penetrating hole formed on a side surface thereof, a second penetrating hole formed on a rear surface, and a noise absorbing member formed at the first and the second penetrating hole.  
         [0007]     However, the devices of Korean Patent Publication No. 1997-32650 and Japanese Patent Publication No. H01-268524 require an extra noise absorbing member to reduce noise, and thus have a complicated structure and increases a manufacturing cost. Although both disclosures reduce a blade passing frequency (BPF) noise and an entire level of noise, they do not effectively reduce a low frequency band noise and a peak component.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention has been developed in order to solve the above described problems in the related art.  
         [0009]     To this end, a first aspect of the invention provides a motor assembly, including: a motor; at least one inner casing adapted to enclose at least a part of the motor; and at least one outer casing configured to enclose at least a part of the at least one inner casing, wherein a diffusion passage is formed between the at least one inner casing and the at least one outer casing and has an average cross-section that gradually increases to allow air to diffuse therein.  
         [0010]     Another aspect provides a vacuum cleaner, including: a cleaner body having an air pipe and a discharge pipe; a motor disposed at the cleaner body; at least one inner casing configured to enclose at least a part of the suction motor and to enable fluid communication with the air suction pipe; and at least one outer casing enclosing at least a part of the inner casing and configured to enable fluid communication with the air discharge pipe, wherein a diffusion passage is formed between the at least one inner casing and the at least one outer casing and has an average cross-section that gradually increases to allow the air to diffuse therein.  
         [0011]     Yet another aspect provides a motor assembly, including: at least one motor; at least one first casing configured to enclose at least a part of the at least one motor; at least one second casing configured to enclose at least a part of the at least one first casing; and means for diffusing air.  
         [0012]     Still further, the invention provides a vacuum cleaner, including: a cleaner body; at least one motor disposed of the cleaner body; at least one first casing configured to enclose at least a part of the at least one motor; at least one second casing configured to enclose at least a part of the at least one first casing; and means for diffusing air. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     These and/or other aspects of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:  
         [0014]      FIG. 1  is a perspective view illustrating a motor assembly according to a non-limiting embodiment of the present invention;  
         [0015]      FIG. 2  is a sectional view illustrating a cleaner body having the motor assembly of  FIG. 1  mounted therein and a main part of the motor assembly;  
         [0016]      FIG. 3  is a cross section view of  FIG. 2  cut along a line III-III, illustrating the motor assembly and the cleaner body when being viewed from top;  
         [0017]      FIG. 4  is a graph illustrating change in a cross section of a diffusion passage at points {circle around ( 1 )}, {circle around ( 2 )}, {circle around ( 3 )}, {circle around ( 4 )}, {circle around ( 5 )}, {circle around ( 6 )}, {circle around ( 7 )}, {circle around ( 8 )} of  FIG. 3 ;  
         [0018]      FIG. 5  is a graph illustrating a noise reduction effect achieved by the motor assembly according to a non-limiting embodiment of the present invention; and  
         [0019]      FIG. 6  is a graph illustrating a peak component reduction effect achieved by the motor assembly according to a non-limiting embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0020]     Hereinafter, a motor assembly and a vacuum cleaner including the motor assembly according to a non-limiting embodiment of the present invention will now be described with reference to the accompanying drawings. Referring to  FIGS. 1 and 2 , a motor assembly  100  may include a motor, such as suction motor  110 , an inner casing  120 , and an outer casing  130 . The suction motor  110  may be configured to generate a suction force and may be disposed in a vertical relation to cleaner body  10 . The suction motor  110  may include an air discharge window  110   a  formed on a lower circumference thereof to discharge air therethrough. The air, which may be drawn in through a first air passing hole  121   a , may exit from the suction motor  110  through the air discharge window  110   a.    
         [0021]     The suction motor  110  may include a high output motor capable of generating a high number of revolutions per minute (RPMs). As a result, suction motor  110  may generate vibration. In order to prevent vibration and to support the suction motor  110  in a vertical direction (preferably opposite to the direction of load), a support member  140  may be provided. The support member  140  may be disposed at a center of the inner casing  120 . The support member  140  may be made of rubber to prevent vibration while supporting the suction motor  110 . The support member  140  may be approximately 20 mm to approximately 40 mm.  
         [0022]     The inner casing  120  may include a first inner casing  121  and a second inner casing  122 . The first inner casing  121  may be configured to enclose an upper side of the suction motor  110  and may include first air passing hole  121   a  to guide the air toward the suction motor  110 . The first air passing hole  121   a  may fluidly communicate with a suction pipe  11 .  
         [0023]     A dust bag (not illustrated), which may serve as a dust collector, and a cyclone dust collecting device (not illustrated) may be provided proximate to the suction pipe  11 . Air separated from dust in the dust collector may flow in through the first air passing hole  121   a  after passing through the suction pipe  11 .  
         [0024]     The second inner casing  122  may be adapted to enclose at least a portion of the lower part of the suction motor  110  that is not enclosed by the first inner casing  121 . The second inner casing  122  may also include a second air passing hole  122   b  formed on a circumference thereof to discharge the air to a diffusion passage P 1 .  
         [0025]     The first and the second inner casings  121  and  122  may be detachably fastened to each other. In this non-limiting embodiment, they are fastened using a first fastener (e.g., a bolt)  20 . Of course, there are other fastening methods such as hinge fastening or force fitting, which are other non-limiting examples considered to be in the scope of the present invention.  
         [0026]     The outer casing  130  may include a first outer casing  131  and a second outer casing  132 . The first outer casing  131  may be adapted to enclose an upper portion of the second inner casing  122 .  
         [0027]     The second outer casing  132  may be adapted to enclose at least a part of the lower portion of the second inner casing  122  which is not enclosed by the first outer casing  131 . The first outer casing  131  and the second outer casing  132  may be fastened to each other to form a third air passing hole  130   a  to discharge the air from the diffusion passage P 1  (see  FIG. 3 ) to an air discharge pipe  12 . Of course, the third air passing hole  130   a  may be formed on either the first outer casing  131  or the second outer casing  132 , as well as partially in each.  
         [0028]     The third air passing hole  130   a  may be formed opposite to the second air passing hole  122   b . Accordingly, the air exiting through the second air passing hole  122   b  may not directly flow into the third air passing hole  130   a . Instead, the air may turn in a circumferential direction along the diffusion passage P 1  and then exit through the third air passing hole  130   a . As such, there may be a change in an air flow direction such that noise can be reduced. The discharge pipe  12  may be disposed adjacent to the third air passing hole  130   a  so that the air exiting from the third air passing hole  130   a  can be promptly discharged.  
         [0029]     The first outer casing  131  and the second outer casing  132  may be detachably fastened to each other. In this non-limiting embodiment, a second fastener (e.g., a bolt)  30  may be used to secure the first outer casing  131  and the second outer casing  132 . Of course, there are other fastening methods such as hinge fastening and force fitting, which are non-limiting examples considered to be within the scope of the present invention.  
         [0030]     Referring to  FIG. 2  and  FIG. 3 , the diffusion passage P 1  may be formed between the inner casing  120  and the outer casing  130  to diffuse the air. More specifically, the diffusion passage P 1  may be a space formed by the outer casing  130  and the inner casing  120  and may have an average cross-section that gradually increases along the air flow direction.  
         [0031]     The diffusion passage P 1  will now be described in detail with reference to  FIGS. 3 and 4 .  FIG. 3  is a cross-sectional view of the motor assembly and the cleaner body viewed from above, and  FIG. 4  is a graph showing the changes in the cross-section of the diffusion passage P 1  at points {circle around ( 1 )}, {circle around ( 2 )}, {circle around ( 3 )}, {circle around ( 4 )}, {circle around ( 5 )}, {circle around ( 6 )}, {circle around ( 7 )}, {circle around ( 8 )} of  FIG. 3 .  
         [0032]     Referring to  FIGS. 3 and 4 , the cross-section of the diffusion passage P 1  irregularly repeats increasing and decreasing from the point {circle around ( 1 )} where the second air passing hole  122   b  is located, the points {circle around ( 2 )}, {circle around ( 3 )}, {circle around ( 4 )}, {circle around ( 5 )} where the air flows along the diffusion passage P 1 , the point {circle around ( 6 )} where the third air passing hole  130   a  is located, to the points {circle around ( 7 )}, {circle around ( 8 )} where the air exiting form the third air passing hole  130   a  is discharged to the air discharge pipe  12  (see  FIG. 2 ), which is expressed by the dashed line in the graph of  FIG. 4 . However, it turns out that the average cross-section gradually increases from the point {circle around ( 1 )} to the point {circle around ( 8 )}. The change in the average cross-section is expressed by a solid line.  
         [0033]     Of course, it may be preferable to regularly increase the cross-section of the diffusion passage P 1  from the first points {circle around ( 1 )} to {circle around ( 8 )}. However, in this non-limiting embodiment, the diffusion passage P 1  may be configured to have the cross-section irregularly repeating increasing and decreasing while having the average cross-section gradually increasing.  
         [0034]     The air exiting from the air discharge window  110   a  of the suction motor  110  diffuses when passing through the diffusion passage P 1 , the third air passing hole  130   a , and the air discharge pipe  12 . As a result, the air has a slow flux. Also, the air exiting from the air discharge window  110   a  may be diffused in a circumferential direction and discharged to the diffusion passage P 1  through the second air passing hole  122   b . The air may flow in a circumferential direction in the diffusion passage P 1  while turning, and its flowing direction may change several times when ascending through the third air passing hole  130   a  and being discharged from the cleaner body  10  through the air discharge pipe  12 .  
         [0035]     Since the air flux becomes slow and the air flowing direction changes, noise is reduced. In particular, a low frequency band noise and a peak component may be effectively reduced. With reference to  FIGS. 5 and 6 , the noise reduction effect will be described in detail.  FIG. 5  is a graph illustrating a noise reduction effect achieved by the motor assembly, and  FIG. 6  is a graph illustrating a peak component reduction effect achieved by the motor assembly.  
         [0036]     The noise is reduced by approximately 4.8 dBA if the motor assembly  100  is employed, compared to the case that the motor assembly  100  is not employed. The noise is noticeably reduced in a low frequency area (0˜2000 Hz).  
         [0037]     The noise is reduced by approximately 9.0 dBA at the position ‘a’ where the first peak component appears, and reduced by approximately 20 dBA at the position ‘b’ where the second peak component appears, and reduced by approximately 7.0 dBA at the position ‘c’ where the third peak component appears. Accordingly, the peak component is greatly improved if the motor assembly  100  is employed compared to the case that the motor assembly  100  is not employed.  
         [0038]     Hereinafter, the air flowing path in the motor assembly  100  and the cleaner body  10  will now be described. Referring to  FIGS. 2 and 3 , the air drawn in through the suction pipe  11  and the first air passing hole  121   a  may descend along an inside of the suction motor  110  and may then exit from the suction motor  110  through the air discharge window  110   a.    
         [0039]     The air discharged from the air discharge window  110   a  may be diffused and discharged to the diffusion passage P 1  through the second air passing hole  122   b . The air may flow in a circumferential direction in the diffusion passage P 1  and may then exit from the diffusion passage P 1  through the third air passing hole  130   a . The air exiting through the third air passing hole  130   a  may vertically ascend and exit from the air discharge pipe  12 .  
         [0040]     In the motor assembly  100  and the vacuum cleaner having the same according to a non-limiting embodiment of the present invention as described above, the air is diffused, and thus has a slow flux and changes in direction while passing through the second air passing hole  122   b , the diffusion passage P 1 , the third air passing hole  130   a , and the air discharge pipe  12 . Accordingly, the overall level of noise can be reduced. Especially, the low frequency band noise and the peak component can be effectively reduced. Accordingly, noise generated while cleaning with the vacuum cleaner is greatly reduced.  
         [0041]     Also, since the motor assembly  100  has the diffusion passage P 1  formed between the inner casing  120  and the outer casing  130 , without having an extra noise absorbing member, the motor assembly  100  has a simplified configuration and its manufacturing cost is decreased.  
         [0042]     The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teachings can be readily applied to other types of devices. Also, the description of the embodiments of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art, and are considered to be within the scope of the present invention.