Abstract:
A motor assembly includes: a motor including at least a motor body and a motor blade portion; at least one inner motor casing configured to enclose at least a part of the motor; and at least one outer motor casing configured to enclose at least a part of the at least one inner motor casing, wherein air in the motor is caused to change direction when passing along at least one of the at least one inner motor casing and the at least one outer motor casing.

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. 2005-40203, filed May 13, 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. 116511-00202, 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 configured to reduce noise generated in a 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 generated by a motor and collects the dust in a dust collecting chamber. The vacuum cleaner employs a high output motor having a high number of RPMs. However, such a high output motor causes a large volume of noise when it is driven.  
         [0006]     Korean Patent Publication No. 1997-32650 describes a motor casing including a noise absorbing member and a noise blocking member. The noise blocking member encloses the noise absorbing member and has diffusion 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, a second penetrating hole formed on a rear surface, and a noise absorbing member disposed at the first and the second penetrating holes.  
         [0007]     However, since the disclosures of the Korean Patent Publication No. 1997-32650 and Japanese Patent Publication No. H01-268524 require the extra noise absorbing member to reduce noise, their structures are complicated and their manufacturing cost is high.  
         [0008]     Also, although both disclosures can reduce a blade passing frequency (BPF) and the entire noise level, they do not effectively reduce a low frequency band noise.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention has been developed in order to solve the above problems in the related art. A first aspect of the present invention is to provide a motor assembly having a simplified configuration and a vacuum cleaner having the same.  
         [0010]     To this end, the present invention provides a motor assembly that includes: a motor including at least a motor body and a motor blade portion; at least one inner motor casing configured to enclose at least a part of the motor; and at least one outer motor casing configured to enclose at least a part of the at least one inner motor casing, wherein air in the motor is caused to change direction when passing along at least one of the at least one inner motor casing and the at least one outer motor casing.  
         [0011]     Another aspect of the invention provides a vacuum cleaner that includes: a cleaner body including at least a dust collecting chamber and a motor chamber; a brush assembly configured to be connected to the dust collecting chamber; a motor disposed at the motor chamber and including at least a motor body and a motor blade portion; at least one inner motor casing configured to enclose at least a part of the motor; and at least one outer motor casing configured to enclose at least a part of the at least one inner motor casing, wherein air in the motor is caused to change direction when passing along at least one of the at least one inner motor casing and the at least one outer motor casing.  
         [0012]     Another aspect provides a motor assembly, which includes: a motor; at least one inner motor casing configured to enclose at least a part of the motor; at least one outer motor casing configured to enclose at least a part of the at least one inner motor casing; and means for changing a direction of air flow between the at least one motor casing and the at least one outer motor casing. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     These and 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 view schematically illustrating a cleaner body in which a motor assembly according to a non-limiting embodiment of the present invention may be mounted;  
         [0015]      FIG. 2  is a view illustrating the motor assembly of  FIG. 1 , in which a contour line of an outer motor casing is expressed by a dashed line such that only an inner motor casing is shown;  
         [0016]      FIG. 3  is an exploded perspective view illustrating the motor assembly of  FIG. 2 ; and  
         [0017]      FIG. 4  is a graph illustrating a noise reduction effect achieved by the motor assembly according to a non-limiting embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0018]     Hereinafter, a motor assembly and a vacuum cleaner having the same according to a non-limiting embodiment of the present invention will now be described with reference to the accompanying drawings. For reference, arrows in the drawings indicate an air flow direction.  
         [0019]      FIG. 1  is a view illustrating a cleaner body in which a motor assembly according to a non-limiting embodiment of the present invention is mounted. Referring to  FIG. 1 , the cleaner body  10  may include a dust collecting chamber S 1  and a motor chamber S 2 .  
         [0020]     The dust collecting chamber S 1  may be a space that may be partitioned from the motor chamber S 2  by a partition  10   a  and may be formed in a front portion of the cleaner body  10 . The dust collecting chamber S 1  may have a dust collector to separate and collect dust. In this embodiment, a dust bag  11  may be provided as the dust collector. Instead of the dust bag  11 , a single or multi-cyclone dust collecting apparatus (capable of being used repeatedly) may be provided in the dust collecting chamber S 1 .  
         [0021]     A suction pipe  12  may be disposed at an upper portion of the dust collecting chamber S 1  and may protrude to the outside of the cleaner body  10  as well as to the inside of the cleaner body  10 . Dust may be drawn in through the suction pipe  12 . The suction pipe  12  may be connected to a flexible hose  14  outside the cleaner body  10  and to the dust bag  11  inside the cleaner body  10 . The flexible hose  14  may be connected to a brush assembly (not shown) through an extension pipe (not shown). The brush assembly may draw in dust from a cleaning surface therethrough.  
         [0022]     According to the above-described configuration, the dust drawn in through the brush assembly (not shown), the extension pipe (not shown), the flexible hose  14 , and the suction pipe  12  may be collected in the dust bag  11 , whereas the air may escape from the dust bag  11  in the direction of arrow and may flow into the motor chamber S 2  through a filter  40 .  
         [0023]     The motor chamber S 2  may include a space that is partitioned from the dust collecting chamber S 1  by partition  10   a  and may be formed in a rear portion of the cleaner body  10 . The motor chamber S 2  may include a first motor chamber S 21  and a second motor chamber S 22 .  
         [0024]     The first motor chamber S 21  may be enclosed by an upper wall  10   b  and a side wall  10   c  and may be located in front of the second motor chamber S 2 . A motor assembly  19  may be disposed in the first motor chamber S 21 . A motor  20  may use a high-output motor capable of generating a high number of revolutions per minute (RPMs). The high output motor may generate a large volume of noise when it is driven. In order to reduce the noise, the motor assembly  19  may be provided in the first motor chamber S 21 . The second motor chamber S 22  may be formed in the rear portion of the motor chamber S 2  by the side wall  10   c.    
         [0025]     A discharge pipe  16  may be disposed at a rear upper portion of the motor chamber S 2  to discharge the air to the outside therethrough. A discharge filter  30  may be disposed in an outlet of the discharge pipe  16  to filter dust included in the air.  
         [0026]     Referring to  FIGS. 2 and 3 , the motor assembly  19  according to an embodiment of the present invention may include the motor  20  which may include a motor body  20   a  and a motor blade portion  20   b.  A motor casing  100  may also be provided to enclose the motor  20  and may include an inner motor casing  110  and an outer motor casing  120 . The configuration of the motor  20  may be similar to those known to those of skill in the art.  
         [0027]     The inner motor casing  110  may enclose the motor body  20   a  and may be spaced away from the motor body  20   a  by a predetermined distance such that a first air passage P 1  (see  FIG. 1 ) may be formed between the motor  20  and the inner motor casing  110 . A plurality of first air passing holes  110   a  may be formed along a circumference of the inner motor casing  110 . The inner motor casing  110  may include a first securing protrusion  111  formed at a circular edge of the inner motor casing  110  and may include a first securing hole  110   b  through which a screw is inserted. The outer motor casing  120  may include a front casing  121  and a rear casing  122 , which may be separable from each other.  
         [0028]     The front casing  121  may enclose the motor blade portion  20   b  and may have a second securing protrusion  121   b  formed at a circular edge of the front casing  121  to be connected to the rear casing  122 . The securing protrusion  121   b  may include a second securing hole  121   bb  corresponding to the first securing hole  110   b  of the first securing protrusion  111 .  
         [0029]     The rear casing  122  may enclose the inner motor casing  110 , which may be spaced from the inner motor casing  110  by a predetermined distance such that a second air passage P 2  (see  FIG. 1 ) may be formed between the inner motor casing  110  and the rear casing  122 . The rear casing  122  may have a plurality of second air passing holes  122   a  defined on a surface (e.g., a rear surface) of the rear casing  122  in a radial direction. The second air passing holes may be omitted from the center of the rear casing  122 . Of course, the arrangement of the second air passing holes  122   a  may extend to the center of the rear casing  122 .  
         [0030]     The rear casing  122  may have a third securing protrusion  122   b  formed at a circular edge thereof to be connected with the front casing  121 . The third securing protrusion  122   b  may include a third securing hole  122   bb  corresponding to the first and the second securing holes  110   b,    121   bb  of the first and the second securing protrusions  111 ,  121   b.    
         [0031]     Although the inner motor casing  110  may enclose only the motor body  20   a  in this non-limiting embodiment, it may also be designed to enclose the motor blade portion  20   b  as well as the motor body  20   a.  Also, the outer motor casing  120  may be designed to enclose the entire motor  20  or to enclose only the motor body  20   a.  Also, variations of the air channel are possible. For example, two or more outer motor casings  120  may enclose the inner motor casing to reduce noise.  
         [0032]     Referring to  FIG. 1 , when the air escapes from the motor  20 , it may be deflected by the first air passage P 1 , may pass through the first air passing holes  110   a,  may again be deflected by the second air passage P 2 , and then may pass through the second air passing holes  122 a. At this time, the air may change its direction when it flows from the first air passage P 1  to the second air passage P 2 . For example, the air may change its direction by substantially 90° to 180° when it flows into the second air passage P 2  from the first air passage P 1 .  
         [0033]     When the air is deflected by the first air passage P 1 , passes through the first air passing holes  110   a,  is again deflected by the second air passage P 2 , and then passes through the second air passing holes  122   a,  its flow velocity changes. Also, when the air changes its direction as it flows from the first air passage P 1  to the second air passage P 2 , noise is reduced.  
         [0034]      FIG. 4  is a graph illustrating a noise reduction effect achieved by the motor assembly. Referring to  FIG. 4 , noise is measured as 73.5 dBA if the motor assembly  19  is provided, whereas noise is measured as 78.7 dBA if there is no motor assembly  19 . In other words, the noise is reduced by as much as 5.2 dBA. The amount of noise reduction is large in a low frequency band (0˜2000 Hz).  
         [0035]     Hereinafter, the operation of the vacuum cleaner employing the motor assembly  19  will now be described. Referring to  FIG. 1 , a suction force is generated when the motor  20  is driven, and dust is drawn in through the brush assembly (not shown), the extension pipe (not shown), the flexible hose  14 , and the suction pipe  12  by the suction force, and collected in the dust bag  11 .  
         [0036]     Cleaned air escapes from the dust bag  11  and flows into the motor  20  disposed in the first motor chamber S 21  after passing through the filter  40 . When the air escapes from the motor  20 , it is deflected by the first air passage P 1  by 90°. Then, the air passes through the first air passing holes  110   a,  is again deflected by the second air passage P 2 , and then passes through the second air passing holes  122   a.  After that, the air may be discharged from the cleaner body  10  through the second motor chamber S 22 , the discharge pipe  16 , and the discharge filter  30 .  
         [0037]     According to the present invention as described above, the motor assembly  19  and the vacuum cleaner having the same have the following advantages.  
         [0038]     First, since the motor assembly  19  may include the inner motor casing  110  having the first air passing holes  110   a  and the outer motor casing  120  having the second air passing holes  122   a,  and may not require an extra noise-absorbing member, the motor assembly  19  has a simplified configuration and its manufacturing costs decrease.  
         [0039]     Second, the air changes its flow velocity while being deflected by the first air passage P 1 , passing through the first air passing holes  110   a,  being again deflected by the second air passage P 2 , and then passing through the second air passing holes  122   a.  Also, since the air changes its direction while moving from the first air passage P 1  to the second air passage P 2 , a noise is reduced. Especially, a low frequency band noise is effectively reduced. Accordingly, a user can clean without much noise.  
         [0040]     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 apparatuses. 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.