Patent Publication Number: US-2011061350-A1

Title: Dust collection unit for vacuum cleaner

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of prior U.S. patent application Ser. No. 11/258,997 filed Oct. 27, 2005, which claims priority under 35 U.S.C. §119 to Korean Application Nos. 10-2004-0087104 filed on Oct. 29, 2004, whose entire disclosures are hereby incorporated by reference. 
    
    
     BACKGROUND 
     1. Field 
     The present invention relates to a vacuum cleaner, and particularly, to a dust collection unit OF a vacuum cleaner, which has a first dust collection part for filtering relatively large foreign objects and a second dust collection part for filtering relatively small foreign objects, the first and second dust collection parts being separated from each other. In addition, the present invention further relates to a dust collection unit for a vacuum cleaner, which is designed in a proper size and shape so that it can be easily mounted in a main body of the vacuum cleaner. 
     2. Background 
     A vacuum cleaner is used to clean a room or other spaces by sucking air containing foreign objects and filtering the foreign object using vacuum pressure generated therein. In order to filter the foreign objects contained in the sucked air, a dust collection unit is provided in the vacuum cleaner and a paper filter designed with a predetermined structure is provided in the dust collection unit. 
     The paper filter is formed of porous material so that the foreign objects are filtered while the air containing the foreign objects passes through the filter. 
     However, since it is inconvenient to reuse the paper filter and it is difficult to clean the filter, a cyclone type vacuum cleaner has been recently proposed. In the cyclone type vacuum cleaner, outer air containing foreign objects is sucked through a suction nozzle is directed to a collection chamber through a suction guide. Since the suction guide extends in a tangential direction of the collection chamber, the sucked air containing the foreign objects spirally rotates in the collection chamber, in the course of which relatively heavy foreign objects falls downward. Then, the air passes through a filter member, in the course of which relatively small foreign objects contained in the air are filtered by the filter. 
     However, when the filter member formed of a porous filter is combined with the cyclone unit, the problem of periodically cleaning the filter still remains. When the foreign objects clogs the porous filter, an airflow rate is reduced, thereby deteriorating the operational efficiency of the vacuum cleaner. 
     To solve the above problems, in recent years, a multi-cyclone type dust collection unit in which the cyclone unit is provided in plurality to generate a plurality of cyclone air flows so that the foreign objects contained in the air can be filtered by only the cyclone air flows, has been developed. 
     However, in order to generate a variety of cyclone airflows, a relatively large space must be defined in the multi-cyclone type dust collection unit. In this case, an overall size of the dust collection unit increases, thereby undesirably increasing an overall volume of the vacuum. Therefore, it is not easy for the user to handle the vacuum cleaner. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a dust collection unit for a vacuum cleaner that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
     An object of the present invention is to provide a dust collection unit for a vacuum cleaner, in which an arrangement of a dust collection part is optimized. 
     Another object of the present invention is to provide a dust collection unit for a vacuum cleaner, which can effectively filter small foreign objects as well as large foreign objects, thereby improving the dust collection efficiency. 
     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a dust collection unit for a vacuum cleaner, including: a first dust collection part for filtering foreign objects in air; a second dust collection part for filtering foreign objects in the air that has passed through the first dust collection part; and a dust collection container having first and second dust collection chambers that correspond to the first and second dust collection parts, respectively, wherein the first and second dust collection chambers store the foreign objects filtered by the respective first and second dust collection parts in a state where parts of the respective first and second dust collection parts are received in the respective first and second dust collection chambers and the first and second dust collection chambers are provided in a line. 
     In another aspect of the present invention, there is provided a dust collection unit for a vacuum cleaner, including: a dust collection container provided with first and second dust collection chambers divided from each other and arranged in a line; a bottom cover for opening and closing a lower portion of the dust collection container; an airflow guide plate provided above the dust collection plate to guide the air that has passed through the first dust collection chamber to the second dust collection chamber; a plurality of small cyclones extending downward from the airflow guide plate and opened toward the second dust collection chamber; a discharge guide tube for receiving a part of each small cyclone and guiding the air that has passed through the small cyclones upward; an exhaust guide plate integrally formed with the discharge guide tube to cover the airflow guide plate; and a top cover provided above the exhaust guide plate to guide the air discharged through the discharge guide tube to an external side. 
     In another aspect of the present invention, there is provided a dust collection unit for a vacuum cleaner, comprising: a dust collection container provided with first and second dust collection chambers divided from each other and arranged in a line; a bottom cover for opening and closing a lower portion of the dust collection container; an airflow guide plate provided above the dust collection plate to guide the airflow; a plurality of small cyclones extending downward from the airflow guide plate to filter minute particles contained in the air; a discharge guide tube for guiding the air that has passed through the small cyclones upward; an exhaust guide plate integrally formed with the discharge guide tube to cover the airflow guide plate; and a top cover provided above the exhaust guide plate to guide the air discharged through the discharge guide tube to an external side. 
     In still another aspect of the present invention, there is provided a dust collection unit for a vacuum cleaner, including: a dust collection container provided with first and second dust collection chambers divided from each other and arranged in a line; an airflow guide plate provided above the dust collection plate to guide the airflow; a plurality of small cyclones extending downward from the airflow guide plate to filter minute particles contained in the air; a discharge guide tube for guiding the air that has passed through the small cyclones upward; and an exhaust guide plate integrally formed with the discharge guide tube to cover the airflow guide plate, wherein outer edges of the dust collection container, the airflow guide plate and the exhaust guide plate are formed to be similar to each other. 
     According to the present invention, the dust collection efficiency is improved. 
     In addition, a variety of cyclone airflows are possibly generated and no filter member is provided, thereby effectively removing small foreign objects as well as large foreign objects and providing the convenience in use to a user. 
     Furthermore, since the airflow system is effectively designed, the airflow resistance can be reduced to improve the dust collection efficiency. 
     In addition, the collected foreign objects can be exhausted by opening a lower cover, thereby further improving the user&#39;s convenience. 
     A dust collection unit for a vacuum cleaner, comprises a first chamber ( 111 ) having a top and a bottom and a filter ( 170 ) provided therein, the filter ( 170 ) having a cylindrical shape with an opening in a middle and a plurality of holes ( 172 ) formed on a surface of the filter ( 170 ), the first chamber ( 111 ) further having an air guide ( 112 ) provided near the top of the first chamber to guide the air introduced in a tangential direction along an inner surface of a wall of the first chamber such that the air spirally rotates in the first chamber ( 111 ) and foreign objects of a first type in the air drops toward the bottom of the first chamber, and the air passes through the holes of the filter to flow through the opening in the middle of the filter; a second chamber ( 112 ) having a top and a bottom, a portion of the wall of the first chamber ( 111 ) being commonly shared by the second chamber; a bottom cover ( 113 ) commonly shared by the first chamber and the second chamber, the bottom cover being pivotally connected to the wall for opening or closing both bottoms of the first and second chambers, wherein a first surface area of the bottom cover is used to cover the bottom of the first chamber and a second surface area of the bottom cover is used to cover the bottom of the second chamber, and the first surface area is larger than the second surface area; a first guide plate ( 150 ) having an air intake tube ( 152 ) provided on a portion of the first guide plate, which is provided over the top of the first chamber ( 111 ), and a plurality of air intake holes ( 166 ) provided on another portion of the first guide plate ( 150 ), which is provided over the top of the second chamber, each of the plurality of air intake holes ( 166 ) having a smaller diameter than the air intake tube ( 152 ) and the air intake tube ( 152 ) being aligned with the opening in the middle of the filter ( 170 ), a plurality of small cyclones ( 160 ) aligned under the plurality of the air intake holes ( 166 ), a plurality of air intake guide members ( 168 ) aligned over the plurality of air intake holes ( 166 ), and an airflow guide ( 154 ) provided on the first guide plate ( 150 ) and a portion of the air flow guide ( 154 ) being provided immediately adjacent to a portion of the air intake tube ( 152 ), wherein the air flowing through the middle of the filter ( 170 ) is guided through the air intake tube ( 152 ), the airflow guide ( 154 ) directs the air towards the plurality of air intake holes ( 166 ) and the plurality of air intake guide members ( 168 ) guide the air into the plurality of cyclones ( 160 ) such that the air spirally rotates and foreign objects of a second type in the air drop toward the bottom of the second chamber; a second guide plate ( 140 ) provided over the first guide plate ( 150 ), the second guide plate ( 140 ) having a plurality of openings and a first barrier ( 145 ) to guide the flow of air, air flowing upwards from the plurality of small cyclones ( 160 ) flow through the plurality of openings; and a top cover ( 120 ) provided over the second guide plate ( 140 ), the top cover ( 120 ) having an air exhaust guide ( 122 ) on one side of the top cover ( 120 ), wherein the air flowing through the openings is directed by the first barrier ( 145 ) to the air exhaust guide ( 122 ). 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
         FIG. 1  is a perspective view of a dust collection unit according to an embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of a dust collection unit depicted in  FIG. 1 ; 
         FIG. 3  is a bottom perspective view of an air exhaust guide plate depicted in  FIG. 2 ; 
         FIG. 4  is a sectional view taken along line I-I′ of  FIG. 1 ; and 
         FIG. 5  is a view illustrating a state where collected foreign objects are removed from the dust collection unit according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
       FIGS. 1 and 2  show a dust collection unit according to an embodiment of the present invention. 
     Referring to  FIGS. 1 and 2 , the inventive dust collection unit includes a dust collection container  110  having an 8-shaped section. 
     An inner space of the dust collection container  110  is divided into first and second dust collection chambers  111  and  112  that are arranged in a line and designed to respectively receive first and second dust collection parts that will be described later. 
     A barrier  113  is formed between the first and second dust collection chamber  111  and  112 . The barrier  113  is curved toward the second dust collection chamber  112  such that the first collection chamber  111  can be formed in a cylindrical shape. Therefore, a horizontal section of the first dust collection chamber  111  is formed in a circular shape by which cyclone airflow occurs in the first dust collection chamber  111 . 
     Since the first and second dust collection chambers  111  and  112  are arranged in a line, a length of the dust collection unit is increased while a width is reduced. That is, a section of the dust collection unit is generally formed to be relatively flat. Therefore, when the dust collection unit can be easily inserted even in an upright type vacuum cleaner having a relatively narrow width. For example, when the dust collection unit  100  is inserted in the upright type vacuum cleaner, it becomes possible that the first dust collection chamber  111  is disposed in the vacuum cleaner while the second dust collection chamber  112  is projected out of the vacuum cleaner, making it easy to mount the dust collection unit in the vacuum cleaner. In addition, the first and second dust collection chambers are completely separated from each other, the airflow in one of the chambers does not affect the airflow in the other of the chambers, thereby further improving the dust collection efficiency. 
     The dust collection parts will be now described more in detail. 
     A suction guide  115  is formed on an upper portion of the dust collection container  110  defining the first dust collection chamber ill. The suction guide  115  has a first end projected out of the dust collection container  110  to guide the air introduced into the dust collection container  110  in a tangential direction along an inner wall of the dust collection container  110 . Therefore, the suction guide is formed to be inclined at an outer surface of the dust collection container  110 . 
     A handle  114  is formed on a side portion of the dust collection container  110 . The handle  114  is designed such that the user can easily grasp the same. That is, the handle  114  is formed extending outward from the side portion of the dust collection container  110 . 
     A coupling hinge (see  116  of  FIG. 4 ) is provided on a lower end of the side portion of the dust collection container  110 . A bottom cover  130  is pivotally coupled to the coupling hinge  116 . The coupling hinge  116  is partly grooved toward an inside of the dust collection container  110  so that there is no confliction when the dust collection container  110  is mounted in a main body of the vacuum cleaner. 
     A top of the dust collection container  110  is closed by a top cover  120 . The top cover  120  is formed corresponding to the upper portion of the dust collection container  110  and detachably installed on the top of the dust collection container  110 . The top cover  120  is provided with an air exhaust guide  122  extending upward. The air whose foreign objects are filtered by the first and second dust collection parts is exhausted by the air exhaust guide  122 . 
     A bottom of the dust collection container  110  is closed by a bottom cover  130 . The bottom cover  130  is formed corresponding to a lower portion of the dust collection container  110  to simultaneously open and close the first and second dust collection chambers  111  and  112 . 
     The bottom cover  130  is pivotally mounted by the coupling hinge  116  provided on the dust collection container  110 . That is, a right end of the bottom cover  130  is hingedly coupled to the coupling hinge  116  and a left end thereof is selectively coupled to a lower end by a coupling member such as a hook projection. 
     An exhaust guide plate  140  is provided under the top cover  120 , having a shape corresponding to the top cover  120  to divide the inner space of the dust collection container  110  into upper and lower chambers. Therefore, an exhaust passage  142  is formed between the top cover  120  and the exhaust guide plate  140 . That is, since the exhaust guide plate  140  is spaced downward form the top cover  120 , a space is defined between the exhaust guide plate  140  and the top cover  120 . This space functions as an exhaust passage through which the air is directed to the exhaust guide  122 . 
     A plurality of discharge guide tubes  144  are formed on the exhaust guide plate  140 . As shown in  FIG. 3 , each of the discharge guide tube  144  is formed in a cylindrical shape and projected downward from the exhaust guide plate  140 . The discharge guide tubes  144  are located in a small cyclone  160  that will be described later. Therefore, the discharge guide tubes  144  guides the air to the exhaust passage  142  via the exhaust guide plate  140 . 
     Left and right barriers  147  and  146  are formed on left and right portions of the top of the exhaust guide plate  140 . The barriers are provided to guide the airflow. The left barrier  147  is located at a left side of the discharge guide tubes  144  to prevent the air directed upward through the exhaust guide tube  144  from flowing leftward. The right barrier  146  is located at a left side of the discharge guide tubes  144  to prevent the air directed upward through the exhaust guide tube  144  from flowing rightward. The right barrier  146  is provided with a semi-circular groove  145 , which corresponds to a lower end of the exhaust guide  122  to guide the air in the exhaust passage  142  to the exhaust guide  122 . 
     Furthermore, the exhaust guide plate  140  is provided with screw holes  148  through which screws penetrate. Preferably, the screw holes  148  are provided on front, rear, left and right portions of the exhaust guide plate  140 . Therefore, the exhaust guide plate  140  can be fixed on the top cover  120  by the screws. 
     Meanwhile, an airflow guide plate  150  is provided under the exhaust guide plate  140 . The airflow guide plate  150  is spaced away from the exhaust guide plate  140  and formed in a shape corresponding to that of the exhaust guide plate  140 . Therefore, a sealed space is defined between the exhaust guide plate  140  and the airflow guide plate  150 . The air flows along the sealed space. 
     A plurality of small cyclones  160  functioning as the second duct collection part is formed on the airflow guide plate  150 . The small cyclones  160  are formed on a left portion of the airflow guide plate  150  to filter the relatively small foreign objects using centrifugal force generated by the spiral flow of the fluid. 
     That is, each of the small cyclones  160  includes a cylindrical tube  162  and a cone-shaped tube  164  extending from the cylindrical part  162 . A diameter of the cone part  164  is gradually reduced it goes downward. Since the small cyclones  160  are collected at a side of the air intake tube  152 , the airflow resistance applied to an airflow path is reduced. 
     An air intake hole  166  through which the air passed through the first collection part is introduced is formed on a side portion of the upper end of the cylindrical tube  162  of the small cyclone  160 . The air intake hole  166  is formed corresponding to an upper end side of the cylindrical tube  162  extending upward from the airflow guide plate  150 . 
     An air intake guide member  168  is formed on the air intake hole  166  and projected outward. The air intake guide member  168  is formed at least one of the left and right sides of the air intake hole  166  and oriented toward an air intake tube  152  that will be described later. 
     The discharge guide tube  144  is located in the corresponding cylindrical tube  162  of the small cyclone  160 . Therefore, the air that is flowing downward by the small cyclone  160  is guided by the discharge guide tube  144  and discharged above the exhaust guide plate  140 . 
     The air intake tube  152  is integrally formed with a right portion of the airflow guide plate  150 . The air intake tube  152  partly extends downward from the airflow guide plate  150  to guide the air passed through the first collection part above the airflow guide plate  150 . 
     An airflow guide  154  is further formed on the top of the airflow guide plate  150 . The airflow guide  154  extends upward to the top of the airflow guide plate  150  to prevent the flow of the dust and foreign objects so that the air guided above the airflow guide plate through the air intake tube  152  can be directed toward the air intake hole  166  of the small cyclone  160  without being dispersed at the top portion of the airflow guide plate  150 . Therefore, the airflow guide  154  is formed in a &gt;-shape when it is viewed from a top to enclose the upper-right portion of the air intake tube  152 . 
     The airflow guide plate  150  is further provided with screw-coupling portions  156  corresponding to the screw holes  148  formed on the exhaust guide plate  140 . Therefore, a screw passing through the screw hole  148  is coupled to the screw coupling portion  156 , thereby fixing the exhaust and airflow guide plates  140  and  150  on the top cover  120 . 
     Sealing members may be provided between the top cover  120 , the exhaust guide plate  140  and the airflow guide plate  150 . The sealing members may be formed in an elastic material. 
     A filter member  170  is installed on a right-lower portion of the airflow guide plate  150 . The filter member  70  constitutes the first dust collection part that primarily filter the foreign objects contained in the air introduced from the suction guide  115  of the dust collection container  110 . The filter member  170  is formed in a cylindrical shape and provided with a plurality of air holes  172 . The filter member  170  provided with the air holes  172  may be made through an injection molding process. Each of the air holes  172  is designed having a predetermined diameter that allows only minute particles to pass therethrough. That is, relatively large foreign objects cannot pass through the air holes  172  but falls downward. Preferably, the air holes are not formed at a colliding portion with which the air introduced through the suction guide  115  directly collides. That is, when the air holes are formed at the colliding portion, the air introduced in the tangential direction along the inner wall of the dust collection container  110  through the suction guide  115  may be goes out through the air holes  172  before the air spirally rotates. Therefore, it is preferable that the air holes are not formed on the colliding portion. The filter member  170  is located on a center portion of the first dust collection chamber  111  and detachably mounted on the bottom of the airflow guide plate  150 . Accordingly, the air intake tube  152  formed on the airflow guide plate  150  is to be located in an upper end of the filter member  170 . The filter member  170  may be omitted when the foreign objects can be completely filtered by the first and second dust collection parts. In this case, there is no need to wash the filter member, improving the user&#39;s convenience. 
     A dividing plate  174  is provided on a lower end of the filter member  170 . The dividing plate  174  divides the first dust collection chamber  111  into upper and lower chambers, functioning to prevent the foreign objects dropt into the lower chamber from being scattered into the upper chamber. 
     Foreign object passing holes  175  are formed on both side ends of the dividing plate  174 . The foreign objects in the upper chamber are dropt into the lower chamber through the foreign object passing holes  175 . That is, the foreign objects contained in the air introduced through the suction guide  115  are filtered by the filter member  170  and descends along the inner wall of the dust collection container  110 . Then, they are dropt into the lower chamber through the foreign object passing holes  175  and accumulated on the bottom cover  130 . 
     A plurality of coupling ribs  176  are formed on an upper end of the filter member  170 . The coupling ribs  176  functions to be detachably mounted the filter member  170  on the airflow guide plate  150 . Therefore, a plurality of fixing ribs (not shown) coupled to the coupling ribs  176  are formed on the airflow guide plate  150 . 
     The operation of the above-described dust collection unit will be described hereinafter with reference to the accompanying drawing of  FIG. 4 . 
     When the vacuum cleaner is turned on, air containing foreign objects is sucked through a suction nozzle. The sucked air is directed into the first dust collection chamber  111  of the dust collection container  110  through the suction guide  115 . 
     Since the suction guide  115  extends in the tangential direction of the dust collection container  110 , the sucked air spirally rotates in the first dust collection chamber  111 , in the course of which relatively large foreign objects are dropt down through the foreign object passing holes  175  and the air still containing relatively small foreign objects is directed into the filter member  170  through the air passing holes  172  of the filter member  170 . While the air passes through the filter member  170 , relatively large foreign objects d contained in the air are primarily filtered. The air, which has passed through the filter member  170  is directed above the airflow guide plate  150  through the air intake tube  152 . 
     The air directed above the airflow guide plate  150  is directed into the small cyclones  160 . At this point, the air directed into each of the small cyclones  160  is guided by the air intake guide member  168  and directed into the cylindrical tube  162  through the air intake hole  166 . Since the small cyclone is provided in plurality, there is not confliction between the airflow paths. 
     The air directed into the cylindrical tube  162  flows in the tangential direction from the sidewall of the cylindrical tube  162 , it spirally rotates and descends toward the cone-shaped tube  164 . 
     When the air reaches the lower end of the cone-shaped tube, the air changes its flowing direction along the inner wall of the cone-shaped tube  164  to flow upward. That is, when the air spirally rotates and descends along the inner wall of the cone-shaped tube  164 , a rising air current is generated at a center portion. The rising air current is directed to the exhaust passage  142  formed above the exhaust guide plate  140  through the discharge guide tube  144 . 
     In the above process, minute particles d′ contained in the air spirally rotates and drops along the inner wall of the cone-shaped tube  164  and are exhausted through a lower opening of the cone-shaped tube  164 . In addition, since the first and second dust collection chambers  111  and  112  are completely separated from each other by the barrier  113 , the foreign objects d and d′ collected in the respective dust collection chambers  111  and  112  are affected by totally different airflow. Therefore, the foreign objects d and d′ can be stably collected without being affected by other airflow. 
     The air guided upward through the discharge guide tube  144  is exhausted to an external side through the exhaust guide  122  of the top cover  120  via the exhaust passage  142 . 
     The airflow direction and foreign object collection are indicated by arrow in  FIG. 4 . 
     In order to remove the foreign objects accumulated on the bottom cover  130 , the bottom cover  130  is opened. This state is shown in  FIG. 5 . 
     At this point, the coupling state of the coupling device provided on the left end of the bottom cover  130  is released so that the bottom cover  130  pivots downward about the coupling hinge  116  formed on the right end of the bottom cover  130 , by which the foreign objects d and d′ accumulated on the bottom cover  130  is exhausted. 
     Meanwhile, the foreign objects may be partly accumulated on the dividing plate  174 . These foreign objects are removed after separating the filter member  170  and the airflow guide plate  150  from the dust collection container  10 . 
     In order to separate the airflow guide plate  150 , the top cover  120  is first separated from the dust collection container  110 . That is, since the airflow guide plate  150  and the exhaust guide plate  140  are coupled to the top cover  120  by a single group of screws, when the top cover  120  is separated, the airflow and exhaust guide plates  150  and  140  are simultaneously separated from the dust collection container  110 . 
     Then, the filter member  170  is rotated and separated from the airflow guide plate  150 . That is, when the filter member  170  is rotated, the coupling ribs  176  of the filter member  170  are released from the fixing ribs of the airflow guide plate  150 , thereby separating the filter member  170  from the airflow guide plate  150 . 
     After the filter member  170  is separated, it is washed by water. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. 
     For example, the second dust collection part may be provided on a right, front or rear portion of the first dust collection part instead of the left portion. 
     In addition, the filter member may be formed through other manufacturing process instead of the injection molding process. Further more, other types of filters such as the bending filter or multi-filter may be used. 
     Furthermore, the exhaust and airflow guide plates  140  and  150  may be coupled to the top cover  120  by other types of fasteners instead of the screws. 
     In addition, the exhaust and airflow guide plates  140  and  150  may be coupled to the dust collection container  110  instead of to the top cover  120 .