Patent Publication Number: US-10314447-B2

Title: Surface cleaning apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. 120 as a continuation application of co-pending U.S. patent application Ser. No. 15/076,959 which was filed on Mar. 22, 2016, which itself is a continuation of U.S. patent application Ser. No. 14/875,381, filed on Oct. 5, 2015, now U.S. Pat. No. 9,545,181, issued on Jan. 17, 2017, which Itself is a continuation of co-pending U.S. patent application Ser. No. 13/782,217, filed on Mar. 1, 2013, now U.S. Pat. No. 9,192,269, issued on Nov. 24, 2015, which itself is a continuation in part of co-pending U.S. patent application Ser. No. 13/720,754, filed on Dec. 19, 2012, which issued as U.S. Pat. No. 8,752,239 on Jun. 17, 2014, which itself is a divisional application of co-pending U.S. patent application Ser. No. 11/954,331, filed on Dec. 12, 2007, which issued as U.S. Pat. No. 8,359,705 on Jan. 29, 2013, which itself claims priority from U.S. Provisional patent applications 60/870,175 (filed on Dec. 15, 2006), and 60/884,767 (filed on Jan. 12, 2007), all of which are incorporated herein by reference in their entirety. 
    
    
     FIELD 
     This specification relates to a surface cleaning apparatus comprising a base with a removable portable surface cleaning unit such as a pod or other hand carriable surface cleaning apparatus wherein the portable surface cleaning apparatus is usable when mounted on the base or when removed therefrom. 
     INTRODUCTION 
     The following is not an admission that anything discussed below is part of the prior art or part of the common general knowledge of a person skilled in the art. 
     Various types of surface cleaning apparatuses are known in the art. Such surface cleaning apparatuses include vacuum cleaners, including upright vacuum cleaners, hand carriable vacuum cleaners, canister type vacuum cleaners, and Shop-Vac™ type vacuum cleaners. Some such vacuum cleaners are provided with wheels. For example, typical upright vacuum cleaners are provided with a surface cleaning head that includes wheels mounted to a bottom surface thereof. Upright vacuum cleaners are easy for a consumer to use since the consumer does not have to carry the vacuum cleaner but merely push it over a surface. However, depending on the size of the surface cleaning head, an upright vacuum cleaner may not be useable in smaller or crowded areas. Canister vacuum cleaners have a flexibly hose extending between a surface cleaning head and the canister body, thereby improving mobility of the cleaning head. However, consumers must separately move a canister body, which can add an extra step during the cleaning process. 
     SUMMARY 
     This summary is intended to introduce the reader to the more detailed description that follows and not to limit or define any claimed or as yet unclaimed invention. One or more inventions may reside in any combination or sub-combination of the elements or process steps disclosed in any part of this document including its claims and figures. 
     According to one broad aspect of this invention, a surface cleaning apparatus comprises a portable cleaning unit, which may be carried by hand or a shoulder strap such as a pod, which is removably mounted on a wheeled base. The portable cleaning unit may be provided with a suction motor and an energy storage member (such as batteries). Accordingly, the suction motor of the portable cleaning unit may be operable on DC current. However, in accordance with this embodiment, the wheeled base may include a second suction motor (e.g. an AC powered suction motor). Accordingly, when the portable cleaning unit is provided on the wheeled base and the wheeled base is connected to a source of current, the suction motor in the wheeled base may be operated, e.g. on AC current, and used to draw air through an airflow path to the air treatment member in the portable cleaning unit. An advantage of this design is that the suction motor provided in the wheeled base may produce a higher airflow and therefore increase cleanability when the portable cleaning unit is provided on the wheeled base. However, when the portable cleaning unit is removed from the wheeled base, a smaller and lighter suction motor is utilized. While the velocity of the airflow through the portable cleaning unit when removed from the base may be decreased, the reduced weight of the suction motor may be beneficial. In addition, a smaller airflow path may be provided when the portable cleaning unit is removed from the base, and, accordingly, a smaller DC power suction motor may provide substantially similar airflow in the hand carriable mode. 
     The portable cleaning unit may comprise at least one cyclonic separation stage and a suction motor. Accordingly, the portable cleaning unit is useable, e.g., as a vacuum cleaner or the like, when removed from the wheeled base. The cyclonic separation stage comprises a cyclone chamber and a material collection chamber. The portable cleaning unit is configured such that the material collection chamber is removable for emptying when the portable cleaning unit is mounted on the wheeled base. For example, the material collection chamber may be removed by itself when the portable cleaning unit is mounted on the wheel base. Alternately, the material collection chamber and the cyclone chamber may be removable as a unit (e.g. a cyclone bin assembly). It will be appreciated that the material collection chamber, either by itself or in conjunction with the cyclone chamber and possibly other elements, may be removable from the portable cleaning unit when the portable cleaning unit has been removed from the wheeled base. An advantage of this design is that the usability of the surface cleaning apparatus is increased. In particular, when it is needed to empty the dirt collection chamber, all that is needed is to remove the dirt collection chamber either by itself, or, for example, together with the cyclone chamber for emptying. Accordingly, a user did not carry the weight of the motor when the user is emptying the dirt collection chamber. 
     Preferably, in accordance with this embodiment, the dirt collection chamber and, optionally, the cyclone chamber may be provided on an upper portion of the portable cleaning unit so as to be removable upwardly therefrom. 
     It will be appreciated by a skilled person in the art that any of the features of the configuration of a portable cleaning unit to permit a dirt collection chamber to be removed from the portable cleaning unit when the portable cleaning unit is mounted on the wheeled base as discussed herein may not be utilized with dual motor design disclosed herein, but may be used by itself or in combination with any other feature disclosed herein. 
     In accordance with another embodiment, the portable cleaning unit may be provided with a pod hose which is removable with the portable cleaning unit from the wheeled base. The pod hose may have a smaller diameter and, accordingly, may be used only when the portable cleaning unit has been removed from the wheeled base. Accordingly, when the portable cleaning unit is on a wheeled base, the pod hose does not form part of the fluid flow path. Accordingly, the smaller diameter of the pod hose does not restrict the airflow path when the portable cleaning unit is placed on a wheeled base. An advantage of this design is that the portable cleaning unit may carry a longer hose without increasing the volume taken by the pod hose. In addition, the pod hose, being a smaller diameter, may be more flexible and enhance the usability of the portable cleaning unit in a hand carriable mode. For example, the pod hose may have a greater stretch ratio, for example, of 4:1 to 7:1 or more. 
     In accordance with this embodiment, a valve may be provided on the portable cleaning unit whereby the pod hose is not in airflow communication with the suction motor when the portable cleaning unit is mounted on the wheeled base. However, when the portable cleaning unit is removed from the wheeled base, the valve may be actuated (e.g. automatically upon removal of the portable cleaning unit from the wheeled base, manually by the user or automatically when the hose is deployed for use) such that pod hose form part of the air flow path. 
     It will be appreciated by a person skilled in the art that any of the features of the pod hose which are discussed herein may not be utilized with the dual motor design disclosed herein, but may be used by itself or in combination with any other feature disclosed herein. 
     In accordance with another embodiment, the portable cleaning unit may be operable by AC power supplied to the base when the portable cleaning unit is mounted on the base and may be operable on DC power when the portable cleaning unit is removed from the base. Accordingly, the portable cleaning unit may include an energy storage member (e.g. one or more batteries) which may power the suction motor when the portable cleaning unit is removed from the base. Accordingly, the suction motor may be operable on DC current. When the pod is mounted on the wheeled base, and the wheeled base is connected to a source of current by an electrical cord, then the suction motor may be in electrical communication with the base so as to be powered by AC current supplied through the electrical cord. For example, the suction motor could have dual winding so as to be operable on both AC and DC current. Alternately, the base may include a power supply to convert the AC current to DC current which is then supplied to the suction motor when the portable cleaning unit is placed on the base. For example, the power supply may comprise an inverter. 
     In this particular embodiment, it will be appreciated that the batteries in the portable cleaning unit may be charged while the portable cleaning unit is mounted on the wheeled base and the wheeled base is plugged into an electrical outlet. 
     In a further alternate embodiment, instead of utilizing electricity from an electrical outlet, the wheeled base may include a fuel cell or an alcohol powered internal or external combustion engine. In such an embodiment, the wheeled base may produce AC current or DC current, which is then supplied to the suction motor when the portable cleaning unit is mounted on the wheeled base and actuated. 
     It will be appreciated by a person skilled in the art that any of the features of a portable cleaning unit which is operable on AC and DC current as disclosed herein may not be utilized with the dual motor design disclosed herein, but may be used by itself or in combination with any other feature disclosed herein. 
     In accordance with the further embodiment, the portable cleaning unit may comprise both an energy storage member and a power supply. Accordingly, when the portable cleaning unit is connected to a power source (e.g. a cord extends from the portable cleaning unit to an electrical outlet), AC power may be supplied to the power supply (e.g. an inverter) to convert the AC current to DC which is then utilized to power the suction motor. When a user is unable to or does not want to plug the portable cleaning unit into a wall outlet, the portable cleaning unit may be powered by the energy storage member (e.g. batteries), which provide DC current to a suction motor. Accordingly, the portable cleaning unit may be powered by both AC current from a wall outlet and DC current supplied by batteries as may be desired. In a further alternate embodiment, the suction motor may be provided with two windings. In such a case, the power supply is not required and the suction motor may be powered by both DC current from the batteries and AC current from a wall outlet. 
     It will be appreciated by a person skilled in the art that any of the features of a pod operable with both AC and DC current as discussed herein may not be utilized with dual motor design disclosed herein, but may be used by itself or in combination with any other feature disclosed herein. 
     In one embodiment, there is provided a surface cleaning apparatus comprising 
     (a) a wheeled base comprising an AC suction motor; 
     (b) a portable cleaning unit removably mounted on the wheeled base and comprising at least one cyclonic separation stage, a first energy storage member and a portable cleaning unit suction motor that is operable on DC power; and, 
     (c) a fluid flow path extending from a first dirty fluid inlet to a clean air outlet of the surface cleaning apparatus, 
     wherein the AC suction motor provides motive power to move fluid through the fluid flow path when the surface cleaning unit is switched on and when the portable cleaning unit is mounted on the wheeled base, and 
     wherein the portable cleaning unit suction motor provides motive power to move fluid through the fluid flow path when the portable cleaning unit is switched on and when the portable cleaning unit is removed from the wheeled base 
     In some embodiments, the wheeled base may further comprise or is connectable to a power cord and the portable cleaning unit is powered solely by the first energy storage member when the portable cleaning unit is removed from the wheeled base. 
     In some embodiments, the wheeled base may further comprise or is connectable to a power cord, the first energy storage member comprises batteries and the batteries are charged when the portable cleaning unit is mounted on the wheeled base. 
     In some embodiments, the suction motor in the portable cleaning unit may not be used to provide motive power to move fluid through the fluid flow path when the surface cleaning unit is switched on and when the portable cleaning unit is mounted on the wheeled base. 
     In some embodiments, the fluid flow path may comprise an upstream portion that extends from the first dirty fluid inlet to the portable cleaning unit and the AC suction motor is in the fluid flow path. 
     In some embodiments, the fluid flow path may comprise a downstream fluid flow path extending through the portable cleaning unit to the clean air outlet and the portable cleaning unit suction motor is in the downstream fluid flow path. 
     In some embodiments, the portable cleaning unit may comprise a flexible hose having a second dirty fluid inlet and the flexible hose is part of the downstream fluid flow path when the portable cleaning unit is removed from the wheeled base. 
     In some embodiments, the flexible hose may be an electrified flexible hose. 
     In some embodiments, the wheeled base may further comprise a second energy storage member. 
     In some embodiments, the second energy storage member may charge the first energy storage member when the portable cleaning unit is mounted on the wheeled base. 
     In some embodiments, the portable cleaning unit suction motor may be a DC motor. 
     In one embodiment, there is provided a surface cleaning apparatus comprising 
     (a) a wheeled based connectable to a source of current; 
     (b) a portable cleaning unit removably mounted on the wheeled base and comprising at least one cyclonic separation stage, a first energy storage member and a portable cleaning unit suction motor that is operable on DC power; and, 
     (c) a fluid flow path extending from a first dirty fluid inlet to a clean air outlet of the surface cleaning apparatus, 
     wherein the portable cleaning unit suction motor is operable on DC power when removed from the wheeled base and is operable on power provided by the wheeled base when mounted on the wheeled base. 
     In some embodiments, the portable cleaning unit suction motor may be a DC motor. 
     In some embodiments, the wheeled base may further comprise or is connectable to a power cord and the portable cleaning unit is powered solely by the first energy storage member when the portable cleaning unit is removed from the wheeled base. 
     In some embodiments, the wheeled base may further comprise or is connectable to a power cord, the first energy storage member comprises batteries and the batteries are charged when the portable cleaning unit is mounted on the wheeled base. 
     In some embodiments, the wheeled base may further comprise or is connectable to a power cord, the wheeled base further comprises a circuit that receives AC current and outputs DC current and the portable cleaning unit is powered the DC current when the portable cleaning unit is mounted on the wheeled base. 
     In some embodiments the portable cleaning unit suction motor may operate at a first power level when removed from the wheeled base and at a second power level when is mounted on the wheeled base. 
     In some embodiments the first power level may be less than the second power. 
     In accordance with another aspect, a surface cleaning apparatus, preferably a canister or Shop-Vac™ style vacuum cleaner is provided which comprises a portable cleaning unit and a wheeled base. Preferably, the cleaning unit is removably mounted to the wheeled base. Alternately, or in addition, the wheeled base has wheels mounted outward of the wheeled base, and which are preferably of a larger diameter (e.g., 1-3 inches in diameter, preferably 1.5-2.5 inches in diameter). 
     According to this aspect, the surface cleaning apparatus may comprise a member having a dirty fluid inlet. A fluid flow path extends from the dirty fluid inlet to a clean air outlet of the surface cleaning apparatus. The surface cleaning apparatus further comprises a wheeled based. A portable cleaning unit is removably mounted on the wheeled base and comprising at least one cyclonic separation stage and a suction motor positioned in the fluid flow path. 
     Embodiments in accordance with this broad aspect may be advantageous because the surface cleaning apparatus may have increased maneuverability. That is, the surface cleaning apparatus may be used as a wheel mounted surface cleaning apparatus when convenient for a user since the user need not carry the surface cleaning apparatus, or as a hand or strap carriable surface cleaning apparatus, such as when a stairs or a smaller or crowded area is to be cleaned, according to the user&#39;s preference. 
     In some embodiments, the at least one cyclonic separation stage may comprise a cyclone chamber having at least one material outlet, a divider plate associated with the material outlet and an associated material collection chamber in flow communication with the material outlet. 
     In some embodiments, the material collection chamber may be positioned below the material outlet. In a further embodiment, the divider plate may be positioned in the material outlet. 
     In some embodiments, the material collection chamber may be moveable relative to the cyclone chamber. In a further embodiment the material collection chamber may be removable from the at least one cyclone chamber. 
     In some embodiments, the material collection chamber may have a portion that is openable. In a further embodiment, the portion that is openable may be a bottom wall. Such embodiments may be advantageous because the wheeled base may prevent accidental opening of the material collection chamber. 
     In some embodiments, the suction motor may be positioned laterally spaced from the at least one cyclonic separation stage. Accordingly, the surface cleaning apparatus may have a relatively wide stance and low center of mass, and therefore may have increased stability. 
     In some embodiments, the cleaning unit has a front end having the dirty fluid inlet and the front end of the cleaning unit is positioned at a front end of the wheeled base and the suction motor is positioned rearward of the at least one cyclonic separation stage. 
     In some embodiments, the wheeled base may have a length greater than its width. In further embodiments, the wheeled base may be generally polygonal, and preferably generally triangular in shape. Such embodiments may be advantageous because the surface cleaning apparatus may have both increased maneuverability and increased stability. 
     In some embodiments, the wheeled base may have at least one front wheel and at least two rear wheels, the rear wheels may have a larger diameter then the at least one front wheel and the at least one front wheel may be steerable. Such embodiments may be advantageous because the larger rear wheels may provide the wheeled base with increased stability, and the steerable front wheel may provide the wheeled base with increased maneuverability. Alternately, the front wheels may have a larger diameter or essentially the same diameter as the rear wheels. 
     In some embodiments, the wheeled base may have at least one front wheel and at least two rear wheels and the rear wheels may have a larger diameter then the at least one front wheel. 
     In some embodiments, the wheeled base may have at least one front wheel and at least two rear wheels and the rear wheels may have a smaller diameter then the at least one front wheel. 
     In some embodiments, the at least one front wheel may be steerable. 
     In some embodiments, the wheeled base may have rear wheels that are positioned outwardly of an area occupied by the cleaning unit when the cleaning unit is mounted on the wheeled base. Alternately, or in addition, the wheeled base may have front wheels that are positioned outwardly of an area occupied by the cleaning unit when the cleaning unit is mounted on the wheeled base. Such embodiments may be advantageous because the wheeled base may have a relatively wide stance, thereby providing greater stability to the surface cleaning apparatus. Additionally, the surface cleaning apparatus may be relatively close to the ground, and may therefore have a lower center of mass and increased stability. 
     In some embodiments, the cleaning unit may have a front end having a fluid inlet downstream from the dirty fluid inlet and the front end of the cleaning unit is positioned at a front end of the wheeled base. 
     In some embodiments, the cleaning unit may be lockably receivable on the wheeled base. 
     In some embodiments, the wheeled base may have at least one front wheel having a diameter of 1 to 3 inches and at least two rear wheels having a diameter of 1 to 3 inches. 
     In some embodiments, the cleaning unit may have a carry handle and/or a shoulder strap. 
     In some embodiments, the wheeled base may have at least one front wheel and at least two rear wheels, and the cleaning unit is receivable on an open platform. 
     In some embodiments, the wheeled base may have an absence of operating components. 
     It will be appreciated by a person skilled in the art that a surface cleaning apparatus may embody any one or more of the features contained herein and that the features may be used in any particular combination or sub-combination. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings included herewith are for illustrating various examples of articles, methods, and apparatuses of the teaching of the present specification and are not intended to limit the scope of what is taught in any way. 
       In the drawings: 
         FIG. 1  is a perspective view of an embodiment of a surface cleaning apparatus of the present invention; 
         FIG. 2  is a front view of the embodiment of  FIG. 1 ; 
         FIG. 3  is a side view of the embodiment of  FIG. 1 ; 
         FIG. 4  is a top view of the embodiment of  FIG. 1 ; 
         FIG. 5  is a perspective view of the embodiment of  FIG. 1 , showing a surface cleaning unit removed from a wheeled base; 
         FIG. 6  is a side view of the embodiment of  FIG. 1 , showing a surface cleaning unit removed from a wheeled base; 
         FIGS. 7-9  are cross-sections taken along line  7 - 7  in  FIG. 1 , showing alternate configurations of a cleaning unit; 
         FIG. 10 a    is a perspective illustration of an alternate embodiment of a surface cleaning apparatus of the present invention, showing a lid in an open position; 
         FIG. 10 b    is a perspective illustration of the surface cleaning apparatus of  FIG. 10 a   , showing the lid in the open position with a filter assembly and cylindrical housing removed; 
         FIG. 11  is a perspective view of another embodiment of a surface cleaning apparatus; 
         FIG. 12  is another perspective view of the surface cleaning apparatus of  FIG. 11 ; 
         FIG. 13  is a perspective view of the surface cleaning apparatus of  FIG. 11  with a surface cleaning unit detached; 
         FIG. 14  is another perspective view of the surface cleaning apparatus of  FIG. 11  with a surface cleaning unit detached; 
         FIG. 15  is a schematic representation of another embodiment of a surface cleaning apparatus; 
         FIG. 16  is a schematic representation of the surface cleaning apparatus of  FIG. 15  with a surface cleaning unit detached; 
         FIG. 17  is a schematic representation of another embodiment of a surface cleaning apparatus; 
         FIG. 18  is a perspective view of another embodiment of a surface cleaning apparatus; 
         FIG. 19  is another perspective view of the surface cleaning apparatus of  FIG. 18  with a cyclone bin assembly removed; 
         FIG. 20  is a perspective view of the surface cleaning apparatus of  FIG. 18  with a surface cleaning unit detached and a cyclone bin assembly removed from the surface cleaning unit; and, 
         FIG. 21  is a bottom perspective view of the cyclone bin assembly of the surface cleaning apparatus of  FIG. 18  in the open position. 
     
    
    
     DESCRIPTION OF VARIOUS EMBODIMENTS 
     Various apparatuses or processes will be described below to provide an example of an embodiment of each claimed invention. No embodiment described below limits any claimed invention and any claimed invention may cover processes or apparatuses that differ from those described below. The claimed inventions are not limited to apparatuses or processes having all of the features of any one apparatus or process described below or to features common to multiple or all of the apparatuses described below. It is possible that an apparatus or process described below is not an embodiment of any claimed invention. Any invention disclosed in an apparatus or process described below that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicants, inventors or owners do not intend to abandon, disclaim or dedicate to the public any such invention by its disclosure in this document. 
     Portable Cleaning Unit Construction 
     The following is a description of portable cleaning unit constructions that may be used by itself in any surface cleaning apparatus or in any combination or sub-combination with any other feature or features disclosed herein. 
     Referring to  FIGS. 1-4 , an embodiment of a surface cleaning apparatus  10  of the present invention is shown. Surface cleaning apparatus  10  may be a canister type vacuum cleaner, a Shop-Vac™ type vacuum cleaner, or another type of vacuum cleaner that may be mounted to a wheeled base. Surface cleaning apparatus  10  comprises a dirty fluid inlet  12 , a clean air outlet  14 , and a fluid flow path extending therebetween. A portable cleaning unit  16  is provided in the fluid flow path. Cleaning unit  16  comprises at least one cyclonic separation stage  18  for removing dirt from air, or for removing liquid from air or to pick up liquid. Cleaning unit  16  further comprises a suction motor  20  for drawing fluid from the dirty fluid inlet  12  to the clean air outlet  14 . 
     Dirty fluid inlet  12  is provided in a member  34 . In the embodiment shown in  FIGS. 1-6 , member  34  is a hose. In the embodiment shown in  FIGS. 7-10 , member  34  is a nozzle. In other embodiment, member  34  may be, for example, a surface cleaning head. It will be appreciated that a flexible hose, a rigid wand or other attachment may be affixed or removably affixed to portable cleaning unit  16 . 
     Referring to the exemplified embodiments of  FIGS. 7-9 , from dirty fluid inlet  12 , fluid is directed to cleaning unit  16 . Cleaning unit  16  may be of a variety of configurations. In the embodiment of  FIGS. 7 and 8 , cleaning unit  16  comprises a single cyclonic cleaning stage  18  preferably comprising a single cyclone housed in a first housing  44 , and a filter assembly  38  and motor  20  housed in a second housing  46  adjacent the first housing. Accordingly, in this embodiment, the suction motor  20  is positioned laterally adjacent and laterally spaced from the cyclonic cleaning stage  18 . In the embodiment of  FIG. 9 , cleaning unit  16  comprises first  18  and second  48  cleaning stages housed in first housing  44 , and filter assembly  38  and motor  20  housed in second housing  46  laterally adjacent the first housing. In this embodiment, motor  20  is positioned laterally spaced from and laterally adjacent both of first  18  and second  48  cleaning stages. It will be appreciated that portable cleaning unit may utilize one or more cyclonic cleaning stages, each of which may comprise a single cyclone or a plurality of cyclones in parallel. In any embodiment, one or more additional cleaning stages may be used such as one or more filters. 
     For example, in the embodiments exemplified, cyclonic cleaning stage  18  includes a single cyclone chamber  22 . Cyclone chamber  22  comprises a dirty air inlet  24 , a separated or dirty material outlet  26 , and a clean air outlet  28 . A dirty or separated material collection chamber  30  is mounted below dirty material outlet  26 , for collecting material removed from the air in cyclone chamber  22 . In the embodiment shown, a divider plate  32  is associated with dirty material outlet  26 . Divider plate  32  is positioned below the dirty material outlet  26 , within the material collection chamber  30 . It will be appreciated that a divider plate may be used any one or more of the cyclones and it may be of any configuration and located at any position known in the art. Alternately, a divider plate may not be used and the cyclone chambers may be of any design. 
     Material collection chamber  30  may be of any configuration and may be emptied by a user in any manner known in the art. In the embodiment shown in  FIGS. 7 and 8 , material collection chamber  30  has a bottom  31  that is openable by pivoting about a pivot pin  33 . In this embodiment, material collection chamber further comprises a latch  35 , for locking bottom  31  in place, and a button  37  for releasing the latch. In other embodiments, material collection chamber  30  may be emptied in another manner. For example, material collection chamber  30  may be movable or removable from surface cleaning apparatus  10 , such that it may be emptied, or may have another portion that opens. It may be removable from portable cleaning unit with the associated cyclone or cyclones as a sealed unit. See for example the embodiments of  FIGS. 14 and 19 . 
     In some embodiments, a filter or a screen may be associated with clean air outlet  28 . For example, as shown in  FIG. 8 , a cylindrical housing  53  may be mounted on clean air outlet  28  and may have a plurality of openings  55  which are provided with a screen (e.g. a wire mesh). Cylindrical housing  53  may be slidably mounted in outlet  28  such that when lid  45  is open, as shown in  FIG. 10 a   , cylindrical housing  53  may be pulled upwardly for removal and cleaning (see  FIG. 10 b   ). Any such screen or filter known in the art may be used. 
     In the embodiment of  FIGS. 7 and 8 , air is directed from cyclone chamber  22  out of clean air outlet  28 , and into an airflow passage  36 , which extends between first housing  44  and second housing  46 . From airflow passage  36 , air is directed through a filter assembly  38 , which, in the embodiments exemplified, comprises a pre-motor foam filter  40 , and a screen filter  42 . In some examples, as shown in  FIG. 10 b   , filter assembly  38  may also include a removable filter housing  57  that can be removably mounted in second housing  46 . The filters  40  and  42  can be removably mounted in filter housing  57 . From filter assembly  38 , air is drawn past motor  20 , and out of clean air outlet  14 . 
     In the exemplified embodiment of  FIG. 9 , from cyclone chamber  22 , air is directed out of clean air outlet  28  and into second cyclonic cleaning stage  48 . Second cyclonic cleaning stage  48  comprises a plurality of second stage cyclones  50  in parallel. Each second stage cyclone comprises an inlet (not shown) in fluid communication with clean air outlet  28 , and an outlet  52  in fluid communication with airflow passage  36 . Each second stage cyclone comprises a cyclonic cleaning region  54 , and a dirt collection region  56 . From outlets  28 , air is directed into airflow passage  36 , and into filter assembly  38 . From filter assembly  38 , air is drawn past motor  20 , and out of clean air outlet  14 . 
     In other embodiments, cleaning unit  16  may be otherwise configured. For example, cleaning unit  16  may not comprise a filter assembly, or may comprise a plurality of filter assemblies. Additionally, cleaning unit  16  may comprise additional cleaning stages, which may be positioned laterally adjacent each other or above each other. 
     In the embodiments shown, the first  44  and second  46  housings are integrally molded. In other embodiments, the first  44  and second  46  housings may be separately manufactured and then secured together, such as by a common base or by gluing, welding or mechanically securing the two housings together. In some embodiments, first  44  and/or second  46  housing may be provided with an openable lid  45 , as shown in  FIG. 10 . When a user opens lid  45 , the user may have access to components housed in first  44  and/or second housing  46 . For example, as shown in  FIG. 10 , lid  45  may be provided with a plurality of flanges  47 , which are mounted on flanges  49  provided on housings  44  and/or  46 . Flanges  47  are pivotally connected together by pivot pins  51 . Accordingly, lid  45  may be pivoted from the closed position, as shown in  FIGS. 1-9 , to the opened position, as shown in  FIG. 10 . 
     Referring to  FIG. 11 , another embodiment of a surface cleaning apparatus  110  is shown. Surface cleaning apparatus  110  is generally similar to surface cleaning apparatus  10 , and analogous features are identified using like reference characters indexed by  100 . 
     Surface cleaning apparatus  110  comprises a dirty fluid inlet  112 , a clean air outlet  114 , and a fluid flow path extending therebetween. A portable cleaning unit  116  is provided in the fluid flow path. Cleaning unit  116  comprises at least one cyclonic separation stage  118  for removing dirt from air, or for removing liquid from air or to pick up liquid. Cleaning unit  116  further comprises a suction motor  120  for drawing fluid from the dirty fluid inlet  112  to the clean air outlet  114 . Dirty fluid inlet  112  is provided in a member  134 , which in this embodiment is a surface cleaning head. 
     In this embodiment the cleaning unit  116  is mounted to a wheeled base  158 . Wheeled base  158  comprises a plurality of wheels  160 , and a cradle  162 , which receives cleaning unit  116 . The portable cleaning unit  116  can be operated while seated in the cradle  162  ( FIGS. 11 and 12 ) and can be lifted out of the cradle  162  and used as a hand carriable apparatus ( FIG. 13 ). 
     Referring to  FIG. 14 , in this embodiment the cyclone cleaning stage  118  includes a cyclone chamber  122 . Cyclone chamber  122  comprises a dirty air inlet  124 , a separated or dirty material outlet  126 , and a clean air outlet  128  ( FIG. 14 ). A dirty or separated material collection chamber  130  is beside the cyclone chamber  122  and in communication with the dirty material outlet  126 , for collecting material removed from the air in cyclone chamber  122 . 
     Material collection chamber  130  may be of any configuration and may be emptied by a user in any manner known in the art. In the embodiment shown in  FIG. 14 , material collection chamber  130  has a bottom  131  that is openable by pivoting about a pivot pin  133 . In this embodiment, material collection chamber further comprises a latch  135 , for locking bottom  131  in place, and a button  137  for releasing the latch. In this embodiment the material collection chamber  130  may be movable or removable from surface cleaning apparatus  110  and from the portable cleaning unit  116 , such that it may be emptied, and is removable from portable cleaning unit  116  with the associated cyclone  118  or cyclones as a sealed unit. 
     Referring to  FIGS. 18-21 , another embodiment of a surface cleaning apparatus  510  is shown. Apparatus  510  is generally similar to surface cleaning apparatus  10 , and analogous features are identified using like reference characters indexed by  500 . 
     Referring to  FIG. 18 , surface cleaning apparatus  510  comprises a dirty fluid inlet  512 , a clean air outlet  514 , and a fluid flow path extending therebetween. A portable cleaning unit  516  is provided in the fluid flow path. Cleaning unit  516  comprises at least one cyclonic separation stage  518  ( FIG. 21 ) for removing dirt from air, or for removing liquid from air or to pick up liquid. Cleaning unit  516  further comprises a suction motor  520  ( FIG. 20 ) for drawing fluid from the dirty fluid inlet  512  to the clean air outlet  514 . Dirty fluid inlet  512  is provided in a member  534 , which in this embodiment is a surface cleaning head. 
     In this embodiment the cleaning unit  516  is mounted to a wheeled base  558 . Wheeled base  558  comprises a plurality of wheels  560 , and a cradle  562  ( FIG. 20 ), which receives cleaning unit  516 . The portable cleaning unit  516  can be operated while seated in the cradle  562  ( FIG. 18 ) and can be lifted out of the cradle  562  and used as a hand carriable apparatus ( FIG. 20 ). 
     Referring to  FIG. 21 , in this embodiment the cyclone cleaning stage  518  includes a cyclone chamber  522 . Cyclone chamber  522  comprises a dirty air inlet  524  ( FIG. 19 ), a separated or dirty material outlet  526 , and a clean air outlet  528 . A dirty or separated material collection chamber  530  is beside the cyclone chamber  522  and in communication with the dirty material outlet  526 , for collecting material removed from the air in cyclone chamber  522 . 
     Material collection chamber  530  may be of any configuration and may be emptied by a user in any manner known in the art. In the embodiment shown in  FIG. 21 , material collection chamber  530  has a bottom  531  that is openable by pivoting about a pivot pin  533 . In this embodiment, material collection chamber further comprises a latch  535 , for locking bottom  531  in place, and a button  537  for releasing the latch. 
     Wheeled Base Construction 
     The following is a description of a wheeled base construction that may be used by itself in any surface cleaning apparatus or in any combination or sub-combination with any other feature or features disclosed herein. 
     Referring again to  FIGS. 1-4 , portable cleaning unit  16  is mounted to a wheeled base  58 . Wheeled base  58  comprises a plurality of wheels  60 , and a cradle  62 , which receives cleaning unit  16 . 
     In some embodiments, cleaning unit  16  may be permanently mounted to wheeled base  58 , for example via one or more bolts. In other embodiments, cleaning unit  16  may be removably mounted to wheeled base  58 . For example, a user may remove cleaning unit  16  from wheeled base in order to maneuver cleaning unit  16 , or to empty material collection chamber  30 . In such embodiments, cleaning unit  16  is portable. For example, as shown in  FIGS. 5 and 6 , cleaning unit  16  may be removed from wheeled base  58  by lifting cleaning unit  16  off of wheeled base  58 . 
     In any embodiment, surface cleaning apparatus  10  may comprise a handle  64 , and/or a shoulder strap  65  (shown in  FIG. 8 ) for maneuvering cleaning unit  16  when it is removed from wheeled base  58 . In some embodiments, handle  64  may be integrally formed with one or both of first  44  and second  46  housings. 
     Surface cleaning apparatus  10  may further comprise a locking member (not shown), such that cleaning unit  16  may be lockably received on wheeled base  58 . The locking member may comprise any suitable locking member known in the art, such as, for example, a quick release latch, a friction or snap fit, a set screw, a tie down strap (e.g., a strap which may be wrapped around cleaning unit  16 ) or the like. The lock may be actuatable by a foot pedal. Alternately wheeled base  58  may have side wall extending up around cradle  62  within which portable cleaning unit  16  is received. It will be appreciated that cradle  64  may be any member on which portable cleaning unit  16  may be received or secured, such as a flat base with or without side walls. 
     In the embodiments exemplified, wheeled base  58  comprises a front wheel  66 , and two rear wheels  68   a ,  68   b . Accordingly, cradle  62  is a platform that is generally polygonal and, preferably, generally triangular in configuration. This configuration may provide increased maneuverability to surface cleaning apparatus  10 . In other embodiments, wheeled base  58  may comprise another number of wheels. For example, in some embodiments, wheeled base  58  may comprise two front wheels and two rear wheels. It will be appreciated that, as exemplified, housings  44 ,  46  may be oriented on cradle  62  with the suction motor at the rearward end of portable cleaning unit  16  and the inlet to portable cleaning unit  16  at the forward end of the front housing. In alternate configurations, housings  44 ,  46  may be positioned side by side. Further, if more than two housings  44 ,  46  are provided, then the housings may be arranged linearly, in a triangular configuration or any other desired configuration. 
     In some embodiments, front wheel  66  is rotatably mounted about a vertical axis to cradle  62  (e.g., is a caster wheel), and rear wheels are non-rotatably mounted about a vertical axis. Accordingly, front wheel  66  may be steerable. In other embodiments, all of front wheel  66  and rear wheels  68  may be caster wheels, or may be non-rotatably mounted wheels. 
     In some embodiments, wheeled base  58  has a length greater than its width. That is, the distance L between front wheel  66  and axis  67  extending between rear wheels  68   a ,  68   b , is greater than the distance W between rear wheels  68   a ,  68   b , along axis  67 . In other embodiments, wheeled base  58  may have a width W greater than its length L, or may have width W equal to its length L. 
     In the embodiments shown, front wheel  66  is of a smaller diameter than rear wheels  68   a ,  68   b . Alternately, rear wheels  68   a ,  68   b  may be smaller than front wheel  66 . Preferably, both the front and rear wheels are each relatively large. For example, in some embodiments, front wheel(s) may have a diameter of between about 0.5-4 inches, preferably 1-3 inches and more preferably 1.5-2.5 inches. In some embodiments, rear wheels may have a diameter of between about 0.5-4 inches, preferably 1-3 inches and more preferably 1.5-2.5 inches. In one particular embodiment, both front wheel(s)  66  and rear wheels  68   a ,  68   b  have a diameter in the same range. Such embodiments may be advantageous to provide surface cleaning apparatus  10  with increased maneuverability and with increased stability. 
     In the embodiments shown, wheeled base  58  is configured such that, when cleaning unit  16  is mounted on cradle  62 , rear wheels  58  are positioned outwardly of cleaning unit  16 . That is, rear wheels  58  are separated by a distance W that is greater than the width W′ of cleaning unit  16 . Such embodiments may provide surface cleaning apparatus  10  with a wider stance, and accordingly with increased stability. Additionally, because rear wheels  68  are positioned outwardly of cleaning unit  16 , rear wheels  68  may be provided with an increased diameter, as previously mentioned, without increasing the distance between cleaning unit  16  and a surface such as a floor. Accordingly, the center of mass of cleaning unit  16  may remain low, which further increases the stability of surface cleaning apparatus  10 . 
     In some embodiments, wheeled base  58  may comprise operating components of surface cleaning apparatus  10 , such as a suction motor (see  FIG. 17 ). For example, wheeled base may comprise a portion that is provided in the fluid flow path, and includes a filter assembly (not shown). In other embodiments, as exemplified, wheeled base  58  may not comprise any operating components (i.e. wheeled base has an absence of operating components). 
     In the embodiments shown, cleaning unit  16  is oriented such that dirty fluid inlet  12  is provided at a front end  70  of surface cleaning apparatus  10 , adjacent front wheel  66 , and suction motor  20  is provided at a rear end  72  of surface cleaning apparatus  10 , adjacent rear wheels  68 . In other embodiments, cleaning unit  16  may be otherwise oriented. For example, suction motor  20  may be provided at front end  70 , and dirty fluid inlet  12  may be provided at rear end  72 . Alternatively, cleaning unit  16  may be oriented such that suction motor  20  and dirty fluid inlet  12  are equally spaced from front wheel  66  and rear wheels  68 . That is, cleaning unit  16  may be positioned substantially sideways in wheeled base  58 . 
     In some embodiments, portable cleaning unit  16  may be connected to a remote surface cleaning head by connected in air flow communication with the wheeled base, wherein the remote surface cleaning head may be connected or removably connected in air flow communication with the wheeled base. Accordingly, when portable cleaning unit  16  is placed on the wheeled base, it may be automatically connected in air flow communication with the wheeled base (see for example  FIGS. 15, 17 and 19 ) or the user may have to connect portable cleaning unit  16  in air flow communication with the wheeled base, such as by connecting a hose of portable cleaning unit  16  in air flow communication with an air outlet of the wheeled base (see for example  FIGS. 5 and 6 ). 
     As exemplified in  FIGS. 5 and 6 , wheeled base  62  may comprise a floor cleaning mount  82  coupled to cradle  62 . A first end  84  of mount  82  is configured for receiving member  34 , which, in the embodiments exemplified in  FIGS. 1-6 , is a hose. A second end  86  of mount  82  is configured for receiving another member, for example a remote surface cleaning head that is preferably at the distal end of a wand and a flexible hose extends between the wand and mount  82  (not shown). It will be appreciated that portable cleaning unit  16  may be designed such that the inlet of the portable cleaning unit automatically is connected in flow communication with mount  82  when portable cleaning unit  16  is positioned on wheeled base  58 , such as by use of an inlet port aligned with first end  84  or a rigid pipe that is fittable thereon. Alternately, as exemplified, a flexible hose  34  that is manually insertable may be used. An advantage of this design is that the attachment member for a wand or the like is provided on the platform and not the portable cleaning unit. Therefore, the wand may be used to pull wheeled base  58  without risk of pulling portable cleaning unit  16  off of wheeled base  58 . Further, preferably the attachment point is close to the floor, preferably at the level of cradle  62 , thereby lowering the point at which wheeled base  58  may be pulled and increasing the stability of wheeled base  58  when it is being pulled. 
     It will be appreciated that in the portable mode, a wand or flexible hose and wand, or other member known in the art may be attached to hose  34  or hose  34  may be removed and the wand or flexible hose and wand, or other member known in the art may be attached directly to the inlet to housing  44 . 
     In some embodiments, one or more accessories, such as cleaning brush  74  and wand extension  76  may be secured to the upper surface of lid  45 , such as by means of mounts  78 . Accordingly, extension  76  may be configured to function as a handle (e.g. central section  76  may be arcuate in shape or be spaced from lid  45 ), to define an opening  80  between the upper surface of lid  34  such that extension  76  of brush  74  may be a carry handle  64  for the vacuum cleaner. Alternately, extension  76  may be configured to seat on handle  64  and permit handle  64  to be used when brush  74  is mounted on portable cleaning unit  16 . In other embodiments, one or more accessories may be provided in a recess in the lower surface of portable cleaning unit  16  or in an upper surface of wheeled base  58 . 
     Removable Dirt Chamber 
     The following is a description of a portable cleaning unit having a removable dirt chamber that may be used by itself in any surface cleaning apparatus or in any combination or sub-combination with any other feature or features disclosed herein. 
     As exemplified in  FIG. 14 , the cyclone chamber  118  and material collection chamber  130  may be constructed as a one piece assembly and are referred to collectively as a cyclone bin assembly  188 . In accordance with this aspect, cyclone bin assembly  188  may be removed from the portable surface cleaning unit  116  when the portable surface cleaning unit  116  is seated on the base  158  ( FIGS. 14 and 19 ) and when the portable surface cleaning unit  116  is separated from the base  158  ( FIG. 13 ). This may allow a user to remove only the cyclone bin assembly  188 , for example for emptying, regardless of whether the surface cleaning unit  116  is docked on the base  158 . 
     As exemplified in  FIGS. 18-21 , the material collection chamber  530  may be movable or removable from surface cleaning apparatus  510  and from the portable cleaning unit  516 , such that it may be emptied, and is removable from portable cleaning unit  516  with the associated cyclone  518  or cyclones as a sealed unit. 
     In the illustrated embodiment, the cyclone chamber  518  and material collection chamber  530 , referred to collectively as a cyclone bin assembly  588 , can be removed from the portable surface cleaning unit  516  when the portable surface cleaning unit  516  is seated on the base  558  ( FIG. 19 ) and when the portable surface cleaning unit  516  is separated from the base  558  ( FIG. 20 ). This may allow a user to remove only the cyclone bin assembly  588 , for example for emptying, regardless of whether the surface cleaning unit  516  is docked on the base  558 . 
     Referring to  FIG. 18 , in the illustrated embodiment, when the surface cleaning unit  516  is mounted on the base  558  the air flow path between the surface cleaning head  534  and the suction motor in the surface cleaning unit  516  includes a rigid conduit  589 , a flexible hose  590   a.    
     In this embodiment, the first hose  190   a  is connected to the surface cleaning unit  516  and extends between a downstream end  592   a  (with reference to the direction of airflow through the hose  590   a ) that is connected to the surface cleaning unit  516  and the rigid conduit  589 . In this configuration, when the surface cleaning unit  516  is removed from the base  558  the hose  590   a  comes with the surface cleaning unit  516  ( FIG. 20 ). 
     It will be appreciated that, in alternate embodiments, material collection chamber  130  may be a separate unit and may be removable without the cyclone chamber. Alternately, or in addition, material collection chamber  130  may be removed with the handle of the portable cleaning unit. An advantage of this design is that the handle of the portable cleaning unit may be useable to manipulate the material collection chamber  130  or cyclone bin assembly when removed for emptying. 
     Automatic Portable Cleaning Unit Hose Connection 
     The following is a description of automatically connecting a hose of the portable cleaning unit in air flow communication with the base when the portable cleaning unit is placed on the base that may be used by itself in any surface cleaning apparatus or in any combination or sub-combination with any other feature or features disclosed herein. 
     Referring to  FIG. 12 , in the illustrated embodiment, when the surface cleaning unit  116  is mounted on the base  158 , the air flow path between the remote surface cleaning head  134  and the suction motor in the surface cleaning unit  116  includes a rigid conduit or wand  189 , a first flexible hose  190   a  and a second flexible hose  190   b  (see also  FIG. 14 ) positioned downstream from the first hose  190   a.    
     The first hose  190   a  extends from its upstream that is connected to rigid conduit  189  to its downstream end  192   a  (with reference to the direction of airflow through the hose  190   a ) that is connected to the base  158 . The first hose  190   a  has a diameter  191   a . While the first hose  190   a  may be removably connectable to the base  158 , first hose  109   a  remains attached to the base  158  regardless of the position of the surface cleaning unit  116  ( FIGS. 12 and 14 ). 
     Referring to  FIG. 13 , the second hose  190   b  is attached to and is removable with the surface cleaning unit  116 . A downstream end  192   b  of the hose  190   b  is attached to the air inlet  124  of the cyclone chamber  118  and the upstream end  193   b  is removably connectable in air flow communication with the air outlet of the base  158  (e.g., opening  195  of coupling  194 ). When the surface cleaning unit  116  is removed from the base  158 , the upstream or inlet end  193   b  of the hose  190   b  can be used as a second or auxiliary dirty air inlet for drawing fluid and debris into the air flow path. Optionally, auxiliary cleaning tools may be attached to the inlet end  193   b  of the hose  190   b . In this configuration, the first hose  190   a  does not form part of the airflow path to the surface cleaning unit  116 . 
     The second hose  190   b  is shown in a wrapped or storage position in  FIG. 13  in which it is wrapped around part of the surface cleaning unit  116 . When the surface cleaning unit  116  is in use as a portable cleaning unit the second hose  190   b  can be unwound and extended. Preferably, the second hose  190   b  is extensible to increase its cleaning range. The second hose  190   b  has a diameter  191   b , which optionally may be smaller than diameter  191   a . This may help reduce the overall size of the surface cleaning unit  116  and may help it nest on the base  158 . However, it is preferred that they have the same or similar diameters so as to provide an air flow path that has a generally constant diameter. The hoses  190   a  and  190   b  may be generally similar. Alternatively, they may have different properties. For example, the first hose  190   a  may be non-extensible and relatively stiff (to allow a user to pull the hose  190   a  to advance the base  158  across the surface) and the second hose  190   b  may be extensible and less stiff. 
     Referring to  FIG. 12 , when the surface cleaning unit  116  is seated on the base  158 , the inlet end  193   b  of the second hose  190   b  is connected in air flow communication with the downstream end  192   a  of the first hose  190   a , using coupling  194 , thereby re-establishing air flow communication between the cleaning head  134  and the surface cleaning unit  116 . 
     Referring to  FIG. 13 , the coupling  194  may be any suitable connector, and in the example illustrated, is an elbow-type connector with a downstream opening  195  surrounded by a sealing face  196 . The surface cleaning unit  116  may be configured such that the upstream end  193   b  of the second hose  190   b  is aligned with the opening  195  and seals against seal face  196  to establish the air flow path when the surface cleaning unit  116  is placed on base  158 . Accordingly, sealing face  196  is sealed by the inlet end  193   b  automatically when the surface cleaning unit  116  is inserted vertically onto the base  158 . 
     In order to provide a seal, one or both of base  158  and surface cleaning unit  116  may be configured to provide sufficient abutment therebetween so that an air tight seal is created. As exemplified in  FIG. 13 , the rear face of coupling  194  is angled and a mating angled surface may be provided on portable cleaning unit  116 . Accordingly, when portable cleaning unit is placed on base  158 , portable cleaning unit is urged rearwardly and the rear end of portable cleaning unit  116  may abut the rear wall of base  158  thereby pressing the upstream end  193   b  of the second hose  190   b  against the opening  195  and optionally compressing a gasket or the like to create an air tight seal. 
     If the cyclone bin assembly is removable, then the remaining body of portable cleaning unit  116  may also or alternately be angled to press the cyclone inlet  524  against opening  195  (see for example  FIG. 19 ). 
     Valve to Switch Between Hoses 
     The following is a description of alternate air flow paths that may be used by itself in any surface cleaning apparatus or in any combination or sub-combination with any other feature or features disclosed herein. 
     In accordance with this aspect, the portable cleaning unit may incorporate a hose which is different to first hose  190   a . For example, it may have a smaller diameter. Accordingly, it may be preferred not to use such a hose in the air flow path when portable cleaning unit  116  is mounted on the base since the smaller diameter hose would reduce air flow and increase the back pressure. However, the smaller diameter hose may be lighter and easier to use in a portable mode (i.e., when surface cleaning unit  116  is removed from base  158 ). In such a case, a valve may be provided to selective connect the cyclone air inlet with the different hoses or air flow paths. The valve may be manually operable or automatically operable. For example, the valve may be actuated automatically when the surface cleaning unit  116  is removed from the base or when the smaller diameter hose is deployed from a storage position for use. 
     Accordingly, if second hose  190   b  has a smaller diameter into the air flow path when the surface cleaning unit  116  is docked, a user may optionally detach the downstream end  192   b  of the second hose  190   a  from the air inlet  124  (thereby removing the second hose  190   b  from the air flow circuit) and can reposition the downstream end  192   a  of the hose  190   a  to be connected directly to the inlet  124 . Alternately, inlet  124  could be automatically connected in air flow communication with opening  195  when surface cleaning unit  116  is placed on base  158 . 
     Optionally, instead requiring a user to reconfigure a hose, the surface cleaning apparatus may include a valve positioned in the air flow path that allows the air flow to be switched between the first and second hoses. In this configuration, both hoses can remain attached to their respective components, and the air flow path to the surface cleaning unit  116  can include either of the first and second hoses. Optionally, one of the hoses may be detachable and connectable to the other of the hoses, such that one large hose is created and forms the air flow path to the surface cleaning unit. 
     Referring to  FIGS. 15 and 16 , a schematic representation of another embodiment of a surface cleaning apparatus  210  is illustrated. Surface cleaning apparatus  210  is generally similar to apparatus  10 , and analogous features are identified using like reference characters indexed by  200 . 
     In this embodiment, the surface cleaning unit  216  includes a valve  297  provided in the air flow path, upstream from the air inlet of the cyclone chamber  218 . The valve is connected to the downstream end  292   b  of the second hose  290   b , and the valve  297  and second hose  290   b  are removable with the surface cleaning unit  216  ( FIG. 16 ). When the surface cleaning unit  216  is seated on base  258 , the valve can connect to coupling  294  automatically or manually. An actuating lever  298  allows a user to change to position of the valve  297  so that, when the surface cleaning unit  216  is docked, the first hose  290   a  is connected in air flow communication with the surface cleaning unit  216  and the second hose  290   b  is sealed (but remains attached and does not require re-configuration). Optionally, the valve  297  can be automatically actuated when the surface cleaning unit  216  is placed on or removed from the base  258  to adjust the air flow path accordingly. 
     Use of Dual Suction Motors 
     The following is a description of the use of dual suction motors that may be used by itself in any surface cleaning apparatus or in any combination or sub-combination with any other feature or features disclosed herein. 
     Optionally, the base of the surface cleaning apparatus may include some operating components of the surface cleaning apparatus, including, for example a suction motor, the power cord and a cord reel. Providing components in the base may help reduce the weight and/or overall size of the portable surface cleaning unit. 
     Referring to  FIG. 17 , a schematic representation of another embodiment of a surface cleaning apparatus  310  is shown. The surface cleaning apparatus  310  is generally similar to surface cleaning apparatus  10 , and analogous features are identified using like reference characters indexed by  300 . 
     In the illustrated embodiment, the surface cleaning apparatus  310  includes a base  358  and a surface cleaning unit  316  that can be mounted on the base  358  (as illustrated), and can be detached to be used separately from the base  358 . 
     The surface cleaning unit  316  includes a cyclone bin assembly  388  that has a cyclone chamber  318  and a dirt collection chamber  330 . The cyclone chamber  318  has an air inlet  324  and an air outlet  328 . A dirt outlet in the form of a slot  326  provides communication between the cyclone chamber  318  and the dirt collection chamber  330 . 
     A first suction motor  320   a  is provided in the surface cleaning unit  316 . An air flow conduit  400  provides an air flow path between the air outlet of the pre-motor filter housing and the suction motor  320   a . Accordingly, a pre-motor filter  338  is provided in the air flow path between the air outlet  328  of the cyclone chamber  318  and the motor  320   a.    
     In the illustrated embodiment the electrical cord  401  is wound around a cord reel  402  that is provided in the base  358 . In addition, a second suction motor  320   b  is provided in the base  358  and is in electrical communication with the power cord  401  such that the second suction motor  358  can be powered by an external power supply (e.g. a wall socket). A base conduit  403  provides air flow communication between the second suction motor  320   b  and a port  404  on the upper surface of the base  358 . 
     When the surface cleaning unit  316  is mounted on the base  358 , a mating port  406  on the surface cleaning unit  316  may connect to and seal the port  404 . Preferably, a valve  407  (e.g. any suitable valve such as a two position valve and a ball valve) is provided, e.g., in the air flow path between the filter  338  and the motor  320   a . The valve  407  is also in air flow communication with the port  406 , and is operable to selectively connect either port  406  or conduit  400  in airflow communication with the cyclone bin assembly  388 . When conduit  400  is connected, suction motor  320   a  may be used draw air through the surface cleaning unit  316  (and preferably motor  320   b  is not). When port  406  is connected, suction motor  320   b  may be used to draw air through the surface cleaning unit  316  (and preferably motor  320   a  is not). Preferably, the valve  407  is configured (for example via a biasing member or linkage member) so that when the surface cleaning unit  316  is lifted off the base  358  the valve  407  automatically seals port  406  and connects conduit  400 . 
     It will be appreciated that valve may be actuatable by other means, such as a member that is drivingly connected to the valve and the member is operable as the surface cleaning unit is paced and or removed from base  358 . It will be appreciated that motor  320   b  may be connected in air flow communication at an alternate location. For example, it could be downstream of motor  320   a . Alternately, it could be a dirty air motor and located upstream of cyclone chamber  318 . 
     Because the electrical cord  401  is provided in the base  358 , when the surface cleaning unit  316  is detached from the base  358 , it may no longer be connected to the external power source (e.g. wall socket). To provide power to the surface cleaning unit  316  when it is detached, the surface cleaning unit  316  includes an on-board energy storage member, e.g., one or more batteries  405 . Alternatively, any other suitable energy storage member or power source can be used (fuel cell, combustion engine, solar cells, etc.). In the illustrated example, the batteries  405  provide DC power. In this configuration, when the surface cleaning unit  316  is detached from base  358 , the suction motor  320   a  may operate using DC power, and may operate solely on the power supplied by batteries  405 . 
     Optionally, when the surface cleaning unit  316  is re-attached to the base  358 , power from the base  358  can be transferred to the surface cleaning unit  316 , for example via detachable electrical connector  408 . Preferably, if an electrical connector  408  is provided the power received from the base  358  can be used to charge the batteries  405  to help ensure the batteries  405  are charged when the surface cleaning unit  316  is removed. 
     Alternatively, there need not be an electrical connection between the base  358  and the surface cleaning unit  316 . In such a configuration the batteries  405  may be charged via an alternate power source, or may be replaced with fresh batteries as needed. For example, the surface cleaning unit  116  may be provided with its own power cord, or the power cord  401  may be removable from base  358  and may be plugged into surface cleaning unit  116 . 
     Optionally, the suction motor  320   a  may be smaller and/or less powerful than the suction motor  320   b . Making the suction motor  320   a  smaller and lighter than suction motor  320   b  may help reduce the overall size and weight of the surface cleaning unit  316 . For example, the suction motor  320   b  may be a  1000  watt motor, and the suction motor  320   a  may be a  600  watt motor. Reducing the power consumption of the suction motor  320   a  may also help prolong the amount of cleaning time that can be achieved using the batteries  405 , before they need to be replaced and/or recharged. 
     In the illustrated embodiment, because suction motor  320   b  is in the base  358  with the electrical cord, it may be an AC motor that can run on AC power received from a wall socket. Motor  320   a  may be operated on DC power supplied by the batteries  405 . 
     In this configuration, a user may be able to select which suction motor  320   a  or  320   b  is to be used when the surface cleaning unit  316  is docked. For example, if performing a small job or if it is desirable to keep the noise level low a user may activate the smaller suction motor  320   a . Alternatively, if performing a large job a user may select to use the suction motor  320   b  by activating the motor  320   b  and positioning the valve  407  as appropriate. 
     Dual Operational Mode for a Portable Surface Cleaning Unit 
     The following is a description of the use of a dual operational mode for a portable surface cleaning unit that may be used by itself in any surface cleaning apparatus or in any combination or sub-combination with any other feature or features disclosed herein. 
     Alternately, or in addition to providing a motor  320   b  in the base  358 , the suction motor  320   a  in the surface cleaning unit may be operable on current supplied by an on board energy storage member (e.g., batteries  405 ) when removed from base  358  and may be operable on current supplied from base  358  when mounted thereon. 
     Accordingly, when removed from the base  358 , motor  320   a  may be operable on DC current supplied from batteries  405 . However, when mounted on the base  358  and electrical code  401  is plugged into an electrical outlet, current may be supplied from base  358  to motor  320   a . The current may be AC, in which case, motor  320   a  may be operable on both AC and DC current (e.g., it has dual windings) or the AC current may be converted to DC current (such as by providing a power supply in one or both of the base  358  and the surface cleaning unit  116 ). 
     Accordingly, for example, as shown in  FIG. 17 , an electrical connector  408  may be used to power the suction motor  320   a  when the surface cleaning apparatus is docked on the base  358 . In this configuration the suction motor  320   a  may be configured to also run on AC power or a power supply or converter module  409  may be provided to convert the incoming AC power to DC power. Optionally, the convertor module  409  may be in the base  358  so that the connector  408  is provided with DC power. 
     It will be appreciated that the suction motor of the portable cleaning unit may be operable on different power levels. It may be operable on a first or higher power level when mounted to the base and operable on power supplied from the base (which may be AC or DC). It may be operable on a lower power level when removed from the base. 
     It will be appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments or separate aspects, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment or aspect, may also be provided separately or in any suitable sub-combination. 
     What has been described above has been intended to be illustrative of the invention and non-limiting and it will be understood by persons skilled in the art that other variants and modifications may be made without departing from the scope of the invention as defined in the claims appended hereto. The scope of the claims should not be limited by the preferred embodiments and examples, but should be given the broadest interpretation consistent with the description as a whole.